draft-ietf-idr-sla-exchange-01.txt   draft-ietf-idr-sla-exchange-02.txt 
Network Working Group S. Shah Network Working Group S. Shah
Internet-Draft K. Patel Internet-Draft K. Patel
Intended status: Standards Track Cisco Systems Intended status: Standards Track Cisco Systems
Expires: December 29, 2013 S. Bajaj Expires: May 8, 2014 S. Bajaj
Juniper Networks Juniper Networks
L. Tomotaki L. Tomotaki
Verizon Verizon
M. Boucadair M. Boucadair
France Telecom France Telecom
Jun 27, 2013 Nov 04, 2013
Inter-domain SLA Exchange Inter-domain SLA Exchange
draft-ietf-idr-sla-exchange-01 draft-ietf-idr-sla-exchange-02
Abstract Abstract
Network administrators typically provision QoS (Quality of Service) Network administrators typically enforce Quality of Service (QoS)
policies for their application traffic (such as voice, video) based policies according to Service Level Agreement (SLA) with their
on SLAs (Service Level Agreements) negotiated with their providers, providers. The enforcement of such policies often relies upon
and translate those SLAs to vendor specific configuration language. vendor-specific configuration language. Both learning of SLA, either
Both learning of SLA, either thru SLA documents or via some other thru SLA documents or via some other out-of-band method, and
out-of-band method, and translating them to vendor specific translating them to vendor specific configuration language is a
configuration language is a complex, many times manual, process and complex, many times manual, process and prone to errors. This
prone to errors. This document proposes an in-band method of SLA document proposes an in-band method of SLA signaling which can help
signaling which can help to simplify some of the complexities. to simplify some of the complexities.
This document defines an operational transitive attribute to signal This document defines an optional transitive attribute to signal SLA
SLA details in-band, across administrative boundaries (considered as details in-band, across administrative boundaries (considered as
Autonomous Systems (AS)), thus simplify and speed-up some of the Autonomous Systems (AS)), thus simplifying and facilitating some of
complex provisioning tasks. the complex provisioning tasks.
Though the use case with the proposed attribute is explicitly defined Though the use case with the proposed BGP attribute is explicitly
in this document, purpose of this attribute is not limited to this defined in this document, purpose of this attribute is not limited to
use case only. this use case only.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 29, 2013. This Internet-Draft will expire on May 8, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. QoS Attribute Definition . . . . . . . . . . . . . . . . . . . 6 3. QoS Attribute Definition . . . . . . . . . . . . . . . . . . . 5
3.1. SLA, QoS attribute sub-type, Definition . . . . . . . . . 7 3.1. SLA, QoS attribute sub-type, Definition . . . . . . . . . 6
4. Originating SLA Notification . . . . . . . . . . . . . . . . . 16 4. Originating SLA Notification . . . . . . . . . . . . . . . . . 16
4.1. SLA Contexts . . . . . . . . . . . . . . . . . . . . . . . 16 4.1. SLA Contexts . . . . . . . . . . . . . . . . . . . . . . . 16
4.1.1. SLA Advertisement for Point-to-Point Connection . . . 16 4.1.1. SLA Advertisement for Point-to-Point Connection . . . 16
4.1.2. SLA Advertisement for Destination AS Multiple Hops 4.1.2. SLA Advertisement for Destination AS Multiple Hops
Away . . . . . . . . . . . . . . . . . . . . . . . . . 17 Away . . . . . . . . . . . . . . . . . . . . . . . . . 17
5. SLA Attribute Handling at Forwarding Nodes . . . . . . . . . . 17 5. SLA Attribute Handling at Forwarding Nodes . . . . . . . . . . 17
5.1. BGP Node Capable of Processing QoS Attribute . . . . . . . 17 5.1. BGP Node Capable of Processing QoS Attribute . . . . . . . 17
5.2. BGP Node not Capable of Processing QoS Attribute . . . . . 18 5.2. BGP Node not Capable of Processing QoS Attribute . . . . . 18
5.3. Aggregator . . . . . . . . . . . . . . . . . . . . . . . . 18 5.3. Aggregator . . . . . . . . . . . . . . . . . . . . . . . . 18
6. SLA Attribute Handling at Receiver . . . . . . . . . . . . . . 18 6. SLA Attribute Handling at Receiver . . . . . . . . . . . . . . 18
6.1. Traffic Class Mapping . . . . . . . . . . . . . . . . . . 19 6.1. Traffic Class Mapping . . . . . . . . . . . . . . . . . . 19
7. Deployment Considerations . . . . . . . . . . . . . . . . . . 20 7. Deployment Considerations . . . . . . . . . . . . . . . . . . 20
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 21
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
10. Security Considerations . . . . . . . . . . . . . . . . . . . 22 10. Security Considerations . . . . . . . . . . . . . . . . . . . 22
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 22
11.1. Normative References . . . . . . . . . . . . . . . . . . . 22 11.1. Normative References . . . . . . . . . . . . . . . . . . . 22
11.2. Informative References . . . . . . . . . . . . . . . . . . 23 11.2. Informative References . . . . . . . . . . . . . . . . . . 23
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
Typically there is a contractual Service Level Agreement (SLA) Typically there is a contractual Service Level Agreement (SLA)
negotiated between Customer and Provider or between one Provider to established between Customer and Provider or between providers,
another Provider [CPP]. This contractual agreement defines the possibly using one or the other form of the template [CPP]. This
nature of the various traffic classes (i.e., traffic match contractual agreement usually defines the nature of the various
conditions) and services needed for each traffic class. The contract traffic classes (i.e., traffic match conditions) and services needed
may exist at different levels of traffic granularity. The contract for each traffic class. The contract may exist at different levels
could be full line-rate or sub rate for aggregate traffic or it could of traffic granularity. The contract could be for the full line-rate
be even finer granular traffic distinction with services defined for or sub line-rate without granular traffic distinction or it could be
standard code-points or for specific set of prefix or for set of for finer granular traffic classes, with services defined. Finer
well-known application types. granular classes can be based on some standard code-points (like
DSCP) or for a specific set of prefixes or for a set of well-known
application types.
Once the SLA is negotiated, it needs to be translated into enforcing Once the SLA is established, SLA parameters are enforced in some or
configuration data and policies on the Provider's Edge (PE) as well all participating devices by deriving SLA parameters into
as on the Customer's Edge (CE). At the Customer side, a person configuration information on respective devices. SLA parameters may
administering the CE device may be a different person, or even a have to be exchanged through organizational boundaries, thru SLA
different department, from the ones negotiating SLA contracts with documents or via some other off-band method to an administrator
the Provider and thus an administrator at the CE first requires to provisioning actual devices. In a subsequent step, administrator
manually learn negotiated SLA, thru SLA documents or via some other requires to translate SLA to QoS policies using router (vendor)
off-band method. In a subsequent step an administrator requires to specific provisioning language. In a multi-vendor network,
translate SLA to QoS policies using router (vendor) specific translating SLAs into technology-specific and vendor-specific
provisioning language. In a multi-vendor environment, translating configuration requires to consider specificities of each vendor.
the SLA into technology-specific configuration and then enforcing
that configuration requires to consider specificities of each vendor.
There does not exist any standard protocol to translate SLA There does not exist any standard protocol to translate SLA
agreements into technical clauses and configurations and thus both agreements into technical clauses and configurations and thus both
the steps of out of band learning of negotiated SLA and provisioning the steps of out of band learning of negotiated SLA and provisioning
them in a vendor specific language can be complex and error-prone. them in a vendor specific language can be complex and error-prone.
As an example for voice service, the Provider may negotiate service As an example for voice service, the Provider may negotiate QoS
for such traffic thru use of EF code-point in Diffserv-enabled parameters (like min/max rates) for such traffic based upon the EF
[RFC2475] networks. Administrator at the CE side not only will have code-point in Diffserv-enabled [RFC2475] networks. Administrator at
to know that Provider's service for voice traffic is EF-based but the CE side not only will have to know that Provider's service for
will also have to implement DSCP EF classification rule along with voice traffic is EF-based, so that traffic exiting CE is marked
Low Latency Service rule as per vendor's provisioning language. properly, but will also have to know how to implement DSCP EF
classification rule along with Low Latency Service, and possibly min/
max rate enforcement for the optimal use of bandwidth, as per vendor
specific provisioning language.
Given the Provider also maintains established contracts, which very An in-band signaling method of propagating SLA parameters from
well may even be enforced at the PE, an in-band method of signaling provider, PE in an example above, to contractual devices, CE in an
it from the PE to the CE can help eliminate manual administrative example above, can help eliminate manual administrative process
process, at the CE, described above. Provider may have SLA described above. Provider may have SLA negotiated with the Customer
negotiated with the Customer via some defined off-band method (could via some defined off-band method (based on the specifics defined by
be specifics defined by Provider or could be based on some protocols the Provider or using protocols like [CPNP]. The Inter-domain SLA
like [CPNP]), orthogonal to actual SLA exchange proposal described in exchange proposal described in this document does not pre-requisite
this document. Once negotiated, the Provider may translate that SLA any specific method of establishing SLAs). The Provider provisions
in networking language on the PE (this process remains same as is established SLA on the Provider device. This SLA instance then can
done today). This SLA instance then can be signaled to the CE via be signaled to the Customer via in-band signaling protocol. In
some in-band protocol exchange. In reaction to that message, reaction to this signal, receiver router may translate that to
receiver CE router may automatically translate that to relevant QoS relevant QoS policy definition on the device.
policy definition on the box. This in-band signaling method helps
eliminate manual complex process required by administrator at the CE.
Taking same voice service as an example, a given Provider might
already provision definition of EF code-point for such traffic.
Signaling EF code-point for this traffic class along with signaling
low latency service definition, would avoid manual administration at
the CE.
For in-band signaling, we propose to use BGP as a transport. The For an in-band signaling, we propose to use BGP as a transport. The
details of SLAs are independent of BGP and are specific to the details of SLA parameters are specific to the granularity of traffic
granularity of traffic classes and their subsequent treatment. classes and their respective treatment, which is independent of the
Though we find BGP as a suitable transport for inter-domain SLA BGP protocol itself. Though we find BGP as a suitable transport for
exchange for the following reasons: inter-domain SLA exchange for the following reasons:
- The most common use case of SLA exchange is across Autonomous - The need to exchange SLA parameters between domains (Automated
Systems. And BGP is the most suitable protocol for any inter- Systems (AS)), where in use-cases described in this document,
domain exchange [RFC4271][RFC4364] BGP is a suitable protocol for inter-domain exchange [RFC4271]
- There is no other suitable protocol available today for SLA [RFC4364]
exchange - There is no specifically defined protocol available today for
SLA exchange
- BGP updates already advertise specific set of prefixes (flow - BGP updates already advertise specific set of prefixes (flow
or flow-group). Other QoS-related attributes, apart from the or flow-group). Other QoS-related attributes, apart from the
the use of SLA advertisement, can be added to these updates the use of SLA advertisement, can be added to these updates
in the future in the future
The proposal is to define a new BGP attribute to advertise/learn SLA The proposal is to define a new BGP attribute to advertise/learn SLA
details in-band. The proposed attribute is intended to advertise SLA details in-band. The proposed attribute is intended to advertise SLA
from one AS to a list of interested ASes. QoS services advertised from one AS to a list of destined ASes. The advertised QoS
could be for the incoming traffic to the AS community, that is information could be for the incoming traffic to the advertiser, that
advertising SLA or could be for the outgoing traffic from the is advertising SLA or could be for the outgoing traffic from the
advertiser or could be for both directions. Reception of and advertiser or could be for both directions. Reception of and
reaction to advertised SLAs are optional for the receiver. reaction to advertised SLAs are optional for the receiver.
The aim with the signaling of this attribute, across administrative
boundaries, is to help network administrators speed up and simplify
QoS provisioning with automatic learning of SLAs and thus avoiding
complexities and possible errors with manual learning.
We propose QoS as an optional transitive attribute, keeping SLA We propose QoS as an optional transitive attribute, keeping SLA
advertisement and discovery (request) as one of the sub-types of QoS advertisement and discovery (request) as one of the sub-types of QoS
attribute. This is to keep QoS attribute open for extensions, in attribute. This is to keep the QoS attribute open for extensions.
future, for other SLA specific requirements or even beyond SLA For example, SLA Negotiation and Assurance is out of scope of this
specific needs. For example, SLA Negotiation and Assurance is out of document but can be envisioned as another sub-type.
scope of this document which can be envisioned as another sub-type.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. QoS Attribute Definition 3. QoS Attribute Definition
The QoS Attribute proposed here is an optional transitive attribute The QoS Attribute proposed here is an optional transitive attribute
(attribute type code to be assigned by IANA). SLA is defined as one (attribute type code to be assigned by IANA). SLA is defined as one
of the sub-types in the QoS attribute. of the sub-types in the QoS attribute.
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Attr flag | QoS Attr type | | | Attr flag | Attr type QoS | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
~ ~ ~ ~
| QoS Attr length/Value | | QoS Attr length/Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.......................... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..........................
Attribute flags Attribute flags
highest order bit (bit 0) - highest order bit (bit 0) -
MUST be set to 1, since this is an optional attribute MUST be set to 1, since this is an optional attribute
2nd higher order bit (bit 1) - 2nd higher order bit (bit 1) -
MUST be set to 1, since this is a transitive attribute MUST be set to 1, since this is a transitive attribute
The first octet in the Value field of the QoS attribute is QoS
attribute specific flags
highest order bit (bit 0) -
It defines if update message MUST be dropped (if set to 1)
without updating routing information base, when this is the
last BGP receiver from the list of AS this attribute is
announced to, or MUST announce (if set to 0) further to BGP
peers
The purpose of this bit is discussed further in subsequent
sections.
Remaining bits are currently unused and MUST be set to 0
3.1. SLA, QoS attribute sub-type, Definition 3.1. SLA, QoS attribute sub-type, Definition
The value field of the QoS Attribute contains further TLVs, following The value field of the QoS Attribute contains TLVs, followed to QoS
QoS Attribute flags described in the previous section. One of the Attribute flags described in the previous section. One of the TLVs
TLVs that we define is a tuple of (SLA sub-type, Length, Value) that we define is a tuple of (SLA sub-type, Length, Value)
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| QoS Attr flags| subType | sub type Length | | QoS Attr flags| subType | sub type Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~ ~ ~
| Value | | Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.......................... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+..........................
The first octet in the Value field of the QoS attribute is QoS
attribute specific flags
highest order bit (bit 0) -
It defines if update message MUST be dropped (if set to 1)
without updating routing information base, when this is the
last BGP receiver from the list of destination ASes this
attribute is announced to, or MUST announce (if set to 0)
further to BGP peers
The purpose of this bit is discussed further in subsequent
sections.
Remaining bits are currently unused and MUST be set to 0
subType - 8 bits subType - 8 bits
0x00 = reserved 0x00 = reserved
0x01 = SLA 0x01 = SLA
0x02 - 0x0f = for future use 0x02 - 0x0f = for future use
SLA sub-type specific value field details 1) sender and receiver(s) SLA sub-type specific value field details. These details contain
and 2) SLA parameters. SLA Parameters include SLA event type (such information about 1) sender and receiver(s) and 2) SLA parameters.
as Advertise, Request) and content associated to that event type. SLA Parameters include SLA event type (such as Advertise, Request)
and contents associated to that event type.
The format of SLA message is, The format of SLA message is,
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 32-bit source AS (Advertiser) | | 32-bit source AS (Advertiser) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Optional advertiserid total len| Advertiser id TLVs | |Optional advertiserid total len| Advertiser id TLVs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ~
| | | |
~ ~ ~ ~
| | | |
skipping to change at page 8, line 9 skipping to change at page 7, line 42
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Content as per SLA Event | | Content as per SLA Event |
~ ~ ~ ~
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Source AS Source AS
32-bit source AS number. This is the AS that is advertising SLA 32-bit source AS number. This is the AS that is advertising SLA
0 = ignore Source and Destination AS list from this Value field. 0 = ignore Source and Destination AS list from this Value field.
Instead refer to Source and Destination AS as defined by BGP Instead refer to Source and Destination AS as defined by BGP
message. SLA sub-type specifics, from the QoS attribute, message.
MUST be removed by the receiver in such case.
Optional advertiser id total len Optional advertiser id total len
16-bit Source address identifier (optional). 16-bit Source address identifier (optional).
0 = No optional identifier 0 = No optional identifier
In general any additional qualifier for an advertiser is not In general any additional qualifier for an advertiser is not
required. The SLA definition is in the context of prefix required. The SLA definition is in the context of prefix
advertised in the NLRI definition. The exception is where a BGP advertised in the NLRI definition. The exception is where a BGP
speaker, in the middle of an update path to the destination AS, speaker, in the middle of an update path to the destination AS,
aggregates prefixes. We will refer this middle BGP speaker,that aggregates prefixes. We will refer this middle BGP speaker, that
aggregates routes, as an Aggregator. Aggregator is then required aggregates routes, as an Aggregator. Aggregator is then required
to insert original NLRI details in the optional advertiser field to insert original NLRI details in the optional advertiser field
Optional Advertiser id TLV Optional Advertiser id TLV
4-bit type 4-bit type
0x0 = reserved 0x0 = reserved
0x1 = ORIGIN_NLRI, variable length 0x1 = ORIGIN_NLRI, variable length
0x2 to 0xf = for future use, 0x2 to 0xf = for future use,
Destination AS count Destination AS count
32-bit destination AS count to take variable length AS list. 32-bit destination AS count to take variable length AS list.
This count has no functional value when Source AS is 0 This count has no functional value when Source AS is 0
0 = broadcast 0 = QoS attribute is relevant to every receiver of the message
Destination AS list Destination AS list
32-bit destination AS number, this field is omitted if broadcast 32-bit destination AS number
.... ....
.... [as many as AS count] .... [as many as AS count]
SLA Event Type SLA Event Type
4-bits 4-bits
0x0 = reserved 0x0 = reserved
0x1 = ADVERTISE 0x1 = ADVERTISE
0x2 = REQUEST 0x2 = REQUEST
0x3 to 0xf, for future use 0x3 to 0xf, for future use
SLA Id SLA Id
16-bit identifier unique within the scope of source AS 16-bit identifier unique within the scope of source AS
The significance of an SLA identifier is in the context of the The significance of an SLA identifier is in the context of the
source that is advertising SLA. SLA identifier is not globally source that is advertising SLA parameters. The SLA identifier
unique but it MUST be unique in the context of the source is not globally unique but it MUST be unique within the source
AS (advertiser). AS (advertiser).
The SLA content is optional for an advertised SLA id. If SLA The SLA content is optional for an advertised SLA id. If SLA
content does not exist in BGP update messages with advertised content does not exist in BGP update messages with advertised
SLA attribute then receiver MUST inherit prior advertised SLA QoS attribute, that contains the SLA sub-type, then receiver
content for the same SLA id from the same Source AS. MUST inherit prior advertised SLA content for the same SLA id
from the same Source AS.
If advertised SLA id is different from earlier advertised one, If advertised SLA id is different from earlier advertised one,
for the same prefix, previous SLA MUST be replaced with the new for the same prefix, previous SLA content MUST be replaced
advertised one. with the new advertised one.
SLA is aggregate for all the traffic to prefixes that share SLA is aggregate for all the traffic to prefixes that share
same source AS and SLA id. same source AS and SLA id.
SLA Length SLA Length
12-bits 12-bits
The format of SLA ADVERTISE event message is, The format of SLA ADVERTISE event message is,
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 10, line 14 skipping to change at page 9, line 46
Direction Direction
02-bit for incoming or outgoing traffic, 02-bit for incoming or outgoing traffic,
0x0 = reserved 0x0 = reserved
0x1 = incoming, from destination AS towards source AS 0x1 = incoming, from destination AS towards source AS
0x2 = outgoing, from source AS towards destination AS 0x2 = outgoing, from source AS towards destination AS
0x3 = for future use 0x3 = for future use
Traffic Class count (Classifier Groups count) Traffic Class count (Classifier Groups count)
16-bit, count of number of classifier groups 16-bit, count of number of classifier groups
00 = Advertisement to invalidate previous advertised SLA if was 00 = Advertisement to invalidate previous advertised SLA if any
any
Traffic Class Descr Length Traffic Class Descr Length
08-bit, size of the length 08-bit, size of the length
0 = No description 0 = No description
Traffic Class Description Traffic Class Description
Ascii Description of the Traffic Class Ascii Description of the Traffic Class
Traffic Class Elements Count in a Traffic Class, Traffic Class Elements Count in a Traffic Class,
08-bit count of classifier elements in a specific Traffic Class 08-bit count of classifier elements in a specific Traffic Class
00 = this has relative definition. It means classify rest all 00 = this has relative definition. It means classify rest all
skipping to change at page 10, line 32 skipping to change at page 10, line 16
Traffic Class Description Traffic Class Description
Ascii Description of the Traffic Class Ascii Description of the Traffic Class
Traffic Class Elements Count in a Traffic Class, Traffic Class Elements Count in a Traffic Class,
08-bit count of classifier elements in a specific Traffic Class 08-bit count of classifier elements in a specific Traffic Class
00 = this has relative definition. It means classify rest all 00 = this has relative definition. It means classify rest all
traffic that is not classified via earlier described traffic that is not classified via earlier described
Traffic Classes. Traffic Classes.
It is RECOMMENDED to have 0 elements Traffic Class It is RECOMMENDED that Traffic Class, that has 0 elements,
definition last in the ordered list.If Advertised SLA does is present last in the advertised list of Traffic Classes.
not have this Traffic Class last in the advertised list, If Advertised message has it positioned some-where else,
receivers MUST re-order it, for the forwarding purpose, as then receiver MUST re-order it, for the forwarding purpose,
the last Traffic Class, in the ordered list, from the to the last position in the advertised list of Traffic
source AS. It is MUST that advertisement from a specific Classes from a given source AS. QoS attribute advertised
source does not have more than one Traffic classes with from a specific source MUST NOT have more than one such
element count 0. If there are more than one such Traffic Traffic Classes (Traffic Class with 0 element count). If
Classes then advertised SLA MUST be ignored. It is okay there are more than one such Traffic Classes present then
for SLA message though to have none Traffic Class with advertised SLA parameters MUST be ignored. It is okay
element count 0. though to have none Traffic Class with element count 0.
Classifier Element values in a Traffic Class (optional), Classifier Element values in a Traffic Class (optional),
08-bit = IPFIX Element Identifier 08-bit = IPFIX Element Identifier
variable-length = based on type of the Element variable-length = based on type of the Element
Given IPFIX [RFC5102] has well defined identifier set for a Given IPFIX [RFC5102] has well defined identifier set for a
large number of packet attributes, IPFIX IANA registry is large number of packet attributes, IPFIX IANA registry is
"https://www.ietf.org/assignments/ipfix" chosen to specify "https://www.ietf.org/assignments/ipfix" chosen to specify
packet classification attributes. However, since not all packet classification attributes. However, since not all
identifiers from IPFIX would be applicable to this proposal, identifiers from IPFIX would be applicable to this proposal,
only a limited set identified here can be supported by BGP only a limited set identified here can be supported by BGP
SLA exchange. Any new element identifier, in future, added SLA exchange. Any new element identifier, in future, added
to the IPFIX IANA registry does not automatically mean to the IPFIX IANA registry does not automatically mean
supported for this proposal. supported for this proposal.
skipping to change at page 12, line 12 skipping to change at page 11, line 41
16-bit = type of the field 16-bit = type of the field
variable-length = based on type of the service variable-length = based on type of the service
- 0x00 = reserved - 0x00 = reserved
- 0x01 = TRAFFIC_CLASS_TSPEC - 0x01 = TRAFFIC_CLASS_TSPEC
160-bits TSpec Parameter 160-bits TSpec Parameter
The TRAFFIC_CLASS_TSPEC parameter consists of the (r), (b), (p), The TRAFFIC_CLASS_TSPEC parameter consists of the (r), (b), (p),
(m) and (M) parameters as described in Invocation Information (m) and (M) parameters as described in Invocation Information
section of [RFC2212]. section of [RFC2212]. Note that inheriting definition of TSpec
here does not enable RFC2212 functionality. It purely is the
Traffic Specification that is inherited here for the purpose of
SLA exchange.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Rate (r) (32-bit IEEE floating point number) | | Minimum Rate (r) (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Burst Size (b) (32-bit IEEE floating point number) | | Burst Size (b) (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Maximum Rate (p) (32-bit IEEE floating point number) | | Maximum Rate (p) (32-bit IEEE floating point number) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Minimum Policed Unit (m) (32-bit integer) | | Minimum Policed Unit (m) (32-bit integer) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 12, line 41 skipping to change at page 12, line 30
SLA unless the traffic class definition clearly represents a sole SLA unless the traffic class definition clearly represents a sole
receiver of an SLA. If there is no SLA for min-rate, the value of receiver of an SLA. If there is no SLA for min-rate, the value of
(r) MUST be set to 0. (r) MUST be set to 0.
Parameter (b) indicates maximum burst size, measured in bytes of Parameter (b) indicates maximum burst size, measured in bytes of
L2 datagram size. Since queuing delay can be considered a L2 datagram size. Since queuing delay can be considered a
function of burst size (b) and min-rate (r), in presence of non- function of burst size (b) and min-rate (r), in presence of non-
zero parameter (r), parameter (b) represents bounded delay for zero parameter (r), parameter (b) represents bounded delay for
the Traffic Class. This delay is a single hop queuing delay when the Traffic Class. This delay is a single hop queuing delay when
SLA is to be implemented at the resource constrained bottleneck. SLA is to be implemented at the resource constrained bottleneck.
In another words this burst size can be considered buffer size. In other words this burst size can be considered as a buffer
Value of 0 for parameter (b) means advertiser does not mandate size. Value of 0 for parameter (b) means the advertiser does not
specific bounded delay. mandate specific bounded delay.
Parameter (p) indicates max-rate of the traffic class. Just like Parameter (p) indicates max-rate of the traffic class. Just like
min-rate, max-rate, measured in bytes of L2 datagrams per second, min-rate, max-rate, measured in bytes of L2 packets per second,
field here also indicates service provided by advertiser. If field here also indicates service provided by advertiser. If
advertiser does not have any specific value to set for a given advertiser does not have any specific value to set for a given
class of traffic, it MAY be set to physical interface line rate class of traffic, it MAY be set to physical interface line rate
or any other indirect limit that may affect this class' maximum or any other indirect limit that may affect this class' maximum
rate. In absence of any such known value, it MUST be set to rate. In absence of any such known value, it MUST be set to
positive infinity. Value 0 is considered an error. positive infinity. Value 0 is considered an error.
Parameters (r), (b) and (p) are set each as 32-bit IEEE floating Parameters (r), (b) and (p) are each set as 32-bit IEEE floating
point numbers. Positive infinity is represented as an IEEE single point numbers. Positive infinity is represented as an IEEE single
precision floating-point number with an exponent of all ones and precision floating-point number with an exponent of all ones and
a sign mantissa of all zeros. The format of IEEE floating-point a sign mantissa of all zeros. The format of IEEE floating-point
numbers is further summarized in [RFC4506]. numbers is further summarized in [RFC4506].
The minimum policed unit (m) and maximum packet size (M) The minimum policed unit (m) and maximum packet size (M)
parameters have no relevance for the purpose of SLA exchange. parameters have no relevance for the purpose of SLA exchange.
Thus they MUST be ignored. Thus they MUST be ignored.
- 0x02, L2_OVERHEAD - 0x02, L2_OVERHEAD
08-bit, value 08-bit, value
By default specification of rate and other packet size related By default specification of rate and other packet size related
parameters, advertised in an SLA, includes L2 overhead. This parameters, advertised in an SLA, includes L2 overhead. For the
overhead by default is L2 overhead of the local link to which SLA receiver next hop, this overhead is the L2 overhead of the local
is advertised to. However, in cases where advertised SLA is for a link where advertised SLA is received. However, in cases where
receiver multiple hops away, L2 overhead consideration from the advertised SLA is for a receiver multiple hops away, L2 overhead
source perspective may be different from the local L2 overhead at consideration from the source perspective may be different from
the receiver. Explicit notification of size of L2 overhead from a the local L2 overhead at the receiver. Explicit notification of
sender, in such cases, is useful for a receiver to distinguish size of L2 overhead from a sender, in such cases, is useful for
local L2 overhead from the sender advertised one. When receiver a receiver to distinguish local L2 overhead from the sender
choose to react to an advertised SLA and if this service type is advertised one. When receiver choose to react to an advertised
present in advertised SLA, receiver MUST use advertised L2 SLA and if this service type is present in advertised SLA,
overhead over local L2 overhead. receiver MUST use advertised L2 overhead over local L2 overhead.
If SLA is required to consider only IP datagram size, sender can If SLA is required to consider only IP packet size, sender may
advertise this service with a value of 0. advertise this service with a value of 0.
- 0x03 = MINRATE_IN_PROFILE_MARKING - 0x03 = MINRATE_IN_PROFILE_MARKING
08-bit = IPFIX Element Identifier 08-bit = IPFIX Element Identifier
variable-length = based on type of the Element variable-length = based on type of the Element
00 Identifier = drop, variable-length for this id is 0.
+----+----------------------------+ +----+----------------------------+
| ID | Name | | ID | Name |
+----+----------------------------+ +----+----------------------------+
|195 | ipDiffServCodePoint | |195 | ipDiffServCodePoint |
|203 | mplsTopLabelExp | |203 | mplsTopLabelExp |
|244 | dot1qPriority | |244 | dot1qPriority |
+----+----------------------------+ +----+----------------------------+
- 0x04 = MINRATE_OUT_PROFILE_MARKING - 0x04 = MINRATE_OUT_PROFILE_MARKING
08-bit = IPFIX Element Identifier 08-bit = IPFIX Element Identifier
variable-length = based on type of the Element variable-length = based on type of the Element
00 Identifier = drop, variable-length for this id is 0.
+----+----------------------------+ +----+----------------------------+
| ID | Name | | ID | Name |
+----+----------------------------+ +----+----------------------------+
|195 | ipDiffServCodePoint | |195 | ipDiffServCodePoint |
|203 | mplsTopLabelExp | |203 | mplsTopLabelExp |
|244 | dot1qPriority | |244 | dot1qPriority |
+----+----------------------------+ +----+----------------------------+
- 0x05 = MAXRATE_IN_PROFILE_MARKING - 0x05 = MAXRATE_IN_PROFILE_MARKING
08-bit = IPFIX Element Identifier 08-bit = IPFIX Element Identifier
variable-length = based on type of the Element variable-length = based on type of the Element
00 Identifier = drop, variable-length for this id is 0.
+----+----------------------------+ +----+----------------------------+
| ID | Name | | ID | Name |
+----+----------------------------+ +----+----------------------------+
|195 | ipDiffServCodePoint | |195 | ipDiffServCodePoint |
|203 | mplsTopLabelExp | |203 | mplsTopLabelExp |
|244 | dot1qPriority | |244 | dot1qPriority |
+----+----------------------------+ +----+----------------------------+
- 0x06 = MAXRATE_OUT_PROFILE_MARKING - 0x06 = MAXRATE_OUT_PROFILE_MARKING
08-bit = IPFIX Element Identifier 08-bit = IPFIX Element Identifier
variable-length = based on type of the Element variable-length = based on type of the Element
00 Identifier = drop, variable-length for this id is 0.
+----+----------------------------+ +----+----------------------------+
| ID | Name | | ID | Name |
+----+----------------------------+ +----+----------------------------+
|195 | ipDiffServCodePoint | |195 | ipDiffServCodePoint |
|203 | mplsTopLabelExp | |203 | mplsTopLabelExp |
|244 | dot1qPriority | |244 | dot1qPriority |
+----+----------------------------+ +----+----------------------------+
In the case when MINRATE_IN_PROFILE_MARKING, In the case when MINRATE_IN_PROFILE_MARKING,
MINRATE_OUT_PROFILE_MARKING, MAXRATE_IN_PROFILE_MARKING and MINRATE_OUT_PROFILE_MARKING, MAXRATE_IN_PROFILE_MARKING and
skipping to change at page 15, line 24 skipping to change at page 15, line 18
+----+----------------------------+ +----+----------------------------+
| ID | Name | | ID | Name |
+----+----------------------------+ +----+----------------------------+
|195 | ipDiffServCodePoint | |195 | ipDiffServCodePoint |
|203 | mplsTopLabelExp | |203 | mplsTopLabelExp |
|244 | dot1qPriority | |244 | dot1qPriority |
+----+----------------------------+ +----+----------------------------+
This finer granular drop threshold does not require separate This finer granular drop threshold does not require separate
buffer space from the aggregate buffer space. It is just an buffer space from the aggregate buffer space. It is just an
indicator that beyond what size from the aggregate space, this indicator beyond which code-point specific traffic to be
code-point specific traffic should all be dropped. discarded when occupancy of aggregate buffers reached to that
threshold.
- 0x08 = RELATIVE_PRIORITY - 0x08 = RELATIVE_PRIORITY
04-bit, priority value 04-bit, priority value
lower the value, higher the priority lower the value, higher the priority
Relative priority indicates scheduling priority. For example Relative priority indicates scheduling priority. For example
voice traffic, that requires lowest latency compare to any voice traffic, which requires lowest latency compare to any
other traffic, will have lowest value advertised in relative other traffic, may have lowest value advertised in relative
priority. For two different traffic classification groups priority. For two different traffic classification groups
where one application group may be considered more important where one application group may be considered more important
than the other but from scheduling perspective do not require than the other but from a scheduling perspective does not
to be distinguish with different priority, relative priority require to be distinguished with a different priority, relative
for those classification groups may be advertised with the priority for those classification groups may be advertised with
same value. the same value.
- 0x09 = SUB_TRAFFIC_CLASSES - 0x09 = SUB_TRAFFIC_CLASSES
variable-length, repeats all content described above from Traffic variable-length, repeats all content described above from Traffic
Class count onwards. Class count onwards.
For SLAs where a specific Traffic Class may further have For SLAs where a specific Traffic Class may further have
different sub-services for sub-group of Classifier Elements, different sub-services for sub-group of Classifier Elements,
this service type SHOULD be used to further divide Traffic Class this service type SHOULD be used to further divide Traffic Class
in multiple sub-classes. Each sub-class then defined with their in multiple sub-classes. Each sub-class then defined with their
own classifier elements and service types. own classifier elements and service types.
4. Originating SLA Notification 4. Originating SLA Notification
QoS attribute to advertise SLA MUST be added by the originator of a The QoS attribute to advertise SLA sub-type MUST be added by the
BGP UPDATE message. Any BGP speaker in the forwarding path of a originator of a BGP UPDATE message.
message MUST NOT insert QoS attribute for the same prefix.
SLA messages SHOULD NOT be sent periodically just for the purpose of SLA messages SHOULD NOT be sent periodically just for the purpose of
keep alive. Since SLA changes are in-frequent, some sort of SLA keep alive. Some sort of SLA policy change may be considered as a
policy change can be considered as a trigger for the advertisement. trigger for the advertisement.
For any SLA modification, originator MUST re-advertise entire SLA. For any modified SLA parameters, the originator MUST re-advertise the
There is no provision to advertise partial SLA. To invalidate entire set of SLA parameters. There is no provision to advertise
previously advertised SLA, a message MUST be sent with new SLA partial set of parameters. To invalidate previously advertised SLA
advertisement with Traffic Class count as 0. parameters, a message MUST be sent with the same SLA id for the same
source with the Traffic Class count set to 0.
4.1. SLA Contexts 4.1. SLA Contexts
In certain cases, the advertisement may be to establish SLA for In certain cases, the advertisement may relate to an SLA for
aggregate traffic on a point to point connection between a specific aggregate traffic over a point-to-point connection between a specific
destination and a specific source. A point to point connection may destination and a specific source. A point-to-point connection may
be a physical link, connecting BGP peers, or may be a virtual link be the physical link, that connects two BGP peers, or may be a
(like tunnel). A BGP update message, in such cases, with source AS virtual link (e.g. a tunnel). A BGP update message, in such cases,
number and NLRI prefix of source end-point can uniquely identify with source AS number and NLRI prefix of source end-point can
physical/virtual link and so establishes advertised SLA's context for uniquely identify physical/virtual link and so establishes advertised
aggregate traffic for that point to point link. SLA's context for that point to point link.
In the simplest case where PE and CE are directly connected via a In the simplest case where Provider (e.g. PE) and Customer (e.g.
physical link and have only single link between them, CE can uniquely CE) devices are directly connected via a physical link and have only
identify forwarding link to PE with AS number of the PE and NLRI single link between them, CE can uniquely identify the forwarding
prefix being an address of PE, to CE (that is next hop address from link to PE with AS number of the PE and NLRI prefix being an IP
CE to PE). SLA advertised thru BGP update message from PE to CE, address of PE, to CE (that is the next hop address from CE to PE).
with PE's AS number and IP address, establishes SLA context for the SLA advertised thru BGP update message from PE to CE, with PE's AS
aggregate traffic through link CE to PE. SLA advertised thru BGP number and IP address, establishes SLA context for the aggregate
update message from PE to CE, with PE's AS number and any other traffic through link CE to PE. SLA advertised thru BGP update
prefix establishes SLA for that specific prefix, subset of traffic message from PE to CE, with PE's AS number and any other prefix
under CE to PE link. establishes SLA for that specific prefix, subset of traffic under CE
to PE link.
Even though this example is in the context of IP prefix, SLA exchange Even though this example is in the context of IP prefixes, SLA
does not have to be limited to IPv4 family only. SLA advertisement exchange does not have to be limited to the IP address family only.
is generic to all forms of NLRI types that are supported by the BGP SLA advertisement is generic to all forms of NLRI types that are
protocol specification (like IPV4, IPV6, VPN-IPV4, VPN-IPV6). supported by the BGP protocol specification (like IPv4, IPv6, VPN-
IPv4, VPN-IPv6).
4.1.1. SLA Advertisement for Point-to-Point Connection 4.1.1. SLA Advertisement for Point-to-Point Connection
When SLA messages are intended to be advertised for the point to When SLA messages are intended to be advertised for the point-to-
point connection (physical or logical), the message is destined for point connection (physical or logical), the message is destined for
the next hop and advertised message is in the context of the prefix the next hop and advertised message is in the context of the prefix
of the source end-point of the point to point connection. of the source end-point of the point to point connection.
The destination AS number set to, within QoS SLA attribute, typically The destination AS number set to, within QoS SLA attribute, typically
is of the neighbor BGP speaker's. Alternatively, originator MAY not is of the neighbor BGP speaker's. Alternatively, the originator MAY
encode source/destination AS numbers (that is source AS set to 0 and not encode source/destination AS numbers (that is the source AS is
destination AS count set to 0), in the QoS attribute. The most set to 0 and destination AS count is set to 0), in the QoS attribute.
significant bit of the QoS attribute flag MAY be set to 1, The most significant bit of the QoS attribute flag MAY be set to 1,
specifically it MUST be set to 1 when intention is to not install specifically it MUST be set to 1 when intention is to not install
route update, at the receiver, for the advertised message. route update, at the receiver, for the advertised message.
4.1.2. SLA Advertisement for Destination AS Multiple Hops Away 4.1.2. SLA Advertisement for Destination AS Multiple Hops Away
When SLA messages are to be advertised beyond next hop, value of When SLA messages are to be advertised beyond next hop, value of
source AS, in the QoS attribute, MUST be set by the originator of the source AS, in the QoS attribute, MUST be set by the originator of the
update message. If such update is meant to be for a specific list of update message. If such update is meant to be for a specific list of
AS(es) as receiver then list of destination AS MUST be populated in AS(es) as receivers, then the list of destination AS MUST be
the QoS attribute message to avoid flooding of the QoS attribute data explicitly described in the QoS attribute message to avoid flooding
in the network beyond those destinations. of the QoS attribute data in the network beyond those destinations.
When a new prefix is added in the AS, AS for which SLA has already When a new prefix is added in the AS, AS for which SLA parameters
been advertised before for other existing prefixes, then to advertise have already been advertised before for other existing prefixes, and
that new prefix to be part of earlier advertised SLA, a trigger of if traffic to this new prefix is subject to the same SLA advertised
new BGP update message with QoS attribute containing SLA id is earlier then BGP update for this new prefix may include QoS attribute
sufficient. Update message does not require to have whole SLA containing just an SLA id, an id that was advertised earlier. The
content. corresponding Update message does not require to have the whole SLA
content. SLA id is sufficient to relate SLA parameters to new
advertised prefix.
When BGP update messages are triggered as a result of SLA policy When BGP update messages are triggered as a result of SLA policy
change and thus only for the purpose of SLA exchange, forwarding BGP change and thus only for the purpose of SLA exchange, forwarding BGP
update messages beyond intended receivers are not necessary. Highest update messages beyond intended receivers are not necessary. Highest
order bit in the QoS Attribute flag MUST be set to suggest receiver order bit in the QoS Attribute flag MUST be set to suggest receiver
to drop entire BGP update message [Note that it is an indication to to drop entire BGP update message [Note that it is an indication to
drop entire update message, not only QoS attribute], after all drop entire update message, not only QoS attribute], after all
intended receivers have processed it. If update message contains intended receivers have processed it. If update message contains a
list of destination AS then message MUST be dropped only after all list of destination ASes, then the message MUST be dropped only after
intended receivers (destinations) have received it. all intended receivers (destinations) have received it.
5. SLA Attribute Handling at Forwarding Nodes 5. SLA Attribute Handling at Forwarding Nodes
5.1. BGP Node Capable of Processing QoS Attribute 5.1. BGP Node Capable of Processing QoS Attribute
If a BGP node is capable of processing QoS attribute, it optionally If a BGP node is capable of processing QoS attribute, it optionally
MAY process the message. If advertised SLA has list of destination MAY process the message. If advertised SLA has a list of destination
AS, it MAY trim list and so count of destination AS to exclude ones ASes, it MAY trim list and so count of destination AS to exclude ones
that are not required in further announcement of BGP updates. that are not required in further announcement of BGP updates.
BGP node MUST drop SLA related sub type from the QoS attribute, if BGP node MUST drop SLA related sub-type from the QoS attribute, if
none of the AS from the destination list is in the forwarding path. none of the AS from the destination list is in the forwarding path.
The rest of the QoS attribute contents MAY be forwarded if there
exist other sub-types of QoS attribute and forwarding rules meets
other sub-types requirements. If there is no other sub-types in the
QoS attribute content then the node MUST drop the QoS attribute all
together. The other attributes and NLRI information may be announced
further if they meet rules defined by other attributes and BGP
protocol.
Rest of the QoS attributes message MAY be forwarded if there exist If the most significant bit in the QoS attribute flag is set to 1
other sub-types of QoS attribute and forwarding rules meets other then the entire BGP update message MUST be dropped if there are no
sub-types requirements. If there is no other sub-types existing in destinations left in the list to advertise to.
the QoS attribute message then node MUST drop QoS attribute all
together. Rest other attributes and NLRI may be announced further if
it meets rules defined by other attributes and BGP protocol.
If most significant bit in the QoS attribute flag is set to 1 then
entire BGP update message MUST be dropped if there are no destination
left in the list to advertise to. However, If SLA message is meant
to be broadcast then message MUST NOT be dropped/trimmed.
Except extracting entire SLA sub-type of the QoS attribute and Except extracting the entire SLA sub-type of the QoS attribute and
trimming the list of destination AS list and inserting NLRI at the trimming the list of destination AS list and inserting NLRI at the
Aggregator node, rest all other content MUST NOT be modified by any Aggregator node, all other content MUST NOT be modified by any
intermediate receivers of the message. intermediate receivers of the message.
5.2. BGP Node not Capable of Processing QoS Attribute 5.2. BGP Node not Capable of Processing QoS Attribute
If BGP node is not capable of processing QoS attribute, it MUST If the BGP node is not capable of processing QoS attribute, it MUST
forward attribute message as it is received. forward the QoS attribute message unaltered.
5.3. Aggregator 5.3. Aggregator
It is RECOMMENDED to not aggregate prefixes from BGP update messages It is RECOMMENDED to not aggregate prefixes from 2 or more BGP update
that contain QoS SLA attribute. If Aggregator MUST aggregate messages into one BGP update, when original messages contain the QoS
prefixes then it MUST copy QoS SLA attribute in new aggregated BGP attribute with SLA sub-type contents. If Aggregator MUST aggregate
update message. At the same time, it MUST also insert NLRI, from the them then it MUST copy entire parameter set of an SLA sub-type from
original update message, as an optional advertiser id to go along the QoS attribute in the new aggregated BGP update message. At the
with source AS inside the QoS attribute. same time, it MUST also insert NLRI information, from the original
update message, as an optional advertiser id to go along with source
AS inside the QoS attribute.
To support SLA exchange multiple hops away in the path that has one To support SLA exchange multiple hops away in the path that has one
of the forwarding node in the path acting as Aggregator, it is of the forwarding node acting as an Aggregator, it is required that
required Aggregator node to be capable of processing QoS attribute. the Aggregator node is capable of processing the QoS attribute.
6. SLA Attribute Handling at Receiver 6. SLA Attribute Handling at Receiver
Reception of and reaction to advertised messages are optional for the Reception of and processing of advertised QoS SLA content are
receiver. optional for the receiver.
As described in earlier section, while reacting to SLA advertisement While reacting to SLA advertisement
- receiver SHOULD invalidate previous advertised SLA and then if one - receiver SHOULD invalidate previous advertised SLA parameters if
exists for advertised NLRI. If new advertised SLA update is with one exists for the same SLA id and source AS. If new advertised
non-zero Traffic Class count, new advertised SLA SHOULD be SLA update is with non-zero Traffic Class count, new advertised
installed. If new advertised SLA update is with Traffic Class SLA SHOULD be installed. If new advertised SLA update is with
count 0, no action is required. Traffic Class count 0, no action is required.
- If advertised QoS Attribute, inside an update message, is with a - If advertised QoS Attribute, inside an update message, is with a
flag set indicating to drop that message, a receiver MUST drop flag set indicating to drop that message, a receiver MUST drop
message if it is the last receiver, in update path, that message message if it is the last receiver, in update path, that message
is advertised to. is advertised to.
If advertised SLA is from the next hop, in reverse path, the receiver If the advertised SLA is from the next hop, in the reverse path, the
can establish advertised SLA for the whole link, the link could be receiver may implement advertised SLA for the whole link, the link
physical or virtual link, associated with the next hop. If NLRI could be physical or virtual link, associated with the next hop. If
advertised in update message is not of the next hop, receiver may NLRI advertised in update message is not of the next hop, receiver
establish advertised SLA for that specific prefix list under the may establish advertised SLA for that specific prefix list under the
relevant link. It is completely up to the receiver to decide for relevant link. It is completely up to the receiver to decide for
which prefixes to accept advertised SLA and for which ones to not. which prefixes it should accept advertised SLA and for which ones it
won't.
For cases where if earlier message has not yet reached to the For cases where if earlier messages have not reached the intended
intended receiver, a re-signaling is required. A signaling event receiver yet, a re-signaling is required. A receiver may intend to
REQUEST is required, for this purpose, to be triggered by intended request an SLA message from the originator in such case. Since BGP
receiver. Since BGP messages are considered reliable, it is assumed messages are considered reliable, it is assumed that advertised
that advertised messages always reach intended receivers. Thus messages always reach intended receivers. Thus discussion of REQUEST
discussion of REQUEST message, for this purpose or any other purpose, message, for this purpose or any other purpose, is considered out of
is considered out of the scope of this document. the scope of this document.
To handle error conditions, the approach of "attribute-discard" as To handle error conditions, the approach of "attribute-discard" as
mentioned in [IDR-ERR] MAY be used in an event if a QOS attribute mentioned in [IDR-ERR] MAY be used in the event QOS attribute parsing
parsing results in any attribute errors. Alternatively, an approach results in any attribute errors. Alternatively, an approach of
of "treat-as-withdraw" MAY be used as mentioned in [IDR-ERR] if an "treat-as-withdraw" MAY be used as mentioned in [IDR-ERR] if an
implementation also wishes to withdraw the associated prefix. implementation also wishes to withdraw the associated prefix.
6.1. Traffic Class Mapping 6.1. Traffic Class Mapping
It is common that switching/routing methods used in 2 different AS It is possible that switching/routing methods used in 2 different
could be different. For example, Provider may tunnel Customer's IP ASes could be different. For example, Provider may tunnel Customer's
traffic thru MPLS cloud. In such cases traffic class definition for IP traffic thru MPLS cloud. In such cases traffic class definition
QoS services may differ in both ASes. For the meaningful use of for QoS services may differ in both ASes. For the meaningful use of
advertised SLA in such cases, receiver is required to map traffic advertised SLA in such cases, receiver is required to map traffic
class from one type to another. class from one type to the other.
In the example given, traffic classification in Customer AS could be In the example given, traffic classification in Customer AS could be
IP Diffserv based whereas traffic classification in Provider AS could IP Diffserv-based whereas traffic classification in Provider AS could
be MPLS TC based. Thus for advertised MPLS TC based SLA from PE, CE be MPLS TC-based. Thus for advertised MPLS TC-based SLA would
would require to map traffic class from IP Diffserv based to MPLS TC require to map traffic class from IP Diffserv-based to MPLS TC type.
type.
There are well-defined recommendations that exist for traffic class There are well-defined recommendations that exist for traffic class
mapping between two technologies. Receiver MAY use those defined mapping between two technologies. Receiver MAY use those defined
recommendations for traffic class mapping or MAY define its own as recommendations for traffic class mapping or MAY define its own as
per its network Traffic Class service definition to map to advertised per its network Traffic Class service definition to map to advertised
Traffic Classes. It is completely up to the receiver how to define Traffic Classes. It is completely up to the receiver how to define
such traffic class mapping. such traffic class mapping.
7. Deployment Considerations 7. Deployment Considerations
Typical use case aimed with this proposal is for Provider to One of the use cases is for a Provider to advertise contracted SLA
advertise contracted SLA to Customer Edge. SLA established between parameters to Customer Edge (CE). The SLA parameters are provisioned
customer and Provider is provisioned by the provider on the PE device by the provider on the PE device (facing CE). This provisioned SLA
(facing Customer Edge). This provisioning, in a form supported by parameters are then advertised thru proposed BGP QoS attribute to the
Provider, is advertised thru proposed BGP QoS attribute to the CE device. CE device may read the attribute and SLA sub-type content
Customer Edge. Customer may read thru advertised SLA to provision to implement the QoS policy on the device.
one on the Customer Edge link facing towards PE.
Contracted SLA from PE to CE may be full line-rate or sub-rate of a Contracted SLA from PE to CE may be full line-rate or sub line-rate
link or finer granular controlled services. SLA is not required to or finer granular controlled services. SLA advertise can be useful
be advertised if the SLA contract is simply a physical link. SLA when contracted service is sub-rate of a link and/or when for finer
advertise can be useful when contracted service is sub-rate of a link granular traffic classes that are controlled (e.g. voice, video
and/or if for finer granular traffic classes that are controlled. services may be capped to certain rate)
Like voice, video services may be capped to certain rate.
_______________ _______________
__________ / \ __________ / \
/ \ / \ / \ / \
/ \ / \ / \ / \
|CustomerSite|-----| Provider | |CustomerSite|-----| Provider |
\ C/E P\E / \ C/E P\E /
\__________/ \ / \__________/ \ /
\_______________/ \_______________/
AS 3 AS 2 AS 3 AS 2
SLA_ADVERTISE: AS2 to AS3 SLA_ADVERTISE: AS2 to AS3
NLRI = PE ip address NLRI = PE ip address
Another use case can be to advertise SLA among different network Another use case can be to advertise SLAs among different network
sites within one Enterprise network. In Hub and Spoke deployments, sites within one Enterprise network. In Hub and Spoke deployments,
Administrator, being aware of each Spoke's SLA, may define SLAs for Administrator, being aware of each Spoke's SLA, may define SLAs for
each of them at the Hub and advertise them thru BGP updates, where at each of them at the Hub and advertise them thru BGP updates, where at
each Spoke advertised SLA may translate to a forwarding policy. each Spoke, advertised SLA may translate to a forwarding policy. In
Today administrator has to manually define SLA based forwarding a scale network, managing a large number of Spokes can be complex.
policy separately on the Hub as well as on each Spoke. In a scale The proposal in such cases would be to provision SLA parameters at
network, managing large number of Spokes can be complex. The the Hub only and distribute them to each Spoke with SLA exchange
proposal in such cases would be to define SLAs, to be implemented protocol described here.
both at the Hub and each Spoke side, on the Hub only and distribute
them to each Spoke with SLA exchange.
Alternatively, in a fully automated SLA exchange network, manual Alternatively, in a network that supports SLA parameters signaling
administration can be avoided or minimized even at the Hub. As shown capabilities with the Provider, manual administration can be avoided
in the figure below, AS2 may first learn its SLA with the Provider or minimized even at the Hub. As shown in the figure below, AS2 may
from the Provider Edge it is connected to. AS2 then can advertise first learn its SLA with the Provider from the Provider Edge it is
the same or subset of that SLA to AS3 in the context of tunnel's ip connected to. AS2 can advertise the same or a subset of that SLA to
address. AS3 in the context of tunnel's ip address.
AS 2 AS 2
_______________ ________ _______________ ________
/ \ / \ / \ / \
__________ / \-----| Spoke2 | __________ / \-----| Spoke2 |
/ \ / \ \________/ / \ / \ \________/
| Hub |-----| Provider | ________ | Hub |-----| Provider | ________
\__________/ \ / / \ \__________/ \ / / \
\ /-----| Spoke1 | \ /-----| Spoke1 |
AS 3 \_______________/ \________/ AS 3 \_______________/ \________/
AS 1 AS 1
SLA_ADVERTISE: AS2 to AS3 SLA_ADVERTISE: AS2 to AS3
NLRI = AS2 tunnel address NLRI = AS2 tunnel address
SLA_ADVERTISE: AS1 to AS3 SLA_ADVERTISE: AS1 to AS3
NLRI = AS1 tunnel address NLRI = AS1 tunnel address
Deployment options are not limited to involving CEs, PE-to-CE or CE- Deployment options are not limited to involving CEs, PE-to-CE or CE-
to-CE, only. For any contract between Provider to Provider, SLA may to-CE, only. For any contract between two providers, SLA parameters
be advertised from one PE to another PE also. may be advertised from one to the other.
8. Acknowledgements 8. Acknowledgements
Thanks to Fred Baker, David Black, Sue Hares and Benoit Claise for Thanks to Fred Baker, David Black, Sue Hares and Benoit Claise for
their suggestions and to Ken Briley, Rahul Patel, Fred Yip, Lou their suggestions and to Christian Jacquenet, Ken Briley, Rahul
Berger, Brian Carpenter, Bertrand Duvivier for the review. Patel, Fred Yip, Lou Berger, Brian Carpenter, Bertrand Duvivier for
the review.
9. IANA Considerations 9. IANA Considerations
The proposal in this document defines a new BGP attribute. IANA The proposal in this document defines a new BGP attribute. IANA
maintains the list of existing BGP attribute types. A new type to be maintains the list of existing BGP attribute types. A new type to be
added in the list for the QoS attribute. added in the list for the QoS attribute.
The proposal also defines a list for Service types associated to The proposal also defines a list for Service types associated to
Traffic Class. IANA will be required to maintain this list for Traffic Class. IANA will be required to maintain this list for
Traffic Class Service type as a new registry. Where-as Traffic Class Traffic Class Service type as a new registry. Where-as Traffic Class
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