Internet DRAFT - draft-hu-bier-multicast-group-information
draft-hu-bier-multicast-group-information
BIER WG Fangwei. Hu
Internet-Draft Ran. Chen
Intended status: Standards Track ZTE Corporation
Expires: May 7, 2016 November 4, 2015
BIER Multicast Group Information
draft-hu-bier-multicast-group-information-00.txt
Abstract
This draft proposes to solve the multicast group address
announcement. The multicast group address information is
encapsulated as the BIER data payload. A new TLV is defined in this
document to carry the multicast group address information.
Status of This Memo
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This Internet-Draft will expire on May 7, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Multicast Group Address Announcement Mechanism . . . . . . . 2
3. BIER-GROUP-ADDRESS LV . . . . . . . . . . . . . . . . . . . . 3
4. ISIS Extension . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Normative References . . . . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Bit Index Explicit Replication (BIER)[I-D.ietf-bier-architecture]
proposes an architecture that provides optimal multicast forwarding
through a "BIER domain" without requiring intermediate routers to
maintain any multicast related per-flow state. BIER also does not
require any explicit tree-building protocol for its operation. BIER
accomplishes this by addressing each of the targeted egress router in
a bit mask in the BIER header. A multicast data packet enters a BIER
domain at a "Bit-Forwarding Ingress Router" (BFIR), and leaves the
BIER domain at one or more "Bit-Forwarding Egress Routers" (BFERs) .
The BIER header is encapsulated in the BFIR and decapsulated in the
BFER. Each BIER Forwarding Router (BFR) is assigned and uniquely
identified by a BFR-prefix which is a routable ipv4 or ipv6 address.
Each BIER egress (BFER) router needs a BFR-Identifier (1..65535) in
addition to BFR-prefix. To accomplish forwarding in a BIER network,
ingress router needs to know the list of egress routers to which the
flow is supposed be multicasted.
This document proposes a method to solve the issue. The ISIS or OSPF
protocol is extended for a BFER to announce its supported multicast
group address. A new TLV (BIER-GROUP-ADDRESS TLV) is defined to
carry the multicast group address for a BFER and encapsulated as the
BIER data payload. When BFER receives a new multicast group through
IGMP/MLD protocol, it sends the BIER data payload with the new
multicast group address information to all the other edge BFRs to
announce this new multicast group information in the BIER domain.
2. Multicast Group Address Announcement Mechanism
In order to improve the IGP (ISIS or OSPF protocol) stability, the
multicast group address information is encapsulated and carried as
the BIER data payload rather than IGP protocol directly. The
protocol field in in the MPLS BIER header
encapsulation[I-D.ietf-bier-mpls-encapsulation] is coded (7, to be
assigned by IANA) to indicated that the payload is the multicast
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group address information. The structure is as following (take the
MPLS encapsulation as the example):
+-----------+-----------+-----------------------------------+
|MPLS header|BIER header|Multicast group address information|
+-----------+-----------+-----------------------------------+
Figure 1 Mutlicast Group Address Information Encapsulation
The multicast group address information is formatted as TLV (section
3) and filled in LSP or LSA in the BFER. The BFER sends the BIER
data payload with the multicast group address information to all the
other edge BFRs in the BIER domain. When the BFIR receives the
multicast group address information, it keeps and maintains the
multicast group and BFR-prefix entries in the local, which is to
guide the multicast flow forwarding.
3. BIER-GROUP-ADDRESS LV
The format of BIER-GROUP-ADDRESS TLV is specified in figure 2.
+--------------+
| Type |
+--------------+--------------+
| Length |
+-----------------------------+-------------------------------------+
|Res|mutlicast group address type|Number of multicast Group address |
+-------------------------------------------------------------------+
| Multicast Group address (1) |
+-------------------------------------------------------------------+
| ... |
+-------------------------------------------------------------------+
| Multicast Group address (i) |
+-------------------------------------------------------------------+
| Multicast Group address (n) |
+-------------------------------------------------------------------+
Figure 2 BIER-GROUP-ADDRESS TLV
The description for each field is as following:
Type: 8 bits.
Length: 16 bits, the whole length for this tlv.
Res: 8 bits, it is reserved for future use.
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Multicast Group address type: 8 bits, it indicates the type for
the multicast group address. If it is 1, the multicast group
address is IPv4 address, while if 2, the multicast group address
is IPv6 address.
Number of multicast group address: 16 bits, the number for the
multicast group address.
Multicast Group address[i]: the multicast group addresses for the
BFER to be announced.
4. ISIS Extension
If the IGP is ISIS protocol in the BIER domain, the detailed format
of Mutlicast Group Address Information is as figure 3.
The label is MPLS-BIER label, and the S filed is 1(the end of the
MPLS stack) in the MPLS header.
All the Bitstring fields in the BEIR header is All-Edge-BFRs
(0xFFFF). The protocol fields is 7(to be assigned by IANA) to
indicate that that the payload of BIER is the multicast group
information payload. The multicast group information payload is
formatted as ISIS protocol. The multicast group information TLV is
filled in the ISIS LSP. We named this ISIS LSP as MGAA-LSP
(Multicast Group Address Announcement) to difference with the common
ISIS LSP. While the flooding and synchronization mechanism is
similar with the common ISIS LSP.
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MPLS header
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Label | Cos |S| TTL |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
BIER header
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 1 0 1| Ver | Len | Entropy |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| BitString (first 32 bits) ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~ BitString (last 32 bits) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|OAM| Reserved |Proto=7| BFIR-id |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Multicast Group address payload(Formated as ISIS)
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IS-IS Common Header, IS-IS PDU Specific Fields, IS-IS TLVs |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3 Multicast Group Address Format
All the transit BFR forward MGAA packet as if they were ordinary BIER
data packet. All the edge BFRs (BFERs and BFIRs) supporting
multicast group address announcement are full mesh logically.
5. Security Considerations
TBD.
6. Acknowledgements
TBD.
7. IANA Considerations
TBD.
8. Normative References
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[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-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.
Authors' Addresses
Fangwei Hu
ZTE Corporation
No.889 Bibo Rd
Shanghai 201203
China
Phone: +86 21 68896273
Email: hu.fangwei@zte.com.cn
Ran Chen
ZTE Corporation
No.50 Software Avenue,Yuhuatai District
Nanjing, Jiangsu Province 210012
China
Phone: +86 025 88014636
Email: chen.ran@zte.com.cn
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