1. Home
  2. Cisco Systems
  3. Why Bridge configuration filters RSTP (BPDU packets) from LAN

Why Bridge configuration filters RSTP (BPDU packets) from LAN

Hi,

Any ideas why Rapid Spanning Tree protocol (802.1w) does not go through my cisco 827 router with bridging configuration? Every other traffic flows ok from LAN to WAN.

My configuration is:

formatting link
formatting link
With above configurations, Rapid Spanning Tree enabled switch that is connected to Cisco827 routers LAN, cannot sent its BPDU packets to the WAN. These RSTP packets seems to be blocked somehow by router? but why.. because every other traffic is passed.

All i need, is pure bridge (Layer2) to the WAN.

[switch] ---eth[Cisco827 ]atm--->ATMnet

Is there some other configuratios to solve this, or is there some commands to be added this particular configuration?

thanks,

-T

snipped-for-privacy@hotmail.com

Reply to
Tee Mat
Loading thread data ...

the router only understand 802.1D BPDU and drops RSPT BPDUs.

The ether switch should sense the 802.1D BPDU's from the router and change into compatibility mode

see

formatting link

Reply to
Merv

So, there is no way to say cisco827/837 routers "Take no action" to these RSTP packets from LAN to WAN and from WAN to LAN? I fullfil my scenario if there is still some solution hanging on the air.. other than using old STP

802.1D. Thanks Merv for the first answer.

With RFC1483 bridging configuration on both cisco827_1 and cisco827_2, switch_2 can now see all the traffic from switch_1 and otherwise, EXCEPT Rapid Spanning Tree Protocol traffic. It is blocked by routers.

Routers should not take any actions to these RSTP packets change between switch_1 and switch_2. It is necessery that bridge from endpoint 1 to endpoint 2 is pure L2 bridge without filtering/dropping anything. There is no need routers to change Spanning Tree information to anywhere. Only switch_1 and switch_2 need to change each others spanning tree information through the bridge.

LAN WAN

endpoint 1

-[switch_1]---[cisco827_1]---ATM | |

-[switch_2]---[cisco827_2]---ATM endpoint 2

If Cisco827/837 is not capable of doing this, any ideas which routers can handle this (allow RSTP flow between endpoints) ?

Thanks,

-T

snipped-for-privacy@hotmail.com

formatting link

Reply to
Tee Mat

Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.