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New Member

Nexus 5548UP vPC fex interfaces configuration

 Hello Forum Team!

     I have a pair of Nexus 5548UP configured as a vPC domain active-standby couple with six Nexus 2248TP Fex's in a dual-homed scenario (each fex is connected to each 5548UP). At the same time, both 5548UP are dual-homed to a pair of VSS Catalyst 6509.

I have a couple of questions regarding performance and configuration:

1. When configuring a fex interface, I've noticed that if the configuration is not the same or replicated on both 5548UP, the fex interface won't come up; is this normal behaviour? For now I am replicating manually the configuration on both 5548UP (not confyg-sync).

2. When performing ICMP tests from the 2248TP to the VSS, the response time is around 1ms to 2ms; from the 5548UP to the VSS pair is approximately 0.5ms. Is that normal delay response time from the 2248TP? I was expecting less response time from the 2248TP (the fex's have 20 Gigs of uplink bandwidth to the 5548UP pair and the 5548UP pair have 40 gig's of bandwidth to the VSS pair).

Thanks in advanced team!





New Member

 5K is not exactly similar to


5K is not exactly similar to VSS, where one switch become active and other remain standby.

They  sync the config with each other which requires during failover.



Where as N5K works independently. On N5K, we require to have to put config on peer 5K though they are similar



For ICMP delay, to VSS, is it going across L3 or is it in same broadcast  domain.





New Member

Hello Arvind and thanks for

Hello Arvind and thanks for reply;

   For ICMP tests, the L3 gateway is the VSS.


New Member

For ICMP.  Here in my Lab,




Here in my Lab, From host when I send ICMP to upstream 7K here, respone time is 1 to 2 ms.

Whereas do the same from N5k, reponse time varies from 64 ms to 1.103 ms

Its looks normal.


New Member

Excellent guys. Thanks for

Excellent guys. Thanks for your reply and support.

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