Newbie Question about bridge-group and bvi

bt snipped-for-privacy@gmx.de schrieb:

You can enable bridging on most( or all?? ) Routers.

enable bridge irb | bridge crb

interface E0 bridge group 1 exit interface E1 bridge group 1 exit interface BVI 1 exit

Now all frames are forwarded to other interfaces in the bridge group as the MAC addresses are learned. This is protocol independent (works at layer 2).

The BVI is the logical interface that joins the bridge group.

Greetings...

On Routers, an Ethernet port can operate at Layer 2 or Layer 3, it all depends on how you configure it.

If you have a need to apply a MAC ACL to an Ethernet interface, you can only do this when they are configured to operate in Layer 2 mode. In Layer 2 mode you cannot apply an IP address to that Interface, and this is where the BVI comes in.

A BVI (Bridged Virtual Interface) provides a "layer 3 hook" into all the Ethernet ports that are configured as part of a BRIDGE group, and the IP address goes on the BVI interface.

EG One solution I have used is to apply a MAC ACL to a Router Ethernet interface and Bridge that to a BVI so I can Route off that to a Serial Link. bridging directly to the Serial link causes dramatic performance impacts to be applied (the Ethernet is slowed to WAN speeds), so the solution was to implement a BVI, Bridge the Ethernet to the BVI , apply the MAC ACL to the Ethernet, IP address to the BVI and and Route off the BVI.

The only down side to this is that the Bridging does mean the segment operates in Half-Duplex mode, however as the BVI interface operates at processor speed performance is still very good.

Cheers........................pk.