Problem in 3750 with multiple IP segment in same VLAN

[tingchang]

Hi,

I've problems in 3750 and would like to ask for help.

I've 3750 switch with standard image. Because of lacking IP addresses, I'm going to redesign the IP scheme. Before complete migrate to new IP range, I've to let new IP segment co-exist with old IP segment for a while (I've 3 VLANs that have same situation). For example, 10.10.13.0/24 (old) will co-exist with 10.10.32.0/21 (new) in same VLAN (let say VLAN 32).

Below is the partial configuration in 3750:

interface VLAN 32

ip address 10.10.13.2 255.255.255.0 secondary

ip address 10.10.32.2 255.255.248.0

standby 14 ip 10.10.13.3

standby 40 ip 10.10.32.3

I've two PCs. PC-A is 10.10.13.250 and PC-B is 10.10.33.250, both are using HSRP IP as default gateway (the subnet mask are correct).

My problem is:

Two PCs can not ping to each other. I can not ping to both PCs from 3750. But if I'm using physical IP as their gateway (such as 10.2.13.2 for PC-A and 10.2.32.2 for PC-B), then both PCs can be ping each others.

How can I solve the problems if I've to use HSRP IP as default gateway?

[thisisshanky]

Why are you using HSRP in your case, when you dont have two devices (L3 switches - 3750) in question. You can point the users to the physical IP as default gateway and that should take care of this.

[tingchang]

I do have another 3750 (with old IP segments VLANs configured) in production line. That's why I need to use HSRP and need to test new configuration is working before put them on-line.

[thisisshanky]

Ok. ..Can the two 3750s ping each other on either networks ? Are they in Active/Standby mode ? Sh standby

[tingchang]

The 2nd 3750 (configured with multiple IP segments in a VLAN) is not connected to my company network.

Are you suspecting it might be caused by HSRP setting?

My 1st 3750 (without multiple IP segment in a VLAN) does configure HSRP and it works fine.

[thisisshanky · Accepted solution]

I think what you need is this.

standby 1 ip x.x.x.x <--- from primary subnet

standby 2 ip y.y.y.y secondary <--- from sec. subnet

Try this out.

[tingchang]

It works now. Thanks for your help.

[muaamir]

I don't get it. What is the significance of standby 1 and 2 VS standby 14 and 40? The only difference I noticed is the lower number of standby group goes with primry and higher goes with secondary.

If possible, can you also try the same config you used before except swapping the group number?

e.g.

interface VLAN 32

ip address 10.10.13.2 255.255.255.0 secondary

ip address 10.10.32.2 255.255.248.0

standby 40 ip 10.10.13.3

standby 14 ip 10.10.32.3

[tingchang]

Yes, it works also as you said.