< draft-ietf-idr-bgpls-segment-routing-epe-18.txt   draft-ietf-idr-bgpls-segment-routing-epe-19.txt >
Inter-Domain Routing S. Previdi Inter-Domain Routing S. Previdi
Internet-Draft Individual Internet-Draft Individual
Intended status: Standards Track K. Talaulikar, Ed. Intended status: Standards Track K. Talaulikar, Ed.
Expires: September 25, 2019 C. Filsfils Expires: November 17, 2019 C. Filsfils
Cisco Systems, Inc. Cisco Systems, Inc.
K. Patel K. Patel
Arrcus, Inc. Arrcus, Inc.
S. Ray S. Ray
Individual Contributor Individual Contributor
J. Dong J. Dong
Huawei Technologies Huawei Technologies
March 24, 2019 May 16, 2019
BGP-LS extensions for Segment Routing BGP Egress Peer Engineering BGP-LS extensions for Segment Routing BGP Egress Peer Engineering
draft-ietf-idr-bgpls-segment-routing-epe-18 draft-ietf-idr-bgpls-segment-routing-epe-19
Abstract Abstract
Segment Routing (SR) leverages source routing. A node steers a Segment Routing (SR) leverages source routing. A node steers a
packet through a controlled set of instructions, called segments, by packet through a controlled set of instructions, called segments, by
prepending the packet with an SR header. A segment can represent any prepending the packet with an SR header. A segment can represent any
instruction, topological or service-based. SR segments allow instruction, topological or service-based. SR segments allow
steering a flow through any topological path and service chain while steering a flow through any topological path and service chain while
maintaining per-flow state only at the ingress node of the SR domain. maintaining per-flow state only at the ingress node of the SR domain.
This document describes an extension to BGP Link State (BGP-LS) for This document describes an extension to BGP Link-State (BGP-LS) for
advertisement of BGP Peering Segments along with their BGP peering advertisement of BGP Peering Segments along with their BGP peering
node information so that efficient BGP Egress Peer Engineering (EPE) node information so that efficient BGP Egress Peer Engineering (EPE)
policies and strategies can be computed based on Segment Routing. policies and strategies can be computed based on Segment Routing.
Requirements Language Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
skipping to change at page 2, line 10 skipping to change at page 2, line 10
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 25, 2019. This Internet-Draft will expire on November 17, 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 3, line 27 skipping to change at page 3, line 27
o Peer Node Segment (PeerNode SID) : instruction to steer to a o Peer Node Segment (PeerNode SID) : instruction to steer to a
specific peer node specific peer node
o Peer Adjacency Segment (PeerAdj SID) : instruction to steer over a o Peer Adjacency Segment (PeerAdj SID) : instruction to steer over a
specific local interface towards a specific peer node specific local interface towards a specific peer node
o Peer Set Segment (PeerSet SID) : instruction to load-balance to a o Peer Set Segment (PeerSet SID) : instruction to load-balance to a
set of specific peer nodes set of specific peer nodes
SR can be directly applied to either an MPLS dataplane (SR/MPLS) with SR can be directly applied to either to an MPLS dataplane (SR/MPLS)
no change on the forwarding plane or to a modified IPv6 forwarding with no change on the forwarding plane or to a modified IPv6
plane (SRv6). forwarding plane (SRv6).
This document describes extensions to the BGP Link State NLRI (BGP-LS This document describes extensions to the BGP Link-State NLRI (BGP-LS
NLRI) and the BGP-LS Attribute defined for BGP-LS [RFC7752] for NLRI) and the BGP-LS Attribute defined for BGP-LS [RFC7752] for
advertising BGP peering segments from a BGP node along with its advertising BGP peering segments from a BGP node along with its
peering topology information (i.e. its peers, interfaces, and peering peering topology information (i.e., its peers, interfaces, and
ASs) to enable computation of efficient BGP Egress Peer Engineering peering ASs) to enable computation of efficient BGP Egress Peer
(BGP-EPE) policies and strategies using the SR/MPLS dataplane. The Engineering (BGP-EPE) policies and strategies using the SR/MPLS
corresponding extensions for SRv6 are specified in dataplane. The corresponding extensions for SRv6 are specified in
[I-D.dawra-idr-bgpls-srv6-ext]. [I-D.dawra-idr-bgpls-srv6-ext].
[I-D.ietf-spring-segment-routing-central-epe] illustrates a [I-D.ietf-spring-segment-routing-central-epe] illustrates a
centralized controller based BGP Egress Peer Engineering solution centralized controller-based BGP Egress Peer Engineering solution
involving SR path computation using the BGP Peering Segments. This involving SR path computation using the BGP Peering Segments. This
use-case comprises of a centralized controller that learns the BGP use case comprises a centralized controller that learns the BGP
Peering SIDs via BGP-LS and then uses this information to program a Peering SIDs via BGP-LS and then uses this information to program a
BGP-EPE policy at any node in the domain to perform traffic steering BGP-EPE policy at any node in the domain to perform traffic steering
via a specific BGP egress node to a specific EBGP peer(s) optionally via a specific BGP egress node to a specific EBGP peer(s) optionally
also over a specific interface. The BGP-EPE policy can be realized also over a specific interface. The BGP-EPE policy can be realized
using the SR Policy framework using the SR Policy framework
[I-D.ietf-spring-segment-routing-policy]. [I-D.ietf-spring-segment-routing-policy].
This document introduces a new BGP-LS Protocol-ID for BGP and defines This document introduces a new BGP-LS Protocol-ID for BGP and defines
new BGP-LS Node and Link Descriptor TLVs to facilitate advertising new BGP-LS Node and Link Descriptor TLVs to facilitate advertising
BGP-LS Link NLRI to represent the BGP peering topology. Further, it BGP-LS Link NLRI to represent the BGP peering topology. Further, it
specifies the BGP-LS Attribute TLVs for advertisement of the BGP specifies the BGP-LS Attribute TLVs for advertisement of the BGP
Peering Segments (i.e. PeerNode SID, PeerAdj SID, and PeerSet SID) Peering Segments (i.e., PeerNode SID, PeerAdj SID, and PeerSet SID)
to be advertised in the same BGP-LS Link NLRI. to be advertised in the same BGP-LS Link NLRI.
2. BGP Peering Segments 2. BGP Peering Segments
As described in [RFC8402], a BGP-EPE enabled Egress PE node As described in [RFC8402], a BGP-EPE enabled Egress PE node
instantiates SR Segments corresponding to its attached peers. These instantiates SR Segments corresponding to its attached peers. These
segments are called BGP Peering Segments or BGP Peering SIDs. In segments are called BGP Peering Segments or BGP Peering SIDs. In
case of EBGP, they enable the expression of source-routed inter- case of EBGP, they enable the expression of source-routed inter-
domain paths. domain paths.
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Any BGP Peering SIDs instantiated on the node are advertised via BGP- Any BGP Peering SIDs instantiated on the node are advertised via BGP-
LS Link NLRI type as described in the sections below. An LS Link NLRI type as described in the sections below. An
illustration of the BGP Peering SIDs' allocations in a reference BGP illustration of the BGP Peering SIDs' allocations in a reference BGP
peering topology along with the information carried in the BGP-LS peering topology along with the information carried in the BGP-LS
Link NLRI and its corresponding BGP-LS Attribute are described in Link NLRI and its corresponding BGP-LS Attribute are described in
[I-D.ietf-spring-segment-routing-central-epe]. [I-D.ietf-spring-segment-routing-central-epe].
3. BGP-LS NLRI Advertisement for BGP Protocol 3. BGP-LS NLRI Advertisement for BGP Protocol
his section describes the BGP-LS NLRI encodings that describe the BGP This section describes the BGP-LS NLRI encodings that describe the
peering and link connectivity between BGP routers. BGP peering and link connectivity between BGP routers.
This document specifies the advertisement of BGP peering topology This document specifies the advertisement of BGP peering topology
information via BGP-LS Link NLRI type which requires use of a new information via BGP-LS Link NLRI type which requires use of a new
BGP-LS Protocol-ID. BGP-LS Protocol-ID.
+-------------+----------------------------------+ +-------------+----------------------------------+
| Protocol-ID | NLRI information source protocol | | Protocol-ID | NLRI information source protocol |
+-------------+----------------------------------+ +-------------+----------------------------------+
| 7 | BGP | | 7 | BGP |
+-------------+----------------------------------+ +-------------+----------------------------------+
skipping to change at page 7, line 5 skipping to change at page 7, line 5
Member-AS Number [RFC5065]. Member-AS Number [RFC5065].
3.2. Mandatory BGP Node Descriptors 3.2. Mandatory BGP Node Descriptors
The following Node Descriptors TLVs MUST be included in BGP-LS NLRI The following Node Descriptors TLVs MUST be included in BGP-LS NLRI
as Local Node Descriptors when distributing BGP information: as Local Node Descriptors when distributing BGP information:
o BGP Router-ID (TLV 516), which contains a valid BGP Identifier of o BGP Router-ID (TLV 516), which contains a valid BGP Identifier of
the local BGP node. the local BGP node.
o Autonomous System Number (TLV 512), which contains the ASN or AS o Autonomous System Number (TLV 512) [RFC7752], which contains the
Confederation Identifier (ASN) [RFC5065], if confederations are ASN or AS Confederation Identifier (ASN) [RFC5065], if
used, of the local BGP node. confederations are used, of the local BGP node.
Note that [RFC6286] (section 2.1) requires the BGP identifier Note that [RFC6286] (section 2.1) requires the BGP identifier
(Router-ID) to be unique within an Autonomous System and non-zero. (Router-ID) to be unique within an Autonomous System and non-zero.
Therefore, the <ASN, BGP Router-ID> tuple is globally unique. Their Therefore, the <ASN, BGP Router-ID> tuple is globally unique. Their
use in the Node Descriptor helps map Link-State NLRIs with BGP use in the Node Descriptor helps map Link-State NLRIs with BGP
protocol-ID to a unique BGP router in the administrative domain where protocol-ID to a unique BGP router in the administrative domain where
BGP-LS is enabled. BGP-LS is enabled.
The following Node Descriptors TLVs MUST be included in BGP-LS Link The following Node Descriptors TLVs MUST be included in BGP-LS Link
NLRI as Remote Node Descriptors when distributing BGP information: NLRI as Remote Node Descriptors when distributing BGP information:
o BGP Router-ID (TLV 516), which contains the valid BGP Identifier o BGP Router-ID (TLV 516), which contains the valid BGP Identifier
of the peer BGP node. of the peer BGP node.
o Autonomous System Number (TLV 512), which contains the ASN or the o Autonomous System Number (TLV 512) [RFC7752], which contains the
AS Confederation Identifier (ASN) [RFC5065], if confederations are ASN or the AS Confederation Identifier (ASN) [RFC5065], if
used, of the peer BGP node. confederations are used, of the peer BGP node.
3.3. Optional BGP Node Descriptors 3.3. Optional BGP Node Descriptors
The following Node Descriptors TLVs MAY be included in BGP-LS NLRI as The following Node Descriptors TLVs MAY be included in BGP-LS NLRI as
Local Node Descriptors when distributing BGP information: Local Node Descriptors when distributing BGP information:
o Member-ASN (TLV 517), which contains the ASN of the confederation o Member-ASN (TLV 517), which contains the ASN of the confederation
member (i.e. Member-AS Number), if BGP confederations are used, member (i.e., Member-AS Number), if BGP confederations are used,
of the local BGP node. of the local BGP node.
o Node Descriptors as defined in [RFC7752]. o Node Descriptors as defined in [RFC7752].
The following Node Descriptors TLVs MAY be included in BGP-LS Link The following Node Descriptors TLVs MAY be included in BGP-LS Link
NLRI as Remote Node Descriptors when distributing BGP information: NLRI as Remote Node Descriptors when distributing BGP information:
o Member-ASN (TLV 517), which contains the ASN of the confederation o Member-ASN (TLV 517), which contains the ASN of the confederation
member (i.e. Member-AS Number), if BGP confederations are used, member (i.e., Member-AS Number), if BGP confederations are used,
of the peer BGP node. of the peer BGP node.
o Node Descriptors as defined in [RFC7752]. o Node Descriptors as defined in [RFC7752].
4. BGP-LS Attributes for BGP Peering Segments 4. BGP-LS Attributes for BGP Peering Segments
This section defines the BGP-LS Attributes corresponding to the This section defines the BGP-LS Attributes corresponding to the
following BGP Peer Segment SIDs: following BGP Peer Segment SIDs:
Peer Node Segment Identifier (PeerNode SID) Peer Node Segment Identifier (PeerNode SID)
Peer Adjacency Segment Identifier (PeerAdj SID) Peer Adjacency Segment Identifier (PeerAdj SID)
Peer Set Segment Identifier (PeerSet SID) Peer Set Segment Identifier (PeerSet SID)
The following new BGP-LS Link attributes TLVs are defined for use The following new BGP-LS Link attributes TLVs are defined for use
with BGP-LS Link NLRI for advertising BGP Peering SIDs: with BGP-LS Link NLRI for advertising BGP Peering SIDs:
+----------+---------------------------+----------+ +----------+---------------------------+
| TLV Code | Description | Length | | TLV Code | Description |
| Point | | | | Point | |
+----------+---------------------------+----------+ +----------+---------------------------+
| 1101 | PeerNode SID | variable | | 1101 | PeerNode SID |
| 1102 | PeerAdj SID | variable | | 1102 | PeerAdj SID |
| 1103 | PeerSet SID | variable | | 1103 | PeerSet SID |
+----------+---------------------------+----------+ +----------+---------------------------+
Figure 2: BGP-LS TLV code points for BGP-EPE Figure 2: BGP-LS TLV code points for BGP-EPE
PeerNode SID, PeerAdj SID, and PeerSet SID have all the same format PeerNode SID, PeerAdj SID, and PeerSet SID have all the same format
defined here below: defined here below:
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 |
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SHOULD be persistent across router restart. SHOULD be persistent across router restart.
When enabled for Egress Peer Engineering, the BGP router MUST include When enabled for Egress Peer Engineering, the BGP router MUST include
the PeerNode SID TLV in the BGP-LS Attribute for the BGP-LS Link NLRI the PeerNode SID TLV in the BGP-LS Attribute for the BGP-LS Link NLRI
corresponding to its BGP peering sessions. The PeerAdj SID and corresponding to its BGP peering sessions. The PeerAdj SID and
PeerSet SID TLVs MAY be included in the BGP-LS Attribute for the BGP- PeerSet SID TLVs MAY be included in the BGP-LS Attribute for the BGP-
LS Link NLRI. LS Link NLRI.
Additional BGP-LS Link Attribute TLVs, as defined in [RFC7752] MAY be Additional BGP-LS Link Attribute TLVs, as defined in [RFC7752] MAY be
included with the BGP-LS Link NLRI in order to advertise the included with the BGP-LS Link NLRI in order to advertise the
characteristics of the peering link. characteristics of the peering link. E.g., one or more interface
addresses (TLV 259 or TLV 261) of the underlying link(s) over which a
multi-hop BGP peering session is setup may be included in the BGP-LS
Attribute along with the PeerNode SID TLV.
4.1. Advertisement of the PeerNode SID 4.1. Advertisement of the PeerNode SID
The PeerNode SID TLV includes a SID associated with the BGP peer node The PeerNode SID TLV includes a SID associated with the BGP peer node
that is described by a BGP-LS Link NLRI as specified in Section 3. that is described by a BGP-LS Link NLRI as specified in Section 3.
The PeerNode SID, at the BGP node advertising it, has the following The PeerNode SID, at the BGP node advertising it, has the following
semantics (as defined in [RFC8402]): semantics (as defined in [RFC8402]):
o SR operation: NEXT. o SR operation: NEXT.
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The PeerNode SID is advertised with a BGP-LS Link NLRI, where: The PeerNode SID is advertised with a BGP-LS Link NLRI, where:
o Local Node Descriptors include: o Local Node Descriptors include:
* Local BGP Router-ID (TLV 516) of the BGP-EPE enabled egress PE. * Local BGP Router-ID (TLV 516) of the BGP-EPE enabled egress PE.
* Local ASN (TLV 512). * Local ASN (TLV 512).
o Remote Node Descriptors include: o Remote Node Descriptors include:
* Peer BGP Router-ID (TLV 516) (i.e.: the peer BGP ID used in the * Peer BGP Router-ID (TLV 516) (i.e., the peer BGP ID used in the
BGP session) BGP session)
* Peer ASN (TLV 512). * Peer ASN (TLV 512).
o Link Descriptors include the addresses used by the BGP session o Link Descriptors include the addresses used by the BGP session
encoded using TLVs as defined in [RFC7752]: encoded using TLVs as defined in [RFC7752]:
* IPv4 Interface Address (TLV 259) contains the BGP session IPv4 * IPv4 Interface Address (TLV 259) contains the BGP session IPv4
local address. local address.
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The PeerAdj SID is advertised with a BGP-LS Link NLRI, where: The PeerAdj SID is advertised with a BGP-LS Link NLRI, where:
o Local Node Descriptors include: o Local Node Descriptors include:
* Local BGP Router-ID (TLV 516) of the BGP-EPE enabled egress PE. * Local BGP Router-ID (TLV 516) of the BGP-EPE enabled egress PE.
* Local ASN (TLV 512). * Local ASN (TLV 512).
o Remote Node Descriptors include: o Remote Node Descriptors include:
* Peer BGP Router-ID (TLV 516) (i.e. the peer BGP ID used in the * Peer BGP Router-ID (TLV 516) (i.e., the peer BGP ID used in the
BGP session). BGP session).
* Peer ASN (TLV 512). * Peer ASN (TLV 512).
o Link Descriptors MUST include the following TLV, as defined in o Link Descriptors MUST include the following TLV, as defined in
[RFC7752]: [RFC7752]:
* Link Local/Remote Identifiers (TLV 258) contains the 4-octet * Link Local/Remote Identifiers (TLV 258) contains the 4-octet
Link Local Identifier followed by the 4-octet Link Remote Link Local Identifier followed by the 4-octet Link Remote
Identifier. The value 0 is used by default when the link Identifier. The value 0 is used by default when the link
skipping to change at page 12, line 48 skipping to change at page 12, line 48
This document defines: This document defines:
A new Protocol-ID: BGP. The codepoint is from the "BGP-LS A new Protocol-ID: BGP. The codepoint is from the "BGP-LS
Protocol-IDs" registry. Protocol-IDs" registry.
Two new TLVs: BGP-Router-ID and BGP Confederation Member. The Two new TLVs: BGP-Router-ID and BGP Confederation Member. The
codepoints are in the "BGP-LS Node Descriptor, Link Descriptor, codepoints are in the "BGP-LS Node Descriptor, Link Descriptor,
Prefix Descriptor, and Attribute TLVs" registry. Prefix Descriptor, and Attribute TLVs" registry.
Three new BGP-LS Attribute TLVs: Peer-Node-SID, Peer-Adj-SID and Three new BGP-LS Attribute TLVs: PeerNode SID, PeerAdj SID and
Peer-Set-SID. The codepoints are in the "BGP-LS Node Descriptor, PeerSet SID. The codepoints are in the "BGP-LS Node Descriptor,
Link Descriptor, Prefix Descriptor, and Attribute TLVs" registry. Link Descriptor, Prefix Descriptor, and Attribute TLVs" registry.
5.1. New BGP-LS Protocol-ID 5.1. New BGP-LS Protocol-ID
This document defines a new value in the registry "BGP-LS Protocol- This document defines a new value in the registry "BGP-LS Protocol-
IDs": IDs":
+------------------------------------------------------+ +------------------------------------------------------+
| Codepoint | Description | Status | | Codepoint | Description | Status |
+------------------------------------------------------+ +------------------------------------------------------+
skipping to change at page 13, line 46 skipping to change at page 13, line 46
| 517 | BGP Confederation Member | Early Allocation by IANA | | 517 | BGP Confederation Member | Early Allocation by IANA |
+------------+------------------------------------------------------+ +------------+------------------------------------------------------+
Figure 6: BGP-LS Descriptor TLVs Codepoints Figure 6: BGP-LS Descriptor TLVs Codepoints
The following new Link Attribute TLVs are defined: The following new Link Attribute TLVs are defined:
+-------------------------------------------------------------------+ +-------------------------------------------------------------------+
| Codepoint | Description | Status | | Codepoint | Description | Status |
+-------------------------------------------------------------------+ +-------------------------------------------------------------------+
| 1101 | Peer-Node-SID | Early Allocation by IANA | | 1101 | PeerNode SID | Early Allocation by IANA |
| 1102 | Peer-Adj-SID | Early Allocation by IANA | | 1102 | PeerAdj SID | Early Allocation by IANA |
| 1103 | Peer-Set-SID | Early Allocation by IANA | | 1103 | PeerSet SID | Early Allocation by IANA |
+------------+------------------------------------------------------+ +------------+------------------------------------------------------+
Figure 7: BGP-LS Attribute TLVs Codepoints Figure 7: BGP-LS Attribute TLVs Codepoints
6. Manageability Considerations 6. Manageability Considerations
The new protocol extensions introduced in this document augment the The new protocol extensions introduced in this document augment the
existing IGP topology information BGP-LS distribution [RFC7752] by existing IGP topology information BGP-LS distribution [RFC7752] by
adding support for distribution of BGP peering topology information. adding support for distribution of BGP peering topology information.
As such, the Manageability Considerations section of [RFC7752] As such, the Manageability Considerations section of [RFC7752]
applies to these new extensions as well. applies to these new extensions as well.
Specifically, the malformed Link-State NLRI and BGP-LS Attribute Specifically, the malformed Link-State NLRI and BGP-LS Attribute
tests for syntactic checks in the Fault Management section of tests for syntactic checks in the Fault Management section of
[RFC7752] now apply to the TLVs defined in this document. The [RFC7752] now apply to the TLVs defined in this document. The
semantic or content checking for the TLVs specified in this document semantic or content checking for the TLVs specified in this document
and their association with the BGP-LS NLRI types or their associated and their association with the BGP-LS NLRI types or their associated
BGP-LS Attributes is left to the consumer of the BGP-LS information BGP-LS Attributes is left to the consumer of the BGP-LS information
(e.g. an application or a controller) and not the BGP protocol. (e.g., an application or a controller) and not the BGP protocol.
A consumer of the BGP-LS information retrieves this information from A consumer of the BGP-LS information retrieves this information from
a BGP protocol component, that is doing the signaling over a BGP-LS a BGP Speaker, over a BGP-LS session (refer Section 1 and 2 of
session, via some APIs or a data model (refer Section 1 and 2 of
[RFC7752]). The handling of semantic or content errors by the [RFC7752]). The handling of semantic or content errors by the
consumer would be dictated by the nature of its application usage and consumer would be dictated by the nature of its application usage and
hence is beyond the scope of this document. It may be expected that hence is beyond the scope of this document. It may be expected that
an error detected in the NLRI descriptor TLVs would result in that an error detected in the NLRI descriptor TLVs would result in that
specific NLRI update being unusable and hence its update to be specific NLRI update being unusable and hence its update to be
discarded along with an error log. While an error in Attribute TLVs discarded along with an error log. While an error in Attribute TLVs
would result in only that specific attribute being discarded with an would result in only that specific attribute being discarded with an
error log. error log.
The operator MUST be provided with the options of configuring, The operator MUST be provided with the options of configuring,
enabling, and disabling the advertisement of each of the Peer-Node- enabling, and disabling the advertisement of each of the PeerNode
SID, Peer-Adj-SID, and Peer-Set-SID as well as control of which SID, PeerAdj SID, and PeerSet SID as well as control of which
information is advertised to which internal or external peer. This information is advertised to which internal or external peer. This
is not different from what is required by a BGP speaker in terms of is not different from what is required by a BGP speaker in terms of
information origination and advertisement. information origination and advertisement.
BGP Peering Segments are associated with the normal BGP routing BGP Peering Segments are associated with the normal BGP routing
peering sessions. However, the BGP peering information along with peering sessions. However, the BGP peering information along with
these Peering Segments themselves are advertised via a distinct BGP- these Peering Segments themselves are advertised via a distinct BGP-
LS peering session. It is expected that this isolation as described LS peering session. It is expected that this isolation as described
in [RFC7752] is followed when advertising BGP peering topology in [RFC7752] is followed when advertising BGP peering topology
information via BGP-LS. information via BGP-LS.
skipping to change at page 15, line 30 skipping to change at page 15, line 29
[RFC7752] defines BGP-LS NLRI to which the extensions defined in this [RFC7752] defines BGP-LS NLRI to which the extensions defined in this
document apply. The Security Considerations section of [RFC7752] document apply. The Security Considerations section of [RFC7752]
also applies to these extensions. The procedures and new TLVs also applies to these extensions. The procedures and new TLVs
defined in this document, by themselves, do not affect the BGP-LS defined in this document, by themselves, do not affect the BGP-LS
security model discussed in [RFC7752]. security model discussed in [RFC7752].
BGP-EPE enables engineering of traffic when leaving the BGP-EPE enables engineering of traffic when leaving the
administrative domain via an egress BGP router. Therefore precaution administrative domain via an egress BGP router. Therefore precaution
is necessary to ensure that the BGP peering information collected via is necessary to ensure that the BGP peering information collected via
BGP-LS is limited to specific consumers in a secure manner. By BGP-LS is limited to specific consumers in a secure manner. Segment
default, Segment Routing operates within a trusted domain [RFC8402] Routing operates within a trusted domain [RFC8402] and its security
and its security considerations also apply to BGP Peering Segments. considerations also apply to BGP Peering Segments. The BGP-EPE
The BGP-EPE policies are expected to be used entirely within this policies are expected to be used entirely within this trusted SR
trusted SR domain (e.g. between multiple AS/domains within a single domain (e.g., between multiple AS/domains within a single provider
provider network). network).
The isolation of BGP-LS peering sessions is also required to ensure The isolation of BGP-LS peering sessions is also required to ensure
that BGP-LS topology information (including the newly added BGP that BGP-LS topology information (including the newly added BGP
peering topology) is not advertised to an external BGP peering peering topology) is not advertised to an external BGP peering
session outside an administrative domain. session outside an administrative domain.
8. Contributors 8. Contributors
Mach (Guoyi) Chen Mach (Guoyi) Chen
Huawei Technologies Huawei Technologies
skipping to change at page 16, line 27 skipping to change at page 16, line 27
Retana for his extensive review and comments which helped correct Retana for his extensive review and comments which helped correct
issues and improve the document. issues and improve the document.
10. References 10. References
10.1. Normative References 10.1. 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-12 Routing", draft-ietf-idr-bgp-ls-segment-routing-ext-14
(work in progress), March 2019. (work in progress), May 2019.
[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>.
[RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous
System Confederations for BGP", RFC 5065, System Confederations for BGP", RFC 5065,
DOI 10.17487/RFC5065, August 2007, DOI 10.17487/RFC5065, August 2007,
<https://www.rfc-editor.org/info/rfc5065>. <https://www.rfc-editor.org/info/rfc5065>.
skipping to change at page 17, line 20 skipping to change at page 17, line 20
Decraene, B., Litkowski, S., and R. Shakir, "Segment Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>. July 2018, <https://www.rfc-editor.org/info/rfc8402>.
10.2. Informative References 10.2. Informative References
[I-D.dawra-idr-bgpls-srv6-ext] [I-D.dawra-idr-bgpls-srv6-ext]
Dawra, G., Filsfils, C., Talaulikar, K., Chen, M., Dawra, G., Filsfils, C., Talaulikar, K., Chen, M.,
daniel.bernier@bell.ca, d., Uttaro, J., Decraene, B., and daniel.bernier@bell.ca, d., Uttaro, J., Decraene, B., and
H. Elmalky, "BGP Link State Extensions for SRv6", draft- H. Elmalky, "BGP Link State Extensions for SRv6", draft-
dawra-idr-bgpls-srv6-ext-05 (work in progress), March dawra-idr-bgpls-srv6-ext-06 (work in progress), March
2019. 2019.
[I-D.ietf-spring-segment-routing-central-epe] [I-D.ietf-spring-segment-routing-central-epe]
Filsfils, C., Previdi, S., Dawra, G., Aries, E., and D. Filsfils, C., Previdi, S., Dawra, G., Aries, E., and D.
Afanasiev, "Segment Routing Centralized BGP Egress Peer Afanasiev, "Segment Routing Centralized BGP Egress Peer
Engineering", draft-ietf-spring-segment-routing-central- Engineering", draft-ietf-spring-segment-routing-central-
epe-10 (work in progress), December 2017. epe-10 (work in progress), December 2017.
[I-D.ietf-spring-segment-routing-policy] [I-D.ietf-spring-segment-routing-policy]
Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d., Filsfils, C., Sivabalan, S., daniel.voyer@bell.ca, d.,
bogdanov@google.com, b., and P. Mattes, "Segment Routing bogdanov@google.com, b., and P. Mattes, "Segment Routing
Policy Architecture", draft-ietf-spring-segment-routing- Policy Architecture", draft-ietf-spring-segment-routing-
policy-02 (work in progress), October 2018. policy-03 (work in progress), May 2019.
Authors' Addresses Authors' Addresses
Stefano Previdi Stefano Previdi
Individual Individual
Email: stefano@previdi.net Email: stefano@previdi.net
Ketan Talaulikar (editor) Ketan Talaulikar (editor)
Cisco Systems, Inc. Cisco Systems, Inc.
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