HSRP Traffic flow

[Tarun Vyas]

Suppose I have three server in HSRP in vlan-100. Please find attachment for example diagram.

           A) All of server are connected to active and standby switch in vlan 100. ( All server are having teaming).
           B) Suppose only server-3 lost the connectivity from activity switch. (so its standby link will become active)

          => How data will flow from in-side to out-side from Server -3

           A) First server-3 data will go to standby switch and through HSRP link will go to active switch then will go to outside.
                                                                                 OR
          B) Server-3 pass the in-side to outside traffic directly from standby switch to out-side

[mlund · Accepted solution]

If it is Nexus switch with vpc config, it will go for option B. Otherwise it's option A.

/Mikael

[Tarun Vyas]

@Mlund

I am having cisco 4506 switch.

I spoke with cisco TAC and he told me that option B will work in my scenario.

Can you conform....

[asif.naveed]

I don't think so Option B will work in case of your scenario. Probably TAC engineer is mistaken or you could not understand his statement well.

[Tarun Vyas]

Thnx guys for your support.

I am having sup module 6 so it does not support VSS and so I am using HSRP.

Now TAC also has conformed that option A will work for my scenario...

[Tarun Vyas]

I am having cisco 4506 switch.

I spoke with cisco TAC and he told me that option B will work in my scenario.

Can you conform...

[Jon Marshall]

If your 4500s are running VSS then I agree with TAC.

If they are not then as far as I am aware the traffic has to go across the interconnect to the active switch.

Jon

[asif.naveed]

If 4500 with VSS then it means you have only one active Control Plane and one active Data Plane then there is no Active/Backup so this diagram does not work there.

I mean this diagram does not support VSS concept

[Jon Marshall]

VSS has one control plane but two data planes ie. both switches can forward traffic so it would work with your diagram. 

Jon

[asif.naveed]

I had missed word active but still about your statement confused me.

How diagram supports here VSS

First of all these are not two switches only switch so one Active Control Plane and one Active Data Plane

only in vPC, there are two active control plane and two active data plane.

VSS!! after the configuration, is only one switch not two switches

[Jon Marshall]

You keep saying there is one active data plane but there isn't. 

With VSS both switches are active in forwarding data which is why your scenario would work with VSS. 

Jon

[asif.naveed]

Dear Jon,

Please i will appreciate if you can share any link which is mentioning 2 DP and i will also be clear.

But as per diagram, there are two CP also HSRP and did you ever notice anywhere using VSS and HSRP, then how  diagram can be fit for VSS ? For this i am very much clear

[Jon Marshall]

From the VSS Q&A - 

Q. What is a VSS1440?

A. VSS1440 refers to the VSS formed by two Cisco Catalyst 6500 Series Switches with the Virtual Switching Supervisor 720-10GE. In a VSS, the data plane and switch fabric with capacity of 720 Gbps of supervisor engine in each chassis are active at the same time on both chassis, combining for an active 1400-Gbps switching capacity per VSS. Only one of the virtual switch members has the active control plane. Both chassis are kept in sync with the interchassis Stateful Switchover (SSO) mechanism along with Nonstop Forwarding (NSF) to provide nonstop communication even in the event of failure of one of the member supervisor engines or chassis.

You don't run HSRP because you only have one control plane. 

Jon

[asif.naveed]

Thanks regarding DP, i had one bootcamp for CCIE DC (from ipexpert Rick), trainer had mentioned about difference between vPC <> VSS and he mentioned one CP and one DP in VSS while two in vPC. I will check with him, on what bassis he said so.

Regarding Diagram, for sure it is not suitable for VSS.

Anyway thanks a lot and it was really nice talking to you.

Regards

Asif

[Jon Marshall]

The diagram should work with VSS as I said and I'm not sure how you can be so certain it would not when 5 minutes ago you thought VSS only had one data plane. 

Jon