[j-nsp] "show ip cef exact-route"

[adamv0025 at netconsultings.com]

> [mailto:adamv0025 at netconsultings.com]
> Sent: Tuesday, May 15, 2018 12:51 PM
> To: 'Saku Ytti'; 'Nikolas Geyer'
> Cc: 'juniper-nsp'
> Subject: RE: [j-nsp] "show ip cef exact-route"
> 
> > Of Saku Ytti
> > Sent: Tuesday, May 15, 2018 12:32 AM
> >
> > Have you found cef exact-route to be correct?
> >
> > Last time I used this (ASR9000), it was giving wrong results to me. I
> > think there is entirely separate piece of code for LAG result in
> > software code and the CSCO EZChip microcode, and different people code
> > IOS-XR than ezchip, so I think there is failure mode where one code is
> > updated, and another is not, I hope I'm wrong.
> >
> Isn't it related to different chip versions used in the chassis?
> Haven't you used the commands without an ingress interface please?
> Because that would have been useless, as Jesper mentioned different cards
> (in ASR9k anyways) use different hash computation methods, so you want to
> specify the ingress card.
> 
> I thought the "show cef exact-route" and "show mpls forwarding exact-
> route" actually generates the packet and submits it to the microcode and
> returns the result (rather than running some "simulation" in SW)
> -I doubt the simulation would take the card type and SW version into
> account.
> 
> 
So to clarify couple of things,

First thing first, 
The "show cef exact-route" and "show mpls forwarding exact-route" is just a simulation, so it's not the real thing as I thought unfortunately. 

Secondly,
One can use [ location node-id ] with the above commands to instruct the simulation what hash function to use in an environment with multiple NPU versions (Trident, Typhoon, Tomahawk, etc...).
 
Oh and there's a bug as well, CSCug36061 (affected 4.2.3. and 4.3.2)


adam

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