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Re: IGMP config - how to?

 
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Mutex
Occasional Advisor

Re: IGMP config - how to?

when I connect one client directly to the switch where the server is, then multicast works without problems.
When I switch the client back to the first switch SA004HP00_1 then suddenly the stream works on this switch too, but not on SA004HP00_2.

But when I power off all switches and restart them then streaming on SA004HP00_1 doesn't work again.

It seems that the switches have to learn something but after a restart they have lost this information and need to learn again.

By the way why does the switch loose the ip I set for VLAN 3 everytime I power off the switches?
Natasha Samoylenko
Trusted Contributor

Re: IGMP config - how to?

When multicast is enabled on switches they need to receive IGMP report from hosts to send multicast flow on ports.
After restart they once again must receive IGMP report from host.

Can you copy configurations of all your switches, at least part of config for VLANs 1 and 3?

"By the way why does the switch loose the ip I set for VLAN 3 everytime I power off the switches?"
You need to save your running configuration:
copy run start
Mutex
Occasional Advisor

Re: IGMP config - how to?

"Can you copy configurations of all your switches, at least part of config for VLANs 1 and 3?"
I will do that!

copy run start -> doesn't work!
Maybe there is another command, do you have any idea?
Natasha Samoylenko
Trusted Contributor

Re: IGMP config - how to?

Sorry :)
Instead of copy run start, use:
wr mem
Mutex
Occasional Advisor

Re: IGMP config - how to?

Thanks for your help! I found the command
write memory which is the long version of wr mem.

Moreover the problem is solved:

A querier was need in my topology. Therefore one Switch needs an IP address. -> see attachment.
After I have configured an IP address for one switch, the other switches register the configured switch as querier.

Thank you very much for your help!
Regards Mutex
Natasha Samoylenko
Trusted Contributor

Re: IGMP config - how to?

Glad to hear that your problem is solved.

I also read the docs and copy in my first answer information about querier. :)
But I also remember that in real life I did not face such a problem (I think this is because at least one switch always had an IP). So I was not quite sure about the querier.

For me it also good to recall that querier is always needed.
Pieter 't Hart
Honored Contributor

Re: IGMP config - how to?

It's the IGMP-snooping function that gets in your way.
This is to forward multicasts only to the subbscribed ports an NOT "flood" multicasts to all ports on the switch (all switches).

But there needs to be a DR (designated )router for the multicasts in the network for correct operation of IGMP(snooping).
It's not the switch that specificly need an ip-adress.

Without DR the switch that is NOT directly connected to the multicast source cannot determine what (uplink) port to subscribe to the multicasts.

By giving some switch an ip-address in the network, this takes the DR function and IGMP can forward the multicasts to the subscribed ports.

As such the switch closest to the multicast source seems the best candidate for the ip-adress.

A section from this document may clarify things: http://www.h3c.com/portal/Products___Solutions/Products/Switches/H3C_S5810_Series_Switches/White_Paper/200912/656291_57_0.htm

PIM-DM assumes that at least one multicast group member exists on each subnet of a network, and therefore multicast data is flooded to all nodes on the network. Then, branches without receivers downstream are pruned from the forwarding tree, leaving only those branches with receivers. This ├в flood and prune├в process takes place periodically, that is, pruned branches resume multicast forwarding when the pruned state times out and then data is re-flooded down these branches, and then are pruned again.