802.1d & STP [was: Re: [plug] [OT] fear of posting]

[Mike Groeneweg]

On Mon, 20 Sep 2004 15:08:51 +0800, Leon Blackwell <leon at lostrealm.com> wrote:
> On Mon, Sep 20, 2004 at 03:00:45PM +0800, James Devenish wrote:
> > Is it part of Spanning Tree handling?
> 
> It looks to be -- I don't have a copy of the packet here, but it appears
> to be the "hello" message.
> 
> Having never seen 802.1d before, I'm not sure if this is a normal thing
> to be seeing at this rate.  I don't mind the occasional packet, but one
> every few seconds is a little silly (especially since there are no other
> 802.1d capable routers on the network).

STP isn't used by routers, it's used by Layer 2 devices to eliminate
loops - ie switches. I think the rate is every 5 seconds or so - and
the 'HELLO' is a BPDU - telling other switches/bridges on the network
where it thinks the root node of the spanning tree, as this device
sees things.

See CCNP Switching material for more info. BPDU received by a router
should NOT be forwarded between network segments, ie the router should
just ignore them.

http://www.protocols.com/pbook/bridge.htm#BPDU

Mikeg 

-- 
------------------------------------
Mike Groeneweg
Perth, Western Australia
ICQ: 519 641