1

I'm currently looking at configuring a second bridge on a cisco switch, however it appears that all interfaces are 'automatically' in the first bridging interface because they are part of Vlan1, which is part of the bridge interface.

Is this simply because Vlan1 is the special case of all interfaces until otherwise defined, or am I missing something?

bridge irb
bridge 1 protocol ieee
bridge 1 route ip

interface FastEthernet0
 no ip address
 no cdp enable
!
interface FastEthernet1
 no ip address
 no cdp enable
!

interface Vlan1
 description "my-first-bridge"
 no ip address
 bridge-group 1
 bridge-group 1 spanning-disabled
!

switch1#show bridge

Total of 300 station blocks, 295 free
Codes: P - permanent, S - self

Bridge Group 1:

    Address       Action   Interface       Age   RX count   TX count
0080.XXXX.YYYY   forward   Vlan1             0    1894232     678976
7403.XXXX.YYYY   forward   Vlan1             0     108572       5269
accc.XXXX.YYYY   forward   Vlan1             0     321219     277407
accc.XXXX.YYYY   forward   Vlan1             1     293357     250052
3ca8.XXXX.YYYY   forward   Vlan1             0     465903     846206

--

How would I make one of the interfaces exclusively for vlan2 and bridge-group 2 ?

  • Could it be that this 'switch' is actually a router (which is now functioning as a switch due to the IRB config) ? What would you like to achieve actually? If you only have 2 interfaces and put them in different bridge domains, there will not be much bridging going on... – hertitu Aug 11 '17 at 13:09
  • @hertitu The fact that there's an interface labeled "Vlan1" makes me think it really is a switch. – Ron Trunk Aug 11 '17 at 13:11
  • @RonTrunk you're probably right, I was thinking of interface BVI1 – hertitu Aug 11 '17 at 21:43
4

By default, all switch ports are in VLAN 1. Since you've assigned VLAN 1 to your bridge group, they would all be a part of bridge group 1.

You can assign a switch port to a different VLAN (for example, port 2 to VLAN 2) with the command

interface fastethernet2
 switchport access vlan 2

But...

It's not at all clear what you're trying to do. Bridge groups are generally used on routers that don't have VLAN functions. The main use of the bridge group is to emulate a VLAN -- something switches already have. If you need another VLAN, just create it and assign ports to it.

  • 1
    Addition: If you want to remove a switchport (or a bunch of them) from a VLAN but don't specifically want them in another, you can assign it to a VLAN you don't use, then delete the VLAN. int range g0/1 - 24, switchport mode access, switchport access vlan 66, no vlan 66. You can see that it's VLANless with show vlan – Tim G Aug 11 '17 at 18:48
  • It was never something I setup in the first place, but inherited. We've actually now entirely removed the bridging from this setup (which is indeed on a router, but a router with 2 vlans connected). – djsmiley2k Jul 14 '18 at 17:16

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