routing between different vlan's

[axfalk]

We have a Cat-3550 switch that has another vlan (vlan2) defined in addition to the Management Vlan (Vlan1). A 2600 router is patched into a Vlan1 port on the switch out of its inside interface (FE0). In addition to the router, an NT machine is patched into a Vlan2 port on the switch.From the NT machine, I am unable to ping the other interface (FE1) of the router.

.

Can someone please shed the light as to why ?

thanks.

[thisisshanky]

You will need to enable routing, using

ip routing -->global config mode

int vlan 1

ip add x.x.x.x --- default gw for 2600

int vlan 2

ip add y.y.y.y --- default gw for NT box

Hope that helps!

[axfalk]

Thanks for you response. I thought the ip routing was enabled on the 2600 router by default and the interfaces on the router define the subnets for the two vlans...

Thanks again.

[thisisshanky]

If you are doing routing for the vlans on the 2600 you will need to configure the port on the 3550---2600 as a trunk port carrying both vlans.

On 2600

int fa0/0

no ip add

int fa0/0.1

encapsulation dot1q 1

ip add x.x.x.x

int fa0/0.2

encapsulation dot1q 2

ip add y.y.y.y

On 3550

int fa0/1 (port connected to router)

switchport mode trunk

switchport trunk encap dot1q

switchport trunk allowed vlan 1,2

int fa0/2 (port connected to NT box)

switchport mode access

switchport access vlan 2

and also

3550(config)#vlan 1 name MgmtVlan

3550(config)#vlan 2 name NT Vlan

(The above commands are valid both in Vlan database mode as well as from global config mode on a 3550)..

Hope that helps!!

[axfalk]

Thanks for such a detail response. This would have probably resolved my case, had it not been for one small wrinkle. The x.x.x.x IP address on the first subinterface (Vlan1)in your example happens to be the ip address of the router's other interface (fa0/1), which, in turn, patches into a different switch. So, I have encapsulated only Vlan2 on the router, thinking that Vlan1 does not get encapsulated for 801.q, however that did not work.

Any other suggestions please?

thanks again.

[thisisshanky]

Perhaps a diagram will help me better understand your network..So is Switch 1 (one to which NT box connected) on Vlan 2 (all ports) while Switch 2 (connected to Fa0/1) on Vlan 1 ??

(NT)-Switch1---------fa0/0-Router-fa0/1-----Switch2

??

[axfalk]

(NT - 10.46.24.11) patched into a Vlan2 port of the 3550 Switch (10.46.24.13) - fa0/0 (gateway interface for Vlan2 - 10.46.24.12) - 2600 router - fa0/1 (172.21.72.13) patched into a Vlan1 port of the 2980 switch (172.21.72.202) - 6500 layer3 switch (172.21.72.165).

Thanks.

[Kevin Dorrell]

I think I understand, but correct me if I'm wrong. You have 2 VLANs only, 1 and 2. You have Fa0/0 patched to a VLAN 1 access port on a switch and it has the address of the VLAN1 gateway. You have F0/1 patched to a VLAN 2 port on another switch, and has the address of the VLAN 2 gateway. This should work straight off, no need for a trunk between the router and the switch.

If it does not work, it probably means that the trunk(s) between the two switches is/are not working correctly. From the machine on VLAN 1, can you ping the VLAN 1 gateway address? My guess is that you can. From a machine on VLAN 2, can you ping the VLAN 2 gateway? My guess is that you cannot. In that case, the trunk(s) between the two switches is/are not carrying VLAN 2 correctly. To test this, define another VLAN 2 access port on the switch where F0/1 is patched, and try pinging the gateway from there - I guess it will work.

But that's enough guessing for the moment. What actually happens when you try these tests?

Kevin Dorrell

Luxembourg

[axfalk]

Kevin, thanks for your response.

You got it almost right :-). We have 2 VLANs, 1 (the Management Vlan) and 2. The Fa0/0 is patched to a VLAN 2 access port on a 3550 switch and it has the address of the VLAN2 gateway. The F0/1 patched to a VLAN 1 port on a Cat-2980 switch. The two switches are not connected, though. An NT machine (10.46.24.11 /24)is patched to a Vlan 2 port on the 3550 switch. I can't ping either the 3550 switch (10.46.24.13/24) or the Fa0/0 (10.46.24.12/24) from the NT PC. The Fa0/1 and the Cat-2980 are working fine.

Thanks again.

[axfalk]

Good news - the problem has been resolved. It was an oversite om my part. As Kevin mentioned, the setup ended up being straight off, without trunking between the router and the 3550 switch. I can successfully ping the fa0/0 & fa0/1 ports from the NT PC that is patched into a Vlan 2 port on the 3550 switch. The only thing that I can't do is to ping the 3550 switch from either the NT PC or the fa0/1 - should i have been able to ???

Thank you for all your help. You guys rock!!!

[thisisshanky]

You should be able to do that..because they all are in same vlan/subnet. Can we take a look at the configs...

int vlan 2

no shut

HTH

[axfalk]

well, here is where I am not very clear: the NT is patched into a Vlan2 port and so is the fa0/1. However the 3550 switche's adress is defined on Vlan1 (Management vlan)????

thanks.

[thisisshanky]

I forgot..that this side of the network was on vlan 2. You will have to re-assign the ip address to Vlan 2 instead. and also do a no shut on the vlan 2 interface.

[axfalk]

The interface IS the default gateway for Vlan 2 and it's up. As I mentioned, I can ping the interface from the PC - I just can't ping the switch....

[thisisshanky]

I meant,

int vlan 2

no shut

ip add

int vlan 1

shut

So vlan 2 will be your management vlan on the 3550.