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mahesh18
Frequent Contributor

Both HSRP Switches on Active State.

Hi all,

I have enabled HSRP on 2 Layer 3 switches A and B.

They both connect to different layer 2 switches.

Layer 3 switches  A and B connect directly with each other on gi 1 and 2 ports.

Switch A has standby ip priority config for vlan 10 and 20 as 150 so that it remains active.

This is what i tested.**********************************************************************

when i shutdown the ports gi 1 and 2 then

Both switches A and B become active for vlan 10 and 20.

There  Standby router is unknown undr vlan 10 and 20 for both layer 3 switches.

Need to know why both switches become active for vlan 10 and 20  after i shutdown ports connecting them.?????????

Before shutting down ports Switch A  was active for both vlans 10 and 20.

Thanks

MAhesh

3 ACCEPTED SOLUTIONS

Accepted Solutions
Nandan Mathure
Beginner

Hi Mahesh,

Since both switches cannot communicate using "Hellos" they start thinking they are the only switches go "Active" . When you allow them to communicate then they can negotiate using priorities in Hellos about who will be "active" or "standby".

THanks,

Nandan Mathure

View solution in original post

John Blakley
Advisor

Mahesh,

In addition to what Nandan said, you'll also need to make sure that you're using the same group number between the 2 switches as well. If they're different, they'll become active for their respective group. Also, make sure that the ports that these switches connect to are trunked and have vlans 10 and 20 allowed on the trunk, and if there's a connection between the 2 L2 switches those will need to be trunked as well and also have 10 and 20 allowed on the trunk.

HTH,

John

HTH, John *** Please rate all useful posts ***

View solution in original post

Aileron88
Beginner

It's worth remembering that for HSRP to work correctly traffic needs to flow between 224.0.0.2, so you will need to take this in to account with any access-lists that are applied.

Regards,

Adam

View solution in original post

6 REPLIES 6
Nandan Mathure
Beginner

Hi Mahesh,

Since both switches cannot communicate using "Hellos" they start thinking they are the only switches go "Active" . When you allow them to communicate then they can negotiate using priorities in Hellos about who will be "active" or "standby".

THanks,

Nandan Mathure

due to link failure between routers, when  both router hsrp active, is there will traffic flow ?

John Blakley
Advisor

Mahesh,

In addition to what Nandan said, you'll also need to make sure that you're using the same group number between the 2 switches as well. If they're different, they'll become active for their respective group. Also, make sure that the ports that these switches connect to are trunked and have vlans 10 and 20 allowed on the trunk, and if there's a connection between the 2 L2 switches those will need to be trunked as well and also have 10 and 20 allowed on the trunk.

HTH,

John

HTH, John *** Please rate all useful posts ***
smehrnia
Rising star

Hi Mahesh,

you mean you shut down the ports, Leave them shutdown and both get to be "Active", or you shut / no shut, and still u have them both active?

in case of shutting down the ports, the Lower priority node, remains active, the other one though, thinks it has lost the active member and becomes Active for its group.

if you shut/no shut, and both remain active, add this command under respective HSRP group in ur switches, so the lower priority switch takes control immediately when link is back up:

standby 1 preempt   ....   where 1 is the group number

Hope it Helps,

Soroush.

Hope it Helps!

Soroush.
mahesh18
Frequent Contributor

Hi soroushm,

i mean  when i  shut down the ports connecting layer 2 switches , Leave them shutdown and both get to be "Active",

yes i mean that.

when you say this --

in case of shutting down the ports, the Lower priority node, remains  active, the other one though, thinks it has lost the active member and  becomes Active for its group.

Does this mean that standby switch thinks it has lost the active memeber and then standby becomes active with lower

priority?

Thanks

Mahesh

Aileron88
Beginner

It's worth remembering that for HSRP to work correctly traffic needs to flow between 224.0.0.2, so you will need to take this in to account with any access-lists that are applied.

Regards,

Adam