Subject: [Isis-wg] Clarification..

From: Navaneeth K <[email-masked]>
Date: Thu, 20 Apr 2000 13:14:49 +0530

Hi..

In the case of processing of the LSPs in integrated ISIS , used for IP forwarding, 
How are the interface addresses (4 octet Values without mask)  in the TLVs used in route tabel calculation.
Can any of you help out on how these i/f addresses are used?

Thanx
Navaneeth.

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From: Prashant Kumar <[email-masked]>
Date: Thu, 20 Apr 2000 09:08:03 -0400

Hello Navaneeth,

For route calculation IP Internal reachability, IP external
reachability and IS reachability TLVs are used. Please refer
the SPF calculation section(Dijkstra) C.1 in RFC1195.

Hope this helps you.

Regards,
Prashant.

-- 
Prashant Kumar
Nortel Networks                    Telephone : 978-288-7947(o) 
Billerica, MA 01821                     ESN  : 288-7947

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From: Henk Smit <[email-masked]>
Date: Thu, 20 Apr 2000 10:21:25 -0700 (PDT)

> In the case of processing of the LSPs in integrated ISIS , used for
> IP forwarding, How are the interface addresses (4 octet Values
> without mask) in the TLVs used in route tabel calculation.  Can any
> of you help out on how these i/f addresses are used?

  They are not used for calculating the topology.
 The interface IP addresses are only used to determine the IP address
 of the first next-hop on the path to each destination. When you
 build a routing table, most implementations have entries there that
 look like:
    destination IP prefix, mask, outgoing interface, next-hop IP address

  For p2p interfaces you don't really need the next-hop IP address, the
 interface should be enough info. But for LANs it is much more convenient
 (though in theory the MAC address of the next-hop should be enough).

    Hope this helps,

       Henk.