draft-ietf-idr-bgpls-inter-as-topology-ext-01.txt   draft-ietf-idr-bgpls-inter-as-topology-ext-02.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: September 8, 2019 Huawei Technologies Expires: October 10, 2019 Huawei Technologies
S. Ma S. Ma
Juniper Networks Mellanox Technologies
March 7, 2019 April 8, 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-01 draft-ietf-idr-bgpls-inter-as-topology-ext-02
Abstract Abstract
This document describes the process to build BGP-LS key parameters in This document describes the process to build BGP-LS key parameters in
multi-domain scenario, defines one new BGP-LS NLRI type(Inter-AS TE multi-domain scenario, defines one new BGP-LS NLRI type(Stub Link
Link NLRI) and some new inter-AS TE related TLVs for BGP-LS to let NLRI) and some new inter-AS TE related TLVs for BGP-LS to let SDN
SDN controller retrieve the network topology automatically under controller retrieve the network topology automatically under various
various environments. environments.
Such process and extension can enable the network operator to collect Such process and extension can enable the network operator to collect
the connection 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.
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 September 8, 2019. This Internet-Draft will expire on October 10, 2019.
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
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 20 skipping to change at page 2, line 20
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. Inter-AS Domain Scenarios. . . . . . . . . . . . . . . . . . 3
3.1. IS-IS/OSPF Inter-AS Native IP Scenario . . . . . . . . . 4 4. Stub Link NLRI . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. IS-IS/OSPF Inter-AS TE Scenario . . . . . . . . . . . . . 5 4.1. Inter-AS Native IP Scenario . . . . . . . . . . . . . . . 4
4. Inter-AS TE Link NLRI . . . . . . . . . . . . . . . . . . . . 5 4.2. Inter-AS TE Scenario . . . . . . . . . . . . . . . . . . 4
5. Inter-AS TE NLRI related TLVs . . . . . . . . . . . . . . . . 5 5. Inter-AS TE NLRI related TLVs . . . . . . . . . . . . . . . . 5
5.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 6 5.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 5
5.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7 5.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 6
5.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7 5.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7
6. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 8 6. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8
10. Normative References . . . . . . . . . . . . . . . . . . . . 9 10. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
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 IGP domain.
If the operator has more than one IGP domain, and these domains If the operator has more than one IGP domain, and these domains
interconnect with each other, there is no general TLV within current interconnect with each other, there is no mechanic within current
BGP- LS to transfer the interconnect topology information. 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 PCE/SDN controller, which restricts the
solution deployment flexibility. solution deployment flexibility.
This draft analysis the situations that the PCE/SDN controller needs This draft analysis the situations that the PCE/SDN controller needs
to get the inter-connected topology information between different AS to get the interconnected topology information between different AS
domains, defines the new Inter-AS TE Link NLRI and some new TLVs domains, defines the new Stub Link NLRI and some new TLVs within the
within the BGP-LS protocol to transfer the key information related to BGP-LS protocol to transfer the key information related to them.
them. After that, the SDN controller can then deduce the multi- After that, the SDN controller can then deduce the multi-domain
domain topology automatically based on the information from BGP-LS topology automatically based on the information from BGP-LS protocol.
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. Inter-AS Domain Scenarios.
Fig.1 illustrates the multi-domain scenarios that this draft Fig.1 illustrates the multi-domain scenarios that this draft
discussed. 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 5 skipping to change at page 3, line 48
| +-++ +-++ ++-+ +-++ ++++ +-++| | +-++ +-++ ++-+ +-++ ++++ +-++|
| |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
3.1. IS-IS/OSPF Inter-AS Native IP Scenario 4. Stub Link NLRI
When the IGP A or IGP B runs native IS-IS/OSPF protocol, the operator
can redistributes the IPv4/IPv6 prefixes of interconnect links into
IS-IS/OSPF protocol to ensure the inter-domain connectivity.
If the IGP runs IS-IS protocol, the redistributed link information
will be carried in IP External Reachability Information TLV within
the Level 2 PDU type that defined in [RFC1195], every router within
the IGP domain can deduce the redistributed router from the IS-IS
LSDB.
If the IGP runs OSPF protocol[RFC2328]defines the type 5 external LSA [RFC7752] defines four NLRI types(Node NLRI, Link NLRI, IPv4 Topology
to transfer the external IPv4 routes; Prefix NLRI, IPv6 Topology Prefix NLRI) to transfer the topology and
[I-D.ietf-ospf-ospfv3-lsa-extend] defines the "External-Prefix TLV" prefix information. For inter-as link, the two ends of the link
to transfer the external IPv6 routes; these LSAs have also the locates in different IGP domains, then it is not appropriate to
advertising router information that initiates the redistribute transfer their information within the current defined NLRI types.
activity. Every router within IGP domain can also deduce the
redistributed router from the OSPF LSDB.
For prefix information that associated with each router, BGP-LS This draft defines one new NLRI type, called Stub Link NLRI, which is
[RFC7752] defines the Prefix NLRI which is illustrated below: coded as the following format:
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
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| Protocol-ID | | Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier | | Identifier |
| (64 bits) | | (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Local Node Descriptors (variable) // // Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Prefix Descriptors (variable) // // Inter-AS TE Link Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: The IPv4/IPv6 Topology Prefix NLRI Format Figure 2: The Inter-AS TE Link NLRI Format
For these redistributed inter-domain links, their prefix information The semantics of "Stub Link Descriptors" is same as that defined in
should be included in the "Prefix Descriptor", and the associated [RFC7752] for "Link Descriptor".
redistributed router information should be included in the "Local
Node Descriptors".
When such information is reported via the BGP-LS protocol, the PCE/ This newly defined NLRI can be used to describe the link that has
SDN controller can construct the underlay inter-domain topology only one end located within the IGP domain, as described in the
according to procedure described in section 6. following sections.
3.2. IS-IS/OSPF Inter-AS TE Scenario 4.1. Inter-AS Native IP Scenario
[RFC5316] and [RFC5392] define the IS-IS and OSPF extensions When IGP A or IGP B runs native IS-IS/OSPF protocol, the operator can
respectively to deal with the requirements for inter-AS traffic use passive feature for the inter-domain links to let the routers
engineering. They define some new sub-TLVs(Remote AS within the IGP domain know these links. Such stub links information
Number、IPv4 Remote ASBR ID、IPv6 Remote ASBR ID) which can then be carried within the Stub Link NLRI to be reported via the
are associated with the inter-AS TE link TLVs to report the TE BGP-LS protocol to the SDN controller.
topology between different domains.
These TLVs are flooded within the IGP domain automatically. If the The "Local Node Descriptors" should describe the the characteristics
PCE/SDN controller can know these information via one of the interior of ASBRs that are connected these stub links.
router that runs BGP-LS protocol, the PCE/SDN controller can rebuild
the inter-AS TE topology correctly.
4. Inter-AS TE Link NLRI When such information is reported via the BGP-LS protocol, the PCE/
SDN controller can construct the underlay inter-domain topology
according to procedure described in section 6.
[RFC7752] defines four NLRI types(Node NLRI, Link NLRI, IPv4 Topology 4.2. Inter-AS TE Scenario
Prefix NLRI, IPv6 Topology Prefix NLRI) to transfer the topology and
prefix information. For inter-as TE link, the two ends of the link
locates in different IGP domains, then it is not appropriate to
transfer their information within the current defined NLRI types.
This draft defines then one new NLRI type, called Inter-AS TE Link When IGP A or IGP B run IS-IS TE/OSPF-TE protocol, [RFC5316] and
NLRI, which is coded as the following format: [RFC5392] define the IS-IS and OSPF extensions respectively to deal
with the situation for inter-AS traffic engineering. Three new sub-
TLVs(Remote AS Number、IPv4 Remote ASBR ID、IPv6 Remote
ASBR ID) which are associated with the inter-AS TE link are defined.
0 1 2 3 These TLVs are flooded within the IGP domain automatically. They can
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 also be carried within the newly defined Stub Link NLRI within the
+-+-+-+-+-+-+-+-+ BGP-LS protocol, as the descriptors for the inter-AS stub link.
| Protocol-ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Identifier |
| (64 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Local Node Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Inter-AS TE Link Descriptors (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: The Inter-AS TE Link NLRI Format The "Local Node Descriptors" should describe the the characteristics
of ASBRs that are connected these inter-AS TE links.
The semantics of "Inter-AS TE Link Descriptors" is same as that If the PCE/SDN controller know these information via one of the
defined in [RFC7752] for "Link Descriptor". interior router that runs BGP-LS protocol, the PCE/SDN controller can
rebuild the inter-AS TE topology correctly according to the procedure
described in section 6
5. Inter-AS TE NLRI related TLVs 5. 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
inter-AS TE Link NLRI to transfer the information via BGP-LS, which Stub Link NLRI to transfer the information via BGP-LS, which are
are required to build the inter-AS related topology by the PCE/SDN required to build the inter-AS TE related topology by the PCE/SDN
controller. controller.
The following Link Descriptor TLVs are added into the Inter-AS TE The following Link Descriptor TLVs are added into the BGP-LS protocol
Link NLRI in 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|
| | | | [RFC5392]/3.3.1| | | | | [RFC5392]/3.3.1|
| TBD |IPv4 Remote ASBR ID | 25/22 | [RFC5316]/3.3.2| | TBD |IPv4 Remote ASBR ID | 25/22 | [RFC5316]/3.3.2|
| | | | [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 4: Link Descriptor TLVs for Inter-AS TE Link NLRI Format 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 5.1. 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 7) and is 4 The remote AS number TLV is TLV type TBD (see Section 8) 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 5: 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 5.2. 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 7) and is 4 The IPv4 remote ASBR ID TLV is TLV type TBD (see Section 8) 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 6: 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 5.3. 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 inter-AS reachability TLV when defined for inclusion in the inter-AS reachability TLV when
advertising inter-AS links. The IPv6 remote ASBR ID TLV specifies advertising inter-AS links. The IPv6 remote ASBR ID TLV specifies
the IPv6 identifier of the remote ASBR to which the advertised inter- the IPv6 identifier of the remote ASBR to which the advertised inter-
AS link connects. This could be any stable and routable IPv6 address AS link connects. This could be any stable and routable IPv6 address
of the remote ASBR. Use of the TE Router ID as specified in the IPv6 of the remote ASBR. Use of the TE Router ID as specified in the IPv6
Traffic Engineering router ID TLV [RFC6119] is RECOMMENDED. Traffic Engineering router ID TLV [RFC6119] is RECOMMENDED.
The IPv6 remote ASBR ID TLV is TLV type TBD (see Section 7) and is 16 The IPv6 remote ASBR ID TLV is TLV type TBD (see Section 8) 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote ASBR ID (continued) | | Remote ASBR ID (continued) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: 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. 6. 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 the redistributed prefixes. If they should compares the proximity of these stub links. If they are under
are under the same network scope, then it should find the the same network scope, then it should find the corresponding
corresponding associated router information, build the link between associated router information, build the link between these two
these two border routers. border routers.
After iterating the above procedures for all of the redistributed After iterating the above procedures for all of the stub links, the
prefixes, the SDN controller can then retrieve the connection SDN controller can then retrieve the connection topology between
topology between different domains automatically. different domains automatically.
7. Security Considerations 7. 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 from end to end Network)s/IDCs. When they do traffic engineering which spans MAN-
that spans MAN-backbone-IDC, they need to know the inter-as topology backbone-IDC, they need to know the inter-as topology via the process
via the process described in this draft. Then it is naturally to described in this draft. Using the passive interface features or
redistribute the interconnection prefixes in Native IP scenario. configuring the TE parameters on the interconnect links will not
spread the topology fluctuation across each other domain.
If these IGP domains belong to different operators, it is uncommon do
inter-as traffic engineering under one PCE/SDN controller, then it is
unnecessary to get the inter-as topology. But redistributing the
interconnection prefixes will do no harm to their networks, because
the redistributed interconnection link prefixes belongs to both of
them, they are also the interfaces addresses on the border routers. .
8. IANA Considerations 8. IANA Considerations
TBD. TBD.
9. Acknowledgement 9. Acknowledgement
The author would like to thank Acee Lindem, Ketan Talaulikar, Jie The author would like to thank Acee Lindem, Ketan Talaulikar, Jie
Dong, Jeff Tantsura and Dhruv Dhody for their valuable comments and Dong, Jeff Tantsura and Dhruv Dhody for their valuable comments and
suggestions. suggestions.
10. Normative References 10. Normative References
[I-D.ietf-idr-bgp-ls-segment-routing-ext] [I-D.ietf-idr-bgp-ls-segment-routing-ext]
Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H., Previdi, S., Talaulikar, K., Filsfils, C., Gredler, H.,
and M. Chen, "BGP Link-State extensions for Segment and M. Chen, "BGP Link-State extensions for Segment
Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-11 Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-12
(work in progress), October 2018. (work in progress), March 2019.
[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-17 (work in progress), October 2018. segment-routing-epe-18 (work in progress), March 2019.
[I-D.ietf-ospf-ospfv3-lsa-extend] [I-D.ietf-ospf-ospfv3-lsa-extend]
Lindem, A., Roy, A., Goethals, D., Vallem, V., and F. Lindem, A., Roy, A., Goethals, D., Vallem, V., and F.
Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3- Baker, "OSPFv3 LSA Extendibility", draft-ietf-ospf-ospfv3-
lsa-extend-23 (work in progress), January 2018. lsa-extend-23 (work in progress), January 2018.
[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,
"Scenario, Simulation and Suggestion of PCE in Native IP "Scenario, Simulation and Suggestion of PCE in Native IP
Network", draft-ietf-teas-native-ip-scenarios-02 (work in Network", draft-ietf-teas-native-ip-scenarios-02 (work in
skipping to change at page 10, line 40 skipping to change at page 10, line 4
U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4 U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794, and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
March 2016, <https://www.rfc-editor.org/info/rfc7794>. March 2016, <https://www.rfc-editor.org/info/rfc7794>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and [RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA) F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>. 2018, <https://www.rfc-editor.org/info/rfc8362>.
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: wangaj.bri@chinatelecom.cn
Huaimo Chen Huaimo Chen
Huawei Technologies Huawei Technologies
Boston, MA Boston, MA
USA USA
Email: Huaimo.chen@huawei.com Email: Huaimo.chen@huawei.com
Shaowen Ma Shaowen Ma
Juniper Networks Mellanox Technologies
Email: mashao@juniper.net Email: mashaowen@gmail.com
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