Subject: [Isis-wg] SNPA or IP

From: "Sachidananda K" <[email-masked]>
Date: Tue, 14 Aug 2001 15:06:06 +0000

Hello,

According to the RFC 1195, the OSI addresses may be derived from the IP 
address or the ethernet address.

When it is derived from the IP address, the next hop in the IP routing table 
can be entered as the IP address of the next hop.

Whereas if the it is derived from the ethernet address, what do we enter in 
the IP routing table? I think this a major concern for the Dual IS-IS for 
the reason that if the in IP the address resolution is dine by ARP in the 
DLL.

Please clarify my doubt in this regard.
Thanking you in advance for all the responses.
Sachi

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From: Tayfun Gol <[email-masked]>
Date: Tue, 14 Aug 2001 17:28:45 -0400

> can be entered as the IP address of the next hop.

Sachi, the OSI address is not used to derive the next hop IP address for
adjacenct routers. It simply serves the purpose of uniquely identifiying a
router from others in a topology. ( This is where you can derive the router's
system ID which will be part of the LSP ID  for the LSPs the router will
generate, you can think of an IS-IS router's system ID analogous to an
OSPF router's router ID. )

A router can resolve the next hop IP addresses for its adjacenct routers via
the IP interface address TLV sent in the IIH PDUs and populate the routing
table accordingly.

Hope this helps...

Tayfun Gol

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From: Tayfun Gol <[email-masked]>
Date: Tue, 14 Aug 2001 17:31:35 -0400

> OSPF router's router ID. )

To clarify further, this is at least the case for IP routing if this is all you
are concerned about,  OSI address surely serves other purposes for OSI forwarding
but I am assuming that's not what you are wondering..