Internet Engineering Task Force A. Przygienda
Internet-Draft Ericsson
Intended status: Standards Track L. Ginsberg
Expires: April 26, 2015 Cisco Systems
S. Aldrin
Huawei
J. Zhang
Juniper Networks, Inc.
October 23, 2014
BIER support via ISIS
draft-przygienda-bier-isis-ranges-01
Abstract
Specification of an ISIS extension to support BIER 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
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 26, 2015.
Copyright Notice
Copyright (c) 2014 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
Przygienda, et al. Expires April 26, 2015 [Page 1]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
(http://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 . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
4. Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1. BIER Domains in Extended Reachability TLVs . . . . . . . 4
4.2. BIER Domains . . . . . . . . . . . . . . . . . . . . . . 4
5. Procedures . . . . . . . . . . . . . . . . . . . . . . . . . 4
5.1. Enabling a BIER Domain . . . . . . . . . . . . . . . . . 4
5.2. Encapsulation . . . . . . . . . . . . . . . . . . . . . . 5
5.3. Label Advertisements for MPLS encapsulated BIER domains . 5
5.3.1. Special Consideration . . . . . . . . . . . . . . . . 5
5.4. BFR-id Advertisements . . . . . . . . . . . . . . . . . . 5
5.5. Flooding . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Packet Formats . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. BIER Info sub-TLV . . . . . . . . . . . . . . . . . . . . 6
6.2. BIER MPLS Encapsulation sub-sub-TLV . . . . . . . . . . . 7
7. Security Considerations . . . . . . . . . . . . . . . . . . . 7
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
9. Normative References . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Bit Index Explicit Replication (BIER)
[I-D.draft-wijnands-bier-architecture-00] 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-wijnands-mpls-bier-encapsulation-01]. 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 first attempt at necessary extensions to the
currently deployed ISIS for IP [RFC1195] protocol to support
distribution of information necessary for operation of BIER domains.
This document defines a new TLV to be advertised by every router
participating in such BIER domains.
Przygienda, et al. Expires April 26, 2015 [Page 2]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
2. Terminology
Some of the terminology specified in
[I-D.draft-wijnands-bier-architecture-00] 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).
BM: Bit Mask (A bit stream of a certain fixed length. Each Bit
represents a receiver).
P-BM: Packet Bit Mask (A Bit Mask included in the Multicast Packet).
BP: Bit Position (A single Bit from the Bit Mask that represents a
receiver).
BFR: Bit Forwarding Router (A router that participates in Bit Index
Multipoint Forwarding).
BFIR: Bit Forwarding Ingress Router (The ingress border router that
inserts the BM into the packet).
BFER: Bit Forwarding Egress Router. A router that participates in
Bit Index Forwarding as leaf. Each BFER must be a BFR.
BFT: Bit Forwarding Tree used to reach all BFERs in a domain.
BIFT: Bit Index Forwarding Table (A 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.
Invalid BFR-id: Unassigned BFR-id, consisting of all 0s.
IGP signalled BIER domain: A BIER domain information carried in IGP
and identified by its multi-topology and bitmask length.
Przygienda, et al. Expires April 26, 2015 [Page 3]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
3. IANA Considerations
This document adds the following new sub-TLVs 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
4. Concepts
4.1. BIER Domains in Extended Reachability TLVs
This draft introduces a sub-TLV in the extended reachability TLVs to
distribute information about BIER domains and services they carry.
To satisfy the requirements for BIER prefixes per
[I-D.draft-wijnands-bier-architecture-00] additional information may
be carried in [I-D.draft-ginsberg-isis-prefix-attributes].
4.2. BIER Domains
ISIS extensions are capable of carrying BIER information not only for
a single BIER domains but for multiple ones. A BIER domain in ISIS
is currently always uniquely identified by the tuple of multi-
topology MT and bitmask length ML it belongs to denoted as <MT,ML>.
Each such domain itself has as its unique attributes the
encapsulation used and the type of tree it is using to forward BIER
frames (currently always SPF).
5. Procedures
5.1. Enabling a BIER Domain
A given domain with masklength ML in a multi-topology MT [RFC5120]
(denoted as <MT,ML>) is normally not advertised to preserve the
scaling of the protocol (i.e. ISIS carries no TLVs containing any of
the elements related to <MT,ML>) and is enabled by a first BIER sub-
TLV (Section 6.1) containing <MT,ML> being advertised into the area.
The trigger itself is outside the scope of this draft but can be for
example a VPN desiring to initiate a BIER layer as MI-PMSI [RFC6513]
tree. It is outside the scope of this document to describe what
trigger for a router capable of participating <MT,ML> is used to
start the origination of the necessary information to join into it.
Przygienda, et al. Expires April 26, 2015 [Page 4]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
5.2. Encapsulation
All routers in the flooding scope of the BIER TLVs SHOULD advertise
the same encapsulation for a given <MT,ML>. A router discovering
encapsulation advertised that is different from its own MUST report a
misconfiguration of a specific <MT,ML>. Each router MUST compute
BFTs for <MT,ML> using only routers having the same encapsulation as
its own advertised encapsulation in BIER sub-TLV for <MT,ML>.
5.3. Label Advertisements for MPLS encapsulated BIER domains
Each router MAY advertise within the BIER MPLS Encapsulation sub-sub-
TLV (Section 6.2) of a BIER Info sub-TLV (Section 6.1) for <MT,ML>
(denoted further as TLV<MT,ML>) a valid starting label value and a
non-zero range length. It MUST advertise a valid label value and a
non-zero range length 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 a valid BFR-id) participating in <MT,ML>.
A router CAN decide to not advertise its TLV<MT,ML> if it does not
want to participate in the domain due to resource constraints, label
space optimization, administrative configuration or any other
reasons.
5.3.1. Special Consideration
A router MUST advertise for <MT,ML> label range size that guarantees
to cover the maximum BFR-id injected into <MT,ML> (which implies a
certain set id as described in
[I-D.draft-wijnands-bier-architecture-00]). Any router that violates
this condition MUST be excluded from BIER BFTs for <MT,ML>.
5.4. BFR-id Advertisements
Each BFER MAY advertise with its TLV<MT,ML> the BFR-id that it has
administratively chosen.
If a router discovers that two BFRs it can reach advertise the same
value for BFR-id for <MT,ML>, it MUST report a misconfiguration and
disregard those routers for all BIER calculations and procedures for
<MT,ML> to align with [I-D.draft-wijnands-bier-architecture-00]. It
is worth observing that based on this procedure routers with
colliding BFR-id assignments in <MT,ML> MAY still act as BFIRs in
<MT,ML> but will be never able to receive traffic from other BFRs in
<MT,ML>.
Przygienda, et al. Expires April 26, 2015 [Page 5]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
5.5. Flooding
BIER domain information SHOULD change and force flooding
infrequently. Further discussion TBD.
6. Packet Formats
All ISIS BIER information is carried within the TLVs 235, 237
[RFC5120] and TLVs 135,236 [RFC5305],[RFC5308].
6.1. BIER Info sub-TLV
This sub-TLV carries the information for the BIER domains that the
router participates in as BFR. It can repeat multiple times for
different domain <MT,ML> combinations. If the same <MT,ML> domain is
advertised multiple times with different encapsulations, the result
is unspecified.
The sub-TLV carries a single <MT,ML> combination followed by optional
sub-sub-TLVs specified within its context such as e.g. BIER MPLS
Encapsulation per Section 6.2.
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BM Len|Reservd| BFR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: as indicated in IANA section.
Length: 1 octet.
Local BitMask Length (BM Len): Bitmask length for this BIER domain
that this router is advertising per
[I-D.draft-wijnands-mpls-bier-encapsulation-01]. 4 bits.
Reserved reserved, must be 0 on transmission, ignored on reception.
4 bits
Przygienda, et al. Expires April 26, 2015 [Page 6]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
BFR-id A 2 octet field encoding the BFR-id, as documented in
[I-D.draft-wijnands-bier-architecture-00]. If set to the invalid
BFR-id advertising router is not owning any BFR-id.
6.2. BIER MPLS Encapsulation sub-sub-TLV
This sub-sub-TLV carries the information for the BIER MPLS
encapsulations for a certain <MT,ML> and is carried within the BIER
Info sub-TLV (Section 6.1) that the router participates in as BFR.
It can repeat only once within it. If this sub-sub-TLV is included
more than once, the result is unspecified.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Lbl Range Size|Reservd| Label |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: value of 0 indicating MPLS encapsulation.
Length: 1 octet.
Label Range Size: Number of labels in the range used on
encapsulation for this BIER domain, 1 octet. This MUST never be
advertise 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
domain and service, 20 bits. The label is used for example by
[I-D.draft-wijnands-mpls-bier-encapsulation-01] to forward traffic
to sets of BFERs.
Reserved reserved, must be 0 on transmission, ignored on reception.
4 bits
7. Security Considerations
Implementations must assure that malformed TLV and Sub-TLV
permutations do not result in errors which cause hard protocol
failures.
Przygienda, et al. Expires April 26, 2015 [Page 7]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
8. Acknowledgements
The draft is aligned with the
[I-D.draft-psenak-ospf-bier-extension-01] draft as far as the
protocol mechanisms overlap.
Many thanks for comments from (in no particular order) Hannes
Gredler, Ijsbrand Wijnands and Peter Psenak.
9. Normative References
[I-D.draft-ginsberg-isis-prefix-attributes]
Ginsberg et al., U., "IS-IS Prefix Attributes for Extended
IP and IPv6 Reachability", internet-draft draft-ginsberg-
isis-prefix-attributes-00.txt, October 2014.
[I-D.draft-psenak-ospf-bier-extension-01]
Psenak, P. and IJ. Wijnands, "OSPF Extension for Bit Index
Explicit Replication", internet-draft draft-ietf-ospf-
prefix-link-attr-01.txt, October 2014.
[I-D.draft-wijnands-bier-architecture-00]
Wijnands, IJ., "Stateless Multicast using Bit Index
Explicit Replication Architecture", internet-draft draft-
wijnands-bier-architecture-00.txt, February 2014.
[I-D.draft-wijnands-mpls-bier-encapsulation-01]
Wijnands et al., IJ., "Bit Index Explicit Replication
using MPLS encapsulation", internet-draft draft-wijnands-
mpls-bier-encapsulation-01.txt, February 2014.
[RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4971] Vasseur, JP., Shen, N., and R. Aggarwal, "Intermediate
System to Intermediate System (IS-IS) Extensions for
Advertising Router Information", RFC 4971, July 2007.
[RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi
Topology (MT) Routing in Intermediate System to
Intermediate Systems (IS-ISs)", RFC 5120, February 2008.
[RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic
Engineering", RFC 5305, October 2008.
Przygienda, et al. Expires April 26, 2015 [Page 8]
Internet-Draft draft-przygienda-bier-isis-ranges-01 October 2014
[RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October
2008.
[RFC6513] Rosen, E. and R. Aggarwal, "Multicast in MPLS/BGP IP
VPNs", RFC 6513, February 2012.
Authors' Addresses
Tony Przygienda
Ericsson
300 Holger Way
San Jose, CA 95134
USA
Email: antoni.przygienda@ericsson.com
Les Ginsberg
Cisco Systems
510 McCarthy Blvd.
Milpitas, CA 95035
USA
Email: ginsberg@cisco.com
Sam Aldrin
Huawei
2330 Central Expressway
Santa Clara, CA 95051
USA
Email: aldrin.ietf@gmail.com
Jeffrey (Zhaohui) Zhang
Juniper Networks, Inc.
10 Technology Park Drive
Westford, MA 01886
USA
Email: zzhang@juniper.net
Przygienda, et al. Expires April 26, 2015 [Page 9]