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