Subject: Clarification on Flooding

From: Paresh Khatri <[email-masked]>
Date: Thu, 12 Jun 2003 08:55:34 +1000

HI all,

Would someone be able to explain the following clause in RFC2328 to me ?

This is in Section 13. Flooding Procedure:

    Page 145
    (6) Else, if there is an instance of the LSA on the sending
        neighbor's Link state request list, an error has occurred in the
        Database Exchange process.  In this case, restart the Database
        Exchange process by generating the neighbor event BadLSReq for
        the sending neighbor and stop processing the Link State Update
        packet.

Why is this an error ?  If the LSA is on the Link state request list for the neighbor, are we not expecting that
LSA from that neighbor ?

All responses appreciated.
Paresh Khatri.

---

From: Parag Deshpande <[email-masked]>
Date: Wed, 11 Jun 2003 18:33:35 -0500

From my understanding this is what it means -
A router requests an lsa when either the lsa is not present in its db or the
db copy is older.
When router receives a DD packet that contains a new/newer lsa it would
request that lsa from the nbr.

In this case the nbr sent an lsa which is either same or older which either
means that the request
created was incorrect or the nbr misbehaved, hence the Database exchange
must restart.

Parag

----- Original Message -----
From: Paresh Khatri <[email-masked]>
To: <[email-masked]>
Sent: Wednesday, June 11, 2003 5:55 PM
Subject: Clarification on Flooding

HI all,

    Page 145

Why is this an error ?  If the LSA is on the Link state request list for the
neighbor, are we not expecting that
LSA from that neighbor ?

---

From: Acee Lindem <[email-masked]>
Date: Thu, 12 Jun 2003 00:50:58 -0400

> HI all,

Hi Paresh,

> Why is this an error ?  If the LSA is on the Link state request list for the neighbor, are we not expecting that

Yes - but in this case the instance is the same as the one that is
already in your database. Note that in step (5) (b) it says to
immediately flood a new LSA out some subset of the router's interface.

When this happens the corresponding LSA instance should be removed
from all neighbor's link state request lists (see step (1) (b) on
page 149).

Note that an implemenation may have to make accomodations if LSA
flooding is not immediate. In any case, the specification is correct.

--
Acee