Cisco XR Traffic Controller SR-PCE-CAPABILITY SubTLV

[aseem_rai]

hi All, 

We are using the Cisco XR Traffic controller(version 7.1.2)  to perform our validation of PCC for both SR-TE and RSVP Tunnels as per RFC-5440 and RFC-8664. We are using NCS540 box as the controller 

While running a PCEP session with the XTC, we observed that the XTC sends the OPEN message with the SR-PCE-CAPABILITY as the TLV but the RFC-8664 has changed that to a SubTLV of PATH-SETUP-TYPE-CAPABILITY TLV. When we send our PCC OPEN message as per the RFC, the XTC is not interpreting it.  

The RFC's draft version had the SR-PCE-CAPABILITY defined as TLV but has got changed in the published RFC. 

It will be great if you can help us understand if there is any version of the XTC software which would be supporting the latest RFC-8664. 

Below is the snapshot of the OPEN message sent by Cisco XTC . 

Below is the OPEN message sent from PCC( Us) . 

(The one in the red box shows the SR-PCE-CAPABILITY Sub-TLV which wireshark is not able to resolve as per the current version). 

Thanks

Aseem.

[pigallo]

Hi,

It's weird, i never had any issue with PCEP /XTC path validation/calculation.
I usually configure an instance under XRV9000 with release 7.x

Which platforms/releases are you using as PCC client ?

thanks.

[aseem_rai]

hello pigallo, 

Actually the platform acting as PCC is non cisco platform running OS which has PCC functionality and we are trying to validate our functionality with the PCE XTC . 

Thanks

Aseem. 

[pigallo]

Hello,

AFAIK PCEP interoperability among different platforms is supported:

https://www.cisco.com/c/dam/m/en_us/network-intelligence/service-provider/digital-transformation/knowledge-network-webinars/pdfs/0604-msn-ckn-pdf.pdf

Unfortunately i'm not sure which PCC you use right now. Is it proprietary hardware/software ?

Thanks,

Regards.

[pigallo]

@aseem_rai ,

thank you for your reply.

So are you using the stateful PCE feature, am i correct  ? or is it stateless ?

I'm aware that with stateful PCE there might be the need to add some SMU for capabilities. I'm not sure if with your release is needed.

i should give a check in my lab but unfortunately i do not have other vendor's device to test with it.

[aseem_rai]

hello @pigallo 

Thank you for helping me out here

You are right, I am using PCE as stateful engine for our PCC. The release i am on is 7.1.2 on NCS540 actually . 

Since i am not getting much of a documentation for the XTC, it will be helpful if you can also help me to understand if it does the path calculation on the BANDWIDTH and IRO constraints too ? Or do you think i should create a different question in the community for this ?

Basically, RFC8664 has earlier drafts which used to have the SR-PCE-CAPABILITY as a TLV which i could see cisco is sending OPEN message with . However, after it converted to RFC or sometime in between, the capability changed to subTLV of PATH-SETUP-TYPE capability TLV. Now, RFC also states to have backward compatibility to the earlier versions of draft which ideally our PCC is doing. But, it does not mention if a PCE/PCC implementing an older version of draft should be compatible to the latest RFC ( may be its too much of an ask ) . Thats why we had upgraded our software to a newer release but i would see the implementation still remains the same. 

Would any SMU be there to have it aligned to the RFC , whats your opinion. 

Thanks

Aseem.