VLAN trunking and fragmentation

Sean Chittenden sean at chittenden.org
Wed Mar 12 12:55:49 PDT 2008


> interface ethernet 1/g1
> switchport mode trunk
> switchport trunk allowed vlan add 10
> exit

I think this is an issue with default VLAN membership.  I have this  
config running on *hundreds* of servers without issue.  Since Dell  
should be a cisco rip-off, on your switchport config, throw in  
(haven't tested this, on dell's CLI):

  switchport trunk encapsulation dot1q

then change your ifconfig foo to:

cloned_interfaces="vlan10 vlan11"
ifconfig_re0="media 100baseTX mediaopt full-duplex"
ifconfig_vlan10="vlan 10 vlandev re0"
ifconfig_vlan10_alias0="inet 192.168.60.1 netmask 255.255.255.0"
ifconfig_vlan11="vlan 11 valndev re0"
ifconfig_vlan11_alias0="inet 192.168.100.1 netmask 255.255.255.0"

FWIW, I think you'll find fewer gray hairs if you stick to the  
convention of using a vlan device that has the same VLAN tag.  You may  
be able to have a default VLAN, but I consider it poor practice to  
rely on default VLAN membership.

There are good reasons to have a default VLAN configured, but this  
doesn't sound like one of those cases.

Stick with explicit VLAN tagging on your servers and you can't go wrong.

-sc

--
Sean Chittenden
sean at chittenden.org
http://sean.chittenden.org/



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