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About nadalfan1984
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Feb 28 2019
8:53 PM
What's really interesting is that I'm seeing Dist 2 switch ports 26,27, & 28 in the topology as designated ports and can see them forwarding BPDUs in the wireshark packet captures but when I run a packet capture on all of the LAN interfaces on the MX the only STP traffic is from the root switch (Agg1). I've verified that Dist 2 ports 26,27 & 28 are all in the forwarding state and forwarding traffic including BPDUs but it doesn't appear the MX is receiving them or forwarding them even though they are directly connected. My thought process was that if a BPDU was sent out on port 26 and received by the MX250 it would forward the frame out all ports. When Dist 2 ports 27 and 28 received that BPDU from the MX250 they would then go to the backup port state since they had now received Dist 2's BPDU on those ports. Thoughts? Thanks for all the help!!! This is truly helping my understand of RSTP and the MX!
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Feb 28 2019
10:06 AM
@jdsilva wrote: One note about that example... It's an old diagram I had lying around and shows the MX's directly connected to each other (heartbeat cable). That link is no longer considered best practice so it should not actually ever be used. Thanks for the explanation!!! So just to be clear, only the root BPDUs are forwarded from the MX250? For example, in my topology only Agg1 (root switch) frames would be forwarded out from the MX250s not BPDUs from the Dist 2 switch? I'm guessing this is because the MX250 received a superior BPDU from the root switch? Which is exactly how a switch would behave. Thanks for all the help!!
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Feb 28 2019
8:41 AM
I'm having a hard time understanding the Meraki MX250 BPDU forwarding process. Since Meraki runs RSTP, to my knowledge, any physical loop will be blocked regardless of VLAN configuration (unlike PVST in Cisco). So does the MX250 just forward all BPDUs to all connected LAN interfaces? My assumption is as follows. Note: All ports are forwarding unless there is an X specified for the link in the diagram - Agg1 switch is the root switch in the topology so all connected interfaces go designated/forwarding - Agg1 BPDU is sent out on port 22 to Agg2 & port 24 to MX250-1 - MX250-1 forwards Agg1 BPDU out of all LAN ports - Agg2 now receives Agg1 BPDU on port 24 from MX250-1 and then blocks the connection since it already has a better path to Agg1 (root). - I don't understand how all 3 connections from Dist2 to MX250-1 are in the forwarding state? If all BPDUs are being blindly forwarded by the MX250-1 (similar to a hub) then two of the connections would end up going to backup port state. - All switches are Meraki and RSTP is in use throughout the network Anyways, I'm very confused! Any help would be much appreciated!
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Feb 26 2019
1:56 PM
1 Kudo
Awesome suggestions! Will implement this very soon and am confident it will work well!!
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Feb 26 2019
1:50 PM
1 Kudo
Thanks for your help! I haven't had a chance to implement this yet but I feel confident it will work. I didn't know about the flexible stacking feature and actually I was told by several Meraki techs that stacking wasn't available on the 420 switches but I can see that it is with flexible stacking! Thank you very much for the help!
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Feb 24 2019
4:45 PM
I agree it's a strange situation but building A is the rstp root for the entire network. I believe it may have something to do with the fact that the links between building a and b and building a and c are trunk links that are allowing a few vlans across which is extending the layer 2 broadcast domain. I'm wondering if setting the links to access ports would fix this and allow the separation of rstp instances?
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Feb 24 2019
2:44 PM
Can you illustrate or explain? We already have static routes between each building that do the routing and since Meraki doesn't allow for routed ports how can we do purely L3?
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Feb 24 2019
1:57 PM
Hello everyone, First time poster. Anyways, I'm having some RSTP issues. As you can see below in my diagram, we have 3 buildings that have L3 switches (Buildings A, B & C) which control our routing. The 10.10.1.0/30 & 10.10.2.0/30 networks are intermediary networks between the layer 3 switches at each location via fiber. All traffic leaves thru building A. Buildings A, B & C each have two L3 aggregation switches with redundant fiber links between them to both switches. One major issue I'm having is that the RSTP root for all the interconnected buildings is Aggregation Sw1 at building A. This is causing issues since anytime we have to reboot Aggregation 1 at building A the entire network starts reconverging. Also, when we connect the redundant fiber links between building A and building B (or building C) STP blocks the crosslink between the two aggregation switches at building B instead of the redundant fiber. All L3 switches are MS420s and all switch links via fiber are currently set to trunk. I'm thinking the best solution is to have a seperate RSTP instances running at Building A, B & C. I'm just not sure how to separate the instances since Meraki can't do routed ports. Any help would be much appreciated! Thanks guys!!
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