Question about NCS 540 Buffers

[MaxPeddy70543]

Hello everyone,

I wanted to ask about the performance of the buffers on the NCS 540 platforms. Today we use ASR920s as PE routers to serve DIA circuits to our customers. We have experienced many issues with output drops related to microbursts over the years on the ASR920 platform despite a great deal of troubleshooting from TAC, including increasing the queue size. Today we have many customers that are upgrading to greater than 1G services and our current solution today is to terminate their service to the closest ASR9K with 10G ports available. We have recently overhauled our core network with new 57B1 routers and 100G links to our ASR9Ks, so now we are looking to upgrade our PE routers. The NCS 540 seemed to be the natural successor to the ASR920 but we have concerns about the NCS 540 platform exhibiting similar microburst issues as the ASR920. Could anyone here share their experience with the NCS 540 platform?

[Fredrik Lonnman]

NCS540 is built on Jericho Qumran-AX with 3GB of packet buffer, as compared to the ASR920 that has around 10-12MB or something the like, so that should not be a problem.

See for example https://www.ciscolive.com/c/dam/r/ciscolive/apjc/docs/2019/pdf/BRKSPG-3279.pdf page 32 and onwards.

[MaxPeddy70543]

Thanks for the reply. I had done a bit of reading on the Jericho Qumran-AX ASIC and seen the 3GB buffer size. Even so I just want to be absolutely certain that we won't have microburst issues when ingressing from say a 100G uplink on a NCS 540 and egressing out an interface linked up at 1G and with policies applied for say a 100M or 500M DIA circuit. If we were to go with the NCS 540 platform we would ideally use it to terminate any circuit whose link speed is 1 or 10G.

[smilstea]

There are scenarios you need to be aware of related to encap in the core:

https://community.cisco.com/t5/xr-os-and-platforms/ncs-devices-not-passing-rfc-2544-100g-test/m-p/4821503#M14065

https://community.cisco.com/t5/xr-os-and-platforms/ncs540-is-not-passing-the-benchmark-10g-rfc-test/td-p/4674301

Thanks,

Sam

[MaxPeddy70543]

Sam,

Thanks for sharing the information. Excellent read-up.