InterVlan Routing

[ptorrico]

Hi all,

I'm have some problems with intervlan routing between a 6506 and several 3550 switches. I make trunk (isl) on both sides, the trunk seems to work well, but I cant ping anywhere.

Here is a part of the configuration.

3550 - 48smi

!text deleted

interface Vlan1

ip address 172.16.22.254 255.255.255.0

no ip route-cache

!

ip default gateway 172.16.1.254

swinf#show int g 0/1 swit

Name: Gi0/1

Switchport: Enabled

Administrative Mode: trunk

Operational Mode: trunk

Administrative Trunking Encapsulation: isl

Operational Trunking Encapsulation: isl

Negotiation of Trunking: On

Access Mode VLAN: 1 (default)

Trunking Native Mode VLAN: 1 (default)

Trunking VLANs Enabled: ALL

Pruning VLANs Enabled: 2-1001

Protected: false

Unknown unicast blocked: disabled

Unknown multicast blocked: disabled

6506

Port Mode Encapsulation Status Native vlan

-------- ----------- ------------- ------------ -----------

5/2 on isl trunking 1

5/5 on isl trunking 1

15/1 nonegotiate isl trunking 1

Port Vlans allowed on trunk

-------- ---------------------------------------------------------------------

5/2 1-23,26-27

5/5 1-23,26-27

15/1 1-1005

Port Vlans allowed and active in management domain

-------- ---------------------------------------------------------------------

5/2 1,23,26-27

5/5 1,23,26-27

15/1 1,23,26-27

Port Vlans in spanning tree forwarding state and not pruned

-------- ---------------------------------------------------------------------

5/2 1

5/5 1

15/1 1,23,26-27

Do you have any comments?

If there any in spanish will be great. sorry my bad english

[rwiesmann]

Hi

As i understand you correct you have from the C3550 trunks towards the 6506...is that correct? So the 6506 is kind of you central point and you probably have more then vlan 1?

In my opinion you have to make for each vlan an interface like the one you already have for vlan 1. This interfaces you have to give an IP address which is the default gateway for each client in this vlan.

Sample:

interface vlan 20

ip address 192.168.1.1 255.255.255.0

So that schould be all...hope that helps.

Roger

[ptorrico]

Hi Roger, Thanks for your comments.

You´re correct the 6506 is the central point.

I forgot to say that I have on the routing module a vlan for each vlan in the network.

In the configuration showed the c3550 is a vlan22 and the vlan in the rsm is:

interface vlan1

ip address 172.16.1.254 255.255.255.0

!text deleted

interface vlan22

ip address 172.16.22.1 255.255.255.0

router igrp 1

network 172.16.0.0

Pablo

[rwiesmann]

Hi Pablo

Now i'm a bit confused....you only do the intervlan routing on the 6596?

Because if you only have the intervlan routing on the 6506 i do not see why you are running a routing protocol? Or in other words why do you have the igrp?

And anyway there are better routing protocols then igrp....so if you need a routing protocol i would change to a classless routing protocol....i guess that could be an issue in your setup too.

Regards

Roger

[ptorrico]

Well this is the escenario:

I have several subnets ie:172.16.23.0, 172.16.24.0, 172.16.25.0 and so on.

There are a c3550 which have the 172.16.26.0 and 172.16.27.0 subnets defined on it as vlan 26 and vlan27, the interface which connect to the central switch is gigabit. and I show before is trunking isl.

In the central switch are definded all vlans and in the routing module as I said, are definded one vlan for each subnet. Thats the reason for use a routing protocol, I´m correct?.

Now, it is correct to do intervlan in this way or I´m wrong.

Pablo

[rwiesmann]

Hi Pablo

A routing Protocol is basically used to exchange ip prefix information

between different devices. As i understand it do the 3550 not exchange

such information to the 6506 in your setup. So what i like to say is that the routing modul has all the information if you just define the vlan interfaces....you do not need the routing protocol....if i understand your setup correctly.

Regards

Roger

[rjackson]

Your default gateway on the 3550 is not in the same network as the ip address on int vlan1. It must be on the same network because thats how it finds it way out of the network.

Also the ip network on vlan1 in the 3550 is on vlan 22 in the 6509. You have a different network on vlan1 in the 6509.

[ptorrico]

I try with your recomendation and still doesn´t work.

Yes the vlan22 is in the 3550, in the 6506 is the set vlan 22 defined and in the route module is defined the int vlan 22 as well.

the vlan1 in the 6506 is a diferent network

Am I doing wrong ?

[rjackson]

have you corrected these statements so they are in the same network?

3550 - 48smi

!text deleted

interface Vlan1

ip address 172.16.22.254 255.255.255.0 <-------???

no ip route-cache

!

ip default gateway 172.16.1.254 <---????

What did you change them to?

Each vlan represents a virtual segment and is the same IP network on all interconnected switches with that vlan. So all switches within the same switched network, with vlan1 should use the same IP network on vlan1.

Can the switch ping itself? What is the gateway router address of vlan 1? Where is it and can you ping it from the switch? if its in the 6506 what vlan is it in?

[ptorrico]

May be my configuration is wrong, here is a part of what I do.

These are the changes

3550 - 48smi (switch A)

!text deleted

interface Vlan1

ip address 172.16.22.254 255.255.255.0

no ip route-cache

!

ip default gateway 172.16.22.1 <--

3550 - 48smi (switch B)

!text deleted

interface Vlan1

ip address 172.16.23.254 255.255.255.0

no ip route-cache

!

ip default gateway 172.16.23.1 <--

And yes, the switch can ping it self

In the 6506 is like this

set vlan 1 default

set vlan 22 name Infor

set vlan 23 name Oper

....

int sc0 172.16.1.3/24

ip route default 172.16.1.254

in the route module

int vlan1

ip add 172.16.1.254

int vlan22

ip add 172.16.22.1

int vlan23

ip add 172.16.23.1

router irgp 1

network 172.16.0.0

[rwiesmann]

Try that:

3550 - 48smi (switch A)

interface Vlan1

ip address 172.16.22.254 255.255.255.0

no ip route-cache

!

ip default gateway 172.16.22.1

3550 - 48smi (switch B)

!text deleted

interface Vlan1

ip address 172.16.22.253 255.255.255.0

no ip route-cache

!

ip default gateway 172.16.22.1

In the 6506 is like this

set vlan 1 default

set vlan 22 name Infor

set vlan 23 name Oper

....

int sc0 172.16.22.252/24

in the route module

int vlan1

ip add 172.16.22.1

So what i like to tell you is put an all switches the interface vlan1 into the same

ip subnet.....this is not the case in your config.

Check one's the config i pasted and see if you understand it?

Hope that helps

Roger

[ptorrico]

Hi Roger,

So if I put all switches in the same subnet for int vlan1, what about other vlans?

[rwiesmann]

Yes all management ip of the switches should be in vlan 1.

Leave all other ip's in there correspondig vlan....like all addresses in the subnet 172.25.25.0/24 are in vlan let's say 35. on the 6506 create the inteface vlan 35 and give it the address which will act as the default gateway for that subnet.

Regards

Roger

[ptorrico]

I read that between the rsm and the switch there is a vlan0.

that VLAN0 cannot be accessed by an administrator and is used to provide support for the communication between the RSM and the Catalyst 5000 switch.

In my rsm I don´t have such vlan0

It is something wrong?