1. Xing Li CERNET NOC/TEIN2 NOC 2008-07-16
IPv6 Multicast on TEIN2
Xing Li
CERNET NOC/TEIN2 NOC

2. Outline Review of IP multicast Multicast configurations
Features
IPv4
IPv6
Multicast configurations
TEIN2 example
Multicast tools
ssmping/asmping
smclock6/smjoin6
TEIN2 multicast testing homepage
Multicast debugging
IPv6 Multicast address plan
Discussions
Suggestions
Remarks

3. One to many communication
Application level one to many communication
multiple unicasts
IP multicast S R

4. Why Multicast When sending same data to multiple receivers Application
better bandwidth utilization
less host/router processing
quicker participation
Application
Video/Audio broadcast (One sender)
Video conferencing (Many senders)
Real time news distribution
Interactive gaming

5. Multicast Tree

6. IPv4 multicast protocols
Subnet
IGMPv2 (ASM)
IGMPv3 (SSM)
Inner AS
PIM-SM (ASM/SSM)
RP (ASM)
Anycast RP + MSDP (ASM)
Inter AS
MSDP (ASM)
mBGP

7. IPv6 multicast protocols
Subnet
MLDv1 ASM (IPv4: IGMPv2)
MLDv2 SSM (IPv4: IGMPv3)
Inner AS
PIM-SM (ASM/SSM)
RP (ASM)
Inter AS
mBGP
Embedded RP (ASM)

8. IPv6 Multicast OS support
All IPv6 systems (should) support MLDv1
Linux and Windows Vista support MLDv2

9. ASM: PIM-SM, RP and embedded RP
Multicast routing is usually done via PIM-SM
PIM-SM requires an RP for source discovery
All routers must use the same RP and somehow know its address
Initially packet from a source will be sent to the RP
When a host joins a group, join messages are sent hop by hop towards the RP
The RP serves as a meeting place between source and receivers
This works well within a site or a single administrative domain
MSDP doesn’t scale since source information is flooded to all RPs, so IETF decided not to have MSDP for IPv6
Embedded RP encodes the RP address into the group address
The difference is that with MSDP, there is only (S, G) joints between domains, while with embedded RP, there will also be (*, G) joints between domains

10. SSM: PIM-SM SSM is available for both IPv4 and IPv6
Some believe only SSM is needed for interdomain multicast
SSM simplifies multicast signaling in the network
no needed for RPs, PIM register, switching between shared and source specific trees …
But very difficult for multi-party applications
conferencing where everyone is a source and everyone needs to know the IP address of others
SSM is supported by very few applications and systems
Edge routers and hosts need to support MLDv2
Hosts need to support RFC3678, which is the API for specifying source filters
Applications need to be changed to support this API

11. For cross TEIN2 multicast communication G=FFxE::

12. For TEIN2 Backbone S=2001:254::/32
G=ff3e:0020:2001:254:x:x:x:x
However, the static RP is not supported by TEIN2 backbone, the embedded RP should be used for the NRENs

13. For TEIN2 Backbone S=2001:254::/32
Embedded RP (BJ) A=2001:254::1 G=ff7e:0120:2001:254:x:x:x:x
Embedded RP (HK) A=2001:254::2 G=ff7e:0220:2001:254:x:x:x:x
Embedded RP (SG) A=2001:254:8000::1 G=ff7e:0130:2001:254:8000:x:x:x

14. For TEIN2 Backbone S=2001:254::/32
G=ff3e::x:x:x:x
SSM is more reliable.

15. Multicast configurations (juniper)
pim {
rp {
bootstrap {
family inet {
import im-bs-policy;
export ex-bs-policy; }
family inet6 {
embedded-rp;
static {
address ;
interface all {
mode sparse;
version 2;
interface fxp0.0 {
disable;
interface lo0.0 {
interface so-0/1/0.0 {
protocols {
igmp {
interface all {
disable; }
interface ge-0/3/0.3 {
version 2;
interface ge-0/3/0.4 {
mld {
version 1;

16. TEIN2 NRN Multicast support

17. IPv6 Multicast Challenges
Configuration
Everything has to be correct
Debugging
Methodology
End-systems tools
Router commands
Management
Sender security
Receiver security

18. Tool – ssmping (1)

19. Tool – ssmping (2)

20. Tool - smclock6/smjoin6 (1)

21. Tool - smclock6/smjoin6 (2)

22. Tool - smclock6/smjoin6 (3)

23. TEIN2 multicast testing homepage (1)

24. TEIN2 multicast testing homepage (2)

25. TEIN2 multicast testing homepage (3)

26. TEIN2 multicast testing homepage (4)

27. TEIN2 multicast testing homepage (5)

28. Multicast debugging (1)

29. Multicast debugging (2)

30. Sh commands (cisco)

31. SIGCOMM 2007

32. Multicast address plan (1)
Multicast is hard to control and manage
IPv6 multicast BCP
Source address control
Group address control

33. IPv6 Multicast address plan (2)
Source address control
PI: 2001:DB8::/32
Site: 2001:DB8:yyyy::/48
MCsrc: 2001:DB8:ABCD:yyyy::/64
SSM group address control
Site scope: FF35::wxxx:yyyy/96
Backbone scope: FF38::wxxx:yyyy/96
Global scope: FF3e::wxxx:yyyy/96
w factor
0x8: 0.1Mbps，
0xC: 1Mbps，
0xE: 10Mbps，
0xF：100Mbps，

34. IPv6 Multicast address plan (3)

35. IPv6 Multicast address plan (4)

36. Discussion (1) Router related issues
For the Juniper router (any model and any software version), you cannot configure ASM (IGMPv2/MLDv1) and SSM (IGMPv3/MLDv2) in the same interface. Therefore, you should configure the interface of the router to the corresponding IGMP/MLD version for the the specific testing (ASM or SSM). Also note that this is for the access router directly connected to the host which is receiving the multicast packets and it does not effect the multicast packet sending process.
For the Cisco router (for example 7600 and IOS 12.2(18)SXD6), you cannot configure the IPv4 multicast and IPv6 multicast in the same interface. To fix the problem, you can use IOS 12.2(18)SXF8.
For the Cisco router (for example 7600 and IOS 12.2(18)SXF8), it does not support BGP address family IPv6 multicast (SAFI=2 and SAFI=3). You should use the cisoc IOS hidden command to tell router to use the unicast routing table for the multicast RPF check. Example: 7600(config)#ipv6 rpf use-bgp

37. Discussion (2) Host related issues
The Microsoft Window XP cannot support IPv6 SSM. Therefore, IPv6 ssmping test will fail in the Windows system. In addition XP cannot support IPv6 DNS query, therefore it may not be able to resolve the DNS IPv6 address mapping in pure IPv6 environment
We recommend version or higher for the Linux system to test the IPv6 SSM and ASM embedded RP. The old versions (for example ELsmp) cannot work correctly.
Be careful on the value of IP_MULTICAST_TTL or IPV6_MULTICAST_HOPS of the multicast senders. The old version of the Linux system (for example ) set this value to 1 and the multicast pakcet can only be received in the same subnet and cannot be sent cross routers.
Microsoft Internet Explorer does not support URL containing IPv6 address (for example the URL . You may use Firefox.

38. Discussion (3)
For the inter-domain multicast, SSM is much more reliable and controllable
Windows XP is the most popular DVTS platform, but it does not support SSM
Users may use Linux platform to reply the SSM and ASM, use dvmcast tool or similar tools

39. Discussion (4)

40. Suggestions Form an active inter-domain IPv6 multicast WG
Publish an group address usage guideline
Run distributed IPv6 multicast measurement servers
Promote IPv6 multicast applications

41. Remarks Multicast is very useful for academic applications
IPv6 multicast has more flexibility
Tools and router access are both important.
IPv6 multicast configuration and debugging process is an enjoyable process (-: