OS6250 does not see multicast neighbors

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OS6250 does not see multicast neighbors

Post by MWLosRios »

This is more of an FYI than asking for assistance.

If you enable multicast switching on an OS6250, it will only see multicast neighbors (PIM/DVMRP routers) on VLANs that it has an IP interface on. This is different behavior than the OS6850 or other "true" layer 3 switches.

I opened a PR with Alcatel-Lucent on this. They confirmed behavior, and recently told me that this is "expected." Nowhere in the OS6250 manual does it say that an IP interface is necessary to learn multicast neighbors.

Bear in mind that if there are no neighbors, the switch won't forward multicast frames out uplinks to core or distribution switches. This means no forwarding, which will break applications like Ghost, Samsung MagicInfo, and HP printer discovery, just to name a few.

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Re: OS6250 does not see multicast neighbors

Post by rekeds »

thank you for sharing

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Re: OS6250 does not see multicast neighbors

Post by plegrand »

as i've got some problem with ghost like application multicasting (fog) and as my english is litle poor and i'm not sure to well understand your information i would like to know if my switch configuration is OK according to you.
Then if you think it's ok for switchs configuration i will investigate elsewhere.
Here is the link where i explain that : https://www.alcatelunleashed.com/viewtopic.php?t=28811
I know the thread is very old but may be you could help me.

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Re: OS6250 does not see multicast neighbors

Post by silvio »

in all the omniswitches mc-switching is possible - means mc-stream within the same vlan. But you need an querier = one switch with an ip interface in that vlan.
Only the more expensive switches (like 6850/6860) support mc-routing - stream between vlans.

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