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New Member

Aironet 1200 permanet multicast packet overhead

The aironets in my lan are running on 12.01T because of dot1q.

i saw on the interface statistics in 3 days round about 700MB of traffic without any client connectet. so i did a further look and sniffer. its traffic destined to 01-04-96-ff-ff-ff-00. when i take a look in the config file i saw the dest. ip is 224.0.1.40:2887. so i like to know what is it for and a way to stop this unecessary traffic/load on the devices ???

regards

marco bohlmann

  • Other Network Infrastructure Subjects
2 REPLIES
New Member

Re: Aironet 1200 permanet multicast packet overhead

224.0.1.40 is used by Cisco RP Discovery when running PIM Sparse Mode with Auto-RP.

IP multicast addresses map to MAC addresses 0100.5eXX.XXXX where the last 23 bit of the IP multicast address are mapped to XX.XXXX .

Vendor code/OUI 0004.96 is registered as belonging to Extreme Networks.

(ref: http://standards.ieee.org/cgi-bin/ouisearch)

So something doesn't quite match here.

If you're certaing what you're seeing is traffic to 224.0.1.40 then one option, if applicable, is to turn off PIM on that interface. Alternately filter out the Auto-RP groups (224.0.1.39 and 224.0.1.40) using the "ip multicast boundary" command. http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcpt3/1cfmulti.htm#1002581

New Member

Re: Aironet 1200 permanet multicast packet overhead

Hi,

of course u are right and the 00-04-96 is a extreme mac but my one is

01-04-96 a layer 2 multicast as cdp or bpdu just another destination. i find out that the bridge have some features like update the other bridges in the lan with a new image or communicate the config out in the world. that insn't funny and useless overhead.

u are also right with pim but my one is just a stupid ly 2 brigde :-) and def. know nothing about "ip multicast boundary". there is no cli just a web side with click-and-try or a eye-burning console interface where u can use shortcuts. no conf t etc. ..

so i think cisco used the 224.0.1.40 for their features and i like to get rid of it. i also take a further look for features like igmp snooping but find nothing yet.

regards

marco bohlmann

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