The traffic is CDP - Cisco Discovery Protocol.  It is a heartbeat to detect 
changes i.e. newly attached or detacted cisco equipment.  

You can turn it off with "no cdp run" command at the enable prompt or "no cdp 
enable" at the interface.  
jhh

In a message dated 6/26/2002 7:37:06 AM Eastern Standard Time, 
netfilter-request@lists.samba.org writes:


> This traffic comes from a cisco router.
> what type of traffic is ?
> 
> [root@cuelebre root]# tcpdump -i eth2
> tcpdump: listening on eth2
> 
> 13:19:12.640000 0:4:dd:c:42:a6 0:4:dd:c:42:a6 loopback 60:
>                          0000 0100 0000 0000 0000 0000 0000 0000
>                          0000 0000 0000 0000 0000 0000 0000 0000
>                          0000 0000 0000 0000 0000 0000 0000
> 13:19:22.640000 0:4:dd:c:42:a6 0:4:dd:c:42:a6 loopback 60:
>                          0000 0100 0000 0000 0000 0000 0000 0000
>                          0000 0000 0000 0000 0000 0000 0000 0000
>                          0000 0000 0000 0000 0000 0000 0000