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New Member

Cisco 4500X VSS Issue



I have configured VSS between 4500X switches, show commands showing expected results,

Scenario attached #




When Cisco 300 switch is connected to Active [vss] sw, then I can ping server and 20 which is conncted to 3750 SW, but when I remove uplink of 300 switch from active and connect it to redundant (VSS) switch, then I cannot ping and 20.

Note that there is only one uplink to VSS from 300 switch.

Kindly reply ASAP




Everyone's tags (1)
VIP Super Bronze

Hi,With VSS, you need to


With VSS, you need to connect each access switch to both VSS switches using porchannels.  If you are connecting you access switch to only one switch (not common practice) you need to connecte it to the primary.


New Member

  Thanks Reza for reply, Yes


 Thanks Reza for reply,

 Yes this is not common practice, we need to configure MEC, but in our case only one fibre pair is available between core (4500x_VSS) and access. now customer wants to connect half of fibre connectivity on active and half of on secondary.

 Threre is another site where 6500(2T) VSS is configured and they are connected in this fashion means only one fiber on redundant chassis, and it is working properly.

 It will be very helpful If you share any document on, stating that its not possible in 4500X VSS.

VIP Super Bronze

Hi,I am not stating that it


I am not stating that it is not supported on the 4500x. It should be the same as 6500 VSS, but we would need to look at both VSS conifgs on both sets of VSS. Also, do both sets use ePAGP for dual active recovery?

on the 6500 VSS, the connection is going to active or stand-by chassis?

From the 4500X, Can you post the output of

sh switch redu



New Member

  Hi Reza, Found the solution


 Hi Reza,

 Found the solution for this issue,it is a bug in ios version , so I downgrade to 3.4, and its working properly,

 Release notes details;

Packets that are routed on the same Layer 3 interface (or SVI) that entered on are dropped if received on the VSS standby switch.

Workaround: None. CSCub63571