Posted on June 20, 2019 7:53 pm
 |  Asked by Emiel Raaijmakers
 |  339 views
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We currently have a querier (v3) running on VLAN 400 and it perfectly works for multicast group joins within that VLAN. However when performing a source specific group join it seems to forward traffic from other sources as well.

My transmitting part is sending on group 239.211.4.99 with source address 172.216.0.25
My receiving part is subscribed to group 239.211.4.99 with source address 172.216.0.11

There is not multicast traffic to group 239.211.4.99 from source 172.216.0.11; Expected result is that no multicast packets would be received, but it receives all traffic from 172.216.0.25. What configuration is required to enable source specific multicast on the same VLAN?

arista(config)#show ip igmp snooping querier detail
Vlan IP Address Version Port
—————————————-
400 10.40.0.1 v3 Switch

arista(config)#show ip igmp snooping querier membership
————————————————————————-
Vlan: 400 Elected: 10.40.0.1 QQI: 5 QRV: 2 QRI: 5 GMI: 15

Groups Mode Ver Num of Sources
————————————————————————-
224.0.1.129 EX v2 0 []
239.211.4.99 IN v3 1 [ 172.216.0.11 ]
239.216.0.71 EX v2 0 []
239.216.0.72 EX v2 0 []
239.216.0.73 EX v2 0 []
239.216.0.74 EX v2 0 []
239.220.0.42 EX v2 0 []
239.220.0.43 EX v2 0 []

arista(config)#show ip mfib 239.211.4.99
Activity poll time: 60 seconds
239.211.4.99 172.216.0.11
Vlan400 (iif)
Activity 0:01:54 ago
239.211.4.99 172.216.0.25
Vlan400 (iif)
Activity 0:00:15 ago

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Posted by Alexis Dacquay
Answered on August 16, 2020 6:01 am

Hi Emiel,

If you are on a very very old software (e.g. before 4.14 from ~2014), then it would not work.

Can you please share your pim and general multicast configuration?

sh run section pim

sh run section multicast

You can find the PIM SSM range command here:

https://www.arista.com/en/um-eos/eos-section-40-5-pim-commands#ww1152253

Extract, in case the link changes:

switch(config)#ip access-list standard LIST_1
switch(config-std-acl-LIST_1)#permit 233.0.0.0/24
switch(config-std-acl-LIST_1)#exit
switch(config)#router pim sparse-mode
switch(config-router-pim-sparse)#ipv4
switch(config-router-pim-sparse-ipv4)#ssm range LIST_1
switch(config-router-pim-sparse-ipv4)#

Here are two articles related to PIM SSM:
https://eos.arista.com/mixed-asm-and-ssm-multicast-client-behaviour/

https://eos.arista.com/eos-4-22-1f/pim-ssm-ipv4-non-dr-oif-installation-for-fast-failover/

Some colleague have tested this in lab and it work fine as expected.

They have the following config:

router pim sparse-mode
   ip pim ssm range standard

Then we try to send a IGMPv2 report from the receiver towards the mrouter:

j 232.1.1.1 192.168.10.1
IP_ADD_MEMBERSHIP succeeded

arista...09:31:59(config)#sh ip mroute             Note: no mroute is formed
arista...09:31:59(config)#

Then, we send a leave for IGMPv2 and send a new IGMPv3 report and S,G is formed:

j 232.1.1.1 192.168.10.1 192.168.1.1
IP_ADD_SOURCE_MEMBERSHIP succeeded

arista...09:32:00(config)#sh ip mroute
232.1.1.1
  192.168.1.1, 0:00:03, flags: JED
    Incoming interface: Null
    Outgoing interface list:
      Vlan110

We also tested other groups like 239.1.1.1 and 234.1.1.1 for SSM and  mroute (S,G) for all of them are formed as expected.

After the source starts sending the traffic:

232.1.1.1
  192.168.1.1, 0:08:44, flags: S
    Incoming interface: Ethernet2
    RPF route: [U] 192.168.1.0/24 [110/20] via 172.17.20.254
    Outgoing interface list:
      Vlan110
239.1.1.1
  192.168.1.1, 0:02:33, flags: S
    Incoming interface: Ethernet1
    RPF route: [U] 192.168.1.0/24 [110/20] via 172.17.10.254
    Outgoing interface list:
      Vlan110

Regards,

Alexis

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