Subject: RE: You saw this, right?

From: "Eastlake III Donald-LDE008" <[email-masked]>
Date: Mon, 26 Jun 2006 13:29:34 -0400

See below at @@@ 

-----Original Message-----
From: Bill Woodcock [mailto:[email-masked]] 
Sent: Monday, June 26, 2006 1:05 PM
To: Eastlake III Donald-LDE008
Cc: David Ulevitch; [email-masked]
Subject: RE: You saw this, right?

    > What I was thinking was, assume you have N anycast hosts who are
DNS
    > servers and all receive DNS queries sent to IP address ADDR-0.

All are capable of receiving, but only one actually receives any
specific query...

@@@ Yes, sorry I didn't word that well. If they all received the query,
it would be multicast, not anycast.

    > If they really all think they are just a host at address ADDR-0
and 
    > any of these host sends out a DNS query, presumably the anycast 
    > nature of their address would mean that the response to that query

    > could come back to a different one than the host which originated 
    > the query.

Ah, I see what you were getting at.  In practice, one never originates a
transaction with the anycast address as source.  One only originates
transactions from the host's unique address.  In practice, the anycast
service addresses are loopbacks internal to the host, while the actual
physical interfaces which are used to originate transactions use the
host's unique addresses.

So this is never actually a problem.  I suppose in the interests of
thoroughness, it wouldn't hurt to explain why, so new people don't have
to stub their toes on that same corner-case.

@@@ OK, thanks,
@@@ Donald

                                -Bill

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