vss cisco

[Dhikra Marghli]

Hello

I have a question about configuration VSS for two switch layer 3 :

why number of port channel for two switch are differents ??

exmple:  

interface port-channel1 ( switch 1)

interface port-channel2 ( switch 2)

like  portchannel normal ( same numero )

so please , i wait from expert network answer me and explain me !!!

thanks

[Jon Marshall · Accepted solution]

It is because they act as a virtual switch and you only configure the active switch (you don't configure each switch separately) so there is in effect only one configuration which means  you cannot have the same port channel number for both switches. 

It is like when you have a stack of 3750 switches, the interface numbering is gi1/0/x for the first switch, gi2/0/x for the second switch etc. because it is all one configuration. 

Jon

[MHM Cisco World]

""Then you need to configure VSL with a unique port channel on each switch. During the conversion, the VSS configures both port channels on the VSS Active switch. If the VSS Standby switch VSL port channel number has been configured for another use, the VSS comes up in RPR mode.""

link below

https://ciscoswitchestips.weebly.com/vss-configuration-for-cisco-4500-series-switches.html

[Dhikra Marghli]

you didn't understand my question

if we have two switch 2960 cisco ( configuration normal )

Switch 1:  

interface port-channel 1 
switchport mode trunk
no sh

Switch2
interface port-channel 1 
switchport mode trunk
no sh

So  IN VSS cisco between  6500 cisco : we find

Switch1

interface port-channel21

switch virtual link1

Switch2

interface port-channel22

switch virtual link2

MY question : why  switch VSS have different numero port channel  compared to the first example  ???

i wait a reply from expert cisco

thanks

[Flavio Miranda]

Port channel number has local significance. Dont manter which number you use on botões side.

[Dhikra Marghli]

mean in mode VSS , if i configure the same Port channel number , VSS come up and config is correcte !!!??

i watch more video confi VSS ,  Port channel number are differents !!!

[Jon Marshall · Accepted solution]

I did understand your question. 

Your example of the 2960 switches is not the same because they are separate switches so they each have their own configuration file. 

With VSS the two switches are managed as one which means there is only one configuration file so you have to use different port channel numbers because you cannot have the same port channel number twice in the same configuration. 

Jon

[MHM Cisco World]

must be different, Why ?
as I understand it image you connect two port in SW using PO, 
if the PO is same then the SW is assume that this only ONE PO is connect to other different SW but using different PO then the SW will handle two PO as two different PO. 
same as in VSS.

[Jon Marshall · Accepted solution]

Not sure if your post was directed to me but you have to use different port channel numbers because it is just one configuration file and you have to allocate physical ports to the port channel. 

So to allocate physical ports on both switches to port channels then you would have to use different port channel numbers. 

Jon

[Dhikra Marghli]

Thanks Jon  , it's clear!!