draft-ietf-bier-ospf-bier-extensions-01.txt   draft-ietf-bier-ospf-bier-extensions-02.txt 
OSPF P. Psenak, Ed. OSPF P. Psenak, Ed.
Internet-Draft N. Kumar Internet-Draft N. Kumar
Intended status: Standards Track IJ. Wijnands Intended status: Standards Track IJ. Wijnands
Expires: April 21, 2016 Cisco Expires: September 22, 2016 Cisco
A. Dolganow A. Dolganow
Alcatel-Lucent Alcatel-Lucent
T. Przygienda T. Przygienda
Ericsson Ericsson
J. Zhang J. Zhang
Juniper Networks, Inc. Juniper Networks, Inc.
S. Aldrin S. Aldrin
Google, Inc. Google, Inc.
October 19, 2015 March 21, 2016
OSPF Extensions For BIER OSPF Extensions for BIER
draft-ietf-bier-ospf-bier-extensions-01.txt draft-ietf-bier-ospf-bier-extensions-02.txt
Abstract Abstract
Bit Index Explicit Replication (BIER) is an architecture that Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without provides multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast related per- requiring intermediate routers to maintain multicast related per-flow
flow state. BIER also does not require any explicit tree-building state. Neither does BIER require an explicit tree-building protocol
protocol for its operation. A multicast data packet enters a BIER for its operation. A multicast data packet enters a BIER domain at a
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the "Bit-Forwarding Ingress Router" (BFIR), and leaves the BIER domain at
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). one or more "Bit-Forwarding Egress Routers" (BFERs). The BFIR router
The BFIR router adds a BIER header to the packet. The BIER header adds a BIER header to the packet. Such header contains a bit-string
contains a bit-string in which each bit represents exactly one BFER in which each bit represents exactly one BFER to forward the packet
to forward the packet to. The set of BFERs to which the multicast to. The set of BFERs to which the multicast packet needs to be
packet needs to be forwarded is expressed by setting the bits that forwarded is expressed by the according set of bits switched on in
correspond to those routers in the BIER header. BIER packet header.
This document describes the OSPF protocol extension required for BIER This document describes the OSPF protocol extension required for BIER
with MPLS encapsulation. with MPLS encapsulation.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Flooding of the BIER Information in OSPF . . . . . . . . . . 3 2. Flooding of the BIER Information in OSPF . . . . . . . . . . 3
2.1. The BIER Sub-TLV . . . . . . . . . . . . . . . . . . . . 3 2.1. The BIER Sub-TLV . . . . . . . . . . . . . . . . . . . . 3
2.2. The BIER MPLS Encapsulation Sub-TLV . . . . . . . . . . . 4 2.2. The BIER MPLS Encapsulation Sub-TLV . . . . . . . . . . . 4
2.3. Flooding scope of BIER Information . . . . . . . . . . . 5 2.3. Optional BIER Tree Type Sub-TLV . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6 2.4. Flooding scope of BIER Information . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 3. Security Considerations . . . . . . . . . . . . . . . . . . . 7
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Normative References . . . . . . . . . . . . . . . . . . . . 6 5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 6. Normative References . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction 1. Introduction
Bit Index Explicit Replication (BIER) is an architecture that Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "BIER domain" without provides optimal multicast forwarding through a "BIER domain" without
requiring intermediate routers to maintain any multicast related per- requiring intermediate routers to maintain any multicast related per-
flow state. Neither does BIER explicitly require a tree-building flow state. Neither does BIER explicitly require a tree-building
protocol for its operation. A multicast data packet enters a BIER protocol for its operation. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs). BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs).
The BFIR router adds a BIER header to the packet. The BIER header The BFIR router adds a BIER header to the packet. The BIER header
contains a bit-string in which each bit represents exactly one BFER contains a bit-string in which each bit represents exactly one BFER
to forward the packet to. The set of BFERs to which the multicast to forward the packet to. The set of BFERs to which the multicast
packet needs to be forwarded is expressed by setting the bits that packet needs to be forwarded is expressed by setting the bits that
correspond to those routers in the BIER header. correspond to those routers in the BIER header.
BIER architecture requires routers participating in BIER within a BIER architecture requires routers participating in BIER to exchange
given BIER domain to exchange some BIER specific information among BIER related information within a given domain. BIER architecture
themselves. BIER architecture allows link-state routing protocols to permits link-state routing protocols to perform distribution of such
perform the distribution of these information. In this document we information. This document describes extensions to OSPF necessary to
describe extensions to OSPF to distribute BIER specific information carry BIER specific information in the case where BIER uses MPLS
for the case where BIER uses MPLS encapsulation as described in encapsulation as described in [I-D.wijnands-mpls-bier-encapsulation].
[I-D.wijnands-mpls-bier-encapsulation].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Flooding of the BIER Information in OSPF 2. Flooding of the BIER Information in OSPF
All the BIER specific information that a BIER router needs to All BIER specific information that a BFR needs to advertise to other
advertise to other BIER routers are associated with the BFR-Prefix, a BFRs is associated with a BFR-Prefix. BFR prefix is a unique (within
unique (within a given BIER domain), routable IP address that is a given BIER domain), routable IP address that is assigned to each
assign to each BIER router as described in section 2 of BFR as described in more detail in section 2 of
[I-D.wijnands-bier-architecture]. [I-D.wijnands-bier-architecture].
Given that the BIER information is associated with the prefix, the Given that BIER information must be associated with a BFR prefix, the
OSPF Extended Prefix Opaque LSA [I-D.ietf-ospf-prefix-link-attr] is OSPF Extended Prefix Opaque LSA [I-D.ietf-ospf-prefix-link-attr] has
used to flood BIER related information. been chosen to flood it.
2.1. The BIER Sub-TLV 2.1. The BIER Sub-TLV
A new Sub-TLV of the Extended Prefix TLV (defined in A new Sub-TLV of the Extended Prefix TLV (defined in
[I-D.ietf-ospf-prefix-link-attr]) is defined for distributing BIER [I-D.ietf-ospf-prefix-link-attr]) is defined for distributing BIER
information. The new Sub-TLV is called BIER Sub-TLV. Multiple BIER information. The new Sub-TLV is called BIER Sub-TLV. Multiple BIER
Sub-TLVs may be included in the Extended Prefix TLV. Sub-TLVs may be included in the Extended Prefix TLV.
BIER Sub-TLV has the following format: BIER Sub-TLV has the following format:
skipping to change at page 4, line 12 skipping to change at page 4, line 12
Length: variable Length: variable
Sub-domain-ID: Unique value identifying the BIER sub-domain within Sub-domain-ID: Unique value identifying the BIER sub-domain within
the BIER domain, as described in section 1 of the BIER domain, as described in section 1 of
[I-D.wijnands-bier-architecture]. [I-D.wijnands-bier-architecture].
MT-ID: Multi-Topology ID (as defined in [RFC4915]) that identifies MT-ID: Multi-Topology ID (as defined in [RFC4915]) that identifies
the topology that is associated with the BIER sub-domain. the topology that is associated with the BIER sub-domain.
BFR-id: A 2 octet field encoding the BFR-id, as documented in BFR-id: A 2 octet field encoding the BFR-id, as documented in
section 2 [I-D.wijnands-bier-architecture]. If the BFR-id is section 2 [I-D.wijnands-bier-architecture]. If the BFR is not
zero, it means, the advertising router is not advertising any locally configured with a valid BFR-id, the value of this field is
BIER-id. set to invalid BFR-id per [I-D.wijnands-bier-architecture].
Each BFR sub-domain MUST be associate with a single OSPF topology Each BFR sub-domain MUST be associated with one and only one OSPF
that is identified by the MT-ID. If the association between BEIR topology that is identified by the MT-ID. If the association between
sub-domain and OSPF topology advertised in the BIER sub-TLV is in BIER sub-domain and OSPF topology advertised in the BIER sub-TLV by
conflict with the association locally configured on the receiving other BFRs is in conflict with the association locally configured on
router, BIER sub-TLV SHOULD be ignored. the receiving router, whole BIER sub-TLV of the advertising routers
MUST be ignored.
If a BFR advertises the same Sub-domain-ID in multiple BIER sub-TLVs,
the BRF MUST be treated as if it did not advertise a BIER sub-TLV for
such sub-domain.
All BFRs MUST detect advertisement of duplicate valid BFR-IDs for a
given MT-ID and Sub-domain-ID. When such duplication is detected all
BFRs advertising duplicates MUST be treated as if they did not
advertise a valid BFR-id.
2.2. The BIER MPLS Encapsulation Sub-TLV 2.2. The BIER MPLS Encapsulation Sub-TLV
BIER MPLS Encapsulation Sub-TLV is a sub-TLV of the BIER Sub-TLV. BIER MPLS Encapsulation Sub-TLV is a sub-TLV of the BIER Sub-TLV.
BIER MPLS Encapsulation Sub-TLV is used in order to advertise MPLS BIER MPLS Encapsulation Sub-TLV is used in order to advertise MPLS
specific information used for BIER. It MAY appear multiple times in specific information used for BIER. It MAY appear multiple times in
the BIER Sub-TLV. the BIER Sub-TLV.
BIER MPLS Encapsulation Sub-TLV has the following format: BIER MPLS Encapsulation Sub-TLV has the following format:
skipping to change at page 4, line 42 skipping to change at page 5, line 4
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Lbl Range Size | Label Range Base | |Lbl Range Size | Label Range Base |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BS Length | Reserved | | BS Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: TBD Type: TBD
Length: 4 bytes Length: 4 bytes
Label Range Size: A 1 octet field encoding the label range size of Label Range Size: A 1 octet field encoding the label range size of
the label range. It MUST be greater then 0, otherwise the TLV the label range. It MUST be greater then 0, otherwise the
MUST be ignored. advertising router MUST be treated as if it did not advertise a
BIER sub-TLV.
Label Range Base: A 3 octet field, where the 20 rightmost bits Label Range Base: A 3 octet field, where the 20 rightmost bits
represent the first label in the label range. represent the first label in the label range.
BS Length: A 1 octet field encoding the supported BitString length BS Length: A 1 octet field encoding the supported BitString length
associated with this BFR-prefix. The values allowed in this field associated with this BFR-prefix. The values allowed in this field
are specified in section 3 of are specified in section 3 of
[I-D.wijnands-mpls-bier-encapsulation]. [I-D.wijnands-mpls-bier-encapsulation].
The "label range" is the set of labels beginning with the label The "label range" is the set of labels beginning with the label
skipping to change at page 5, line 24 skipping to change at page 5, line 33
described in [I-D.wijnands-bier-architecture] and described in [I-D.wijnands-bier-architecture] and
[I-D.wijnands-mpls-bier-encapsulation]. [I-D.wijnands-mpls-bier-encapsulation].
The size of the label range is determined by the number of Set The size of the label range is determined by the number of Set
Identifiers (SI) (section 2 of [I-D.wijnands-bier-architecture]) Identifiers (SI) (section 2 of [I-D.wijnands-bier-architecture])
that are used in the network. Each SI maps to a single label in that are used in the network. Each SI maps to a single label in
the label range. The first label is for SI=0, the second label is the label range. The first label is for SI=0, the second label is
for SI=1, etc. for SI=1, etc.
If same BS length is repeated in multiple BIER MPLS Encapsulation If same BS length is repeated in multiple BIER MPLS Encapsulation
Sub-TLV inside the same BIER Sub-TLV, the first BIER MPLS Sub-TLV inside the same BIER Sub-TLV, the advertising router MUST be
Encapsulation Sub-TLV with such BS length MUST be used and any treated as if it did not advertise a BIER sub-TLV.
subsequent BIER MPLS Encapsulation Sub-TLVs with the same BS length
MUST be ignored.
Label ranges within all BIER MPLS Encapsulation Sub-TLV inside the Label ranges within all BIER MPLS Encapsulation Sub-TLV inside the
same BIER Sub-TLV SHOULD NOT overlap. If the overlap is detected, same BIER Sub-TLV MUST NOT overlap. If the overlap is detected, the
overlapping BIER MPLS Encapsulation Sub-TLV SHOULD be ignored. advertising router MUST be treated as if it did not advertise a BIER
sub-TLV.
2.3. Flooding scope of BIER Information All advertised labels MUST be valid, otherwise the advertising router
MUST be treated as if it did not advertise a BIER sub-TLV.
2.3. Optional BIER Tree Type Sub-TLV
This Sub-TLV carries the information associated with the supported
BIER tree type for a subdomain. This Sub-TLV is optional and its
absence has the same semantics as its presence with Tree Type value 0
(SPF). When Tree Type 0 is used it is recommended that this Sub-TLV
is omitted in order to reduce the space consumed in the parent TLV.
This Sub-TLV MAY occur no more than once in a BIER sub-TLV. If
multiple occurences of this Sub-TLV are present in a single BIER Sub-
TLV the advertising router MUST be treated as if it did not advertise
a BIER sub-TLV.
If the tree type (implied or explicitly advertised) does not match
the locally configured tree type associated with the matching
subdomain the advertising router MUST be treated as if it did not
advertise a BIER sub-TLV.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Tree Type |
+-+-+-+-+-+-+-+-+
Type: value of 1 indicating BIER Tree Type.
Length: 1 octet.
Tree Type: 1 octet
2.4. Flooding scope of BIER Information
Flooding scope of the OSPF Extended Prefix Opaque LSA Flooding scope of the OSPF Extended Prefix Opaque LSA
[I-D.ietf-ospf-prefix-link-attr] that is used for advertising BIER [I-D.ietf-ospf-prefix-link-attr] that is used for advertising BIER
Sub TLV is set to area. To allow BIER deployment in a multi-area Sub TLV is set to area. To allow BIER deployment in a multi-area
environment, OSPF must propagate BIER information between areas. The environment, OSPF must propagate BIER information between areas. The
following procedure is used in order to propagate BIER related following procedure is used in order to propagate BIER related
information between areas: information between areas:
When an OSPF ABR advertises a Type-3 Summary LSA from an intra- When an OSPF ABR advertises a Type-3 Summary LSA from an intra-
area or inter-area prefix to all its connected areas, it will also area or inter-area prefix to all its connected areas, it will also
skipping to change at page 6, line 21 skipping to change at page 7, line 14
such BIER MPLS Sub-TLV when advertising BIER MPLS Sub-TLV to such BIER MPLS Sub-TLV when advertising BIER MPLS Sub-TLV to
each connected area. each connected area.
3. Security Considerations 3. Security Considerations
Implementations must assure that malformed TLV and Sub-TLV Implementations must assure that malformed TLV and Sub-TLV
permutations do not result in errors which cause hard OSPF failures. permutations do not result in errors which cause hard OSPF failures.
4. IANA Considerations 4. IANA Considerations
The document requests two new allocations from the OSPF Extended The document requests three new allocations from the OSPF Extended
Prefix sub-TLV registry as defined in Prefix sub-TLV registry as defined in
[I-D.ietf-ospf-prefix-link-attr]. [I-D.ietf-ospf-prefix-link-attr].
BIER Sub-TLV: TBD BIER Sub-TLV: TBD
BIER MPLS Encapsulation Sub-TLV: TBD BIER MPLS Encapsulation Sub-TLV: TBD
BIER Tree Type Sub-TLV: TBD
5. Acknowledgments 5. Acknowledgments
The authors would like to thank Rajiv Asati, Christian Martin, Greg The authors would like to thank Rajiv Asati, Christian Martin, Greg
Shepherd and Eric Rosen for their contribution. Shepherd and Eric Rosen for their contribution.
6. Normative References 6. Normative References
[I-D.ietf-ospf-prefix-link-attr] [I-D.ietf-ospf-prefix-link-attr]
Psenak, P., Gredler, H., rjs@rob.sh, r., Henderickx, W., Psenak, P., Gredler, H., rjs@rob.sh, r., Henderickx, W.,
Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute
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