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

[Kevin.X.White at corusgroup.com]

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> 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 andlat
>                                          |       {
>
>
>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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>> IOS (tm) C3550 Software (C3550-I5Q3L2-M), Version 12.1(20)EA1a,
>
>> I'm currently trying to use CRB Bridging to bridge the routed
>
>CRB is not supported on the 3550.
>
>> I think I could use IRB and use the bvi address as the
>
>IRB also isn't supported on the 3550.
>
>See http://tinyurl.com/us62z
>
>-A

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1) overlooking the support issue and assuming (for a moment) the function
works
(macros do run to create bridge xxx route ip in the config),is what i'm
trying to do sensible?

2) If crb/irb do not work and fallback bridging is the only option on the
3550 how do I get the box to bridge IP when it knows how to route it and
therfore thinks that is what I want?

Kevin




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