Weird Internal Routing problem

[cisconoobie]

Ok I have something wrong going on.

I have 2 core layer 3 switches in HSRP

Vlan 10 172.18.10.0/24

Vlan 20 172.18.20.0/24

Core1

int vlan 10

172.18.10.2

standby ip 172.18.10.1

int vlan 20

172.18.20.2

standby ip 172.18.20.1

Core 2

int vlan 10

172.18.10.3

standby 172.18.10.1

int vlan 20

172.18.20.3

standby 172.18.20.1

I have this setup, Core 1 is primary for Vlan 10 and Core 2 is primary for Vlan 20

Core 1 is trunked to Core 2

Switch 1 is trunked to Core 1

Switch 1 is trunked to Switch 2

Switch 2 is trunked to Core 2

My problem is this , if I trace route from switch 1 to 172.18.10.1, it displays 172.18.10.3 and then 172.18.10.1

And from Switch 2, if I trace route 172.18.20.2, it goes to 172.18.20.1 it displays 172.18.20.2 and then 172.18.20.1

Why doesnt it go to the direct connected trunk ? Why does it go in exact opposite direction?

Is there a way to change the path a switch takes to the default gateway ?

[jackyoung]

In this case, because you trunk all interlinks, it will create loop. So spanning tree will take effect to block one port in each vlan. Try to define the SPT root and the blocking point.

Moreover, you have to define which core switch will be the HSRP primary switch.

E.g. if you configure core 1 as primary HSRP GW, then the traffic should go to core 1 then the rest.

According to the result, it looks like the core 2 is the primary HSRP GW. Please check the HSRP status.

Check below for the configuration guide of HSRP :

http://www.cisco.com/en/US/tech/tk1330/technologies_design_guide_chapter09186a008066670b.html

Hope this helps.

[slindsey]

Try using standby groups for your VLAN's eg. VLAN 10 use standby group 10 and VLAN 20 use standby group 20 and use priority values other than default eg. i use 150 for primary and 130 for secondary with the preempt.

[cisconoobie]

Jack you are right, I will look and see what blocking and what is fwd