Trunking a 2950 to a 3550 not working

whiteford · ‎10-04-2008

Hi,

I'm not sure what I'm missing here, but I'm trying to trunk a L2 2950 switch with a L3 3550 switch.

Ports 1 on each switch are the trunk and I am using a crossover cable.

The 2950 switch looks after VLAN29

The 3550 switch looks after VLAN35

On the L3 3550 I have created:

interface Vlan29

ip address 192.168.2.1 255.255.255.0

interface Vlan35

ip address 192.168.3.1 255.255.255.0

I have a PC2 in port 9 of the 2950 on IP 192.168.2.51/24 and it's gateway as 192.168.2.1

I have a PC1 in port 11 of the 3550 on IP 192.168.3.2/24 gateway 192.168.3.1.

PC1 on the 3550 can only ping 192.168.3.1 and nothing on the 192.168.2.x/24 VLAN29 range.

PC2 on the 2950 can ping 192.168.2.1, 192.168.3.1 only.

3550 can ping all - 192.168.3.1, 192.168.3.2, 192.168.2.1, 192.168.2.51.

Why can't PC 1 ping anything on the L2 2950. I just want the 2 VLAN's to talk to each other.

Hope I have given you enough info.

Thanks

glen.grant · ‎10-04-2008

Make sure both switches are in tranparent mode which I don't think they are because I don't see the layer 2 vlans created in the config. Make sure vlan 29 has been created on both sides with the "show vlan" command. Verify trunk is working and passing both vlans on the trunk with the "show interface trunk detail command. You can also try switchport mode dynamic desirable on both sides of the trunk instead of switchport mode trunk . If this is going to be a production setup I would change your vlan 1 info to a different vlan per cisco best practices.

whiteford · ‎10-04-2008

Hi,

I need a little help:

1.) Where and how can I create these vlans on alyer 2?

2.)You mention that I should change vlan 1 to a different vlan, I didn't think I needed vlan 1 or was using it?

Thanks in advance for you time and help.

glen.grant · ‎10-05-2008

Nope my bad you aren't using vlan 1 , reading too many of these forums, :-) . Creating vlans at layer 2 is simply the command below. Interface vlan 29 is your layer 3 SVI which you already created. It may already be there just check both switches with the show vlan command.

conf t

vlan 29

exit

write memory

eweralan · ‎10-05-2008

Hi .. I think you need to chk your layer 2 ..

maybe you have not set up vtp on bosth switches. no prob

create on 3550

conf t

vlan 29,35

end

and then do a sh int vlan 29 --> should go to up/up

and then do sh int vlan 35 ---> also should be up/up

I think the 3550 doesnt know about vlan 29 and it needs to be created.

there are a few other ways to do this but this sould get you started..

Maybe also give the vtp domain a name so that vlan information is shared across switches ( VLAN as opoosed to Interface VLAN)

regds

eg vtp domain CISCO

whiteford · ‎10-05-2008

This is a lab, so I will try the vtp server/client scenario later.

However here are those vlan outputs for each switch, how does it look?

2950-switch#sh interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1,29

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1,29

2950-switch#sh vlan

VLAN Name Status Ports

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

1 default active Gi0/1, Gi0/2

29 VLAN0029 active Fa0/2, Fa0/3, Fa0/4, Fa0/5

Fa0/6, Fa0/7, Fa0/8, Fa0/9

Fa0/10, Fa0/11, Fa0/12, Fa0/13

Fa0/14, Fa0/15, Fa0/16, Fa0/17

Fa0/18, Fa0/19, Fa0/20, Fa0/21

Fa0/22, Fa0/23, Fa0/24

1002 fddi-default act/unsup

1003 token-ring-default act/unsup

1004 fddinet-default act/unsup

1005 trnet-default act/unsup

3550-switch#sh interfaces trunk

Port Mode Encapsulation Status Native vlan

Fa0/1 on 802.1q trunking 1

Port Vlans allowed on trunk

Fa0/1 1-4094

Port Vlans allowed and active in management domain

Fa0/1 1,29,35

Port Vlans in spanning tree forwarding state and not pruned

Fa0/1 1,29,35

3550-switch#sh vlan

VLAN Name Status Ports

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

1 default active Gi0/1, Gi0/2

29 VLAN0029 active

35 VLAN0035 active Fa0/2, Fa0/3, Fa0/4, Fa0/5

Fa0/6, Fa0/7, Fa0/8, Fa0/9

Fa0/10, Fa0/11, Fa0/12, Fa0/13

Fa0/14, Fa0/15, Fa0/16, Fa0/17

Fa0/18, Fa0/19, Fa0/20, Fa0/21

Fa0/22, Fa0/23, Fa0/24

1002 fddi-default act/unsup

1003 token-ring-default act/unsup

1004 fddinet-default act/unsup

1005 trnet-default act/unsup

glen.grant · ‎10-05-2008

It looks good , should be working just by looking at what you posted. You should be able to communicate between vlans just by looking at the post.

whiteford · ‎10-05-2008

I can only think PC1 that is in vlan 35 on 192.168.3.2 has some routing issues. The firewall is off too.

Here is it's output, maybe a second pair of eyes can help.

IP Address. . . . . . . . . . . . : 192.168.3.2

Subnet Mask . . . . . . . . . . . : 255.255.255.0

Default Gateway . . . . . . . . . : 192.168.3.1

I have a route on the PC - 0.0.0.0 mask 0.0.0.0 192.168.3.1

Jim Coyne · ‎10-05-2008

Enable routing on the 3550

ip routing

!

whiteford · ‎10-05-2008

This was already enabled.

It the end it was an incorrect static route on the laptop.

All working now