I'm running a full redundat layer 2 network in our datacenter with MSTP but im facing some problems and i cant find the resolution for them, so if anyone can help me i will be very apretiated.
My network topology consists in two cisco 3750 in the core/distribution layer that are running MSTP and HSRP and all switchs in the network (mixed environment with Cisco and Procurve) connects to both Cisco 3750. I will attach a picture with the network topology.
Regarding to the spanning tree i have two instances, and for instance 1 router 1 is the root and for instance2 routrr 2 is th root.
The network is working good but the big problem is when i do the show spanningtree command it apears that every switchs are ignoring the spanning tree priorities and they assume they are the root of the two instances, so every switch in the network see's himself as the root of both instances.
I dont know what i'm doing wrong, so if anyone could help me it will be great.
PS: im posting the configuration of the two core switchs/routers and one edge switch, in this case the edge switch is a Cisco 3560.
Have you noticed that you have associated vlans to instance 1 and others to instance2 but also instance0 exists?
MST0 Spanning tree enabled protocol mstp Root ID Priority 0 Address 0022.5628.f300 This bridge is the root
is there any active vlan that is associated to instance 0?
An internal spanning tree (IST), which is the spanning tree that runs in an MST region.
Within each MST region, the MSTP maintains multiple spanning-tree instances. Instance 0 is a special instance for a region, known as the internal spanning tree (IST). All other MST instances are numbered from 1 to 4094.
The IST is the only spanning-tree instance that sends and receives BPDUs. All of the other spanning-tree instance information is contained in M-records, which are encapsulated within MSTP BPDUs. Because the MSTP BPDU carries information for all instances, the number of BPDUs that need to be processed to support multiple spanning-tree instances is significantly reduced.
So all the switches see each other (the access switch has a root port and an alternate port, it sees the agg switches), but the access switch is not in the same region as the aggs. That's why MST instance 1 and 2 don't communicate with the aggregation switches, because MST instances only work within a region.
I checked 20 times the region configuration and think it is identical (feel free to check an additional 20 times, because you never know:-) A "show mst configuration digest" may help compare.
I don't think you are hitting a pre-standard MST/standard MST interaction issue.
I recommend that you do a "clear span detected-protocol" on the access switch. If it does not help, there is I think a "debug spanning-tree mst boundary" (I'm not sure of this any more, I don't have access to a box and it's been litterally years I've not done this, shame on me!). Enable it and do the clear span detected again, that should tell you the reason why the port was put into boundary state.
sorry about the delay in answering this questions but i was out from the work in the last week.
Hi agree with Francois, instance 0 allways exist and in my opinion all vlans that are not mapped to any instance they are mapped to the instance 0.
Besides that a i think that the only instance that is running good is the instance 0 because in that instance all access switchs see the aggregation switchs as the root, in instance 1 and 2 they claim to be te root himselves, as you can see in this show spaning in ofne of the access switch.
MST0 Spanning tree enabled protocol mstp Root ID Priority 0 Address 0022.5628.f300 ------------------------------------------------> this is one of the aggreg switchs so it seems to be working good the instance 0 Cost 20000 Port 47 (GigabitEthernet0/47) Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32768 (priority 32768 sys-id-ext 0) Address 0024.98bb.ba80 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
MST1 Spanning tree enabled protocol mstp Root ID Priority 32769 Address 0024.98bb.ba80 -----------------------------------------------> it claims to be the root wrongly This bridge is the root Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
Bridge ID Priority 32769 (priority 32768 sys-id-ext 1) Address 0024.98bb.ba80 Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec
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