Multicast over load balanced trunk problem

[rojic9]

i've been trying to multicast over a LAN with 2810 and 2520 switches.

all switches support IGMP and it's working as expected except when multicasting over load balanced trunks.

there are two trunks set up one copper and one fibre and multicasting over these connections either fails or works so slowly as to be useless.  other multicast processes that don't utilise a trunk work ok.

the only way i've been able to get multicasting working at a decent speed is to use a single connection in place of the trunk.

is there something that i could be doing to keep the load balanced trunks and multicast over them?

[Vince_Whirlwind]

It might be interesting to see your exact trunking config.

[rojic9]

Sure,

One trunk has 2 ethernet cables, config:

Port Type   Enabled Mode Flow Ctrl Group Type
---- ----   ------- ---- --------- ----- ----
1    1000T  Yes     Auto Enable    Trk2  Trunk
2    1000T  Yes     Auto Enable    Trk2  Trunk

running config shows

interface 1
 flow-control
 no lacp
 exit
interface 2
 flow-control
 no lacp
 exit
....
trunk 1-2 Trk2 Trunk
....
spanning-tree Trk2 priority 64
....

there's 10 VLANs tagged and one untagged VLAN which contains the multicast traffic

[rojic9]

On the switch at the other end of the trunk flow-ctrl is 'disabled'
otherwise it's the same