draft-ietf-idr-bgpls-inter-as-topology-ext-03.txt   draft-ietf-idr-bgpls-inter-as-topology-ext-04.txt 
IDR Working Group A. Wang IDR Working Group A. Wang
Internet-Draft China Telecom Internet-Draft China Telecom
Intended status: Standards Track H. Chen Intended status: Standards Track H. Chen
Expires: January 2, 2020 Futurewei Expires: February 27, 2020 Futurewei
K. Talaulikar K. Talaulikar
Cisco Systems Cisco Systems
S. Ma S. Ma
Mellanox Technologies Mellanox Technologies
July 1, 2019 August 26, 2019
BGP-LS Extension for Inter-AS Topology Retrieval BGP-LS Extension for Inter-AS Topology Retrieval
draft-ietf-idr-bgpls-inter-as-topology-ext-03 draft-ietf-idr-bgpls-inter-as-topology-ext-04
Abstract Abstract
This document describes the process to build BGP-LS key parameters in This document describes the process to build Border Gateway Protocol-
inter-domain scenario, defines one new BGP-LS NLRI type(Stub Link Link State (BGP-LS) key parameters in inter-domain scenario, defines
NLRI) and some new inter-AS TE related TLVs for BGP-LS to let SDN one new BGP-LS Network Layer Reachability Information (NLRI) type
controller retrieve the network topology automatically under various (Stub Link NLRI) and some new inter Autonomous (inter-AS) Traffic
inter-AS environments. Engineering (TE) related Type-Length-Values (TLVs) for BGP-LS to let
Software Definition Network (SDN) controller retrieve the network
topology automatically under various inter-AS environments.
Such extension and process can enable the network operator to collect Such extension and process can enable the network operator to collect
the interconnect information between different domains and then the interconnect information between different domains and then
calculate the overall network topology automatically based on the calculate the overall network topology automatically based on the
information provided by BGP-LS protocol. information provided by BGP-LS protocol.
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.
skipping to change at page 1, line 44 skipping to change at page 1, line 46
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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 January 2, 2020. This Internet-Draft will expire on February 27, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3 2. Conventions used in this document . . . . . . . . . . . . . . 3
3. Inter-AS Domain Scenarios. . . . . . . . . . . . . . . . . . 3 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Stub Link NLRI . . . . . . . . . . . . . . . . . . . . . . . 4 4. Inter-AS Domain Scenarios. . . . . . . . . . . . . . . . . . 3
4.1. Inter-AS Native IP Scenario . . . . . . . . . . . . . . . 5 5. Stub Link NLRI . . . . . . . . . . . . . . . . . . . . . . . 4
4.2. Inter-AS TE Scenario . . . . . . . . . . . . . . . . . . 5 5.1. Inter-AS Native IP Scenario . . . . . . . . . . . . . . . 5
5. Inter-AS TE NLRI related TLVs . . . . . . . . . . . . . . . . 6 5.2. Inter-AS TE Scenario . . . . . . . . . . . . . . . . . . 5
5.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 6 6. Inter-AS TE NLRI related TLVs . . . . . . . . . . . . . . . . 6
5.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7 6.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 6
5.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7 6.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7
6. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 8 6.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8.1. New BGP-LS NLRI type . . . . . . . . . . . . . . . . . . 9 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
8.2. New Link Descriptors . . . . . . . . . . . . . . . . . . 9 9.1. New BGP-LS NLRI type . . . . . . . . . . . . . . . . . . 9
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 10 9.2. New Link Descriptors . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 10 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 10
10.1. Normative References . . . . . . . . . . . . . . . . . . 10 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
10.2. Informative References . . . . . . . . . . . . . . . . . 10 11.1. Normative References . . . . . . . . . . . . . . . . . . 10
11.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
BGP-LS [RFC7752] describes the methodology that using BGP protocol to BGP-LS [RFC7752] describes the methodology that using BGP protocol to
transfer the Link-State information. Such method can enable SDN transfer the Link-State information. Such method can enable SDN
controller to collect the underlay network topology automatically, controller to collect the underlay network topology automatically,
but normally it can only get the information within one IGP domain. but normally it can only get the information within one Interior
If the operator has more than one IGP domain, and these domains Gateway Protocol (IGP) domain. If the operator has more than one IGP
interconnect with each other, there is no mechanic within current domain, and these domains interconnect with each other, there is no
BGP- LS to transfer the interconnect topology information. mechanic within current BGP- LS to transfer the interconnect topology
information.
Draft [I-D.ietf-idr-bgpls-segment-routing-epe] defines some Draft [I-D.ietf-idr-bgpls-segment-routing-epe] defines some
extensions for exporting BGP peering node topology information extensions for exporting BGP peering node topology information
(including its peers, interfaces and peering ASs) in a way that is (including its peers, interfaces and peering ASs) in a way that is
exploitable in order to compute efficient BGP Peering Engineering exploitable in order to compute efficient BGP Peering Engineering
policies and strategies. Such information can also be used to policies and strategies. Such information can also be used to
calculate the interconnection topology among different IGP domains, calculate the interconnection topology among different IGP domains,
but it requires the border routers to run BGP-LS protocol and report but it requires the border routers to run BGP-LS protocol and report
the information to the PCE/SDN controller, which restricts the the information to the SDN controller, which restricts the solution
solution deployment flexibility. deployment flexibility.
This draft analysis the situations that the PCE/SDN controller needs This draft analysis the situations that the SDN controller needs to
to get the interconnected topology information between different AS get the interconnected topology information between different AS
domains, defines the new Stub Link NLRI and some new TLVs within the domains, defines the new Stub Link NLRI and some new TLVs within the
BGP-LS protocol to transfer the key information related to them. BGP-LS protocol to transfer the key information related to them.
After that, the SDN controller can then deduce the multi-domain After that, the SDN controller can then deduce the multi-domain
topology automatically based on the information from BGP-LS protocol. topology automatically based on the information from BGP-LS protocol.
2. Conventions used in this document 2. Conventions used in this document
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 RFC 2119 [RFC2119] . document are to be interpreted as described in RFC 2119 [RFC2119] .
3. Inter-AS Domain Scenarios. 3. Terminology
Fig.1 illustrates the multi-domain scenarios that this draft The following terms are defined in this document:
o IDCs: Internet Data Centers
o MAN: Metrio-Area-Network
o SDN: Software Definition Network
4. Inter-AS Domain Scenarios.
Figure 1 illustrates the multi-domain scenarios that this draft
discusses. Normally, SDN Controller can get the topology of IGP A discusses. Normally, SDN Controller can get the topology of IGP A
and IGP B individually via the BGP-LS protocol, but it can't get the and IGP B individually via the BGP-LS protocol, but it can't get the
topology connection information between these two IGP domains because topology connection information between these two IGP domains because
there is generally no IGP protocol run on the connected links. there is generally no IGP protocol run on the connected links.
+-----------------+ +-----------------+
+----+IP SDN Controller+----+ +----+IP SDN Controller+----+
| +-----------------+ | | +-----------------+ |
| | | |
|BGP-LS |BGP-LS |BGP-LS |BGP-LS
skipping to change at page 4, line 27 skipping to change at page 4, line 27
| +-++ +-++ ++-+ +-++ ++++ +-++| | +-++ +-++ ++-+ +-++ ++++ +-++|
| |S4+--------+S3+---+B3+-----------+B4+---+T3+--------+T4|| | |S4+--------+S3+---+B3+-----------+B4+---+T3+--------+T4||
| +--+ +--+ ++-+ +-++ ++-+ +--+| | +--+ +--+ ++-+ +-++ ++-+ +--+|
| | | | | | | |
| | | | | | | |
| IGP A | | IGP B | | IGP A | | IGP B |
+---------------------+ +--------------------+ +---------------------+ +--------------------+
Figure 1: Inter-AS Domain Scenarios Figure 1: Inter-AS Domain Scenarios
4. Stub Link NLRI 5. Stub Link NLRI
[RFC7752] defines four NLRI types(Node NLRI, Link NLRI, IPv4 Topology [RFC7752] defines four NLRI types(Node NLRI, Link NLRI, IPv4 Topology
Prefix NLRI, IPv6 Topology Prefix NLRI) to transfer the topology and Prefix NLRI, IPv6 Topology Prefix NLRI) to transfer the topology and
prefix information. For inter-as link, the two ends of the link prefix information. For inter-as link, the two ends of the link
locates in different IGP domains, then it is not appropriate to locates in different IGP domains, then it is not appropriate to
transfer their information within the current defined NLRI types. transfer their information within the current defined NLRI types.
This draft defines one new NLRI type, called Stub Link NLRI, which is This draft defines one new NLRI type, called Stub Link NLRI, which is
coded as the following format: coded as the following format:
skipping to change at page 5, line 8 skipping to change at page 5, line 8
// Local Node Descriptors (variable) // // Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Stub Link Descriptors (variable) // // Stub Link Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Stub Link NLRI Format Figure 2: Stub Link NLRI Format
The "Protocol-ID" should be set to the value that indicates "Direct" The "Protocol-ID" should be set to the value that indicates "Direct"
protocol. protocol.
The semantics of "Stub Link Descriptors" is same as that defined in The semantics of "Local Node Descriptors" and "Stub Link Descriptors"
[RFC7752] for "Link Descriptor". are same as that defined in [RFC7752] for "Node Descriptors" and
"Link Descriptor".
This newly defined NLRI can be used to describe the link that has This newly defined NLRI can be used to describe the link that has
only one end located within the IGP domain, as described in the only one end located within the IGP domain, as described in the
following sections. following sections.
4.1. Inter-AS Native IP Scenario 5.1. Inter-AS Native IP Scenario
Draft [I-D.ietf-teas-native-ip-scenarios] describes the situation Draft [I-D.ietf-teas-native-ip-scenarios] describes the situation
that operator needs some traffic engineering solution for the inter- that operator needs some traffic engineering solution for the inter-
as native IP environment. In such situation, different domain may as native IP environment. In such situation, different domain may
run different IGP protocol. The operator needs to know the inter-as run different IGP protocol. The operator needs to know the inter-as
topology first to calculate the end to end optimal centrally. topology first to calculate the end to end optimal centrally.
When IGP A or IGP B in Figure 1 runs native IS-IS/OSPF protocol, the When IGP A or IGP B in Figure 1 runs native IS-IS/OSPF protocol, the
operator can use passive feature for the inter-domain links to let operator can use passive feature for the inter-domain links to let
the routers within the IGP domain know these links. Such stub links the routers within the IGP domain know these links. Such stub links
information can then be carried within the Stub Link NLRI reported information can then be carried within the Stub Link NLRI reported
via the BGP-LS protocol to the SDN controller. via the BGP-LS protocol to the SDN controller.
The "Local Node Descriptors" should describe the the characteristics The "Local Node Descriptors" should describe the the characteristics
of ASBRs that are connected these stub links. of ASBRs that are connected these stub links.
When such information is reported via the BGP-LS protocol, the PCE/ When such information is reported via the BGP-LS protocol, the SDN
SDN controller can construct the underlay inter-domain topology controller can construct the underlay inter-domain topology according
according to procedure described in section 6. to procedure described in Section 7
4.2. Inter-AS TE Scenario 5.2. Inter-AS TE Scenario
When IGP A or IGP B in Figure 1 runs IS-IS TE/OSPF-TE When IGP A or IGP B in Figure 1 runs IS-IS TE/OSPF-TE
protocol,[RFC5316] and [RFC5392] define IS-IS and OSPF extensions protocol,[RFC5316] and [RFC5392] define IS-IS and OSPF extensions
respectively to deal with the situation for inter-AS traffic respectively to deal with the situation for inter-AS traffic
engineering. Three new sub-TLVs(Remote AS Number、IPv4 Remote engineering. Three new sub-TLVs(Remote AS Number、IPv4 Remote
ASBR ID、IPv6 Remote ASBR ID) which are associated with the ASBR ID、IPv6 Remote ASBR ID) which are associated with the
inter-AS TE link are defined. inter-AS TE link are defined.
These TLVs are flooded within the IGP domain automatically. They can These TLVs are flooded within the IGP domain automatically. They
also be carried within the newly defined Stub Link NLRI within the should be carried within the newly defined Stub Link NLRI within the
BGP-LS protocol, as the descriptors for the inter-AS stub link. BGP-LS protocol, as the descriptors for the inter-AS stub link.
The "Local Node Descriptors" should describe the the characteristics The "Local Node Descriptors" should describe the the characteristics
of ASBRs that are connected these inter-AS TE links. of ASBRs that are connected these inter-AS TE links.
If the PCE/SDN controller know these information via one of the If the SDN controller knows these information via one of the interior
interior router that runs BGP-LS protocol, the PCE/SDN controller can router that runs BGP-LS protocol, the SDN controller can rebuild the
rebuild the inter-AS TE topology correctly according to the procedure inter-AS TE topology correctly according to the procedure described
described in section 6 in Section 7
5. Inter-AS TE NLRI related TLVs 6. Inter-AS TE NLRI related TLVs
This draft proposes to add three new TLVs that is included within the This draft proposes to add three new TLVs that is included within the
Stub Link NLRI to transfer the information via BGP-LS, which are Stub Link NLRI to transfer the information via BGP-LS, which are
required to build the inter-AS TE related topology by the PCE/SDN required to build the inter-AS TE related topology by the SDN
controller. controller.
The following Link Descriptor TLVs are added into the BGP-LS protocol The following Link Descriptor TLVs are added into the BGP-LS protocol
: :
+-----------+---------------------+--------------+----------------+ +-----------+---------------------+--------------+----------------+
| TLV Code | Description |IS-IS/OSPF TLV| Reference | | TLV Code | Description |IS-IS/OSPF TLV| Reference |
| Point | | /Sub-TLV | (RFC/Section) | | Point | | /Sub-TLV | (RFC/Section) |
+-----------+---------------------+--------------+----------------+ +-----------+---------------------+--------------+----------------+
| TBD |Remote AS Number | 24/21 | [RFC5316]/3.3.1| | TBD |Remote AS Number | 24/21 | [RFC5316]/3.3.1|
skipping to change at page 6, line 37 skipping to change at page 6, line 37
| | | | [RFC5392]/3.3.2| | | | | [RFC5392]/3.3.2|
| TBD |IPv6 Remote ASBR ID | 26/24 | [RFC5316]/3.3.3| | TBD |IPv6 Remote ASBR ID | 26/24 | [RFC5316]/3.3.3|
| | | | [RFC5392]/3.3.3| | | | | [RFC5392]/3.3.3|
+-----------+---------------------+--------------+----------------+ +-----------+---------------------+--------------+----------------+
Figure 3: Link Descriptor TLVs Figure 3: Link Descriptor TLVs
Detail encoding of these TLVs are synchronized with the corresponding Detail encoding of these TLVs are synchronized with the corresponding
parts in [RFC5316] and [RFC5392], which keeps the BGP-LS protocol is parts in [RFC5316] and [RFC5392], which keeps the BGP-LS protocol is
agnostic to the underly protocol. agnostic to the underly protocol.
5.1. Remote AS Number TLV 6.1. Remote AS Number TLV
A new TLV, the remote AS number TLV, is defined for inclusion in the A new TLV, the remote AS number TLV, is defined for inclusion in the
link descriptor when advertising inter-AS TE links. The remote AS link descriptor when advertising inter-AS TE links. The remote AS
number TLV specifies the AS number of the neighboring AS to which the number TLV specifies the AS number of the neighboring AS to which the
advertised link connects. advertised link connects.
The remote AS number TLV is TLV type TBD (see Section 8) and is 4 The remote AS number TLV is TLV type TBD (seeSection 9 ) and is 4
octets in length. The format is as follows: octets in length. The format is as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote AS Number | | Remote AS Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Remote AS Number TLV Format Figure 4: Remote AS Number TLV Format
The Remote AS number field has 4 octets. When only 2 octets are used The Remote AS number field has 4 octets. When only 2 octets are used
for the AS number, as in current deployments, the left (high-order) 2 for the AS number, as in current deployments, the left (high-order) 2
octets MUST be set to 0. The remote AS number TLV MUST be included octets MUST be set to 0. The remote AS number TLV MUST be included
when a router advertises an inter-AS TE link. when a router advertises an inter-AS TE link.
5.2. IPv4 Remote ASBR ID 6.2. IPv4 Remote ASBR ID
A new TLV, which is referred to as the IPv4 remote ASBR ID TLV, is A new TLV, which is referred to as the IPv4 remote ASBR ID TLV, is
defined for inclusion in the link descriptor when advertising inter- defined for inclusion in the link descriptor when advertising inter-
AS TE links. The IPv4 remote ASBR ID TLV specifies the IPv4 AS TE links. The IPv4 remote ASBR ID TLV specifies the IPv4
identifier of the remote ASBR to which the advertised inter-AS link identifier of the remote ASBR to which the advertised inter-AS link
connects. This could be any stable and routable IPv4 address of the connects. This could be any stable and routable IPv4 address of the
remote ASBR. Use of the TE Router ID as specified in the Traffic remote ASBR. Use of the TE Router ID as specified in the Traffic
Engineering router ID TLV [RFC5305] is RECOMMENDED. Engineering router ID TLV [RFC5305] is RECOMMENDED.
The IPv4 remote ASBR ID TLV is TLV type TBD (see Section 8) and is 4 The IPv4 remote ASBR ID TLV is TLV type TBD (see Section 9) and is 4
octets in length. The format of the IPv4 remote ASBR ID sub-TLV is octets in length. The format of the IPv4 remote ASBR ID sub-TLV is
as follows: as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID | | Remote ASBR ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: IPv4 Remote ASBR ID TLV Format Figure 5: IPv4 Remote ASBR ID TLV Format
The IPv4 remote ASBR ID TLV MUST be included if the neighboring ASBR The IPv4 remote ASBR ID TLV MUST be included if the neighboring ASBR
has an IPv4 address. If the neighboring ASBR does not have an IPv4 has an IPv4 address. If the neighboring ASBR does not have an IPv4
address (not even an IPv4 TE Router ID), the IPv6 remote ASBR ID TLV address (not even an IPv4 TE Router ID), the IPv6 remote ASBR ID TLV
MUST be included instead. An IPv4 remote ASBR ID TLV and IPv6 remote MUST be included instead. An IPv4 remote ASBR ID TLV and IPv6 remote
ASBR ID TLV MAY both be present in an inter-AS TE link NLRI. ASBR ID TLV MAY both be present in an inter-AS TE link NLRI.
5.3. IPv6 Remote ASBR ID 6.3. IPv6 Remote ASBR ID
A new TLV, which is referred to as the IPv6 remote ASBR ID TLV, is A new TLV, which is referred to as the IPv6 remote ASBR ID TLV, is
defined for inclusion in the link descriptor when advertising inter- defined for inclusion in the link descriptor when advertising inter-
AS links. The IPv6 remote ASBR ID TLV specifies the IPv6 identifier AS links. The IPv6 remote ASBR ID TLV specifies the IPv6 identifier
of the remote ASBR to which the advertised inter-AS link connects. of the remote ASBR to which the advertised inter-AS link connects.
This could be any stable and routable IPv6 address of the remote This could be any stable and routable IPv6 address of the remote
ASBR. Use of the TE Router ID as specified in the IPv6 Traffic ASBR. Use of the TE Router ID as specified in the IPv6 Traffic
Engineering router ID TLV [RFC6119] is RECOMMENDED. Engineering router ID TLV [RFC6119] is RECOMMENDED.
The IPv6 remote ASBR ID TLV is TLV type TBD (see Section 8) and is 16 The IPv6 remote ASBR ID TLV is TLV type TBD (see Section 9) and is 16
octets in length. The format of the IPv6 remote ASBR ID TLV is as octets in length. The format of the IPv6 remote ASBR ID TLV is as
follows: follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID | | Remote ASBR ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 8, line 34 skipping to change at page 8, line 34
| Remote ASBR ID (continued) | | Remote ASBR ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: IPv6 Remote ASBR ID TLV Format Figure 6: IPv6 Remote ASBR ID TLV Format
The IPv6 remote ASBR ID TLV MUST be included if the neighboring ASBR The IPv6 remote ASBR ID TLV MUST be included if the neighboring ASBR
has an IPv6 address. If the neighboring ASBR does not have an IPv6 has an IPv6 address. If the neighboring ASBR does not have an IPv6
address, the IPv4 remote ASBR ID TLV MUST be included instead. An address, the IPv4 remote ASBR ID TLV MUST be included instead. An
IPv4 remote ASBR ID TLV and IPv6 remote ASBR ID TLV MAY both be IPv4 remote ASBR ID TLV and IPv6 remote ASBR ID TLV MAY both be
present in an inter-AS TE link NLRI. present in an inter-AS TE link NLRI.
6. Topology Reconstruction. 7. Topology Reconstruction.
When SDN Controller gets such information from BGP-LS protocol, it When SDN Controller gets such information from BGP-LS protocol, it
should compares the proximity of these stub links. If they are under should compares the proximity of these stub links. If they are under
the same network scope, then it should find the corresponding the same network scope, then it should find the corresponding
associated router information, build the link between these two associated router information, build the link between these two
border routers. border routers.
After iterating the above procedures for all of the stub links, the After iterating the above procedures for all of the stub links, the
SDN controller can then retrieve the connection topology between SDN controller can then retrieve the connection topology between
different domains automatically. different domains automatically.
7. Security Considerations 8. Security Considerations
It is common for one operator to occupy several IGP domains that are It is common for one operator to occupy several IGP domains that are
composited by its backbone network and several MAN(Metrio-Area- composited by its backbone network and several MAN(Metrio-Area-
Network)s/IDCs. When they do traffic engineering which spans MAN, Network)s/Internet Data Centers (IDCs). When they do traffic
Backbone and IDC, they need to know the inter-as topology via the engineering which spans MAN, Backbone and IDC, they need to know the
process described in this draft. Using the passive interface inter-as topology via the process described in this draft. Using the
features or configuring the TE parameters on the interconnect links passive interface features or configuring the Traffic Engineering
will not spread the topology fluctuation across each other domain. (TE) parameters on the interconnect links will not spread the
topology fluctuation across each other domain.
8. IANA Considerations 9. IANA Considerations
This document defines: This document defines:
o A new BGP NLRI Type: Stub Link NLRI. The codepoint is from the o A new BGP NLRI Type: Stub Link NLRI. The codepoint is from the
"BGP-LS NLRI Types" "BGP-LS NLRI Types"
o Three new Link Descriptors TLV: Remote AS Number TLV, IPv4 Remote o Three new Link Descriptors TLV: Remote AS Number TLV, IPv4 Remote
ASBR ID, IPv6 Remote ASBR ID. The codepoint are from "BGP-LS Node ASBR ID, IPv6 Remote ASBR ID. The codepoint are from "BGP-LS Node
Descriptor, Link Descriptor, Prefix Descriptor, and Attribute Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
TLVs" registry. TLVs" registry.
8.1. New BGP-LS NLRI type 9.1. New BGP-LS NLRI type
This document defines a new value in the registry "BGP-LS NLRI This document defines a new value in the registry "BGP-LS NLRI
Types": Types":
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code Point | Description | Status | | Code Point | Description | Status |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD | Stub Link NLRI | Allocation from IANA | | TBD | Stub Link NLRI | Allocation from IANA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: Stub Link NLRI Codepoint Figure 7: Stub Link NLRI Codepoint
8.2. New Link Descriptors 9.2. New Link Descriptors
This document defines three new values in the registry "BGP-LS Node This document defines three new values in the registry "BGP-LS Node
Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs": Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs":
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code Point | Description | Status | | Code Point | Description | Status |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD | Remote AS Number | Allocation from IANA | | TBD | Remote AS Number | Allocation from IANA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD |IPv4 Remote ASBR ID| Allocation from IANA | | TBD |IPv4 Remote ASBR ID| Allocation from IANA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TBD |IPv6 Remote ASBR ID| Allocation from IANA | | TBD |IPv6 Remote ASBR ID| Allocation from IANA |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: BGP-LS Link Descriptors TLV Figure 8: BGP-LS Link Descriptors TLV
9. Acknowledgement 10. Acknowledgement
The author would like to thank Acee Lindem, Jie Dong, Jeff Tantsura The author would like to thank Acee Lindem, Jie Dong, Jeff Tantsura
and Dhruv Dhody for their valuable comments and suggestions. and Dhruv Dhody for their valuable comments and suggestions.
10. References 11. References
10.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <https://www.rfc-editor.org/info/rfc5305>. 2008, <https://www.rfc-editor.org/info/rfc5305>.
skipping to change at page 10, line 43 skipping to change at page 10, line 43
[RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic [RFC6119] Harrison, J., Berger, J., and M. Bartlett, "IPv6 Traffic
Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119, Engineering in IS-IS", RFC 6119, DOI 10.17487/RFC6119,
February 2011, <https://www.rfc-editor.org/info/rfc6119>. February 2011, <https://www.rfc-editor.org/info/rfc6119>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
10.2. Informative References 11.2. Informative References
[I-D.ietf-idr-bgpls-segment-routing-epe] [I-D.ietf-idr-bgpls-segment-routing-epe]
Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray, Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray,
S., and J. Dong, "BGP-LS extensions for Segment Routing S., and J. Dong, "BGP-LS extensions for Segment Routing
BGP Egress Peer Engineering", draft-ietf-idr-bgpls- BGP Egress Peer Engineering", draft-ietf-idr-bgpls-
segment-routing-epe-19 (work in progress), May 2019. segment-routing-epe-19 (work in progress), May 2019.
[I-D.ietf-teas-native-ip-scenarios] [I-D.ietf-teas-native-ip-scenarios]
Wang, A., Huang, X., Qou, C., Li, Z., and P. Mi, Wang, A., Huang, X., Qou, C., Li, Z., and P. Mi,
"Scenarios and Simulation Results of PCE in Native IP "Scenarios and Simulation Results of PCE in Native IP
skipping to change at page 11, line 19 skipping to change at page 11, line 19
progress), June 2019. progress), June 2019.
Authors' Addresses Authors' Addresses
Aijun Wang Aijun Wang
China Telecom China Telecom
Beiqijia Town, Changping District Beiqijia Town, Changping District
Beijing, Beijing 102209 Beijing, Beijing 102209
China China
Email: wangaj.bri@chinatelecom.cn Email: wangaj3@chinatelecom.cn
Huaimo Chen Huaimo Chen
Futurewei Futurewei
Boston, MA Boston, MA
USA USA
Email: hchen@futurewei.com Email: hchen@futurewei.com
Ketan Talaulikar Ketan Talaulikar
Cisco Systems Cisco Systems
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