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BIER WG Z. Zhang
Internet-Draft Fangwei. Hu
Intended status: Standards Track ZTE Corporation
Expires: June 23, 2016 December 21, 2015


CONFORMANCE OF ACROSSING NON-BIER NODES
draft-zhang-bier-across-non-bier-nodes-00.txt

Abstract

Bit Index Explicit Replication (BIER) is an architecture that
provides optimal multicast forwarding through a "multicast domain",
without requiring intermediate routers to maintain any per-flow state
or to engage in an explicit tree-building protocol. There may be
some routers which could not support BIER technology (We name them as
non-BIER node in this document) in the BIER domain when deployed.
This document specifies a solution for the BIER packet transiting the
non-BIER nodes.

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 June 23, 2016.

Copyright Notice

Copyright (c) 2015 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
(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



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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. Encapsulation Negotiation of the BIER nodes . . . . . . . . . . 3
2.1. Extension of OSPF protocol . . . . . . . . . . . . . . . . 3
2.2. Extension of IS-IS protocol . . . . . . . . . . . . . . . . 4
3. The Protocol Treatment . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
6. Normative References . . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6



































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1. Introduction

Every node in the BIER domain may support different tunnel technology
to encapsulate BIER packets. For example, There are some non-BIER
nodes between BFR2 and BFR5. If BIER packets should forward to BFR5
via BFR2, suppose that BFR2 encapsulate the BIER packets by GRE
header. When the BIER packets reachs BFR5, BFR5 support only mpls
encapsulation, and can not recognize the encapsulation of GRE. Then
BFR5 will discard the packets.

BFIR1-- BFR2 -- non-BFR3 -- non-BFR4 -- BFR5 -- BFER6
Figure 1: An example of packets forwarding

BFR2 and BFR5 negotiate the encapsulation function in advance. BFR2
will choose the right function that can support by BFR5 to
encapsulate BIER packets. BFR5 can recognize the BIER packets and
forward correctly.


2. Encapsulation Negotiation of the BIER nodes

Network nodes who support BIER use IGP extension to exchange BIER
information. In this document, we define IGP extension to exchange
BIER encapsulation function, include OSPF and IS-IS protocols.

2.1. Extension of OSPF protocol

We define new OSPF Router Information (RI) TLV to indicate the
encapsulation function that supported by BIER nodes.

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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Value //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: format of OSPF extension

o Type : The value is TBD. The Type indicate that it is a non-bier-
tunnel-type sub-tlv.

o Length: The length of this field is 6 bits.

o Value: The length of this field is 16 bits, is used to indicate
every encapsulation type. We define the bit from rightmost bit.



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Now we define three types of encapsulation for BIER packets.
00000001 : MPLS 00000010 : GRE 00000100 : UDP

2.2. Extension of IS-IS protocol

We define new IS-IS Router capability TLV (TLV 242) to indicate the
encapsulation function that supported by BIER nodes.

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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Value //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: format of IS-IS extension

o Type : The value is TBD. The Type indicate it's OSPF-BIER-Encap-
Func sub-tlv.

o Length: The length of this tlv is 6 bits.

o The value of this tlv is 2 octets, 16bits is used to indicate
every encapsulation function. We define the bit from rightmost
bit. Now we define three function of encapsulation of BIER
packets. 00000001 : mpls 00000010 : GRE 00000100 : UDP


3. The Protocol Treatment

At a given BFR, in above example, BFR2 starts with a copy of the IGP-
computed shortest path tree from BFR2 to each router in the domain.

BFIR1 BFR2 non-BFR3 non-BFR4 BFR5 BFER6
| | | | | |
| | | | | |
IP IP IP
GRE GRE GRE
BIER BIER BIER BIER BIER
Figure 4: example of packets forwarding of GRE encapsulation

After IGP computed, BFR2 notice that there are non-BIER nodes between
BFR2 and BFR5. After BFR2 check the IGP BIER-encapsulation tlvs.
BFR2 notices that BFR5 support GRE encapsulation function, and the
non-BIER nodes also support IP encapsulation function. BFR2 will
encapsulate the BIER packets to GRE header and forward the packets to



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non-BIER nodes names non-BIER3. and the destination of packets is the
IP address of BFR5. After the packets reach BFR5, BFR5 will discover
that there are BIER packets after the IP header and GRE header. BFR5
then forward the packets by use BIER forwarding function defined in
draft-ietf-bier-architecture.

BFIR1 BFR2 non-BFR3 non-BFR4 BFR5 BFER6
| | | | | |
| | | | | |
label label label
BIER BIER BIER BIER BIER
Figure 5: example of packets forwarding of mpls encapsulation

After IGP computed, BFR2 notice that there are non-BIER nodes between
BFR2 and BFR5. And all the nodes in domain support MPLS. After BFR2
check the IGP BIER-encapsulation tlvs. BFR2 will encapsulate the
BIER mpls label from the messages advertised by BFR2, and BFR2 will
encapsulate the IP mpls label to BFR5 in front of the packets. Non-
BIER nodes forward packets to BFR5. When the packets reach BFR5,
BFR5 will discover that there are BIER packets after the BIER mpls
label. BFR5 then forward the packets by use BIER forwarding function
defined in draft-ietf-bier-mpls-encapsulation.


4. Security Considerations

For general BIER Security Considerations.


5. IANA Considerations

IANA is requested to allocate the OSPF and IS-IS extension for the
function in this document.


6. Normative References

[I-D.ietf-bier-architecture]
Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and
S. Aldrin, "Multicast using Bit Index Explicit
Replication", draft-ietf-bier-architecture-02 (work in
progress), July 2015.

[I-D.ietf-bier-isis-extensions]
Ginsberg, L., Przygienda, T., Aldrin, S., and J. Zhang,
"BIER support via ISIS",
draft-ietf-bier-isis-extensions-01 (work in progress),
October 2015.



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[I-D.ietf-bier-mpls-encapsulation]
Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and
S. Aldrin, "Encapsulation for Bit Index Explicit
Replication in MPLS Networks",
draft-ietf-bier-mpls-encapsulation-02 (work in progress),
August 2015.

[I-D.ietf-bier-ospf-bier-extensions]
Psenak, P., Kumar, N., Wijnands, I., Dolganow, A.,
Przygienda, T., Zhang, J., and S. Aldrin, "OSPF Extensions
For BIER", draft-ietf-bier-ospf-bier-extensions-01 (work
in progress), October 2015.


Authors' Addresses

Zheng(Sandy) Zhang
ZTE Corporation
No. 50 Software Ave, Yuhuatai Distinct
Nanjing, 210000
China

Email: zhang.zheng@zte.com.cn


Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai, 201203
China

Email: hu.fangwei@zte.com.cn



















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