Could 2 VLANs be merged into one broadcast domain

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Dec 17th, 2008
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Is there a way to expand Ethernet broadcast domain across several VLANs. So far the only apparent solution for this is an x-over patch-cord stuck into a switch's ports. Is there a more elegant way to do this? I use c3750 switch.

Thanks.


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Martin Parry Wed, 12/17/2008 - 06:39
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Hi


You can bridge the two VLANs together.


bridge 10 protocol vlan-bridge

!

vlan 2

!

int vlan 2

bridge-group 10

!

vlan 3

!

int vlan 3

bridge-group 10

!


Hope this helps


Martin

v.shustov Thu, 12/18/2008 - 11:31
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bridge 10 protocol vlan-bridge

!

vlan 2

!

int vlan 2

bridge-group 10

!

vlan 3

!

int vlan 3

bridge-group 10

!


This snippet doesn't seem to work for me. At least I couldn't ping host 192.168.0.1 on vlan 2 from 192.168.0.2 on vlan 3.

As far as I understand bridging the bridge has to forward frames from one vlan to another and build a summarized arp table. So far I haven't seen a host from vlan 3.

Any ideas?

ougryphon Mon, 12/22/2008 - 13:22
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I have a similar setup but I want to do the opposite. I have two VLANs on the same subnet but I want to block certain broadcast traffic from one vlan to the other. I currently do this with a patch cable and access lists on the physical ports.

If I bridge the ports using the above commands, can I place an access list on the vlan interface with the same effect? Also, how does briding work if you are running vtp? Is the bridge local to every switch in the domain, only on the VTP domain master, or only on the switches where it is configured?

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