draft-ietf-idr-bgpls-inter-as-topology-ext-00.txt   draft-ietf-idr-bgpls-inter-as-topology-ext-01.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: April 24, 2019 Huawei Technologies Expires: September 8, 2019 Huawei Technologies
October 21, 2018 S. Ma
Juniper Networks
March 7, 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-00 draft-ietf-idr-bgpls-inter-as-topology-ext-01
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
Native IP multi-domain scenario and defines some new inter-AS TE multi-domain scenario, defines one new BGP-LS NLRI type(Inter-AS TE
related TLVs for BGP-LS to let SDN controller retrieve the network Link NLRI) and some new inter-AS TE related TLVs for BGP-LS to let
topology automatically under various environments. SDN controller retrieve the network topology automatically under
various environments.
Such process and extension can expand the usage of BGP-LS protocol to Such process and extension can enable the network operator to collect
multi- domain, enable the network operator to collect the connection the connection information between different domains and then
relationship between different AS domains and then calculate the calculate the overall network topology automatically based on the
overall network topology automatically based on the information information provided by BGP-LS protocol.
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 April 24, 2019. This Internet-Draft will expire on September 8, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 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.
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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 . . . . . . . . . 3 3.1. IS-IS/OSPF Inter-AS Native IP Scenario . . . . . . . . . 4
3.2. IS-IS/OSPF Inter-AS TE Scenario . . . . . . . . . . . . . 4 3.2. IS-IS/OSPF Inter-AS TE Scenario . . . . . . . . . . . . . 5
4. Inter-AS TE related TLVs . . . . . . . . . . . . . . . . . . 5 4. Inter-AS TE Link NLRI . . . . . . . . . . . . . . . . . . . . 5
4.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 5 5. Inter-AS TE NLRI related TLVs . . . . . . . . . . . . . . . . 5
4.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 6 5.1. Remote AS Number TLV . . . . . . . . . . . . . . . . . . 6
4.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 6 5.2. IPv4 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7
5. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 7 5.3. IPv6 Remote ASBR ID . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 6. Topology Reconstruction. . . . . . . . . . . . . . . . . . . 8
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 8 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
9. Normative References . . . . . . . . . . . . . . . . . . . . 8 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 10. Normative References . . . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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 general TLV within current
BGP- LS to transfer the interconnect 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 to collect but it requires the border routers to run BGP-LS protocol and report
this information and report them to the PCE/SDN controller, which the information to the PCE/SDN controller, which restricts the
restricts the deployment flexibility of BGP-LS protocol. solution deployment flexibility.
This draft analysizes the situations that the PCE/SDN controller This draft analysis the situations that the PCE/SDN controller needs
needs to get about the inter-connected information between different to get the inter-connected topology information between different AS
AS domains, defines new TLVs to extend the BGP-LS protocol to domains, defines the new Inter-AS TE Link NLRI and some new TLVs
transfer the key information related to the interconnect TE topology. within the BGP-LS protocol to transfer the key information related to
After that, the SDN controller can then deduce the multi-domain them. After that, the SDN controller can then deduce the multi-
topology automatically based on the information from BGP-LS protocol. domain 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. Inter-AS Domain Scenarios.
Fig.1 illustrates the multi-domain scenarios that this draft Fig.1 illustrates the multi-domain scenarios that this draft
skipping to change at page 3, line 47 skipping to change at page 4, line 8
| | | | | | | |
| | | | | | | |
| 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 3.1. IS-IS/OSPF Inter-AS Native IP Scenario
When the IGP A or IGP B runs native IS-IS/OSPF protocol, the operator When the IGP A or IGP B runs native IS-IS/OSPF protocol, the operator
often redistributes the IPv4/IPv6 prefixes of interconnect links into can redistributes the IPv4/IPv6 prefixes of interconnect links into
IS-IS/OSPF protocol to ensure the inter-domain connectivity. IS-IS/OSPF protocol to ensure the inter-domain connectivity.
If the IGP runs IS-IS protocol, the redistributed link information If the IGP runs IS-IS protocol, the redistributed link information
will be carried in IP External Reachability Information TLV within will be carried in IP External Reachability Information TLV within
the Level 2 PDU type that defined in [RFC1195], every router 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 the IGP domain can deduce the redistributed router from the IS-IS
LSDB. LSDB.
If the IGP runs OSPF protocol,[RFC2328]defines the type 5 external If the IGP runs OSPF protocol[RFC2328]defines the type 5 external LSA
LSA to transfer the external IPv4 routes; to transfer the external IPv4 routes;
[I-D.ietf-ospf-ospfv3-lsa-extend] defines the "External-Prefix TLV" [I-D.ietf-ospf-ospfv3-lsa-extend] defines the "External-Prefix TLV"
to transfer the external IPv6 routes; these LSAs have also the to transfer the external IPv6 routes; these LSAs have also the
advertising router information that initiates the redistribute advertising router information that initiates the redistribute
activity. Every router within IGP domain can also deduce the activity. Every router within IGP domain can also deduce the
redistributed router from the OSPF LSDB. redistributed router from the OSPF LSDB.
For prefix information that associated with each router, BGP-LS For prefix information that associated with each router, BGP-LS
[RFC7752] defines the Prefix NLRI which is illustrated below: [RFC7752] defines the Prefix NLRI which is illustrated below:
0 1 2 3 0 1 2 3
skipping to change at page 4, line 41 skipping to change at page 4, line 50
Figure 2: The IPv4/IPv6 Topology Prefix NLRI Format Figure 2: The IPv4/IPv6 Topology Prefix NLRI Format
For these redistributed inter-domain links, their prefix information For these redistributed inter-domain links, their prefix information
should be included in the "Prefix Descriptor", and the associated should be included in the "Prefix Descriptor", and the associated
redistributed router information should be included in the "Local redistributed router information should be included in the "Local
Node Descriptors". Node Descriptors".
When such information is reported via the BGP-LS protocol, the PCE/ When such information is reported via the BGP-LS protocol, the PCE/
SDN controller can construct the underlay inter-domain topology SDN controller can construct the underlay inter-domain topology
according to procedure described in section 5 according to procedure described in section 6.
3.2. IS-IS/OSPF Inter-AS TE Scenario 3.2. IS-IS/OSPF Inter-AS TE Scenario
[RFC5316] and [RFC5392] define the IS-IS and OSPF extensions [RFC5316] and [RFC5392] define the IS-IS and OSPF extensions
respectively to deal with the requirements for inter-AS traffic respectively to deal with the requirements for inter-AS traffic
engineering. They define some new sub-TLVs(Remote AS engineering. They define some new sub-TLVs(Remote AS
Number、IPv4 Remote ASBR ID、IPv6 Remote ASBR ID) which Number、IPv4 Remote ASBR ID、IPv6 Remote ASBR ID) which
are associated with the inter-AS TE link TLVs to report the TE are associated with the inter-AS TE link TLVs to report the TE
topology between different domains. topology between different domains.
These TLVs are flooded within the IGP domain automatically. If the These TLVs are flooded within the IGP domain automatically. If the
PCE/SDN controller can know these information via one of the interior PCE/SDN controller can know these information via one of the interior
router that runs BGP-LS protocol, the PCE/SDN controller can rebuild router that runs BGP-LS protocol, the PCE/SDN controller can rebuild
the inter-AS TE topology correctly. the inter-AS TE topology correctly.
4. Inter-AS TE related TLVs 4. Inter-AS TE Link NLRI
[RFC7752] defines four NLRI types(Node NLRI, Link NLRI, IPv4 Topology
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
NLRI, which is coded as the following format:
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
+-+-+-+-+-+-+-+-+
| 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 semantics of "Inter-AS TE Link Descriptors" is same as that
defined in [RFC7752] for "Link Descriptor".
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 inter-AS TE Link NLRI to transfer the information via BGP-LS, which
are required to build the inter-AS related topology by the PCE/SDN are required to build the inter-AS related topology by the PCE/SDN
controller. controller.
The following Link Descriptor TLVs are added into the Link NLRI in The following Link Descriptor TLVs are added into the Inter-AS TE
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
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.
4.1. 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 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 7) 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
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.
4.2. 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 links. The IPv4 remote ASBR ID TLV specifies the IPv4 identifier AS TE links. The IPv4 remote ASBR ID TLV specifies the IPv4
of the remote ASBR to which the advertised inter-AS link connects. identifier of the remote ASBR to which the advertised inter-AS link
This could be any stable and routable IPv4 address of the remote connects. This could be any stable and routable IPv4 address of the
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 7) 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
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.
4.3. 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 7) and is 16
skipping to change at page 7, line 18 skipping to change at page 8, line 18
| 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
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.
5. 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 the redistributed prefixes. If they
are under the same network scope, then it should find the are under the same network scope, then it should find the
corresponding associated router information, build the link between corresponding associated router information, build the link between
these two border routers. these two border routers.
After iterating the above procedures for all of the redistributed After iterating the above procedures for all of the redistributed
prefixes, the SDN controller can then retrieve the connection prefixes, the SDN controller can then retrieve the connection
topology between different domains automatically. topology between different domains automatically.
6. Security Considerations 7. Security Considerations
It is common for one operator to occupy several IGP domains that 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 from end to end
that spans MAN-backbone-IDC, they need to know the inter-as topology that spans MAN-backbone-IDC, they need to know the inter-as topology
via the process described in this draft. Then it is naturally to via the process described in this draft. Then it is naturally to
redistribute the interconnection prefixes in Native IP scenario. redistribute the interconnection prefixes in Native IP scenario.
If these IGP domains belong to different operators, it is uncommon do If these IGP domains belong to different operators, it is uncommon do
inter-as traffic engineering under one PCE/SDN controller, then it is inter-as traffic engineering under one PCE/SDN controller, then it is
unnecessary to get the inter-as topology. But redistributing the unnecessary to get the inter-as topology. But redistributing the
interconnection prefixes will do no harm to their networks, because interconnection prefixes will do no harm to their networks, because
the redistributed interconnection link prefixes belongs to both of the redistributed interconnection link prefixes belongs to both of
them, they are also the interfaces addresses on the border routers. . them, they are also the interfaces addresses on the border routers. .
7. IANA Considerations 8. IANA Considerations
TBD. TBD.
8. 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.
9. 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-08 Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-11
(work in progress), May 2018. (work in progress), October 2018.
[I-D.ietf-idr-bgpls-segment-routing-epe] [I-D.ietf-idr-bgpls-segment-routing-epe]
Previdi, S., Filsfils, C., Patel, K., Ray, S., and J. Previdi, S., Talaulikar, K., Filsfils, C., Patel, K., Ray,
Dong, "BGP-LS extensions for Segment Routing BGP Egress S., and J. Dong, "BGP-LS extensions for Segment Routing
Peer Engineering", draft-ietf-idr-bgpls-segment-routing- BGP Egress Peer Engineering", draft-ietf-idr-bgpls-
epe-15 (work in progress), March 2018. segment-routing-epe-17 (work in progress), October 2018.
[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., Huang, L., and P. Wang, A., Huang, X., Qou, C., Li, Z., and P. Mi,
Mi, "CCDR Scenario, Simulation and Suggestion", draft- "Scenario, Simulation and Suggestion of PCE in Native IP
ietf-teas-native-ip-scenarios-01 (work in progress), June Network", draft-ietf-teas-native-ip-scenarios-02 (work in
2018. progress), October 2018.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195, dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <https://www.rfc-editor.org/info/rfc1195>. December 1990, <https://www.rfc-editor.org/info/rfc1195>.
[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>.
skipping to change at line 433 skipping to change at page 11, line 10
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
Juniper Networks
Email: mashao@juniper.net
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