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VSP 7400 - QoS CoS 7 trouble

VSP 7400 - QoS CoS 7 trouble

New Contributor

We are a service provider and are trying to turn up our first SLA circuit coming off of this fabric network.  We are trying to pass RFC testing across our fabric made up of VSP 7400s.   This is a straight layer 2 transport on our segment.  We are currently unable to pass RFC benchmarks, and what we have found is that the test is running with QoS CoS 7, which on VOSS is rate limited down to 5% by default.   According to the upstream carrier - COS/MEG level 7 is default for both RFC 2544 testing and Y.1731 testing.  So the goal for us is to make all traffic that ingresses the port to go into cos 6 inside of our network, so it gets a strict priority, and we can guarantee bandwidth without messing with COS 7.  I have done the following set of commands on the interfaces that ingress and egress the traffic.  However doing this makes the 2544 test immediately fail.  
#conf t
(config)#int gig 1/3
(config-if)#access-diffserv enable
(config-if)#qos 802.1p-override enable
(config-if)#qos level 6

Am I approaching this right?  Is there a better way we can achieve this?  We did "pass" by turning off rate limiting for cos 7, we do plenty of head space to up the rate limit on cos 7 if that is the best/ least worst option.


New Contributor

Keep in mind queue 7 but also queue 6 are rate limited (to 5 and 50%). In case you need to forward line rate traffic, then use queue 5 (WRR). You can display queues setting with the command :

show qos queue-profile 1 queue all

Simplest is to remark incoming DCSP to queue 5, but then you have to trust dscp (no access-diffserv enable). Here is an example to remark DSCP 56 (111000)

config terminal
qos ingressmap ds 56 5


You can then see remarked traffic on egress port with the command:

5520-24X-FabricEngine:1(config)#% show qos cosq-stats interface 1/21
Port:1/21 QOS CoS Queue Stats
CoS Out Packets Out Bytes Drop Packets Drop Bytes
0 0 0 0 0
1 18 3420 0 0
2 0 0 0 0
3 0 0 0 0
4 0 0 0 0
5 23546697 6545981766 0 0
6 84 7560 0 0
7 72 14158 0 0


You can also create a new queue profile and change setting to disable queue shaper and change all queues to WRR for tests, we recommend to use default queue in production to protect network protocols & voice traffic with default values.