vinodjad1234 wrote:
Hi,
I want to configure the VSS with two 6509 switch :
before that i want to know about control information :
As i have gone through the VSS info. published on cisco site , I have understood that It is active/ active for data plane and active/standby for control plane :
I am somewhat confused , means , all data traffic will be flowing actively in both the chassis but control information will be going through only active sup.
and control info means , routing protocol information , or management info.
but if i configure any routing protocol. and connected two router or some routers to some port in 6509 : and suppose i have scenario with active sup failed :
will i loose the neighborship with all the neighbors for at least some time till active supervisor engine comes?
and what about internal lan traffic : will it have impact because of active sup failure ?
what is that data plane traffic ?
Please share the knowledge ... may be .. to explain we can open packet and describe based on header means control information ?
I am little bit confused with this ?
and what i connect any layer 2 switch to standby box in VSS , how the traffic flows if active supervisor fails or it will not at all flow though sup ... since it is l2 traffic ?
Please share the knowledge about this concept ?
sorry for this basic doubt which i am asking but really it would be great help for me to understand the VSS concept.
Vinod
Yes control plane is handled by the active supervisor whereas the data plane, the actual traffic forwarding is handled by both sups. Control plane traffic is L2 traffic such as STP/CDP/PaGP etc. and L3 traffic such as routing updates between L3 peers.
For the control plane the supervisors run NSF/SSO between them so the high availabilty aware protocols are synchronised between the 2 supervisors. A failure of the active supervisor will failover to the standby supervisor in approx 50ms so it is almost instantaneous.
As for the data plane you should connect your L2 switch to both chassis with an etherchannel. VSS allows the etherchannel to be shared among both chassis so there is no STP blocking on any of the uplink ports. If the active supervisor fails then traffic simply flows across the remaining links to the standby supervisor without any need for an STP recalculation.
If you want more details then please see this doc -
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps9336/white_paper_c11_429338.pdf
Jon
