Inter-Domain Routing S. Previdi, Ed.
Internet-Draft
Intended status: Standards Track K. Talaulikar
Expires: April 22, 2019 C. Filsfils
Cisco Systems, Inc.
H. Gredler
RtBrick Inc.
M. Chen
Huawei Technologies
October 19, 2018
BGP Link-State extensions for Segment Routing
draft-ietf-idr-bgp-ls-segment-routing-ext-10
Abstract
Segment Routing (SR) allows for a flexible definition of end-to-end
paths by encoding paths as sequences of topological sub-paths, called
"segments". These segments are advertised by routing protocols e.g.
by the link state routing protocols (IS-IS, OSPFv2 and OSPFv3) within
IGP topologies.
This draft defines extensions to the BGP Link-state address-family in
order to carry segment routing information via BGP.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 22, 2019.
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Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. BGP-LS Extensions for Segment Routing . . . . . . . . . . . . 5
2.1. Node Attributes TLVs . . . . . . . . . . . . . . . . . . 5
2.1.1. SID/Label Sub-TLV . . . . . . . . . . . . . . . . . . 6
2.1.2. SR-Capabilities TLV . . . . . . . . . . . . . . . . . 7
2.1.3. SR-Algorithm TLV . . . . . . . . . . . . . . . . . . 8
2.1.4. SR Local Block TLV . . . . . . . . . . . . . . . . . 8
2.1.5. SRMS Preference TLV . . . . . . . . . . . . . . . . . 9
2.2. Link Attribute TLVs . . . . . . . . . . . . . . . . . . . 10
2.2.1. Adjacency SID TLV . . . . . . . . . . . . . . . . . . 11
2.2.2. LAN Adjacency SID TLV . . . . . . . . . . . . . . . . 12
2.2.3. L2 Bundle Member . . . . . . . . . . . . . . . . . . 13
2.3. Prefix Attribute TLVs . . . . . . . . . . . . . . . . . . 14
2.3.1. Prefix-SID TLV . . . . . . . . . . . . . . . . . . . 15
2.3.2. Prefix Attribute Flags TLV . . . . . . . . . . . . . 16
2.3.3. Source Router Identifier (Source Router-ID) TLV . . . 17
2.3.4. Range TLV . . . . . . . . . . . . . . . . . . . . . . 17
2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs . . . . . 19
2.5. Equivalent OSPFv2/OSPFv3 Segment Routing TLVs/Sub-TLVs . 20
3. Implementation Status . . . . . . . . . . . . . . . . . . . . 21
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
4.1. TLV/Sub-TLV Code Points Summary . . . . . . . . . . . . . 21
5. Manageability Considerations . . . . . . . . . . . . . . . . 22
6. Security Considerations . . . . . . . . . . . . . . . . . . . 23
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 23
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
9.1. Normative References . . . . . . . . . . . . . . . . . . 24
9.2. Informative References . . . . . . . . . . . . . . . . . 25
9.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28
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1. Introduction
Segment Routing (SR) allows for a flexible definition of end-to-end
paths by combining sub-paths called "segments". A segment can
represent any instruction, topological or service-based. A segment
can have a local semantic to an SR node or global within a domain.
Within IGP topologies an SR path is encoded as a sequence of
topological sub-paths, called "IGP segments". These segments are
advertised by the link-state routing protocols (IS-IS, OSPFv2 and
OSPFv3).
Two types of IGP segments are defined, Prefix segments and Adjacency
segments. Prefix segments, by default, represent an ECMP-aware
shortest-path to a prefix, as per the state of the IGP topology.
Adjacency segments represent a hop over a specific adjacency between
two nodes in the IGP. A prefix segment is typically a multi-hop path
while an adjacency segment, in most of the cases, is a one-hop path.
[RFC8402].
When Segment Routing is enabled in a IGP domain, segments are
advertised in the form of Segment Identifiers (SIDs). The IGP link-
state routing protocols have been extended to advertise SIDs and
other SR-related information. IGP extensions are described in: IS-IS
[I-D.ietf-isis-segment-routing-extensions], OSPFv2
[I-D.ietf-ospf-segment-routing-extensions] and OSPFv3
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]. Using these
extensions, Segment Routing can be enabled within an IGP domain.
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+------------+
| Consumer |
+------------+
^
|
v
+-------------------+
| BGP Speaker | +-----------+
| (Route-Reflector) | | Consumer |
+-------------------+ +-----------+
^ ^ ^ ^
| | | |
+---------------+ | +-------------------+ |
| | | |
v v v v
+-----------+ +-----------+ +-----------+
| BGP | | BGP | | BGP |
| Speaker | | Speaker | . . . | Speaker |
+-----------+ +-----------+ +-----------+
^ ^ ^
| | |
IGP IGP IGP
Figure 1: Link State info collection
Segment Routing (SR) allows advertisement of single or multi-hop
paths. The flooding scope for the IGP extensions for Segment routing
is IGP area-wide. Consequently, the contents of a Link State
Database (LSDB) or a Traffic Engineering Database (TED) has the scope
of an IGP area and therefore, by using the IGP alone it is not enough
to construct segments across multiple IGP Area or AS boundaries.
In order to address the need for applications that require
topological visibility across IGP areas, or even across Autonomous
Systems (AS), the BGP-LS address-family/sub-address-family have been
defined to allow BGP to carry Link-State information. The BGP
Network Layer Reachability Information (NLRI) encoding format for
BGP-LS and a new BGP Path Attribute called the BGP-LS attribute are
defined in [RFC7752]. The identifying key of each Link-State object,
namely a node, link, or prefix, is encoded in the NLRI and the
properties of the object are encoded in the BGP-LS attribute.
Figure 1 describes a typical deployment scenario. In each IGP area,
one or more nodes are configured with BGP-LS. These BGP speakers
form an IBGP mesh by connecting to one or more route-reflectors.
This way, all BGP speakers (specifically the route-reflectors) obtain
Link-State information from all IGP areas (and from other ASes from
EBGP peers). An external component connects to the route-reflector
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to obtain this information (perhaps moderated by a policy regarding
what information is or isn't advertised to the external component).
This document describes extensions to BGP-LS to advertise the SR
information. An external component (e.g., a controller) then can
collect SR information from across an SR domain and construct the
end-to-end path (with its associated SIDs) that need to be applied to
an incoming packet to achieve the desired end-to-end forwarding.
Here the SR domain is defined as a single administrative domain that
may be comprised of a single AS or multiple ASes under consolidated
global SID administration.
2. BGP-LS Extensions for Segment Routing
This document defines SR extensions to BGP-LS and specifies the TLVs
and sub-TLVs for advertising SR information within the BGP-LS
Attribute. Section 2.4 and Section 2.5 illustrates the equivalent
TLVs and sub-TLVs in IS-IS, OSPFv2 and OSPFv3 protocols.
BGP-LS [RFC7752] defines the BGP-LS NLRI that can be a Node NLRI, a
Link NLRI or a Prefix NLRI. The corresponding BGP-LS attribute is a
Node Attribute, a Link Attribute or a Prefix Attribute. BGP-LS
[RFC7752] defines the TLVs that map link-state information to BGP-LS
NLRI and the BGP-LS attribute. This document adds additional BGP-LS
attribute TLVs in order to encode SR information. It does not
introduce any changes to the encoding of the BGP-LS NLRIs.
Some of the TLVs defined in this document contain fields (e.g. flags)
whose semantics need to be interpreted accordingly to the respective
underlying IS-IS, OSPFv2 or OSPFv3 protocol. The receiver of the
BGP-LS update for any of the NLRIs MUST check the Protocol-ID of the
NLRI and refer to the underlying protocol specification in order to
parse such fields. The individual field descriptions in the sub-
sections below point to the relevant underlying protocol
specifications for such fields.
2.1. Node Attributes TLVs
The following Node Attribute TLVs are defined:
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+-----------------+----------+---------------+
| Description | Length | Section |
+-----------------+----------+---------------+
| SID/Label | variable | Section 2.1.1 |
| SR Capabilities | variable | Section 2.1.2 |
| SR Algorithm | variable | Section 2.1.3 |
| SR Local Block | variable | Section 2.1.4 |
| SRMS Preference | variable | Section 2.1.5 |
+-----------------+----------+---------------+
Table 1: Node Attribute TLVs
These TLVs can ONLY be added to the Node Attribute associated with
the Node NLRI that originates the corresponding underlying IGP TLV/
sub-TLV described below.
2.1.1. SID/Label Sub-TLV
The SID/Label TLV is used as sub-TLV by the SR-Capabilities
(Section 2.1.2) and SRLB (Section 2.1.4) TLVs and has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: TBD, see Section 4.
Length: Variable, 3 or 4.
SID/Label: If length is set to 3, then the 20 rightmost bits
represent a label (the total TLV size is 7). If length is set to
4, then the value represents a 32 bit SID (the total TLV size is
8).
The receiving router MUST ignore the SID/Label sub-TLV if the
length is other then 3 or 4.
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2.1.2. SR-Capabilities TLV
The SR-Capabilities TLV is used in order to advertise the node's SR
Capabilities including its Segment Routing Global Base (SRGB)
range(s). In the case of IS-IS, the capabilities also include the
IPv4 and IPv6 support for SR-MPLS forwarding plane. This information
is derived from the protocol specific advertisements.
o IS-IS, as defined by the SR-Capabilities sub-TLV in
[I-D.ietf-isis-segment-routing-extensions].
o OSPFv2/OSPFv3, as defined by the SID/Label Range TLV in
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
The SR Capabilities TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Range Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// SID/Label sub-TLV (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD, see Section 4.
Length: Variable.
Flags: 1 octet of flags as defined in
[I-D.ietf-isis-segment-routing-extensions].
Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on
receipt.
One or more entries, each of which have the following format:
Range Size: 3 octet value indicating the number of labels in
the range.
SID/Label sub-TLV (as defined in Section 2.1.1) which encodes
the first label in the range.
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2.1.3. SR-Algorithm TLV
The SR-Algorithm TLV is used in order to advertise the SR Algorithms
supported by the node. This information is derived from the protocol
specific advertisements.
o IS-IS, as defined by the SR-Algorithm sub-TLV in
[I-D.ietf-isis-segment-routing-extensions].
o OSPFv2/OSPFv3, as defined by the SR-Algorithm TLV in
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
The SR-Algorithm TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Algorithm 1 | Algorithm... | Algorithm N | |
+- -+
| |
+ +
where:
Type: TBD, see Section 4.
Length: Variable.
Algorithm: 1 octet identifying the algorithm.
2.1.4. SR Local Block TLV
The SR Local Block (SRLB) TLV contains the range(s) of labels the
node has reserved for local SIDs. Local SIDs are used, e.g., in IGP
(IS-IS, OSPF) for Adjacency-SIDs, and may also be allocated by
components other than IGP protocols. As an example, an application
or a controller may instruct a node to allocate a specific local SID.
Therefore, in order for such applications or controllers to know the
range of local SIDs available, it is required that the node
advertises its SRLB.
This information is derived from the protocol specific
advertisements.
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o IS-IS, as defined by the SR Local Block sub-TLV in
[I-D.ietf-isis-segment-routing-extensions].
o OSPFv2/OSPFv3, as defined by the SR Local Block TLV in
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
The SRLB TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Range Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// SID/Label sub-TLV (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD, see Section 4.
Length: Variable.
Flags: 1 octet of flags. None are defined at this stage.
Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on
receipt.
One or more entries, each of which have the following format:
Range Size: 3 octet value indicating the number of labels in
the range.
SID/Label sub-TLV (as defined in Section 2.1.1) which encodes
the first label in the range.
2.1.5. SRMS Preference TLV
The Segment Routing Mapping Server (SRMS) Preference TLV is used in
order to associate a preference with SRMS advertisements from a
particular source. [I-D.ietf-spring-segment-routing-ldp-interop]
specifies the SRMS functionality along with SRMS preference of the
node advertising the SRMS Prefix-to-SID Mapping ranges.
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This information is derived from the protocol specific
advertisements.
o IS-IS, as defined by the SRMS Preference sub-TLV in
[I-D.ietf-isis-segment-routing-extensions].
o OSPFv2/OSPFv3, as defined by the SRMS Preference TLV in
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
The SRMS Preference TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preference |
+-+-+-+-+-+-+-+-+
Type: TBD, see Section 4.
Length: 1.
Preference: 1 octet. Unsigned 8 bit SRMS preference.
The use of the SRMS Preference TLV is defined in
[I-D.ietf-isis-segment-routing-extensions],
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
2.2. Link Attribute TLVs
The following Link Attribute TLVs are are defined:
+----------------------------------------+----------+---------------+
| Description | Length | Section |
+----------------------------------------+----------+---------------+
| Adjacency Segment Identifier (Adj-SID) | variable | Section 2.2.1 |
| TLV | | |
| LAN Adjacency Segment Identifier (Adj- | variable | Section 2.2.2 |
| SID) TLV | | |
| L2 Bundle Member TLV | variable | Section 2.2.3 |
+----------------------------------------+----------+---------------+
Table 2: Link Attribute TLVs
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These TLVs can ONLY be added to the Link Attribute associated with
the link whose local node originates the corresponding underlying IGP
TLV/sub-TLV described below.
For a LAN, normally a node only announces its adjacency to the IS-IS
pseudo-node (or the equivalent OSPF Designated and Backup Designated
Routers)[I-D.ietf-isis-segment-routing-extensions]. The LAN
Adjacency Segment TLV allows a node to announce adjacencies to all
other nodes attached to the LAN in a single instance of the BGP-LS
Link NLRI. Without this TLV, the corresponding BGP-LS link NLRI
would need to be originated for each additional adjacency in order to
advertise the SR TLVs for these neighbor adjacencies.
2.2.1. Adjacency SID TLV
The Adjacency SID (Adj-SID) TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+---------------------------------------------------------------+
where:
Type: TBD, see Section 4.
Length: Variable, 7 or 8 depending on Label or Index encoding of
the SID
Flags. 1 octet field of following flags as defined in
[I-D.ietf-isis-segment-routing-extensions],
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
Weight: Weight used for load-balancing purposes.
Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on
receipt.
SID/Index/Label: Label or index value depending on the flags
setting as defined in [I-D.ietf-isis-segment-routing-extensions],
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
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2.2.2. LAN Adjacency SID TLV
The LAN Adjacency SID (LAN-Adj-SID-SID) TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Weight | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Neighbor ID / IS-IS System-ID |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Label/Index (variable) |
+---------------------------------------------------------------+
where:
Type: TBD, see Section 4.
Length: Variable. For IS-IS it would be 13 or 14 depending on
Label or Index encoding of the SID. For OSPF it would be 11 or 12
depending on Label or Index encoding of the SID.
Flags. 1 octet field of following flags as defined in
[I-D.ietf-isis-segment-routing-extensions],
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
Weight: Weight used for load-balancing purposes.
Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on
receipt.
SID/Index/Label: Label or index value depending on the flags
setting as defined in [I-D.ietf-isis-segment-routing-extensions],
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions].
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2.2.3. L2 Bundle Member
The L2 Bundle Member Attribute TLV identifies an L2 Bundle Member
link which in turn is associated with a parent L3 link. The L3 link
is described by the Link NLRI defined in [RFC7752] and the L2 Bundle
Member Attribute TLV is associated with the Link NLRI. The TLV MAY
include sub-TLVs which describe attributes associated with the bundle
member. The identified bundle member represents a unidirectional
path from the originating router to the neighbor specified in the
parent L3 Link. Multiple L2 Bundle Member Attribute TLVs MAY be
associated with a Link NLRI.
The L2 Bundle Member Attribute TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| L2 Bundle Member Descriptor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Link attribute sub-TLVs(variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: TBD, see Section 4.
Length: Variable.
L2 Bundle Member Descriptor: A Link Local Identifier as defined in
[RFC4202].
Link attributes for L2 Bundle Member Links are advertised as sub-TLVs
of the L2Bundle Member Attribute TLV. The sub-TLVs are identical to
existing BGP-LS TLVs as identified in the table below.
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+-----------+----------------------------+--------------------------+
| TLV Code | Description | Reference Document |
| Point | | |
+-----------+----------------------------+--------------------------+
| 1088 | Administrative group | [RFC7752] |
| | (color) | |
| 1089 | Maximum link bandwidth | [RFC7752] |
| 1090 | Max. reservable link | [RFC7752] |
| | bandwidth | |
| 1091 | Unreserved bandwidth | [RFC7752] |
| 1092 | TE default metric | [RFC7752] |
| 1093 | Link protection type | [RFC7752] |
| 1099 | Adjacency Segment | Section 2.2.1 |
| | Identifier (Adj-SID) TLV | |
| 1100 | LAN Adjacency Segment | Section 2.2.2 |
| | Identifier (Adj-SID) TLV | |
| 1104 | Unidirectional link delay | [I-D.ietf-idr-te-pm-bgp] |
| 1105 | Min/Max Unidirectional | [I-D.ietf-idr-te-pm-bgp] |
| | link delay | |
| 1106 | Min/Max Unidirectional | [I-D.ietf-idr-te-pm-bgp] |
| | link delay | |
| 1107 | Unidirectional packet loss | [I-D.ietf-idr-te-pm-bgp] |
| 1108 | Unidirectional residual | [I-D.ietf-idr-te-pm-bgp] |
| | bandwidth | |
| 1109 | Unidirectional available | [I-D.ietf-idr-te-pm-bgp] |
| | bandwidth | |
| 1110 | Unidirectional bandwidth | [I-D.ietf-idr-te-pm-bgp] |
| | utilization | |
+-----------+----------------------------+--------------------------+
Table 3: L2 Bundle Member Link Attribute TLVs
2.3. Prefix Attribute TLVs
The following Prefix Attribute TLVs are defined:
+------------------------+----------+---------------+
| Description | Length | Section |
+------------------------+----------+---------------+
| Prefix SID | variable | Section 2.3.1 |
| Range | variable | Section 2.3.4 |
| Prefix Attribute Flags | variable | Section 2.3.2 |
| Source Router-ID | variable | Section 2.3.3 |
+------------------------+----------+---------------+
Table 4: Prefix Attribute TLVs
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These TLVs can ONLY be added to the Prefix Attribute associated with
the prefix whose local node originates the corresponding underlying
IGP TLV/sub-TLV described below.
2.3.1. Prefix-SID TLV
The Prefix-SID TLV is used in order to advertise information related
to a Prefix-SID. This information is originated in:
o IS-IS, as defined by the Prefix-SID TLV in
[I-D.ietf-isis-segment-routing-extensions].
o OSPFv2 and OSPFv3, as defined by the Prefix-SID TLV in
[I-D.ietf-ospf-segment-routing-extensions] and
[I-D.ietf-ospf-ospfv3-segment-routing-extensions] respectively.
The Prefix-SID has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Algorithm | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SID/Index/Label (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: TBD, see Section 4.
Length: Variable, 7 or 8 depending on Label or Index encoding of
the SID
Flags: 1 octet value which sould be parsed as:
* IS-IS Prefix-SID flags are defined in
[I-D.ietf-isis-segment-routing-extensions] section 2.1.
* OSPFv2 Prefix-SID flags are defined in
[I-D.ietf-ospf-segment-routing-extensions] section 5.
* OSPFv3 Prefix-SID flags are defined in
[I-D.ietf-ospf-segment-routing-extensions] section 5.
Algorithm: 1 octet value identify the algorithm.
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Reserved: 2 octets that SHOULD be set to 0 and MUST be ignored on
receipt.
SID/Index/Label:
* IS-IS: Label or index value as defined in
[I-D.ietf-isis-segment-routing-extensions],
* OSPFv2: Label or index value as defined in
[I-D.ietf-ospf-segment-routing-extensions],
* OSPFv3: Label or index value as defined in
[I-D.ietf-ospf-ospfv3-segment-routing-extensions],
2.3.2. Prefix Attribute Flags TLV
The Prefix Attribute Flags TLV carries IPv4/IPv6 prefix attribute
flags information. These flags are defined for OSPFv2 in [RFC7684],
for OSPFv3 in [RFC5340] and for IS-IS in [RFC7794].
The Prefix Attribute Flags TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// Flags (variable) //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: TBD, see Section 4.
Length: variable.
Flags: a variable length flag field (according to the length
field). Flags are routing protocol specific and are to be parsed
as below:
* IS-IS flags are defined in [RFC7794]
* OSPFv2 flags are defined in [RFC7684]
* OSPFv3 flags map to the Prefix Options field defined in
[RFC7794] and extended via [RFC8362]
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2.3.3. Source Router Identifier (Source Router-ID) TLV
The Source Router-ID TLV contains the IPv4 or IPv6 Router-ID of the
originator of the Prefix. For IS-IS protocol this is as defined in
[RFC7794]. The Source Router-ID TLV may be used to carry the OSPF
Router-ID of the prefix originator.
The Source Router-ID TLV has 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// 4 or 6 octet Router-ID //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Type: TBD, see Section 4.
Length: 4 or 16.
IPv4/IPv6 Address: 4 octet IPv4 address or 16 octet IPv6 address.
2.3.4. Range TLV
The range TLV is used in order to advertise a range of prefix-to-SID
mappings as part of the Segment Routing Mapping Server functionality
[I-D.ietf-spring-segment-routing-ldp-interop], as defined in the
respective underlying IGP SR extensions
[I-D.ietf-ospf-segment-routing-extensions],
[I-D.ietf-ospf-ospfv3-segment-routing-extensions] and
[I-D.ietf-isis-segment-routing-extensions]. The Prefix-NLRI to which
the Range TLV is attached MUST be advertised as a non-routing prefix
where no IGP metric TLV (TLV 1095) is attached.
The format of the Range TLV is as follows:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags | Reserved | Range Size |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// sub-TLVs //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where:
Figure 2: Range TLV format
Type: TBD, see Section 4.
Length: variable
Flags: as defined in [I-D.ietf-ospf-segment-routing-extensions],
[I-D.ietf-ospf-ospfv3-segment-routing-extensions] and
[I-D.ietf-isis-segment-routing-extensions].
Reserved: 1 octet that SHOULD be set to 0 and MUST be ignored on
receipt.
Range Size: 2 octets as defined in
[I-D.ietf-ospf-segment-routing-extensions].
Within the Range TLV, the prefix-to-SID mappings are advertised using
sub-TLVs as below:
Range TLV
Prefix-SID TLV (used as a sub-TLV in this context)
where:
o The Range TLV is defined in Section 2.3.4.
o The Prefix-SID TLV (used as sub-TLV in this context) is defined in
Section 2.3.1.
2.3.4.1. Advertisement Procedure for OSPF
The OSPFv2/OSPFv3 Extended Prefix Range TLV is encoded in the Range
TLV. The flags of the Range TLV have the semantic mapped to the
definition in [I-D.ietf-ospf-segment-routing-extensions] section 4 or
[I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 4.
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Then the prefix-to-SID mapping from the OSPF Prefix SID sub-TLV is
encoded using the BGP-LS Prefix-SID TLV as defined in Section 2.3.1
with the flags set according to the definition in
[I-D.ietf-ospf-segment-routing-extensions] section 5 or
[I-D.ietf-ospf-ospfv3-segment-routing-extensions] section 5.
2.3.4.2. Advertisement Procedure for IS-IS
The IS-IS SID/Label Binding TLV, when used to signal mapping server
label bindings, is encoded in the Range TLV. The flags of the Range
TLV have the sematic mapped to the definition in
[I-D.ietf-isis-segment-routing-extensions] section 2.4.1.
Then the prefix-to-SID mappings from the IS-IS Prefix SID sub-TLV is
encoded using the BGP-LS Prefix-SID TLV as defined in Section 2.3.1
with the flags set according to the definition in
[I-D.ietf-isis-segment-routing-extensions] section 2.4.4.1.
2.4. Equivalent IS-IS Segment Routing TLVs/Sub-TLVs
This section illustrate the IS-IS Segment Routing Extensions TLVs and
sub-TLVs mapped to the ones defined in this document.
The following table, illustrates for each BGP-LS TLV, its equivalence
in IS-IS.
+---------------------------------------+----------+----------------+
| Description | Length | IS-IS TLV/sub- |
| | | TLV |
+---------------------------------------+----------+----------------+
| SR Capabilities | variable | 2 [1] |
| SR Algorithm | variable | 19 [2] |
| SR Local Block | variable | 22 [3] |
| SRMS Preference | 1 | 19 [4] |
| Adjacency Segment Identifier (Adj- | variable | 31 [5] |
| SID) | | |
| LAN Adjacency Segment Identifier | variable | 32 [6] |
| (LAN-Adj-SID) | | |
| Prefix SID | variable | 3 [7] |
| Range | variable | 149 [8] |
| SID/Label TLV | variable | 1 [9] |
| Prefix Attribute Flags | variable | 4 [10] |
| Source Router ID | variable | 11/12 [11] |
| L2 Bundle Member TLV | variable | 25 [12] |
+---------------------------------------+----------+----------------+
Table 5: IS-IS Segment Routing Extensions TLVs/Sub-TLVs
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2.5. Equivalent OSPFv2/OSPFv3 Segment Routing TLVs/Sub-TLVs
This section illustrate the OSPFv2 and OSPFv3 Segment Routing
Extensions TLVs and sub-TLVs mapped to the ones defined in this
document.
The following table, illustrates for each BGP-LS TLV, its equivalence
in OSPFv2 and OSPFv3.
+-------------------------------------+----------+------------------+
| Description | Length | OSPFv2 TLV/sub- |
| | | TLV |
+-------------------------------------+----------+------------------+
| SR Capabilities | variable | 9 [13] |
| SR Algorithm | variable | 8 [14] |
| SR Local Block | variable | 14 [15] |
| SRMS Preference | 1 | 15 [16] |
| Adjacency Segment Identifier (Adj- | variable | 2 [17] |
| SID) | | |
| LAN Adjacency Segment Identifier | variable | 3 [18] |
| (Adj-SID) | | |
| Prefix SID | variable | 2 [19] |
| Range | variable | 2 [20] |
| SID/Label TLV | variable | 1 [21] |
| Prefix Attribute Flags | variable | 4 [22] |
+-------------------------------------+----------+------------------+
Table 6: OSPF Segment Routing Extensions TLVs/Sub-TLVs
+-------------------------------------+----------+------------------+
| Description | Length | OSPFv3 TLV/sub- |
| | | TLV |
+-------------------------------------+----------+------------------+
| SR Capabilities | variable | 9 [23] |
| SR Algorithm | variable | 8 [24] |
| SR Local Block | variable | 14 [25] |
| SRMS Preference | 1 | 15 [26] |
| Adjacency Segment Identifier (Adj- | variable | 5 [27] |
| SID) | | |
| LAN Adjacency Segment Identifier | variable | 6 [28] |
| (Adj-SID) | | |
| Prefix SID | variable | 4 [29] |
| Range | variable | 9 [30] |
| SID/Label TLV | variable | 7 [31] |
| Prefix Attribute Flags | variable | 4 [32] |
+-------------------------------------+----------+------------------+
Table 7: OSPFv3 Segment Routing Extensions TLVs/Sub-TLVs
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3. Implementation Status
Note to RFC Editor: Please remove this section prior to publication,
as well as the reference to RFC 7942.
This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this
Internet-Draft, and is based on a proposal described in [RFC7942].
The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to
RFCs. Please note that the listing of any individual implementation
here does not imply endorsement by the IETF. Furthermore, no effort
has been spent to verify the information presented here that was
supplied by IETF contributors. This is not intended as, and must not
be construed to be, a catalog of available implementations or their
features. Readers are advised to note that other implementations may
exist.
According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as
they see fit".
Several early implementations exist and will be reported in detail in
a forthcoming version of this document. For purposes of early
interoperability testing, when no FCFS code point was available,
implementations have made use of the values described in Table 8.
It will ease implementation interoperability and deployment if the
value could be preserved also due to the large amount of codepoints
this draft requires. However, when IANA-assigned values are
available, implementations will be updated to use them.
4. IANA Considerations
This document requests assigning code-points from the registry "BGP-
LS Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
TLVs" based on table Table 8. The column "IS-IS TLV/Sub-TLV" defined
in the registry does not require any value and should be left empty.
4.1. TLV/Sub-TLV Code Points Summary
This section contains the global table of all TLVs/sub-TLVs defined
in this document.
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+-------------+-------------------------------------+---------------+
| TLV Code | Description | Reference |
| Point | | |
+-------------+-------------------------------------+---------------+
| 1034 | SR Capabilities | Section 2.1.2 |
| 1035 | SR Algorithm | Section 2.1.3 |
| 1036 | SR Local Block | Section 2.1.4 |
| 1037 | SRMS Preference | Section 2.1.5 |
| 1099 | Adjacency Segment Identifier (Adj- | Section 2.2.1 |
| | SID) TLV | |
| 1100 | LAN Adjacency Segment Identifier | Section 2.2.2 |
| | (Adj-SID) TLV | |
| 1158 | Prefix SID | Section 2.3.1 |
| 1159 | Range | Section 2.3.4 |
| 1161 | SID/Label TLV | Section 2.1.1 |
| 1170 | Prefix Attribute Flags | Section 2.3.2 |
| 1171 | Source Router-ID | Section 2.3.3 |
| 1172 | L2 Bundle Member TLV | Section 2.2.3 |
+-------------+-------------------------------------+---------------+
Table 8: Summary Table of TLV/Sub-TLV Codepoints
5. Manageability Considerations
This section is structured as recommended in [RFC5706].
The new protocol extensions introduced in this document augment the
existing IGP topology information that was distributed via [RFC7752].
Procedures and protocol extensions defined in this document do not
affect the BGP protocol operations and management other than as
discussed in the Manageability Considerations section of [RFC7752].
Specifically, the malformed attribute tests for syntactic checks in
the Fault Management section of [RFC7752] now encompass the new BGP-
LS Attribute TLVs defined in this document. The semantic or content
checking for the TLVs specified in this document and their
association with the BGP-LS NLRI types or their BGP-LS Attribute is
left to the consumer of the BGP-LS information (e.g. an application
or a controller) and not the BGP protocol.
A consumer of the BGP-LS information is retrieving this information
from a BGP protocol component that is doing the signaling over a BGP-
LS session, via some APIs or a data model (refer Section 1 and 2 of
[RFC7752]). The handling of semantic or content errors by the
consumer would be dictated by the nature of its application usage and
hence is beyond the scope of this document. This document only
introduces new Attribute TLVs and an error in them would result in
only that specific attribute being discarded with an error log.
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The extensions, specified in this document, do not introduce any new
configuration or monitoring aspects in BGP or BGP-LS other than as
discussed in [RFC7752]. The manageability aspects of the underlying
SR features are covered by [I-D.ietf-spring-sr-yang],
[I-D.ietf-isis-sr-yang] and [I-D.ietf-ospf-sr-yang].
6. Security Considerations
The new protocol extensions introduced in this document augment the
existing IGP topology information that was distributed via [RFC7752].
The Security Considerations section of [RFC7752] also applies to
these extensions. The procedures and new TLVs defined in this
document, by themselves, do not affect the BGP-LS security model
discussed in [RFC7752].
BGP-LS SR extensions enable traffic engineering use-cases within the
Segment Routing domain. SR operates within a trusted domain (refer
Security Considerations section in [RFC8402] for more detail) and its
security considerations also apply to BGP-LS sessions when carrying
SR information.The SR traffic engineering policies using the SIDs
advertised via BGP-LS are expected to be used entirely within this
trusted SR domain (e.g. between multiple AS/domains within a single
provider network). Therefore, precaution is necessary to ensure that
the SR information collected via BGP-LS is limited to specific
controllers or applications in a secure manner within this SR domain.
The isolation of BGP-LS peering sessions is also required to ensure
that BGP-LS topology information (including the newly added SR
information) is not advertised to an external BGP peering session
outside an administrative domain.
7. Contributors
The following people have substantially contributed to the editing of
this document:
Peter Psenak
Cisco Systems
Email: ppsenak@cisco.com
Les Ginsberg
Cisco Systems
Email: ginsberg@cisco.com
Acee Lindem
Cisco Systems
Email: acee@cisco.com
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Saikat Ray
Individual
Email: raysaikat@gmail.com
Jeff Tantsura
Nuage Networks
Email: jefftant.ietf@gmail.com
8. Acknowledgements
The authors would like to thank Jeffrey Haas and Aijun Wang for their
review of this document and their comments.
9. References
9.1. Normative References
[I-D.ietf-idr-te-pm-bgp]
Ginsberg, L., Previdi, S., Wu, Q., Tantsura, J., and C.
Filsfils, "BGP-LS Advertisement of IGP Traffic Engineering
Performance Metric Extensions", draft-ietf-idr-te-pm-
bgp-13 (work in progress), October 2018.
[I-D.ietf-isis-segment-routing-extensions]
Previdi, S., Ginsberg, L., Filsfils, C., Bashandy, A.,
Gredler, H., Litkowski, S., Decraene, B., and J. Tantsura,
"IS-IS Extensions for Segment Routing", draft-ietf-isis-
segment-routing-extensions-19 (work in progress), July
2018.
[I-D.ietf-ospf-ospfv3-segment-routing-extensions]
Psenak, P., Filsfils, C., Previdi, S., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3
Extensions for Segment Routing", draft-ietf-ospf-ospfv3-
segment-routing-extensions-15 (work in progress), August
2018.
[I-D.ietf-ospf-segment-routing-extensions]
Psenak, P., Previdi, S., Filsfils, C., Gredler, H.,
Shakir, R., Henderickx, W., and J. Tantsura, "OSPF
Extensions for Segment Routing", draft-ietf-ospf-segment-
routing-extensions-25 (work in progress), April 2018.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
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[RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions
in Support of Generalized Multi-Protocol Label Switching
(GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005,
<https://www.rfc-editor.org/info/rfc4202>.
[RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008,
<https://www.rfc-editor.org/info/rfc5340>.
[RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
Advertisement", RFC 7684, DOI 10.17487/RFC7684, November
2015, <https://www.rfc-editor.org/info/rfc7684>.
[RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>.
[RFC7794] Ginsberg, L., Ed., Decraene, B., Previdi, S., Xu, X., and
U. Chunduri, "IS-IS Prefix Attributes for Extended IPv4
and IPv6 Reachability", RFC 7794, DOI 10.17487/RFC7794,
March 2016, <https://www.rfc-editor.org/info/rfc7794>.
[RFC8362] Lindem, A., Roy, A., Goethals, D., Reddy Vallem, V., and
F. Baker, "OSPFv3 Link State Advertisement (LSA)
Extensibility", RFC 8362, DOI 10.17487/RFC8362, April
2018, <https://www.rfc-editor.org/info/rfc8362>.
9.2. Informative References
[I-D.ietf-isis-sr-yang]
Litkowski, S., Qu, Y., Sarkar, P., Chen, I., and J.
Tantsura, "YANG Data Model for IS-IS Segment Routing",
draft-ietf-isis-sr-yang-04 (work in progress), June 2018.
[I-D.ietf-ospf-sr-yang]
Yeung, D., Qu, Y., Zhang, Z., Chen, I., and A. Lindem,
"Yang Data Model for OSPF SR (Segment Routing) Protocol",
draft-ietf-ospf-sr-yang-05 (work in progress), July 2018.
[I-D.ietf-spring-segment-routing-ldp-interop]
Bashandy, A., Filsfils, C., Previdi, S., Decraene, B., and
S. Litkowski, "Segment Routing interworking with LDP",
draft-ietf-spring-segment-routing-ldp-interop-15 (work in
progress), September 2018.
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[I-D.ietf-spring-sr-yang]
Litkowski, S., Qu, Y., Sarkar, P., and J. Tantsura, "YANG
Data Model for Segment Routing", draft-ietf-spring-sr-
yang-09 (work in progress), June 2018.
[RFC5706] Harrington, D., "Guidelines for Considering Operations and
Management of New Protocols and Protocol Extensions",
RFC 5706, DOI 10.17487/RFC5706, November 2009,
<https://www.rfc-editor.org/info/rfc5706>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>.
[RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L.,
Decraene, B., Litkowski, S., and R. Shakir, "Segment
Routing Architecture", RFC 8402, DOI 10.17487/RFC8402,
July 2018, <https://www.rfc-editor.org/info/rfc8402>.
9.3. URIs
[1] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-3.1
[2] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-3.2
[3] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-3.3
[4] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-05#section-3.2
[5] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-2.2.1
[6] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-2.2.2
[7] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-2.1
[8] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-2.4
[9] http://tools.ietf.org/html/draft-ietf-isis-segment-routing-
extensions-16#section-2.3
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[10] http://tools.ietf.org/html/RFC7794
[11] http://tools.ietf.org/html/RFC7794
[12] http://tools.ietf.org/html/draft-ietf-isis-l2bundles-07
[13] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-3.2
[14] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-3.1
[15] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-3.3
[16] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-3.4
[17] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-6.1
[18] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-6.2
[19] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-5
[20] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-4
[21] http://tools.ietf.org/html/draft-ietf-ospf-segment-routing-
extensions-25#section-2.1
[22] http://tools.ietf.org/html/RFC7684#section-2.1
[23] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-3.2
[24] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-3.1
[25] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-3.3
[26] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-3.4
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Internet-Draft BGP LS extensions for Segment Routing October 2018
[27] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-6.1
[28] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-6.2
[29] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-5
[30] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-4
[31] http://tools.ietf.org/html/draft-ietf-ospf-ospfv3-segment-
routing-extensions-12#section-2.1
[32] http://tools.ietf.org/html/RFC8362#section-3.1
Authors' Addresses
Stefano Previdi (editor)
Via Del Serafico, 200
Rome 00142
Italy
Email: stefano@previdi.net
Ketan Talaulikar
Cisco Systems, Inc.
S.No. 154/6, Phase I, Hinjawadi
Pune 411 057
India
Email: ketant@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
Brussels
Belgium
Email: cfilsfil@cisco.com
Hannes Gredler
RtBrick Inc.
Email: hannes@rtbrick.com
Previdi, et al. Expires April 22, 2019 [Page 28]
Internet-Draft BGP LS extensions for Segment Routing October 2018
Mach(Guoyi) Chen
Huawei Technologies
Huawei Building, No. 156 Beiqing Rd.
Beijing 100095
China
Email: mach.chen@huawei.com
Previdi, et al. Expires April 22, 2019 [Page 29]
