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Re: IPv6+Linux status page useful?

To: kuznet@xxxxxxxxxxxxx
Subject: Re: IPv6+Linux status page useful?
From: <venaas@xxxxxxxxxxx>
Date: Mon, 20 Dec 1999 22:15:09 +0100
Cc: Cacophonix Gaul <cacophonix@xxxxxxxxx>, pb@xxxxxxxxxxxx, netdev@xxxxxxxxxxx
In-reply-to: <199912201610.TAA05288@xxxxxxxxxxxxx>; from kuznet@xxxxxxxxxxxxx on Mon, Dec 20, 1999 at 07:10:37PM +0300
References: <19991219220045.23997.qmail@xxxxxxxxxxxxxxxxxxxx> <199912201610.TAA05288@xxxxxxxxxxxxx>
Sender: owner-netdev@xxxxxxxxxxx
On Mon, Dec 20, 1999 at 07:10:37PM +0300, kuznet@xxxxxxxxxxxxx wrote:
> Hello!
> 
> > unicast mechanism is different from anycast. Also, there is no
> > need for the receiver to be aware of the fact that it has an
> > anycast address - it could be part of an anycast group without
> > it's knowledge.
> 
> Nope. It's knowledge is the _only_ thing differing anycast of unicasts.
> They are indistingushable outside of receivers.
> I suspect we talk about different things. 8)

My understanding is:

"Classical" anycast addresses are indistuingishable from normal addresses
for both senders and receivers, the trick is the routing. Different
senders may reach different receivers using the same address, but a single
packet should not go to more that one receiver. 

RFC 2373 states though that receivers must be configured to know it's an
anycast address. There are AFAIK a lot of open issues here. If for
instance there are two routers on a link and a host on the link sends a
packet to the subnet-router anycast address, how should one decide which
one to respond, of course this is a problem in some other scenarios as
well.

> > anything formal yet, there was no intent to prohibit it's use within
> > individual administrative domains either.
> 
> It would be pretty funny, if some IETF meeting prohibited to do something
> within an individual administrative domain 8)8)8)

Yes. What should be limited though is global usage, since it increases the
size of the global routing tables.

Stig

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