wdiff draft-ietf-bier-isis-extensions-01.txt draft-ietf-bier-isis-extensions-02.txt

Internet Engineering Task Force L. Ginsberg, Ed.
Internet-Draft Cisco Systems
Intended status: Standards Track A. Przygienda
Expires: April 19, September 20, 2016 Ericsson
S. Aldrin
Google
J. Zhang
Juniper Networks, Inc.
October 17, 2015
March 19, 2016

BIER support via ISIS
draft-ietf-bier-isis-extensions-01
draft-ietf-bier-isis-extensions-02

Abstract

Specification of an ISIS extension to support BIER domains and sub-
domains.

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 http://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
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This Internet-Draft will expire on April 19, September 20, 2016.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. BIER Domains and Sub-Domains . . . . . . . . . . . . . . 4
4.2. Advertising BIER Information . . . . . . . . . . . . . . 5
5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4 5
5.1. Enabling a BIER Sub-Domain . . . . . . . . . . . . . . . 5
5.2. Multi Topology and Sub-Domain . . . . . . . . . . . . . . 5
5.3. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 5 6
5.4. Tree Type . . . . . . . . . . . . . . . . . . . . . . . . 5 6
5.5. Label Advertisements advertisements for MPLS encapsulated BIER sub-
domains . . . . . . . . . . . . . . . . Encapsulation . . . . . . . 6
5.6. BFR-id Advertisements . . 5
5.5.1. Special Consideration . . . . . . . . . . . . . . . . 6
5.6. BFR-id Advertisements . . .
5.7. Reporting Misconfiguration . . . . . . . . . . . . . . . 6
5.7.
5.8. Flooding Reduction . . . . . . . . . . . . . . . . . . . . . . . . 6 7
6. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . 6 7
6.1. BIER Info sub-TLV . . . . . . . . . . . . . . . . . . . . 7
6.2. BIER MPLS Encapsulation sub-sub-TLV . . . . . . . . . . . 8
6.3. Optional BIER sub-domain Tree Type sub-sub-TLV . . . . . 9
6.4. Optional BIER sub-domain BSL conversion sub-sub-TLV . . . 10 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 10
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11 10
9. Normative References . . . . . . . . . . . . . . . . . . . . 11 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 11

1. Introduction

Bit Index Explicit Replication (BIER)
[I-D.draft-ietf-bier-architecture-02]
[I-D.draft-ietf-bier-architecture-03] defines an architecture where
all intended multicast receivers are encoded as bitmask in the
Multicast packet header within different encapsulations such as
[I-D.draft-ietf-bier-mpls-encapsulation-02].
[I-D.draft-ietf-bier-mpls-encapsulation-03]. A router that receives
such a packet will forward the packet based on the Bit Position in
the packet header towards the receiver(s), following a precomputed
tree for each of the bits in the packet. Each receiver is
represented by a unique bit in the bitmask.

This document presents necessary extensions to the currently deployed
ISIS for IP [RFC1195] protocol to support distribution of information
necessary for operation of BIER domains and sub-domains. This
document defines a new TLV to be advertised by every router
participating in BIER signaling.

2. Terminology

Some of the terminology specified in
[I-D.draft-ietf-bier-architecture-02]
[I-D.draft-ietf-bier-architecture-03] is replicated here and extended
by necessary definitions:

BIER: Bit Index Explicit Replication (The overall architecture of
forwarding multicast using a Bit Position).

BIER-OL: BIER Overlay Signaling. (The method for the BFIR to learn
about BFER's).

BFR: Bit Forwarding Router (A router that participates in Bit Index
Multipoint Forwarding). A BFR is identified by a unique BFR-
prefix in a BIER domain.

BFIR: Bit Forwarding Ingress Router (The ingress border router that
inserts the BM into the packet). Each BFIR must have a valid BFR-
id assigned.

BFER: Bit Forwarding Egress Router. A router that participates in
Bit Index Forwarding as leaf. Each BFER must be a BFR. Each BFER
must have a valid BFR-id assigned.

BFT: Bit Forwarding Tree used to reach all BFERs in a domain.

BIFT: Bit Index Forwarding Table.

BMS: Bit Mask Set. Set containing bit positions of all BFER
participating in a set.

BMP: Bit Mask Position, a given bit in a BMS.

Invalid BMP: Unassigned Bit Mask Position, consisting of all 0s.

IGP signalled BIER domain: A BIER underlay where the BIER
synchronization information is carried in IGP. Observe that a
multi-topology is NOT a separate BIER domain in IGP.

BIER sub-domain: A further distinction within a BIER domain
identified by its unique sub-domain identifier. A BIER sub-domain
can support multiple BitString Lengths.

BFR-id: An optional, unique identifier for a BFR within a BIER sub-
domain.

Invalid BFR-id: Unassigned BFR-id, consisting of all 0s.

3. IANA Considerations

This document adds the following new sub-TLVs sub-TLV to the registry of sub-
TLVs for TLVs 235, 237 [RFC5120] and TLVs 135,236
[RFC5305],[RFC5308].

Value: 32 (suggested - to be assigned by IANA)

Name: BIER Info

This document also introduces a new registry for sub-sub-TLVs for the
BIER Info sub-TLV added above. The registration policy is Expert
Review as defined in [RFC5226]. This registry is part of the "IS-IS
TLV Codepoints" registry. The name of the registry is "sub-sub-TLVs
for BIER Info sub-TLV". The defined values are:

Type Name
---- ----
1 BIER MPLS Encapsulation
2 BIER sub-domain Tree Type
3 BIER sub-domain BSL conversion

4. Concepts

4.1. BIER Domains and Sub-Domains

An ISIS signalled BIER domain is aligned with the scope of
distribution of BFR-prefixes that identify the BFRs within ISIS.
ISIS acts in such a case as the according supporting BIER underlay.

Within such a domain, ISIS the extensions are capable of carrying defined in this document
advertise BIER information for multiple one or more BIER sub-domains. Each
sub-domain is uniquely identified by its subdomain-id and each a subdomain-id. Each subdomain can reside
in
is associated with a single ISIS topology [RFC5120], which may be any
of the ISIS topologies [RFC5120]. supported by ISIS. Local configuration controls
which <MT,SD> pairs are supported by a router. The mapping of sub-domains sub-
domains to topologies is MUST be consistent within a local decision of each BFR currently but is
advertised throughout the domain to ensure routing consistency. BIER flooding
domain.

Each BIER sub-domain has as its unique attributes the encapsulation
used and the type of tree it is using to forward BIER frames
(currently always SPF). Additionally, per supported bitstring length
in the sub-domain, each router will advertise the necessary label
ranges to support it.

This RFC introduces

4.2. Advertising BIER Information

BIER information advertisements are associated with a new sub-TLV in
the extended reachability TLVs to
distribute such information about TLVs. BIER sub-domains. To satisfy information is always
associated with a host prefix which MUST be a node address for the
requirements
advertising node. The following restrictions apply:

o Prefix length MUST be 32 for an IPv4 prefix or 128 for an IPv6
prefix

o When the Prefix Attributes Flags sub-TLV is present N flag MUST be
set and X and R flags MUST NOT be set. [RFC7794]

o BIER prefixes per
[I-D.draft-ietf-bier-architecture-02] additional information will sub-TLVs MUST NOT be
carried in [I-D.draft-ietf-isis-prefix-attributes-01]. included when a prefix reachability
advertisement is leaked between levels.

5. Procedures

5.1. Enabling a BIER Sub-Domain

A given sub-domain with identifier SD with supported bitstring
lengths MLs in a multi-topology MT [RFC5120] is denoted further as
<MT,SD,MLs> and dos does not have to be advertised by by default by BFRs to
preserve the scaling of the protocol (i.e. ISIS carries no TLVs
containing any of the elements related to <MT,SD>). The
advertisement may be triggered e.g. by a first BIER sub-TLV
(Section 6.1) containing <MT,SD> advertised into the area. The
specific trigger itself is outside the scope of this RFC but can be
for example a VPN desiring to initiate a BIER sub-domain as MI-PMSI
[RFC6513] tree or a pre-configured BFER (since BFERs will always
advertise the BIER sub-TLV to make sure they can be reached). It is
outside the scope of this document to describe what trigger for a
router capable of participating in <MT,SD> is used to start the
origination of the necessary information to join into it.

5.2. Multi Topology and Sub-Domain

A given sub-domain is supported within one and only one topology.
All routers in the flooding scope of the BIER sub-TLVs MUST advertise
a
the same sub-domain within the same multi-topology. A router discovering a
sub-domain advertised within a topology that is different from its
own
receiving an <MT,SD> advertisement which does not match the locally
configured pair MUST report a misconfiguration of a specific sub-domain. Each
router MUST compute BFTs for a sub-domain using only routers
advertising it in the same multi-topology. received <MT,
SD> pair. All received BIER advertisements associated with the
conflicting <MT, SD> pair MUST be ignored.

5.3. Encapsulation

All routers in the flooding scope of the BIER TLVs MUST advertise the
same encapsulation for a given <MT,SD>. A router discovering
encapsulation advertised that is different from its own MUST report a
misconfiguration of a specific <MT,SD>. Each router MUST compute
BFTs for <MT,SD> using only routers having the same encapsulation as
its own advertised encapsulation in All received BIER sub-TLV for <MT,SD>.
advertisements associated with the conflicting <MT, SD> pair MUST be
ignored.

5.4. Tree Type

All routers in the flooding scope of the BIER TLVs MUST MAY advertise the
same a
supported tree type for a given <MT,SD>. In case of mismatch Tree type indicates the behavior
is analogous to Section 5.3.

5.5. Label Advertisements for MPLS encapsulated BIER sub-domains

Each router MAY advertise within
algorithm used when calculating the BIER MPLS Encapsulation sub-sub-
TLV (Section 6.2) of optimal path. Currently only the
default algorithm "SPF" is defined - which has a BIER Info sub-TLV (Section 6.1) for <MT,SD>
(denoted as TLV<MT,SD>) for every tree type of 0. If
no tree type is advertised tree type 0 is assumed. The supported bitstring length a valid
starting label value and a non-zero range length. It
tree type MUST advertise
at least one valid label value and a non-zero range length be consistent for the
required bitstring lengths per [I-D.draft-ietf-bier-architecture-02]
in case it has computed itself as being on the BFT rooted at any of
the BFRs with valid BFR-ids (except itself if it does NOT have all routers supporting a
valid BFR-id) participating in given
<MT,SD>.

A router MAY decide to not advertise the BIER Info sub-TLV
(Section 6.1)

5.5. Label advertisements for <MT,SD> if it does not want to participate in the
sub-domain due to resource constraints, label space optimization,
administrative configuration or any other reasons.

5.5.1. Special Consideration MPLS Encapsulation

A router that desires to participate in <MT,SD> MUST advertise for
each bitstring length it supports in <MT,SD> a label range size that
guarantees to cover the maximum BFR-id injected into <MT,SD> (which
implies a certain maximum set id per bitstring length as described in
[I-D.draft-ietf-bier-architecture-02]).
[I-D.draft-ietf-bier-architecture-03]). Any router that violates
this condition MUST be excluded from BIER BFTs for <MT,SD>.

5.6. BFR-id Advertisements

Each BFER BFER/BFIR MAY advertise with its TLV<MT,SD> the BFR-id that it
has administratively chosen.

If a router discovers that two BFRs it can reach advertise the same
value for A valid BFR-id for <MT,SD>, it MUST report a misconfiguration and
disregard those routers for all be unique within
the flooding scope of the BIER calculations and procedures advertisments. All BFERs/BFIRs MUST
detect advertisement of duplicate valid BFR-IDs for
<MT,SD> to align with [I-D.draft-ietf-bier-architecture-02]. It a given <MT, SD>.
When such duplication is
worth observing that based on this procedure detected all of the routers with colliding
BFR-id assignments in <MT,SD> MAY still advertising
duplicates MUST be treated as if they did not advertise a valid BFR-
id. This implies they cannot act as BFIRs in <MT,SD> but
will be never able to receive traffic from other BFRs BFER or BFIR in that <MT,SD>.

5.7. Reporting Misconfiguration

Whenever an advertisement is received which violates any of the
constraints defined in this document the receiving router MUST report
the misconfiguration.

5.8. Flooding Reduction

BIER domain information SHOULD change and force flooding infrequently. Especially, the router SHOULD make every possible
attempt to bundle all the Frequent changes necessary to sub-domains
will increase the number of Link State PDU (LSP) updates and ranges
advertised with those into least possible updates.
negatively impact performance in the network.

6. Packet Formats

All ISIS BIER information is carried within the TLVs 235, 237
[RFC5120] and or TLVs 135,236 135 [RFC5305], or TLV 236 [RFC5308].

6.1. BIER Info sub-TLV

This sub-TLV carries the information for the BIER sub-domains that
the router participates in as BFR. It can repeat This sub-TLV MAY appear multiple
times in a given prefix-reachability TLV - once for
different multi-topology and each sub-domain <MT,SD> combinations.
supported in the associated topology.

The sub-TLV carries advertises a single <MT,SD> combination followed by
optional sub-sub-TLVs specified within its context such as e.g. BIER MPLS
Encapsulation per Section 6.2. If the same <MT,SD> combination is
advertised more than once, only the first occurence of the sub-TLV
MUST be used.

On violation of any of the following conditions, the receiving router
SHOULD signal a misconfiguration condition. Further results are
unspecified unless described in the according section of this RFC:

o The subdomain-id MUST be included only within a single topology. following sections.

Type: as indicated in IANA section.

Length: 1 octet.

Reserved: reserved, must MUST be 0 on transmission, ignored on reception. May be
used in future versions. 8 bits

subdomain-id: Unique value identifying the BIER sub-domain. 1 octet

BFR-id: A 2 octet field encoding the BFR-id, as documented in
[I-D.draft-ietf-bier-architecture-02].
[I-D.draft-ietf-bier-architecture-03]. If no BFR-id has been
assigned this field is set to the invalid BFR-
id advertising router is not owning a BFR-id in the sub-domain. BFR-id.

6.2. BIER MPLS Encapsulation sub-sub-TLV

This sub-sub-TLV carries the information for the BIER MPLS
encapsulation and including the necessary label ranges per range for a specific bitstring
length for a certain <MT,SD> and <MT,SD>. It is carried advertised within the BIER Info
sub-TLV (Section 6.1) that the router participates in as BFR. . This sub-sub-TLV MAY appear multiple times
within a single BIER info sub-TLV.

On violation of any of the following conditions, the receiving router
SHOULD signal a misconfiguration condition. Further results are by
default unspecified unless explicitly described:

o The sub-sub-TLV
MUST be included once AND ONLY once within ignore the encapsulating BIER Info sub-TLV. If such a sub-sub-TLV is included more than once, only
the first instance MUST be processed.

o Label ranges within the in multiple sub-sub-TLV MUST NOT overlap, otherwise
the whole sub-sub-TLV MUST be disregarded and the violating
routers are treated per further procedures in Section 5.3. overlap.

o Bitstring lengths within the sub-sub-TLV in multiple sub-sub-TLVs MUST NOT repeat,
otherwise the whole sub-sub-TLV MUST be disregarded and the
violating routers are treated per further procedures in
Section 5.3. identical.

o The sub-sub-TLV MUST include the required bitstring lengths
encoded in precisely the same way as in
[I-D.draft-ietf-bier-architecture-02].
[I-D.draft-ietf-bier-mpls-encapsulation-03].

o All The label range sizes size MUST be greater than 0.

o All labels in the range MUST represent valid label values, otherwise the whole
sub-sub-TLV MUST be disregarded and the violating routers are
treated per further procedures in Section 5.3. values

Type: value of 0 1 indicating MPLS encapsulation.

Length: 1 octet.

Local BitString Length (BS Len): Bitstring Encoded bitstring length for the label
range that this router is advertising as per
[I-D.draft-ietf-bier-mpls-encapsulation-02]. [I-
D.draft-ietf-bier-mpls-encapsulation-03]. 4 bits.

Label Range Size: Number of labels in the range used on
encapsulation for this BIER sub-domain for this bitstring length,
1 octet. This MUST never be advertised as 0 (zero) and otherwise,
this sub-sub-TLV must be treated as if not present for BFT
calculations and a misconfiguration SHOULD be reported by the
receiving router.

Label: First label of the range used on encapsulation for this BIER
sub-domain for this bitstring length, range, 20 bits. The label is used
for example by [I-D.draft-ietf-bier-mpls-encapsulation-02] to
forward traffic to sets of BFERs. labels are as defined
in [I-D.draft-ietf-bier-mpls-encapsulation-03].

6.3. Optional BIER sub-domain Tree Type sub-sub-TLV

This sub-sub-TLV carries the information of associated with the
supported BIER tree type for a <MT,SD> combination. It is carried
within the BIER Info sub-TLV (Section 6.1) that the router
participates in as BFR. This sub-sub-
TLV sub-sub-TLV is optional and its absence
has the same semantics as its presence with Tree Type value 0 (SPF). BIER implementation following
When Tree Type 0 is used it is recommended that this version of sub-sub-TLV be
omitted in order to reduce the RFC SHOULD space consumed in the parent TLV.

This sub-sub-TLV MUST NOT advertise this occur more than once in a BIER Info sub-
TLV.

On violation of any If multiple occurences of the following conditions, the receiving router
implementing this RFC SHOULD signal a misconfiguration condition.
Further results are unspecified unless described further:

o The sub-sub-TLV are present in a
single BIER Info sub-TLV the encapsulating BIER Info sub-TLV MUST NOT be included more than once.

o The Tree Type
ignored.

If the tree type (implied or explicitly advertised) does not match
the locally configured tree type associated with the matching <MT,
SD> pair the encapsulating sub-TLV MUST be 0 (SPF). ignored.

Type: value of 1 indicating BIER Tree Type.

Length: 1 octet.

Tree Type: The only supported value in this specification is 0 and
indicates that BIER uses normal SPF computed reachability to
construct BIFT. BIER implementation following this RFC MUST
ignore the node for purposes of the sub-domain <MT,SD> if this
field has any value except 0.

Tree type specific opaque data: Opaque data up to the length of the
TLV carrying tree type specific parameters. For Tree Type 0 (SPF)
no such data is included and therefore TLV Length is 1. 1 octet

6.4. Optional BIER sub-domain BSL conversion sub-sub-TLV

This sub-sub-TLV indicates whether the BFR is capable of imposing a
different Bit String Length (BSL) than the one it received in a BIER
encapsulated packet. Such a capability may allow future, advanced
tree types which ensure simple migration procedures from one BSL to
another in a given <MT,SD> or prevent stable blackholes in scenarios
where not all routers support the same set of BSLs in a given
<MT,SD>. It is carried within the BIER Info sub-TLV (Section 6.1).
This sub-sub-TLV is optional and its absence indicates that the
router is NOT capable of imposing different BSLs but will always
forward the packet with the BSL unchanged.

On violation of any This sub-sub-TLV MAY
occur at most once in a given BIER info sub-TLV. If multiple
occurences of the following conditions, the receiving router
implementing this RFC SHOULD signal a misconfiguration condition.
Further results are unspecified unless described further:

o The sub-sub-TLV are received in a given BIER info sub-
TLV the encapsulating sub-TLV MUST NOT be included more than once. ignored.

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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Type: value of 2 indicating BIER BSL conversion.

Length: 1 octet.

7. Security Considerations

Implementations must assure that malformed TLV and Sub-TLV
permutations do not result in errors which cause hard protocol
failures.

8. Acknowledgements

The RFC is aligned with the
[I-D.draft-ietf-bier-ospf-bier-extensions-00]
[I-D.draft-ietf-bier-ospf-bier-extensions-01] draft as far as the
protocol mechanisms overlap.

Many thanks for comments from (in no particular order) Hannes
Gredler, Ijsbrand Wijnands, Peter Psenak and Chris Bowers.

9. Normative References

[I-D.draft-ietf-bier-architecture-02]

[I-D.draft-ietf-bier-architecture-03]
Wijnands et al., IJ., "Stateless Multicast using Bit Index
Explicit Replication Architecture", internet-draft draft-
ietf-bier-architecture-02.txt, July 2015.

[I-D.draft-ietf-bier-mpls-encapsulation-02]
ietf-bier-architecture-03.txt, Jan 2016.

[I-D.draft-ietf-bier-mpls-encapsulation-03]
Wijnands et al., IJ., "Bit Index Explicit Replication
using MPLS encapsulation", internet-draft draft-ietf-bier-
mpls-encapsulation-02.txt, Aug 2015.

[I-D.draft-ietf-bier-ospf-bier-extensions-00]
mpls-encapsulation-03.txt, Feb 2016.

[I-D.draft-ietf-bier-ospf-bier-extensions-01]
Psenak et al., P., "OSPF Extension for Bit Index Explicit
Replication", internet-draft draft-ietf-bier-ospf-bier-
extensions-00.txt,
extensions-01.txt, October 2014.

[I-D.draft-ietf-isis-prefix-attributes-01]
Ginsberg et al., U., "IS-IS Prefix Attributes for Extended
IP and IPv6 Reachability", internet-draft draft-ietf-isis-
prefix-attributes-01.txt, June 2015.

[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, DOI 10.17487/RFC1195,
December 1990, <http://www.rfc-editor.org/info/rfc1195>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120,
DOI 10.17487/RFC5120, February 2008,
<http://www.rfc-editor.org/info/rfc5120>.

[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.

[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, DOI 10.17487/RFC5305, October
2008, <http://www.rfc-editor.org/info/rfc5305>.

[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308,
DOI 10.17487/RFC5308, October 2008,
<http://www.rfc-editor.org/info/rfc5308>.

[RFC6513] Rosen, E., Ed. and R. Aggarwal, Ed., "Multicast in MPLS/
BGP IP VPNs", RFC 6513, DOI 10.17487/RFC6513, February
2012, <http://www.rfc-editor.org/info/rfc6513>.

[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, <http://www.rfc-editor.org/info/rfc7794>.

Authors' Addresses

Les Ginsberg (editor)
Cisco Systems
510 McCarthy Blvd.
Milpitas, CA 95035
USA

Email: ginsberg@cisco.com
Tony Przygienda
Ericsson
300 Holger Way
San Jose, CA 95134
USA

Email: antoni.przygienda@ericsson.com

Sam Aldrin
Google
1600 Amphitheatre Parkway
Mountain View, CA
USA

Email: aldrin.ietf@gmail.com

Jeffrey (Zhaohui) Zhang
Juniper Networks, Inc.
10 Technology Park Drive
Westford, MA 01886
USA

Email: zzhang@juniper.net