I have a question about my 6500 CatOS, so those both 6500 Catos are used to connect all my Servers to them, those two 6500 they have redundant Link to our two core switch with layer 2 and 3 switches.
My question is we have backbonefast enabled on both those 6500 Switches running CatOS, so Cisco advise that we have to disable backbonefast before migrating to RPVST, what is the impact to disable this feature on my switches running currently PVST+?
Re: spanning-tree backbonefast + rapid-pvst+ on CatOS
Spanning Tree UplinkFast and BackboneFast features are PVST+ features. These are disabled when you enable rapid-PVST+ because those features are built within rapid-PVST+. Therefore, during the migration you can remove those commands. The configuration of the features such as PortFast, BPDUguard, BPDUfilter, root guard, and loopguard are applicable in rapid-PVST+ mode also. The usage of these features are the same as in PVST+ mode. If you have already enabled these features in the PVST+ mode, the features remain active after the migration to rapid-PVST+ mode.
If you want to migrate your network into RSTP,Better first migrate all the access layer switch to RSTP.then move to server farm switches .Finally make changes of backbone devices.
During the migration process, you can run the LAN in mixed mode, such as a few switches in PVST+ and a few switches in rapid-PVST+ mode. In mixed mode, you do not receive the complete advantages of rapid-PVST+. The overall convergence time is the same as the convergence time of PVST+ mode. In order to take full advantage of rapid-PVST+, all the switches in the spanning tree topology must run the rapid-PVST+.
But Cisco advise that we have to disable backbonefast before migratin:
Access2> (enable) set spantree backbonefast disable
Backbonefast disabled for all VLANs.
Access2> (enable) set spantree mode rapid-pvst+
PVST+ database cleaned up.
Spantree mode set to RAPID-PVST+.
Access2> (enable) clear spantree uplinkfast
This command will cause all portcosts, portvlancosts, and the
bridge priority on all vlans to be set to default.
Do you want to continue (y/n) [n]? y
VLANs 1-4094 bridge priority set to 32768.
The port cost of all bridge ports set to default value.
The portvlancost of all bridge ports set to default value.
uplinkfast all-protocols field set to off.
uplinkfast disabled for bridge.
is there an impact to remove backbonefast like removing uplinkfast from the CatOS?
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