Subject: Re: (ION) RFC 2332 again

From: "Albert Manfredi" <[email-masked]>
Date: Wed, 11 Nov 1998 14:03:52 -0500

-----Original Message-----
From: Archana Nehru <[email-masked]>
Date: Wednesday, November 11, 1998 1:41 PM
Subject: Re: (ION) RFC 2332 again

>Joel Halpern wrote:
>> An NHC can not register a prefix.  A registration is always for a
full
>> address.
>
>I am not sure why you are saying that NHC cannot register a prefix
>(1.2.3.4/16)in its registration. This is the only way an NHC can
>register a subnet.Isn't it?

I guess I'm missing something you're saying here, Archana.

Let's say the NHC registers with its NHS. All the NHC can possibly
say to the NHS is "I am ATM address ____ and IP address ____ and IP
mask ____." That's it. The NHC has no idea what sort of IP routing
that NHS is doing. That NHC's NHS might be the edge router for
_only_ the NHC's IP subnet, or it might be the edge router for a
whole bunch of other subnets as well. How is the NHC to know?

NHCs register themselves. They don't know the topolgy of the
network, right?

>I am not sure why an NHS needs to look up the routing table in
cases
>where the prefix to be filled can be determined from the
registration
>cache itself. Supposing an NHC has registered the subnet 1.2.3.4/16
>(1.2.*.*),when an NHS receives resolution request for 1.2.3.6/16,
the
>look up in the registered cache itself determines the prefix
length.

For all the NHC knows, that NHS might be responding to 1.x.x.x/8.

Bert
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---

From: Archana Nehru <[email-masked]>
Date: Wed, 11 Nov 1998 13:05:47 -0800

> whole bunch of other subnets as well. How is the NHC to know?

The NHC does not know what all the NHS is routing, but it definitely
should know the topology to the extent that it knows why it registered
an entire subnet with the NHS. This will happen only when the NHC is the
only route to the "registered subnet" and NHC knows that it wont cause
any routing loops etc by registering this information. NHC cannot
register a subnet that it has learnt through routing, because such
destinations typically are not stable.
Since an NHS can generate resolution requests only for registered
destinations, all it has to do is look up if it serves the destination
in its registered cache and if some NHC has registered it, then the
prefix length could directly be the registered one itself. If the
destination is not found served by any registered NHC, NHS has to
forward it etc.

> For all the NHC knows, that NHS might be responding to 1.x.x.x/8.

I am not sure what you mean here. The basic assumption is that an NHS
cannot reply unless it finds a registered NHC claiming that it
represents the 1.x.x.x/8. If there is , then NHS has to reply back. If
not, forward it.

Hope I make myself clear
-archana

________________________________________________________________________
Archana Nehru                     :  Trillium Digital Systems, Inc 
E-mail: [email-masked]       :  Los Angeles, California     
Phone: +1 310 442 9222     
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