[Solved] Trunking From 3825 NM-ESW-16 (IOS) to 2948G-GE-TX (CatOS)

[Rob Cluett]

I have been able to get Inter-VLAN routing working from the 3825 router port Gi0/1 to a catalyst 2948G-GE-TX without issue.  VTP mode set to transparent, both sides. both sides set as dot1q nonnegotiate. All VLAN's were manually added to the 2948. This works, I'm happy and all is good.

However, I'd rather use the 3825's Gi0/1 router port for something else (to connect to another router). I purchased the NM-ESW-16 network module which has a single GigabitEthernet switch port and 15 FastEthernet ports. I planned to use that GigabitEthernet as the new uplink to free up the router port.

The 3825 is running IOS

The 2948G-GE-TX is running CatOS

No matter what I do I cannot get that 3825 switchport to pass traffic as a trunk port. I'm at a loss. I've tried every conceivable configuration and it does not work. Can someone give me insight into either what is special about this NM-ESW-16 in relation to trunking or tell me how this should be configued. I'm assuming someone out there has the same hardware and same connections. Help me please

[Reza Sharifi]

What version of IOS are you running? for 3800 series you need 12.3(11)T.

see table-4 in this link:

http://www.cisco.com/en/US/prod/collateral/routers/ps259/product_data_sheet09186a00801aca3e.html

HTH

[Rob Cluett]

I'm running 15.1(4)M5.

[glen.grant]

  How did you set it up ?  Seeing that its part of the switch the only way you may be able to trunk is using vlans and SVI"s .  Subinterfaces will not  work .  It's possible it may not work the way you want as normally the gig port is used to "stack:"  multiple switch modules  together. 

[Rob Cluett]

I resolved this issue. It was complicated by an incompatible hardware configuration. You cannot have two EtherSwitch modules in the same chassis on a 3825 router. I had both an NM-ESW-16 and an an HWIC-ESW4 installed.

In my troubleshooting I had moved the uplink/trunk to the Fa0/0/0 of the HWIC-ESW4 and the trunk came up and was able to pass traffic (with both modules in the chassis). I then began to beleive that the NM-ESW-16 was somehow faulty. This was all apparent because the speed and duplex negotiation wasn't working when I had it set to auto. I hardcoded both sides and the port/interface never went from "not connect" to "connect". I did some more reasearch and came across another post with a similar issue. It was pointed out that you'll see flaky results with them both installed. I powered down, removed the HWIC-ESW4, powered back up and the trunk from the NM-ESW-16 GigabitEthernet 1/0 came up and was passing traffic. Problem resolved. Have to admit. It drove me crazy.

[Rob Cluett]

! For those wondering how I set up the trunks here is how it was done (note that the CatOS switch is between the 3825 router and 2950 switch). For the CatOS commands below I added some defaults that you normally wouldn't have to worry about. Did this just in case you have the defaults changed. Also, the NAT statements are specfic to my environment so ignore them. For simplicity the config reflects a 2 VLAN setup.

3825 Router (IOS)

vtp domain somedomain

vtp mode transparent

vtp version 2

!

! Layer 2 Trunk

interface GigabitEthernet1/0

description "Uplink to switch-core-lan (Catalyst 2948G-GE-TX) on 2/1"

switchport mode trunk

no ip address

!

! Layer 3 VLAN 1

interface Vlan1

description "LAN :: VLAN 1 :: Example VLAN #1"

ip address 192.168.1.1 255.255.255.0

ip nat inside

ip virtual-reassembly in

!       

! Layer 3 VLAN 2

interface Vlan2

description "LAN :: VLAN 2 :: Example VLAN #2"

ip address 172.16.1.1 255.255.255.0

ip nat inside

ip virtual-reassembly in

Catalyst 2948G (CatOS)

set vtp domain somedomain

set vtp mode transparent vlan

set vtp version 2

!

! Layer 2 VLAN 2

set vlan 2 name VLAN2 type ethernet mtu 1500 said 100002 state active

!

set port name 2/1  -> 3825 IOS Gi1/0 ESW-16

set port name 2/2  -> 2950 IOS Switch fa0/1

set vlan 1 2/1-2

set port enable 2/1-2

set port speed 2/1-2 auto

set port vtp enable   2/1-2

set spantree portfast    2/1-2 disable

!

! Trunks

clear trunk 2/1  3-1001,1025-4094

set trunk 2/1  nonegotiate dot1q 1-7,1002-1005

clear trunk 2/2  3-1001,1025-4094

set trunk 2/2  desirable dot1q 1-2,1002-1005

Catalyst 2950 (IOS)

vtp domain somedomain

vtp mode transparent

!

! Layer 2 VLAN 2

vlan 2

name VLAN2

!

! Uplink

interface FastEthernet0/1

description "Uplink to switch-core-lan (Catalyst 2948G-GE-TX) on 2/2"

switchport mode trunk

!

!

[Reza Sharifi]

3825---------------2948G------------2950--------PC(vlan1)

                                                              |-----------PC(vlan2)                                           

So, if you have a host connected to vlan 1 and a host connect to vlan 2 on the 2950 switch, can they ping each other?