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Broadcasts received on serial interfaces...

guibor_p
Beginner
Beginner

This particular network design is a simple hub and spoke configuration. The hub has two remote offices connected to it via leased lines (full T's). EIGRP is the routing protocol used and the hub is also the NTP master.

Both serial interfaces on the hub router are receiving broadcasts from the far end ( Received 35142 broadcasts) .

Does anyone have any idea as to what the source of the broadcasts could be and is there a way to determine this with out the use of a serial line protocol analyzer?

TIA

Paul G.

3 Replies 3

shah
Cisco Employee
Cisco Employee

You can enable netflow temporarily.

Under the interfaces you are interested in, configure 'ip route-cache flow'

Then do 'show ip cache flow' and you will see the source, destination, and protocol for those packets for a particular interface.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fswtch_c/swprt2/xcfnfc.htm#1004643

It is possible that the multicast CDP and EIGRP hellos are included in the broadcasts counter.

Shah,

Thank you for the reply. I will give it a try.

Sincerly,

Paul G.

nuno.morais
Beginner
Beginner

Hi.

I would say that the source of the "broadcasts" is EIGRP. EIGRP uses multicast (224.0.0.10) to "flood" routing information. The broadcasts you see when you type "show interfaces ..." also counts multicast packets.

Hope this helps.

Regards,

NM

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