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Ethernet Switches & Routers

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Posts: 1
Registered: ‎05-27-2012

MRP II L2-Loop problem on FGS-624POE


we have a strange problem with MRP2.

The following switches are in a Metro ring. It is a WAN with fiber and microwave links. Two overlapping  rings are planned to optimize the usage of resources. The six used switches  are FWS and FGS. At the moment only ring 2 is configured.  Firmware on all devices is 07.2.02aT7e1.

---> fgs1 < microwave 200M> fgs2 <cable 300M QinQ> fws3 <microwave 360M> fws4 <mcirowave 360M> fgs5 <Gbit Copper> fws6  <----- Microwave 200M

|                                                                                                                                                                                                                           |


fws4 and fgs5 are at one pop location.

fgs5 (with e0/1/1 and e0/1/24 ring-interfaces) is mrp-master als other switches are ring members. If we close the ring at fgs2 (enable port) the fgs5 is creating a L2-Loop!  In the moment of closing the ring  we see in the log   that fgs5 says that there is an overload at all connected POE-ports. It looks to us if the system will come unstable. What has POE to do with some problems with MRP? We can also see that fgs5 is seeing its own mac as a "duplicate mac" through the ring. The loop will still exist and fgs5 has both ring interfaces in forwarding state. We checked the ring interfaces and we checked the topology-group on all switches.

!!!  If we put the fws6 instead of fgs5 as master the ring behaves (nearly) as wanted. !!! The FWS is blocking one port as it should if it is in the master role. The FGS at the same POP will not block the port if it is master...

Here is some info of the fgs5 (called sw1.24730) without the mrp-master config

telnet@sw1.24730(config-vlan-2-mrp-2)#sh fdp neig

Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge

                  S - Switch, H - Host, I - IGMP, r - Repeater

(*) indicates a CDP device

   Device ID      Local Interface  Holdtm Capability Platform    Port ID

   -------------- ---------------- ------ ---------- ----------- -------------

   sw1.24100      ethernet0/1/1    143    Switch     FWS624POE S ethernet0/1/1

   sw2.24730      ethernet0/1/24   139    Switch     FWS624POE S ethernet0/1/1

telnet@sw1.24730(config-vlan-2-mrp-2)#sh metro

Metro Ring 2 - ring_a


Ring       State      Ring       Master     Topo       Hello      Prefwing

id                    role       vlan       group      time(ms)   time(ms)

2          enabled    member     2          2          100        300

Ring interfaces Interface role Forwarding state Active interface interface type

ethernet 0/1/24 primary        forwarding       ethernet 0/1/24  regular

ethernet 0/1/1  secondary      forwarding       ethernet 0/1/1   regular

RHPs sent            RHPs rcvd            TC RBPDUs rcvd       State changes

0                    0                    0                    0

In the LAB I did a verification setup with two FGS648P-POE with same config. No problems!

Is it a bug? Any idear?


May 27 05:16:02:I:MRP: Ring 2 Port 0/1/1 vlan 2, changing to forwarding

May 27 05:16:02:I:MRP: Ring 2 Port 0/1/24 vlan 2, changing to forwarding

May 27 05:16:02:I:MRP: Ring 2 Port 0/1/24 vlan 2, changing to preforwarding

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