Subject: [rbridge] ARP <whatever> (was it's time to summarize things)

From: Eric.Gray at marconi.com (Gray, Eric)
Date: Fri, 16 Dec 2005 17:49:02 -0500

Joe,

--> I'm not aware ARP Replay being called Proxy ARP - is anyone else? Is
--> there a better name than ARP Replay?

ARP Replay might be clearer in indicating the inherent problems
you pointed out (the implication of "replay" is the potential
for "stale" information).

However, ARP caching (in a sense similar to web caching) has a
"spin" (if you will) that includes mechanisms (such as Radia
suggested) for handling these problems.

As far as the "confusion" over ARP proxy, I am happy to use a
different word if it is confusing.  However, ARP proxy - in the
sense that I've interpreted it in the past is "proxying" the ARP 
service.  That means essentially what Radia said - i.e. - close
in meaning to a name service proxy (but also similar to caching).

What you are talking about is more like ARP spoofing, or ARP for
higher layer (i.e. - layer 3) forwarding.  I don't believe I've
ever heard that called ARP proxy, but it might be.  If that is
the case, then by all means, use a different term. 

--> -----Original Message-----
--> From: rbridge-bounces at postel.org 
--> [mailto:rbridge-bounces at postel.org] On Behalf Of Joe Touch
--> Sent: Friday, December 16, 2005 10:58 AM
--> To: Developing a hybrid router/bridge.
--> Subject: Re: [rbridge] it's time to summarize things
--> 
--> _______________________________________________
--> rbridge mailing list
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--> http://www.postel.org/mailman/listinfo/rbridge
-->

---

From: touch at ISI.EDU (Joe Touch)
Date: Fri, 16 Dec 2005 14:53:05 -0800

> suggested) for handling these problems.

That's a well-known term on the host side; caching prevents the ARP from
being emitted in the first place.

> in meaning to a name service proxy (but also similar to caching).

The term "proxy ARP' is a well-known term on routers that does what I
described; it is described in Cisco literature as such.

> higher layer (i.e. - layer 3) forwarding.

Spoofing is an attack version of proxy ARP. There are legitimate
versions as well.

> I don't believe I've

---

From: harald at alvestrand.no (Harald Tveit Alvestrand)
Date: Sat, 17 Dec 2005 00:22:05 +0100

--On fredag, desember 16, 2005 14:53:05 -0800 Joe Touch <touch at ISI.EDU> 

> described; it is described in Cisco literature as such.

"Proxy ARP" has numerous citations in RFCs dating back to RFC 1009; I 
haven't been able to find "the" authoritative description in 5 mins of 
searching, but some pointers point back to RFC 925 "Multi-LAN Address 
Resolution", which seems to describe what I think of when I say "proxy ARP".

Let's not try to change the meaning of that term.

---

From: touch at ISI.EDU (Joe Touch)
Date: Fri, 16 Dec 2005 15:28:14 -0800

> Resolution", which seems to describe what I think of when I say "proxy ARP".

I was not able to find the word 'proxy' in RFC 925.

The definition in 1009 is exactly what I have been using.

> Let's not try to change the meaning of that term.

I think we've agreed not to. There doesn't appear to be a good term for
replaying a cached ARP response, which is not what proxy ARP does.

Joe