Hi,
Need for advertising of FA by both sides is dictated by OSPFv2 and
IS-IS, because they 1) check presence of adjacency in two directions and
2) cannot distinguish FA from regular P2P link. If latter was possible,
then it would not be needed to perform two-way check for FA (presence of
FA just in forward direction means that ingress "link" on remote
neighbor is working; otherwise LSP in forward direction would be
broken). It can be generalized to all three protocols: if we can somehow
identify link type as FA, we don't need two-way check for FA. We also
don't need Neighbor Interface ID for FA in OSPFv3 in this case.
Thank you.
01.03.2018 19:56, Acee Lindem (acee) пишет:
Hi Alexander,
*From: *Alexander Okonnikov <[email protected]>
*Date: *Thursday, March 1, 2018 at 11:40 AM
*To: *"Goethals, Dirk (Nokia - BE/Antwerp)" <[email protected]>,
"[email protected]" <[email protected]>, Acee Lindem <[email protected]>
*Subject: *Re: [Lsr] advertising tunnels in IGP
Hi,
I think that problem here is that two LSPs are two independent
unidirectional links, rather than one bidirectional. Moreover, LSPs in
two directions are not pairs (some two LSPs are not associated to each
other), and amount of LSPs in each direction is not necessary the
same. I could assume that some router uses Interface IDs for two-way
check, but it is not so straightforward when we have deal with FAs.
Acee, two-way check could be disabled on the router that is owner of
FA, but how other routers will distinguish regular P2P from FA?
Good point – all the transit routers need to agree on the interface IDs.
Thanks,
Acee
Thank you.
Best regards,
Alexander Okonnikov
1 марта 2018 г., 19:37 +0300, Acee Lindem (acee) <[email protected]>, писал:
Hi Dirk,
My memory has faded somewhat on Forwarding Adjacency (FA)
implementation. However, since basic MPLS LSPs are unidirectional,
doesn’t the SPF two-way check have to be disabled anyway? If so,
the Remote Interface ID doesn’t matter.
Thanks,
Acee
*From:* Lsr <[email protected]> on behalf of "Goethals, Dirk
(Nokia - BE/Antwerp)" <[email protected]>
*Date:* Thursday, March 1, 2018 at 11:06 AM
*To:* "[email protected]" <[email protected]>
*Subject:* [Lsr] advertising tunnels in IGP
Hi,
In OSPFv2 (and ISIS), we can add (RSVP) tunnels to the topology
by adding them as a unnumbered link in the router lsa.
In OSPFv3, we can only add a link to the router-lsa if the neighbor
interface ID is known.
So it looks like we can only add a tunnel to the OSPFv3 topology,
if we first exchanging hello packets over the tunnel.
Is that correct?
As this is not needed in the other IGPs, do
we have other possibilities?
Thx,
Dirk
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