Excessive network traffic -

Ed Greshko Ed.Greshko at greshko.com
Thu Nov 29 00:38:45 UTC 2007

John Summerfield wrote:
> Ed Greshko wrote:
>>> 14:48:19.063647 arp who-has tell
>> The above are ARP broadcast packets.  ARP stands for Address Resolution
>> Protocol.
>> It is a bit strange to see these in your network since ARP broadcast
>> packets
>> aren't supposed to survive past the subnet they are transmitted on.  The
>> purpose of the ARP request is to get the MAC address of a given IP
>> address.
>>  Taking one line of your output above...
>> 14:48:10.668593 arp who-has tell
>> The source of the ARP message is  It is sending out a
>> broadcast
>> message asking "Who ever has IP address of, please respond
>> with your MAC address".
>> You aren't seeing the response...but if you had you'd see something like:
>> 07:27:51.893480 arp reply is-at 00:30:6e:c7:63:8f
>> These packets are coming into your network.  They are 42 bytes long. 
>> You'd
>> have to have a whole heck of a lot of these to drive up your network
>> usage.
>>  In any case, they are inbound and not associated with any requests from
>> your side so it is unlikely that the ISP is counting these as your
>> traffic.
> I have seen this kind of thing.
> we were using a four-port ADSL switch/router. Ordinarily, one uses it to
> manage the Internet connexion, and plugs up to four computers into it.
> I think what I tried to do is put it into bridging mode, attach it to
> (say) eth0, run rp-ppp (or similar) on eth0 _and_ give eth0 an IP
> address so it could talk to other computers on the eth0 network.
> I had a reason to run tcpdump and did not like what I saw, so I reverted
> to a more conventional configuration.

I've not experienced that...  But come to think of it, Wild Blue is a
satellite system and while it has been years since I worked on a network
with satellite links I vaguely recall more bridging than routing going on.

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