switch=bridge (multiport in ASIC) = transparent, MAC address learning-type
thing, hence
broadcast > all switches (with that VLAN)
unicast > switch with attached MAC address
proviso:
first packet of unicast stream to unknown MAC > broadcast (to determine
attached switch)
maybe a little after the fact, but makes sense to me at least
Andy
----- Original Message -----
From: John Neiberger <[EMAIL PROTECTED]>
To: Fred Nielsen <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Monday, June 05, 2000 6:02 AM
Subject: Re: VLAN Trunk traffic question
> Thank you! I've been trying to find the answer to that for a while now.
I
> don't have a way to test it on our production network or I would have
simply
> set it up and watched what happened. My bosses get a little upset when I
> start playing with our corporate backbone switches just for the fun of it.
> :-) silly people... It's not like I'd hurt something...well, there was
> that one time when I made the 7513 reboot...during business
> hours....twice....oops...
>
> Thanks again!
>
> John Neiberger
>
> > To answer your question, I believe the switch ports, whether trunked or
> not,
> > still forward based on the table of learned MAC-addresses.
> >
> > Meaning that a VLANx packet, assuming the destination MAC address is
> already
> > learned, will only traverse the trunk port towards the valid
destination.
> >
> > ------
> > Fred Nielsen [[EMAIL PROTECTED]]
> > ------
> >
> >
> > John Neiberger <[EMAIL PROTECTED]> wrote in message
> > 24049784.959891399421.JavaMail.imail@tiptoe">news:24049784.959891399421.JavaMail.imail@tiptoe...
> > : In this case, though, both switches B and C are in the same VLAN, but
I
> > : wouldn't want traffic destined for C going down the trunk connected
to
> B.
> > : This would be a waste of time and bandwidth. I'm trying to determine
> if
> > the
> > : trunk will pass ALL traffic for that VLAN, or only VLAN traffic that
is
> > : actually destined for an endhost on the opposite end of a particular
> > trunk.
> > : :-) That barely makes sense....heh heh.
> > :
> > : > If you use ISL, it will pass traffic only if it is destined for
that
> > : VLAN. It
> > : > does frame tagging.
> > : > It won't pass unnecessary traffic.
> > : >
> > : >
> > : >
> > : > John Neiberger wrote:
> > : >
> > : > > Ok, I'm suffering from a brain cloud at the moment. So, willing
> to
> > : suffer
> > : > > the comic flames and arrows, I ask the following question:
> > : > >
> > : > > Assume we have three switches: A, B, and C. A has a fast
ethernet
> > : > > connection to B and another to C. B and C are not directly
> > connected.
> > : At
> > : > > this point, these are not trunk lines and they are in the same
> VLAN.
> > : That
> > : > > means only traffic destined for B goes down the line to B, and
> > traffic
> > : > > destined for C goes to C.
> > : > >
> > : > > Now, if I were to make both of those connections trunk lines,
> either
> > : ISL or
> > : > > 802.1q, would I still have only B-destined traffic going to B or
> > would
> > : that
> > : > > trunk be passing all traffic for that entire VLAN up to B even
> though
> > : > > C-destined traffic is a waste of bandwidth on the B trunk?
> > : > >
> > : > > Thanks for the help, as always!
> > : > >
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