Subject: Re: ospf te doc

From: "Manral, Vishwas" <[email-masked]>
Date: Thu, 22 Aug 2002 06:07:59 -0400

Hi Kireeti,

My views/answers on the questions you raised: -

a) I would prefer the suggestion to require the "Reserved" field to be 0 for
TE-LSA's and a value of non-zero should be treated as a non-TE LSA(unknown).
(as in the case of Grace-LSA)

If we left the meaning of the text as it is, it could create problems. Two
LSA's with different "Reserved" values but same "Instance" would be treated
as different LSA's by the OSPF process, however for the TE application
because the "Instance" would be the same it would be the same instance
although the contents could well be different.

Besides, the number of "Instance" values are probably sufficient even for
future requirements(every router can originate 65536 TE LSA's). By imposing
the above condition I specified we could use different values of "Reserved"
bits for future uses.

Another less preferable option could be to have all 24 bits as "Instance".

b) A non-zero value of reserved should be treated as a non-TE LSA.

c) Unknown opaque LSA's are flooded(not dropped) further depending on the
flooding scope of the LSA.

Thanks,
Vishwas

-----Original Message-----
From: Kireeti Kompella [mailto:[email-masked]]
Sent: Thursday, August 22, 2002 2:12 AM
To: [email-masked]
Subject: ospf te doc

Hi All,

Here's what the updated section 2.2 of the ospf te doc
(draft-katz-yeung-ospf-traffic-07.txt) looks like:

2.2. LSA ID

   The LSA ID of an Opaque LSA is defined as having eight bits of type
   and 24 bits of type-specific data.  The Traffic Engineering LSA uses
   type 1.  The remaining 24 bits are broken up into eight bits of
   reserved space (which SHOULD be zero on transmission and ignored on
   receipt) and sixteen bits of instance:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |       1       |    Reserved   |           Instance            |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   The Instance field is an arbitrary value used to maintain multiple
   Traffic Engineering LSAs.  A maximum of 65536 Traffic Engineering
   LSAs may be sourced by a single system.  The LSA ID has no
   topological significance.

The issues are
a) what should the wording regarding the "Reserved" field be?
b) how should TE LSAs received with "illegal" values be treated?
   (for example in the wording as above, how should a TE LSA with
   a non-zero Reserved field be treated)?

One suggestion is to require the "Reserved" field to be zero, much
as John Moy requires the Opaque ID to be zero in a Grace LSA.  A
TE LSA received with a non-zero Reserved field is to be treated as
an unknown Opaque LSA (how are unknown Opaque LSAs treated?  Dropped?
Flooded?).

Thoughts?  Other suggestions?

Kireeti.