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Hi there


I have two openbsd 3.6 hosts connected to a cisco catalyst 3550 series
switch.

OpenBSD host A: interface em1 192.168.134.90/29
OpenBSD host B: interface em1 192.168.134.91/29

Host A is connected on FE 0/1 port and host B on FE 0/2 port on the cisco
switch. Both hosts are in vlan 1.

interface FastEthernet0/1
switchport mode dynamic desirable
!
interface FastEthernet0/2
switchport mode dynamic desirable

With this configuration both hosts can ping each other. Now I want to set
up a trunk link on the cisco FE 0/2 port where host B is connected:

interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport mode trunk

hostB# ifconfig em1 delete
hostB# ifconfig em1 up
hostB# ifconfig vlan0 192.168.134.91 netmask 255.255.255.248 vlan 1 vlandev
em1

After this configuration change I can no longer ping from or to host B. Did
I forget a configuration setting or what could be the problem?


Thanks, Daniel

Daniel Eyholzer wrote:
> Hi there
>
>
> I have two openbsd 3.6 hosts connected to a cisco catalyst 3550 series
> switch.
>
> OpenBSD host A: interface em1 192.168.134.90/29
> OpenBSD host B: interface em1 192.168.134.91/29
>
> Host A is connected on FE 0/1 port and host B on FE 0/2 port on the cisco
> switch. Both hosts are in vlan 1.
>
> interface FastEthernet0/1
> switchport mode dynamic desirable
> !
> interface FastEthernet0/2
> switchport mode dynamic desirable
>
> With this configuration both hosts can ping each other. Now I want to set
> up a trunk link on the cisco FE 0/2 port where host B is connected:
>
> interface FastEthernet0/2
> switchport trunk encapsulation dot1q
> switchport mode trunk
>
> hostB# ifconfig em1 delete
> hostB# ifconfig em1 up
> hostB# ifconfig vlan0 192.168.134.91 netmask 255.255.255.248 vlan 1 vlandev
> em1
>
> After this configuration change I can no longer ping from or to host B. Did
> I forget a configuration setting or what could be the problem?
>
>
> Thanks, Daniel

I think the switch is expecting untagged packets at vlan 1 because it is
the native vlan. By changing your configuration on the host you are
likely tagging them as vlan 1. Try putting fa0/1 and 0/2 in vlan2 to
test this.

int fa0/1
switchport mode access
switchport access vlan 2

int fa0/2
switchport mode access
switchport access vlan 2

Test to make sure they can ping one another.

Now take fa0/2 to a trunk

interface FastEthernet0/2
switchport trunk encapsulation dot1q
switchport mode trunk



hostB# ifconfig em1 delete
hostB# ifconfig em1 up
hostB# ifconfig vlan0 192.168.134.91 netmask 255.255.255.248 vlan 1
vlandev em1

You may also be able to change the native vlan as follows. This would
make it expect to see vlan 1 packets tagged.

int fa0/2
switchport trunk native vlan 100

--
-------------------------
Paul Stewart
Lexnet Inc.
Email address is in ROT13

PES <> wrote:
> I think the switch is expecting untagged packets at vlan 1 because it is
> the native vlan. By changing your configuration on the host you are
> likely tagging them as vlan 1. Try putting fa0/1 and 0/2 in vlan2 to
> test this.

Thanks! You are right, moving the hosts to another vlan than vlan 1 did
solve the problem.


Daniel