Softwire Mesh Multicastdraft-xu-softwire-mesh-multicast-00

Mingwei Xu, Yong Cui, Shu YangTsinghua University

Chris Metz, Greg ShephardCisco

IETF79 Meeting, BeijingNov 2010

Outline Background

Mesh multicast framework

Scenarios

IPv4-over-IPv6 scenario

IPv6-over-IPv4 scenario

Summary

Background Softwires Charter and RFC4925 state

multicast is a requirement Operators have expressed requirements

for multicast solution Softwire Mesh Unicast methods have been

defined. Where is the Multicast? Is section 11 of RFC5565 sufficient?

MVPN-like schemes can achieve “many-to-one” mapping

“One-to-one” mapping (Internet-style multicast) is needed

Mesh multicast framework

I-IP Transit Core

E-IP

AFBR

AFBRAFBR

E-IPE-IP

AFBR

E-IPS

R R

I-IP TreeE-IP Tree

Scenario IPv4-over-IPv6 scenario

IPv6-over-IPv4 scenario Remember that IPv6 address is longer

than IPv4 address, thus additional effort will be required

IPv4-over-IPv6

I-IPv6 BackboneCustomernetwork

Clientnetwork

receiver

S

Clientnetwork receiver

(S,G)(p::S,p::

G)(S,G) RPF

RFC 5496

Group address mapping

FFXY must be in accordance with the IPv6 multicast address format of [RFC2373]

The next 10 octets are assigned by ISP

FFXY ISP assigned IPv4

address

0 16 96 127

Actions performed by AFBR Process E-IPv4 PIM messages

Perform E-IPv4 PIM to I-IP PIMv6 message conversion

Transmit and receive I-IP PIMv6 messages

IPv6-over-IPv4 - Difficulty Because of larger space of IPv6

address Hard to map without collision

I-IP IPv4 multicast address limitations: Not all IPv4 multicast addresses are available

Possible Solutions Limit IPv6 address space

Pick up a portion of IPv6 addresses Approximate “one-to-one”

Select a good hashing function to make collision happen occasionally

Inter-AFBR signaling Signal each AFBR about mapping

information

Limit IPv6 address space

IPv4 space

Limited v6

space

IPv6 space

Mapping

Approximate “one-to-one”

IPv6 address

IPv4 address

Inter-AFBR signaling

I-IP BackboneCustomernetwork

Clientnetwork

receiver

S

Clientnetwork receiver

(S,G)(S’,G’)?(S,G)

G G’

Summary Only need changes on AFBR

Reduce redundant traffic compared to MVPN-like schemes

More details will be added