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RE: (ASCEND) Arp routing
-----Original Message-----
From: Andre Beck [mailto:beck@ibh.de]
Sent: Wednesday, April 08, 1998 12:18 PM
To: Ascend Users
Subject: Re: (ASCEND) Arp routing
On Wed, Apr 08, 1998 at 11:19:01AM -0400, Dave Van Allen wrote:
> There's no such thing as "arp routing", what you have here is Tomfoolery.
\While I would also not call it ARP routing, I don't at all see why some
\people bash it or dislike it.
I didn't mean to imply (or perhaps you weren't referring directly to me)
that I dislike arp - obviously one cannot run a network without it. I am
suggesting that in this particular case it is not the place to play arp
follies.
> arp was not designed to be used as a routing or re-direction function
across
> different subnets. Proxy-arp in a situation like this is a bad hack and
\It was not designed for that, but it was designed flexible enough to allow
\for that. It allows for even more esoteric hacks like "ARP-for-everything"
\which is euphemistically called "IP Switching" or "Layer 3 Switching".
Conceptually perhaps, but classical arp is not the element that handles the
tables or the updates. I am a big believer in switch where you can, route
where you must, however we are not speaking about anything that is germane
to this particular user's plight, right?
\If you keep in mind that IP forwarding in a broadcast domain is nothing
\but "find the right MAC to send the frame to" and the IP-Address written
\in your routing table or published with a routing protocol is of no real
\use to forwarding but to find the MAC to which it must send, Proxy ARP
\doesn't look that weird any longer.
Hmmm, I think that's a bit over-simplistic. Actually wouldn't you agree
that it's really "find the right exit-point (xN) then find the MAC". The
MAC will always be found by classic arp, however all the fabric traffic in
the middle is handled quite differently. Proxy-arp is, IMHO a last chance
effort to make up for what could be a better designed topology OR as I think
you are suggesting a very simple nerd-knob to handle a small or simple
function. I guess I disagree that the user here is in a case where a small
or simple function is needed.
Specifically, what does he do when he adds his next Max? or the next? Where
does the (xN) blow up?
> Even RIP2 with small timer values will get you out of your problem in a
> fashionable way. OSPF in the later 5.0p tree works well too for your
> situation and is the preferred method for scaling.
\You need to grow a lot until OSPF becomes really necessary.
One would argue when you've grown " a lot " it's really very difficult to
start over right, too. OSPF from a sheer power and option standpoint is
indeed overkill for this user, however the config to get what he needs done,
where it will work for him, grow with him and allow him to be flexible in
the future requires nothing more than about:
router ospf 1
network xxxx
network xxxx
redistribute connected subnets
and a toggle of two knobs within the Maxen.
Best regards,
David Van Allen - FASTNET(tm) / You Tools Corporation
dave@fast.net (888)321-FAST(3278) http://www.fast.net
FASTNET - Business and Personal Internet Solutions
--
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+-o-+--------------------------------------------------------+-o-+
| o | \\\- Brain Inside -/// | o |
| o | ^^^^^^^^^^^^^^ | o |
| o | Andre' Beck (ABPSoft) beck@ibh-dd.de XLink PoP Dresden | o |
+-o-+--------------------------------------------------------+-o-+
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