Subject: RE: Between OSPF RSVP...

From: Steve Yao <[email-masked]>
Date: Fri, 14 Mar 2003 11:51:09 -0600

>Steve,
>
>In two messages prior you stated:
>
>> The RRO received at the HE only contains the IP addresses 
>that map to half
>> of the LSAs or LSPs that the LSP traversed. 
>
>You mentioned that only half the LSA/LSPDU were in the RRO, so the
>question "What cases were you thinking of?" that you just asked should
>be directed to you.

I asked the question since you mentioned earlier:

>It wasn't intended to cover all cases and does not depricate use of
>path-tear.  You still didn't answer my question.

But it is ok if you don't want to answer the question.

>
>Since you brought up the issue "where RRO may be too large" why don't
>you do the math and tell us 1) how big the RRO would have to be to be
>too large and 2) how likely you think that is of occurring.  RSVPd
>objects can be 64KB each.  The IPv4 address subobject is 8 bytes long,
>including type and length.  Add a label subobject (8 bytes) and fit it
>into a reasonable MTU and you're still at hundreds of hops.  I get
>200+ into a 4KB MTU and most networks seem to be going for 8K MTU so I
>get "not very likely" for question 2).
>
>Curtis
>

I agree that this is not very likely.

Steve

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From: Curtis Villamizar <[email-masked]>
Date: Fri, 14 Mar 2003 13:13:03 -0500

> But it is ok if you don't want to answer the question.

OK.  I wasn't trying to avoid a question, just lost track of which
question you were referring to.  There are a couple of cases.

The topic of running MPLS with an external path computation and
explicitly configured paths comes up from time to time.  Some carriers
claim they'd do this without running an IGP at all.  I don't know of
anyone that has successfully done this and I personnally think it is a
very bad idea but MPLS with explicitly configured paths and no IGP
running is a supported feature for many LSR anyway.

In inter-area MPLS, if hierarchical LSP were not used, the ingress
would set up paths across areas not it would not be notified of links
that went down in other areas.  Not running hierarchical LSP in this
case is probably not very scalable and creates this problem as well
but that network design issue is a matter of best practices.  The LSR
should "do the right thing" even if the network design is poor.

Those were the types of cases I was thinking of.

Curtis