[c-nsp] CRB Bridging subnets with the same IP while routing

[Kevin.X.White at corusgroup.com]

 IOS (tm) C3550 Software (C3550-I5Q3L2-M), Version 12.1(20)EA1a, RELEASE
SOFTWARE (fc1)

      Legacy                               New network
      Network                            example 3550

                                          |             {--------10.56.1.x
                                          | vlana {--------
                                          |              {
                                          |
                                          |
                                          |             {--------10.56.2.x
    1.99.x.x--Routed---   | vlanb {-------
                          Int            |            {
                                          |
                                          |            {-------- legacy
1.99.x.x
                                          | vlanc {-------- and decnet and
lat
                                          |            {


I'm currently trying to use CRB Bridging to bridge the routed uplink to my
legacy network
to (say) vlanC to get groups of hosts onto the new hardware temporarily so
that I can take the old
network kit out and not wait for 1500 pcs to be re addressed over the next
6 mths simply moved from
vlan C into the correct new vlan.

If vlan C and the legacy Vlan used two different subnets and I simply
needed to bridge non routables,
I think I could use IRB and use the bvi address as the gateway for vlan C
and redistribute the BVI along with
everything else via OSPF
However as I want to keep the IPs the same on what is effectively either
side of the router can I route from vlan A & B
to the routed legacy interface while bridging from vlanC to the legacy Vlan

If so this would prevent me having to bridge the whole thing and recreate
the flat network I'm trying to move away from.

This is now at least the third attempt after giving up on tunneling!

Rgds

Kevin White
Process Control Network Manager
Corus Port Talbot Works

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