[c-nsp] Cisco 3700, SMC TigerSwitch, Linux and VLAN Problems

[Michael Smith]

Hello Ray:


On 6/1/06 9:41 PM, "Ray Van Dolson" <rayvd at digitalpath.net> wrote:

> Hope this isn't too off topic.
> 
> 
>                 ^
>                 | FastEth0/0 (WAN)
>     +--------------+
>     |  Cisco 3700  |
>     +-----------+--+
>                 |                                 +-----------------+
>     FastEth0/1  |                                 | SMC TigerSwitch |
>                 +---------------------------------+-----------------+
>              FastEth0/1.1                    Port 1                 | Port 23
>                dot1Q 1 native                                       |
>                192.168.100.1/24                             +-------+
>              FastEth0/1.2                                   |
>                dot1Q 2                                      | eth1
>                192.168.75.17/30                     +-------+ 192.168.75.18/30
>                                                     | Linux |
>                                                     +-------+
> 
> 
> I'm trying to get VLAN tagging set up with a Cisco 3700 router, an SMC
> TigerSwitch 6724AL2 and a Linux box.  The layout is as above.
> 
> I have my VLAN configuration configured as follows on the TigerSwitch:
> 
> (This is an 802.11Q configuration)
> 
> vlan database
>  vlan 1 name DefaultVlan media ethernet state active
>  vlan 2 name RayVlan media ethernet state active
> !
> interface ethernet 1/1
>  switchport native vlan 1
>  switchport mode trunk
>  switchport allowed vlan add 1-2 tagged
> !
> ...
> !
> interface ethernet 1/23
>  switchport allowed vlan add 1-2 untagged
>  switchport native vlan 2
> !
> interface vlan 1
>  ip address 192.168.100.2 255.255.255.0
> !
> 
>> From what I understand packets leaving the Cisco destined for 192.168.75.18
> should be tagged for VLAN 2.  The SMC switch should send the packet out Port
> 23 and remove the VLAN tagging since the port is configured as untagged.
> 
> Packets coming in from the Linux box into Port 23 and destined for
> 192.168.75.17 should be tagged with VLAN 2 because of the "native vlan 2"
> configuration option on the port (basically any untagged packets are tagged
> for VLAN 2).  The switch should send this packet through Port 1 and the Cisco
> sends it to the correct subinterface because of the VLAN tag.
> 
> However, traffic is not passing as I expect it go.  If I run a ping from the
> Cisco to 192.168.75.18 while running a tcpdump on the Linux box's eth1, I
> don't see the ICMP packets nor do I even see any ARP requests.
> 
> Can anyone see anything obviously wrong with my setup?  Maybe I have something
> conceptually wrong.

I'm not totally familiar with the Tigerswitch, but it appears the port
config on 1/23 has a mix of trunk and non-trunk commands.  The Switchport
Native command should be used when the port is an 802.1Q trunk, not when
it's a switchport.  With that said, you should probably just have the
following, but as it's not a Cisco, YMMV.

Interface 1/23
 switchport allowed vlan add 2 untagged


That will identify all inbound traffic on that port with the VLAN 2 header
for movement through the switch.

Good Luck!

Mike