Re: Two questions on draft-dimitri-ccamp-gmpls-ason-routing-ospf draft

[Igor Bryskin <i_bryskin@yahoo.com>]

Dimitri,

> Is the LinkID is the same as Remote TE Router ID?

no

> LinkID unambiguosly identifies remote data plane node,

no, it identifies the remote RC not the remote data plane "node" in case
the remote RC is associate to n "nodes"

IB>> No, I disagree. You see that's why it's so important to quote the RFCs/drafts, because people often interpret them differently.

In RFC 3630 we read:
"

2.5.2.  Link ID



   The Link ID sub-TLV identifies the other end of the link.  For

   point-to-point links, this is the Router ID of the neighbor.

"

Note that it does not say whether this is the advertising Router ID 

(identifying neighbor RC) or TE Router ID (identifying the
 neighbor TE node). However, it does say that it “identifies the other end of the link”. Because a link is terminated by TE nodes (and not advertising routers) I conclude that LinkID identifies the remote TE node.

Furthermore, earlier in RFC 3630 we read:

“

2.4.1.  Router Address TLV

   The Router Address TLV specifies a stable IP address of the

   advertising router that is always reachable if there is any

   connectivity to it; this is typically implemented as a "loopback

   address".  The key attribute is that the address does not become

   unusable if an
 interface is down.  In other protocols, this is known

   as the "router ID"

I interpret that this is the same router ID as in the upper quote. It is advertised in the Router Address TLV, which is the only way today to advertise TE Router ID. Hence the router ID in the context of this RFC is the TE Router ID.

The conclusion #1: the TE Link TLV, as it is today, always contains the ID of the remote TE node.

The conclusion #2: there is a need to advertise several TE Router IDs supported by the same RC (advertising router), which, I think, should be proposed in your draft

ps: second question is trivial, mathematical vs networking formulation (no
real difference)

 

IB>> Well, it changes one of the fundamental definitions of G.8080, and I am asking why is that in the draft which is supposed to define ways to support G.8080

 

Igor

pps: if you want to put guidelines on e-mail responses probably directing
your e-mail to the GEN AREA would be more suitable

hope this helps,
-d.




Igor Bryskin
09/03/2007 00:03

To: Dimitri PAPADIMITRIOU/BE/ALCATEL@ALCATEL
cc: ccamp@ops.ietf.org, "Brungard, Deborah A, ALABS"

Subject: Re: Two questions on
draft-dimitri-ccamp-gmpls-ason-routing-ospf draft


Dimitri, no, it does not help.

You didn't answer the first question, which is:

Is the LinkID is the same as Remote TE Router ID? If no, what is the
difference? If yes, why do you need the latter? Both your pointers explain
why do you need advertising of the local TE Router ID (advertising router
may cover multiple data plane nodes), However, LinkID unambiguosly
identifies remote data plane node, and the need for the advertising of
Remote TE Router ID is not obvious

BTW, You didn't answer the second question either.

Igor

PS, I have a suggestion for the working group: Let us disallow responding
to the comments/questions by just pointing to RFCs or drafts. In my view
it is quite unfriendly. It is always possible to cut and paste a piece
from the relevant RFC or draft confirming the points the writer is trying
to make.

Dimitri.Papadimitriou@alcatel-lucent.be wrote:
igor


pls use version (or 03
when available to make comments)

in that version you will see in Section 5.2

" Note: The Link ID sub-TLV that identifies the other end of the link
(i.e. Router ID of the neighbor for point-to-point links) MUST
appear exactly once per Link TLV. This sub-TLV MUST be processed as
defined in [RFC3630]. "

now why this sub-TLV 17, well for the reason explained at the beginning of

par.5.2
but also in RFC 4652 Section 5.7

hope this helps,
-d.




Igor Bryskin
08/03/2007 22:11

To: Dimitri PAPADIMITRIOU/BE/ALCATEL@ALCATEL
cc: ccamp@ops.ietf.org, "Brungard, Deborah A, ALABS"

Subject: Two questions on
draft-dimitri-ccamp-gmpls-ason-routing-ospf draft


Dimitri,
I have a couple questions wrt the
draft-dimitri-ccamp-gmpls-ason-routing-ospf draft.
In 5.2 a TE Link sub-TLV is introduced for the purpose of advertising
local and remote TE Router ID:

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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 17 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Remote TE Router Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Although I do understand why there is a need for advertising the Local TE
Router ID, I don�t understand why the Remote Te Router ID? Isn�t
this is
the same
information
that is carried in the Link ID sub-TLV?
In 6. you write:

ââ?¬Å?A RA may contain smaller RAs inter-connected by links.
The limit of the subdivision results in
a RA that contains two sub-networks interconnected by a single link.�

In G.8080 I read:
ââ?¬Å?.... A routing area is defined by a set of subnetworks, the SNPP links

that interconnect them, and the SNPPs representing the ends of the SNPP
links exiting that routing area. A routing area may contain smaller
routing areas interconnected by SNPP links. The limit of subdivision
results in a routing area that contains ]one subnetwork.�

Why is the discrepancy?

Thanks,
Igor


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