< draft-ietf-bier-ipv6-requirements-00.txt   draft-ietf-bier-ipv6-requirements-01.txt >
BIER M. McBride Network Working Group M. McBride
Internet-Draft Futurewei Internet-Draft Futurewei
Intended status: Standards Track J. Xie Intended status: Standards Track J. Xie
Expires: November 30, 2019 S. Dhanaraj Expires: January 2, 2020 S. Dhanaraj
Huawei Huawei
R. Asati R. Asati
Cisco Cisco
May 29, 2019 July 1, 2019
BIER IPv6 Requirements BIER IPv6 Requirements
draft-ietf-bier-ipv6-requirements-00 draft-ietf-bier-ipv6-requirements-01
Abstract Abstract
The BIER WG has a charter item to work on mechanisms which use BIER The BIER WG has a charter item to work on mechanisms which use BIER
natively in IPv6. This document is intended to help the WG with this natively in IPv6. This document is intended to help the WG with this
effort by specifying requirements for transporting packets, with Bit effort by specifying requirements for transporting packets, with Bit
Index Explicit Replication (BIER) headers, in an IPv6 environment. Index Explicit Replication (BIER) headers, in an IPv6 environment.
There will be a need to send IPv6 payloads, to multiple IPv6 There will be a need to send IPv6 payloads, to multiple IPv6
destinations, using BIER. There have been several proposed solutions destinations, using BIER. There have been several proposed solutions
in this area. But there hasn't been a document which describes the in this area. But there hasn't been a document which describes the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 30, 2019. This Internet-Draft will expire on January 2, 2020.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3 2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 3
3. BIER IPv6 Scenario's . . . . . . . . . . . . . . . . . . . . 3 3. BIER IPv6 Scenario's . . . . . . . . . . . . . . . . . . . . 3
3.1. BIERv6 for Access Network . . . . . . . . . . . . . . . . 4 3.1. BIERv6 for Access Network . . . . . . . . . . . . . . . . 4
3.2. BIERv6 for Data Center . . . . . . . . . . . . . . . . . 4 3.2. BIERv6 for Data Center . . . . . . . . . . . . . . . . . 4
3.3. BIERv6 for Core Networks . . . . . . . . . . . . . . . . 5 3.3. BIERv6 for Core Networks . . . . . . . . . . . . . . . . 5
3.4. Implications for BIER in SRv6 . . . . . . . . . . . . . . 5 3.4. Implications for BIER in SRv6 . . . . . . . . . . . . . . 5
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. L2 Agnostic . . . . . . . . . . . . . . . . . . . . . . . 5 4.1. L2 Agnostic . . . . . . . . . . . . . . . . . . . . . . . 5
4.2. Hop by hop DA modification . . . . . . . . . . . . . . . 5 4.2. Hop by hop DA modification . . . . . . . . . . . . . . . 5
4.3. L4 Inspection . . . . . . . . . . . . . . . . . . . . . . 5 4.3. L4 Inspection . . . . . . . . . . . . . . . . . . . . . . 6
4.4. Multicast address in SA field . . . . . . . . . . . . . . 5 4.4. Multicast address in SA field . . . . . . . . . . . . . . 6
4.5. Incorrect bits . . . . . . . . . . . . . . . . . . . . . 6 4.5. Incorrect bits . . . . . . . . . . . . . . . . . . . . . 6
4.6. SA filtering . . . . . . . . . . . . . . . . . . . . . . 6 4.6. SA filtering . . . . . . . . . . . . . . . . . . . . . . 6
4.7. BIER architecture support . . . . . . . . . . . . . . . . 6 4.7. BIER architecture support . . . . . . . . . . . . . . . . 6
4.8. Keep it simple . . . . . . . . . . . . . . . . . . . . . 6 4.8. Keep it simple . . . . . . . . . . . . . . . . . . . . . 7
4.9. Hardware fast path . . . . . . . . . . . . . . . . . . . 6 4.9. Hardware fast path . . . . . . . . . . . . . . . . . . . 7
5. Solutions Evaluation . . . . . . . . . . . . . . . . . . . . 6 5. Solutions Evaluation . . . . . . . . . . . . . . . . . . . . 7
5.1. BIER-ETH encapsulation in IPv6 networks . . . . . . . . . 6 5.1. BIER-ETH encapsulation in IPv6 networks . . . . . . . . . 7
5.2. Encode Bitstring in IPv6 destination address . . . . . . 8 5.2. Encode Bitstring in IPv6 destination address . . . . . . 8
5.3. Add BIER header into IPv6 Extension Header . . . . . . . 8 5.3. Add BIER header into IPv6 Extension Header . . . . . . . 9
5.4. Transport BIER as IPv6 payload . . . . . . . . . . . . . 9 5.4. Transport BIER as IPv6 payload . . . . . . . . . . . . . 10
5.5. Tunneling BIER in a IPv6 tunnel . . . . . . . . . . . . . 10 5.5. Tunneling BIER in a IPv6 tunnel . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11 8. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 11
9. Normative References . . . . . . . . . . . . . . . . . . . . 11 9. Normative References . . . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction 1. Introduction
Bit Index Explicit Replication (BIER) [RFC8279] is an architecture Bit Index Explicit Replication (BIER) [RFC8279] is an architecture
that provides optimal multicast forwarding, without requiring that provides optimal multicast forwarding, without requiring
intermediate routers to maintain per-flow state, through the use of a intermediate routers to maintain per-flow state, through the use of a
multicast-specific BIER header. [RFC8296] defines two types of BIER multicast-specific BIER header. [RFC8296] defines two types of BIER
encapsulation to run on physical links: one is BIER MPLS encapsulation to run on physical links: one is BIER MPLS
encapsulation to run on various physical links that support MPLS, the encapsulation to run on various physical links that support MPLS, the
other is non-MPLS BIER Ethernet encapsulation to run on ethernet other is non-MPLS BIER Ethernet encapsulation to run on ethernet
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4.1. L2 Agnostic 4.1. L2 Agnostic
The solution should be agnostic to the underlying L2 data link type. The solution should be agnostic to the underlying L2 data link type.
4.2. Hop by hop DA modification 4.2. Hop by hop DA modification
The solution should not require hop-by-hop modification of the IP The solution should not require hop-by-hop modification of the IP
destination address field. destination address field.
A multicast packet whose DA is multicast address does not require DA
modification hop by hop when replicating the packet to the nexthop
BFR.
An anycast packet whose DA is an anycast address configured on each
BFRs in the domain may be another option does not require DA
modification when replicating the packet to the nexthop BFR.
It is common to get the impression that BIERv6 could use multicast
address, as BIER is kind of one-hop replication on each BFR in normal
cases. However, as described in section 6.9 of [RFC8279], it is
useful to support Non-BIER routers within a BIER domain. From the
discussion about this document on IETF104, focus is on the advantages
of using unicast address that otherwise could not possible by using
multicast address or anycast address for the two cases: replication
from a BFR to other BFR(s) connected by Layer-3 Non-BFR router(s)
without using tunneling techniques, and replication from a BFR to
other BFR(s) connected by Layer-2 switch(es) without broadcasting or
snooping on Layer-2 switch(es) in between. Based on the natural
reachability of an IPv6 unicast address, it can support the multi-hop
replication cases as well as the one-hop replication case.
This requirement may be deprecated if unicast address is prefered as
a solution for both multi-hop replication and one-hop replication
without using two different encapsulations.
4.3. L4 Inspection 4.3. L4 Inspection
The solution should not require the BFRs to inspect layer 4 or The solution should not require the BFRs to inspect layer 4 or
require any changes to layer 4. require any changes to layer 4.
4.4. Multicast address in SA field 4.4. Multicast address in SA field
The solution should not allow a multicast address to be put in the IP The solution should not allow a multicast address to be put in the IP
source address field. source address field.
4.5. Incorrect bits 4.5. Incorrect bits
The solution should not assume that bits never get set incorrectly. The solution should not assume that bits never get set incorrectly.
If a packet with incorrect bits set, it should not damage the
functions like Unicast Reverse Path Forwarding (URPF), or cause loops
or duplicates as described in section 6.8 of [RFC8279].
4.6. SA filtering 4.6. SA filtering
The solution should not require changes in source address filtering The solution should not require changes in source address filtering
procedures. procedures.
4.7. BIER architecture support 4.7. BIER architecture support
The solution should be possible to be used to support the entire BIER The solution should be possible to be used to support the entire BIER
architecture. architecture.
Multiple sub-domains bound to one or many topologies or algorithms,
multiple sets for more BFERs, multiple BIFTs for ECMP should be
supported.
4.8. Keep it simple 4.8. Keep it simple
The solution should avoid having to use different encapsulation The solution should avoid having to use different encapsulation
types, or use complex tunneling techniques, to support BIER as a E2E types, or use complex tunneling techniques, to support BIER as a E2E
multicast transport. multicast transport.
A single encapsulation should support Layer-2 switch within BFRs, or
non-BFR within a BIER domain, or inter-domain deployment of BIER.
4.9. Hardware fast path 4.9. Hardware fast path
The solution should enable the processing and forwarding of BIER The solution should enable the processing and forwarding of BIER
packets in hardware fast path. packets in hardware fast path.
5. Solutions Evaluation 5. Solutions Evaluation
The following are solutions that have been proposed to solve BIER in The following are solutions that have been proposed to solve BIER in
IPv6 environments. IPv6 environments.
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additional extension or encapsulation header is required. Instead of additional extension or encapsulation header is required. Instead of
encapsulating the packet in IPv6, the payload is attached to the BIER encapsulating the packet in IPv6, the payload is attached to the BIER
IPv6 header and the IPv6 protocol number is set to the type of the IPv6 header and the IPv6 protocol number is set to the type of the
payload. If the payload is UDP, the UDP checksum needs to change payload. If the payload is UDP, the UDP checksum needs to change
when the BitString in the IPv6 destination address changes. when the BitString in the IPv6 destination address changes.
5.3. Add BIER header into IPv6 Extension Header 5.3. Add BIER header into IPv6 Extension Header
+---------------+-----------------+------------------- +---------------+-----------------+-------------------
| IPv6 header | IPv6 Ext header | payload | IPv6 header | IPv6 Ext header | payload
|(Multicast DA) | (BIER header in | | | (BIER header in |
| | TLV Type = X) | | | TLV Type = X) |
| Next Header | Next Header | | Next Header | Next Header |
+---------------+-----------------+------------------- +---------------+-----------------+-------------------
According to [RFC8200] In IPv6, optional internet-layer information According to [RFC8200] In IPv6, optional internet-layer information
is encoded in separate headers that may be placed between the IPv6 is encoded in separate headers that may be placed between the IPv6
header and the upper- layer header in a packet. There is a small header and the upper- layer header in a packet. There is a small
number of such extension headers, each one identified by a distinct number of such extension headers, each one identified by a distinct
Next Header value. An IPv6 packet may carry zero, one, or more Next Header value. An IPv6 packet may carry zero, one, or more
extension headers, each identified by the Next Header field of the extension headers, each identified by the Next Header field of the
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9. Normative References 9. Normative References
[I-D.pfister-bier-over-ipv6] [I-D.pfister-bier-over-ipv6]
Pfister, P. and I. Wijnands, "An IPv6 based BIER Pfister, P. and I. Wijnands, "An IPv6 based BIER
Encapsulation and Encoding", draft-pfister-bier-over- Encapsulation and Encoding", draft-pfister-bier-over-
ipv6-01 (work in progress), October 2016. ipv6-01 (work in progress), October 2016.
[I-D.xie-bier-ipv6-encapsulation] [I-D.xie-bier-ipv6-encapsulation]
Xie, J., Geng, L., McBride, M., Dhanaraj, S., Yan, G., and Xie, J., Geng, L., McBride, M., Dhanaraj, S., Yan, G., and
Y. Xia, "Encapsulation for BIER in Non-MPLS IPv6 Y. Xia, "Encapsulation for BIER in Non-MPLS IPv6
Networks", draft-xie-bier-ipv6-encapsulation-00 (work in Networks", draft-xie-bier-ipv6-encapsulation-01 (work in
progress), March 2019. progress), June 2019.
[I-D.xu-bier-encapsulation] [I-D.xu-bier-encapsulation]
Xu, X., somasundaram.s@alcatel-lucent.com, s., Jacquenet, Xu, X., somasundaram.s@alcatel-lucent.com, s., Jacquenet,
C., Raszuk, R., and Z. Zhang, "A Transport-Independent Bit C., Raszuk, R., and Z. Zhang, "A Transport-Independent Bit
Index Explicit Replication (BIER) Encapsulation Header", Index Explicit Replication (BIER) Encapsulation Header",
draft-xu-bier-encapsulation-06 (work in progress), draft-xu-bier-encapsulation-06 (work in progress),
September 2016. September 2016.
[I-D.zhang-bier-bierin6] [I-D.zhang-bier-bierin6]
Zhang, Z. and T. Przygienda, "BIER in IPv6", draft-zhang- Zhang, Z. and T. Przygienda, "BIER in IPv6", draft-zhang-
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