(Only to Acee and Uma. I will let you two sort this out on the list.)
Reading this thread, it look's to me like whatever uses this has, they
are not related to the router ID.
So if there is anything here at all, it is some other service address
advertisement.
Uma, I would point out that currently one can not assume that a received
router ID is a usqble address. Hence, there has to be an upgrade to the
advertising router to indicate this new usage. If there is an upgrade,
then most of the use cases are addressed either by upgrading to the
feature you really want, or by some form of service address
advertisement. Router ID does not seem to be the right hook.
Yours,
Joel
On 5/11/14, 10:29 PM, Uma Chunduri wrote:
Hi Acee,
My comments inline [Uma1]
--
Uma C.
*From:*Acee Lindem
*Sent:* Friday, May 09, 2014 6:47 PM
*To:* Uma Chunduri
*Cc:* Xuxiaohu; [email protected]; Wes George; Anton Smirnov;
[email protected]; Joel jaeggli; OSPF List; [email protected];
[email protected]
*Subject:* Re: [Isis-wg] [OSPF] 答复: 答复: [sunset4] IPv6 router IDs
Hi Uma,
On May 9, 2014, at 8:03 PM, Uma Chunduri <[email protected]
<mailto:[email protected]>> wrote:
Hi Acee,
In-line [Uma]:
I can see these -
1. RLFA TLDP session without having to worry a PQ node supports TE or
not
I don't think this is a good use case. You need to have an the AF
topology in order to compute the remote LFA. Also, you may inherit
remote LFA targets for external and prefixes from other areas but you
will never compute remote LFA targets in other areas (at least not with
today's algorithms).
[Uma]: It doesn't have to be a different area. Take a simplest case of
one area or an L2 domain; after having computed all the PQ nodes in that
area/domain if the PQ node doesn't support TE and doesn't advertise
router ID (TLV 134) which IP address you would pick for TLDP session ?
You can't reliably know from the advertised prefixes from the node that
it is hosted by the node if router ID is not emitted by the node (as it
doesn't support TE).
The only advantage I can see is that a router can explicitly specify
which local address it wants to use for targeted LFA sessions.
[Uma1]: Yes Acee. This is more practical way and a separate IP can be
hosted for this and this has to be advertised as “router IP”
2. Orchestration software on a controller or an application which is
having access to
the topology database of the network may determine the node IP
address without having to go through the hoops (to determine if it's
redistributed or leaked etc..)
with this TLV.
Can you be more precise? If the orchestration application is going to
orchestrate across multiple areas, I would hope it would have visibility
to the topologies of these areas.
[Uma]: Even for a same area or domain having a node advertise it's
loopback as router ID without relation any relation to TE (supported or
not) is a benefit in this case.
The ability of an application on a controller to know this easily is a
huge advantage.
Also there could be multiple loopback and each for different purposes.
For e.g. a PCE on a controller
withhttps://tools.ietf.org/html/draft-ietf-pce-pcepscan know PCC address
with a firewall port/IP opened on the router for TLS connection. It
would be great this can happen easily and automatically.
I don’t think anyone would have a firewall within an IGP routing domain.
Hence, it would be the same purported advantage as above.
[Uma]: IMO, it depends on the controller (where it’s located) and how
many areas/ASes it is overseeing and also depends on applications it’s
giving to access to network nodes.
In a pure IGP environment, application of FW may not be
necessary, but giving access to the nodes through
applications/controller is completely a different thing and security
requirements can be different.
Also the main point as you can see here is not only about
security but it’s about giving visibility of the “router IP” through
topology database to an outside entity.
Overall , FWIW it’s an useful addition to indicate this through (a
sub-tlv of) the router capability TLV as presented here.
--
Uma C.
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