IPv6 Multicast SSM

[ChrisNewnham_]

Hello, trying to configure PIMv6 using SSM.

I enabled IPv6 multicast routing globally

On the interface I configured:

ipv6 mld join-group ff36::1 include source-list MULTICAST_SOURCE

and it says %Error: MLD acl: MULTICAST_SOURCE Ranges are not accepted: 2001:6::/32

Why would that range not be accepted for a Multicast source IP?

Also I find the documentation deeply unhelpful, it just talks about changing PIM timers, what's that got to do with SSM? 

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti_pim/configuration/xe-16/imc-pim-xe-16-book/ip6-mcast-pim-ssm.html

Thanks!

[Harold Ritter · Accepted solution]

Hi @ChrisNewnham_ ,

You can't specify a range (2001:6::/32) in the source-list. It needs to be hosts (/128).

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/command/ipv6-cr-book/ipv6-i2.html#wp2876670758

From the command reference:

"The source-list keyword and acl argument may be used to include or exclude multiple sources for the same group. Each source is included in the access list in the following format:

permit ipv6 host source any"

Regards,

[Ramblin Tech]

Is your ACL something like "permit 2001:6::/32 any"? If so, what (S,G) state are you trying to create with the static MLD join? I may be mistaken here, but would not a /32 mask permit 2^^96 host sources? Obviously, you cannot create (S,G) state for 2^^96 sources.

An ACL can be used for a single join-group statement to config MLD joins for multiple sources to the same group address, but seems like sources should be listed individually in the ACL and not with a range via a mask. This also begs the question: why are static MLD joins required in your config? Do you not have IPv6 receivers attached somewhere that can issue their own MLDv2 joins? If so, static MLD joins are not required except for troubleshooting purposes.

I agree that the IPv6 SSM Config Guide is lacking, as it appears to assume familiarity with IPv4 SSM for the fundamentals.

[ChrisNewnham_]

Many thanks, once I configured a host in the ACL, it worked! Wouldn't have killed them to put an ACL example in the documentation rather than a bunch of random commands with no relevance to anything.

Also on a mildly related sitenote - vIOS on both the switch and router, did not support "ip pim ssm default". I had to manually create an ACL for 232.0.0.0/8 and apply it - "ip pim ssm range 1".

[Harold Ritter]

You are very welcome @ChrisNewnham_ .

> vIOS on both the switch and router, did not support "ip pim ssm default".

This might be due to the version you used. It works for me with the following version.

Cisco IOS Software, IOSv Software (VIOS-ADVENTERPRISEK9-M), Version 15.9(3)M6, RELEASE SOFTWARE (fc1)

CE1#config t

Enter configuration commands, one per line.  End with CNTL/Z.

CE1(config)#ip pim ssm

CE1(config)#ip pim ssm ?

  default  Use 232/8 group range for SSM

  range    ACL for group range to be used for SSM

Regards,

[ChrisNewnham_]

The command is accepted - but doesn't actually work  

Tried on 15.2 (vIOS L2) and 15.8 (vIOS L3)