7 votes

Is Per Vlan Spanning Tree or RPVST an open standard or can it only be implemented by Cisco?

(R)PVST(+) is a proprietary standard defined by Cisco (or a set thereof). However, there are many other vendors and devices supporting it - you may need to check the specifications of your devices. ...
Zac67's user avatar
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7 votes
Accepted

H3C MST BPDU exchange failing

You have a fundamental problem with your configuration, which is that the configuration digests on core and access switches don't match. [Core-sw]dis stp region-configuration Oper Configuration ...
richardb's user avatar
  • 1,598
5 votes

H3C MST BPDU exchange failing

TL;DR: MST (IEEE 802.1s) exchanges BPDUs only on instance 0. Don't expect BPDUs on the other instances. VLAN-to-instance mapping must be identical on all MST switches (ref: richardb's answer) for ...
Marc 'netztier' Luethi's user avatar
5 votes
Accepted

RSTP / MSTP use cases and best practices

what would be the best practice to achieve separate tree topologies for each of the rings? Forget the rings and reconnect the switches in a tree topology with one or two center switches. This double-...
Zac67's user avatar
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3 votes

Spanning tree Priority values

128 is the default bridge priority. 2 is the port number and its default priority. STP always chooses the bridge or port with the lowest number = highest priority. Paths to bridges with higher ...
Zac67's user avatar
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3 votes

Spanning tree Priority values

128 is the default port priority (not cost) for xSTP interfaces, and .2 is the port number (eg: gi0/2). In short, all things being equal (and in their default state), if two switches have multiple ...
Benjamin Dale's user avatar
3 votes

MST region and CST virtual bridge priority

Set the root priority on the 0 instance: spanning-tree mst 0 root primary This will insure this bridge has the lowest priority of any other switch in the region. To configure a switch to become ...
Ron Trunk's user avatar
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3 votes
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MSTP - different VLAN mapping in different regions

Regarding MSTP, is it possible to have different VLAN mapping for different regions ? Example: Region 1: Instance 1: VLAN 10,20,30 Instance 2: VLAN 40,50,60 Region 2: Instance 1: VLAN 10,...
DRP's user avatar
  • 1,491
3 votes

MSTP - different VLAN mapping in different regions

You group VLAN IDs into instances which each form their own spanning tree with its own root bridge. Using different instances has the advantage that some instances/groups can use links that others won'...
Zac67's user avatar
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2 votes
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Edge detection on designated ports

The switch determines this during the listening phase. If no BPDUs are received during the listening phase, the switch knows it's an edge port.
Ron Trunk's user avatar
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2 votes

H3C MST BPDU exchange failing

It could be a spanning tree mode related problem. Among RSTP, MSTP and PVST, each mode has some STP compatibility, with a fallback mechanism to STP for ports that receive STP BPDUs. If a MSTP mode ...
Marco De Lellis's user avatar
2 votes

MST region and CST virtual bridge priority

CIST Root Bridges Election Process When a switch boots up, it declares itself as CIST Root and CIST Regional Root and announces this fact in outgoing BPDUs. The switch will adjust its decision upon ...
Datagram.Network's user avatar
2 votes

RSTP Separation

Since you're using routers, ie. L3 forwarding, there's no need for RSTP/MSTP. xSTP is used to resolve loops for L2 forwarding using bridges/switches. If you were using switches then you could consider ...
Zac67's user avatar
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2 votes
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how ieee 802.11s does channel switching? is it supported?

Think about how that will fail. Each device has a radio, and if a WAP is connected to other WAPs then they must share a channel. If they use a channel, and a new WAP peers with one of them on that ...
Ron Maupin's user avatar
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2 votes

Layer 2 redundant network and OSPF

If you have a fully switched ring MSTP/RSTP is required to avoid the otherwise resulting bridge loop. xSTP blocks one of the links, so it can't be used any more. The routers (L3) can only use what the ...
Zac67's user avatar
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2 votes

STP Priority field and 4 bits in multiples of 4096

Using bridge priority increments of 4,096 is a means to keep compatibility with classic STP where the priority was a 16-bit field. In RSTP/MSTP that field was reduced to 4 bits, so there are 12 lower, ...
Zac67's user avatar
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2 votes

STP Priority field and 4 bits in multiples of 4096

I think you are confusing a couple of things about the 802.1Q tag. The tag is 32 bits, the first 16 bits of which are the TPID (0x8100) field. The last 16 bits are the TCI that consists of three ...
Ron Maupin's user avatar
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2 votes

MST - multiple instance design in single region

There are some things to watch out for here: I would suggest to manually assign root priorities for the instances you're using, including the IST Be aware that any VLAN you create after making the ...
Lysis's user avatar
  • 196
2 votes
Accepted

MST - multiple instance design in single region

Yes, MSTIs need to be identical across a region in order to work. The configs are hashed and if the hashes don't match the instances won't work. When the MSTIs more or less cover the same area - as in ...
Zac67's user avatar
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1 vote

Spanning-tree MSTR port role

MST/RSTP is very old incompatible between switches , it will still work but they should be upgraded to newer IOS versions, You could use this command either under the interface spanning-tree mst pre-...
Jatinder Singh Brar's user avatar

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