Re: [Isis-wg] draft-ginsberg-isis-l2bundles

[<[e-mail]>]

Les,

I thought that column #3 was using L3 bundles with unnumbered interfaces, and in this case you loose the ability to hide topology to some protocols : all layer 3 protocols see individual links. With solution #4, you have the choice per protocol/application to use the LAG or individual interfaces.


As I mentioned in my previous mail, here are my comments :

Column#3 scaling :  it adds some adjacencies, but honestly I don’t think today this is an issue with controlplane resources we have and multithreading. But yes there is an additional cost.


In the table, you can also add  a section regarding failure detection :
As for solution #1 (L2 bundles in ISIS) and solution #2 (BGP-LS), you need a mechanism outside the protocol to monitor the status on each individual link and report it to the protocol which requires to implement something in addition (it does not work by itself), solution#3 and #4 (see above) : ISIS hellos are doing the job if fast detection is not required.


Regarding the risk :
What is the risk to deploy BGP-LS ? It’s an operational cost (and you already count it before) but IMO there is no risk associated with. Do you know networks that would use this feature and that does not have already a BGP controlplane ?
For column#3, all the individual links have to be seen by the management system, so whatever they are L2 or L3, there is no scaling issue here.

Column#3 impact on base routing, what is the impact on the base routing ?

Regarding the criteria : “Using 1 protocol for diverse functionalities”, This is always counted in “Mandate the deployment of a protocol that was not deployed before” moreover using IMO, 1 protocol to do everything is never good … (like using a single router to do every features ☺ )



Best Regards,

Stephane


From: Les Ginsberg (ginsberg) [mailto:[e-mail]]
Sent: Monday, August 17, 2015 16:41
To: LITKOWSKI Stephane SCE/IBNF; Ahmed Bashandy (bashandy); Acee Lindem (acee); Ebben Aries; [e-mail]<mailto:[e-mail]> list ([e-mail]<mailto:[e-mail]>)
Subject: RE: [Isis-wg] draft-ginsberg-isis-l2bundles

Stephane –

Your new column is already covered by Ahmed’s column #3: “L2 bundles as unnumbered interfaces in ISIS”

Problem is – the two of you disagree on what is +/- for a number of rows.

I don’t think assigning addresses for a much larger set of interfaces (e.g. if there are 128 bundle members this is 128 * the number of L3 interfaces) should be considered easy to do – which is why Ahmed suggested using unnumbered.

Perhaps you could explain why you disagree with Ahmed’s assessment of the rows for his column #3??

    Les



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