Ingress policing on NCS 55x (Jericho+)

[danailpetrov]

Hi guys,

I have some question around ingress policing on NCS and I will appreciate any inputs on that.

Let's consider the following scenario:

[10G server] -- [10G SWITCH] -- [CISCO NCS]

Typical server connected to 10G switch and then to 10G on NCS. 

What I want to do is to limit the traffic of 10G server, which is blasting at line rate for a very short period of time. (e.g It will take 100ms to serialize 1Gbps (125MB) on 10G link. However, that'll cause me problems elsewhere on the network and I want to avoid it. )

So what I want to do is to limit the burst basically and say that I don't allow this server (or physical port) to be able to burst above 1G rates and my calculations work as follow: 

For a CIR of 1Gbps, I want to configure Tc of 10 ms and Bc value of 1.25 mbytes. I know this is rather "extreme" approach, but it is what I need, considering the nature of the traffic, which should be able to adapt to dropped packets.  

My question is - is the Tc value on the NCS fixed or is it going to be deducted from the burst/cir? 

If I configure this:

policy-map POLICER-1G-IN
 class class-default
  police rate 1000 mbps burst 1250 kbytes

will the NCS configure the Tc interval to 10 ms ? 

Hope the above makes sense & thanks in advance

[smilstea]

The queue-limit on 5500s is set to 10ms of service-rate (1s) by default. However, queue-limit is something reserved for queuing actions, which can only apply to egress policies.

There is minimal queuing that occurs on ingress from what I have been able to find on the subject, if I had to guess it would probably be 10ms or less.

If you need a definitive answer I can look into this more.

Sam

[danailpetrov]

Hi Sam and thanks for your response.

If you can dig out something that’ll be really appreciated! 

For now I am only interested on the ingress. 

Thanks

[smilstea · Accepted solution]

I checked with development and TC is statically set to 10ms, irrespective of any configuration value.

Sam

[danailpetrov]

Thanks very much for confirming this, Sam!

Do you have any reference/document which you can share with me so I can use for reference within our internal design rationalses? 

Also, can you confirm for which platform is this? Is it for all the Jericho+ based ones? (55A1/55A2/540?) 

Many thanks once again!

[smilstea]

This all comes from internal Broadcom design specs.

AFAIK all Jericho+ platforms, I did not specify a particular model number when asking my question to development.

Sam