Spanning tree Priority values
show spanning-tree interface gigabitethernet 0/2
Switch default
Instance Role State Cost Prio type
-------- ---- ----- ---- ---- ----
MST00 Designated Forwarding 20000 128.2 P2P
MST01 Designated Forwarding 20000 128.2 P2P
MST02 Designated Forwarding 20000 128.2 P2P
How the value 128.2 is calculated?
switching spanning-tree ieee-802.1s
edited 15 hours ago
Cown
6,26131030
asked 15 hours ago
kamakshikamakshi
111
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show spanning-tree interface gigabitethernet 0/2
Switch default
Instance Role State Cost Prio type
-------- ---- ----- ---- ---- ----
MST00 Designated Forwarding 20000 128.2 P2P
MST01 Designated Forwarding 20000 128.2 P2P
MST02 Designated Forwarding 20000 128.2 P2P
How the value 128.2 is calculated?
switching spanning-tree ieee-802.1s
edited 15 hours ago
Cown
6,26131030
asked 15 hours ago
kamakshikamakshi
111
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
show spanning-tree interface gigabitethernet 0/2
Switch default
Instance Role State Cost Prio type
-------- ---- ----- ---- ---- ----
MST00 Designated Forwarding 20000 128.2 P2P
MST01 Designated Forwarding 20000 128.2 P2P
MST02 Designated Forwarding 20000 128.2 P2P
How the value 128.2 is calculated?
switching spanning-tree ieee-802.1s
edited 15 hours ago
Cown
6,26131030
asked 15 hours ago
kamakshikamakshi
111
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
show spanning-tree interface gigabitethernet 0/2
Switch default
Instance Role State Cost Prio type
-------- ---- ----- ---- ---- ----
MST00 Designated Forwarding 20000 128.2 P2P
MST01 Designated Forwarding 20000 128.2 P2P
MST02 Designated Forwarding 20000 128.2 P2P
How the value 128.2 is calculated?
switching spanning-tree ieee-802.1s
switching spanning-tree ieee-802.1s
edited 15 hours ago
Cown
6,26131030
asked 15 hours ago
kamakshikamakshi
111
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 15 hours ago
Cown
6,26131030
asked 15 hours ago
kamakshikamakshi
111
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited 15 hours ago
Cown
6,26131030
edited 15 hours ago
Cown
6,26131030
edited 15 hours ago
Cown
6,26131030
6,26131030
asked 15 hours ago
kamakshikamakshi
111
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 15 hours ago
kamakshikamakshi
111
asked 15 hours ago
kamakshikamakshi
111
111
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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kamakshi is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
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 links joining them together, the lowest physical port number will generate the lowest port priority, and hence become the preferred root port.
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
Thanks for Info.
– kamakshi
15 hours ago
add a comment |
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 numbers are blocked. Put another way, the bridge with the overall lowest priority number is elected as root bridge. All ports leading to the root bridge are compared by their cost (lowest cost is chosen) and when there's a tie between bridges, the path to the bridge with the lowest priority number is chosen.
When there's a tie between ports (=two ports connecting to the same bridge) the ports' priorities are used.
Note that in both bridge and port priorities, the configured priority is prepended to the bridges MAC address or the port number. So, even with identical configured priorities there can never be a tie between bridges or ports as each hardware number is unique.
answered 15 hours ago
Zac67Zac67
29.7k21859
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
add a comment |
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2 Answers
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oldest
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2 Answers
2
active
oldest
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votes
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 links joining them together, the lowest physical port number will generate the lowest port priority, and hence become the preferred root port.
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
Thanks for Info.
– kamakshi
15 hours ago
add a comment |
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 links joining them together, the lowest physical port number will generate the lowest port priority, and hence become the preferred root port.
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
Thanks for Info.
– kamakshi
15 hours ago
add a comment |
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 links joining them together, the lowest physical port number will generate the lowest port priority, and hence become the preferred root port.
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
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 links joining them together, the lowest physical port number will generate the lowest port priority, and hence become the preferred root port.
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
answered 15 hours ago
Benjamin DaleBenjamin Dale
6,9641036
6,9641036
Thanks for Info.
– kamakshi
15 hours ago
add a comment |
Thanks for Info.
– kamakshi
15 hours ago
Thanks for Info.
– kamakshi
15 hours ago
Thanks for Info.
– kamakshi
15 hours ago
add a comment |
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 numbers are blocked. Put another way, the bridge with the overall lowest priority number is elected as root bridge. All ports leading to the root bridge are compared by their cost (lowest cost is chosen) and when there's a tie between bridges, the path to the bridge with the lowest priority number is chosen.
When there's a tie between ports (=two ports connecting to the same bridge) the ports' priorities are used.
Note that in both bridge and port priorities, the configured priority is prepended to the bridges MAC address or the port number. So, even with identical configured priorities there can never be a tie between bridges or ports as each hardware number is unique.
answered 15 hours ago
Zac67Zac67
29.7k21859
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
add a comment |
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 numbers are blocked. Put another way, the bridge with the overall lowest priority number is elected as root bridge. All ports leading to the root bridge are compared by their cost (lowest cost is chosen) and when there's a tie between bridges, the path to the bridge with the lowest priority number is chosen.
When there's a tie between ports (=two ports connecting to the same bridge) the ports' priorities are used.
Note that in both bridge and port priorities, the configured priority is prepended to the bridges MAC address or the port number. So, even with identical configured priorities there can never be a tie between bridges or ports as each hardware number is unique.
answered 15 hours ago
Zac67Zac67
29.7k21859
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
add a comment |
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 numbers are blocked. Put another way, the bridge with the overall lowest priority number is elected as root bridge. All ports leading to the root bridge are compared by their cost (lowest cost is chosen) and when there's a tie between bridges, the path to the bridge with the lowest priority number is chosen.
When there's a tie between ports (=two ports connecting to the same bridge) the ports' priorities are used.
Note that in both bridge and port priorities, the configured priority is prepended to the bridges MAC address or the port number. So, even with identical configured priorities there can never be a tie between bridges or ports as each hardware number is unique.
answered 15 hours ago
Zac67Zac67
29.7k21859
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 numbers are blocked. Put another way, the bridge with the overall lowest priority number is elected as root bridge. All ports leading to the root bridge are compared by their cost (lowest cost is chosen) and when there's a tie between bridges, the path to the bridge with the lowest priority number is chosen.
When there's a tie between ports (=two ports connecting to the same bridge) the ports' priorities are used.
Note that in both bridge and port priorities, the configured priority is prepended to the bridges MAC address or the port number. So, even with identical configured priorities there can never be a tie between bridges or ports as each hardware number is unique.
answered 15 hours ago
Zac67Zac67
29.7k21859
answered 15 hours ago
Zac67Zac67
29.7k21859
answered 15 hours ago
Zac67Zac67
29.7k21859
answered 15 hours ago
Zac67Zac67
29.7k21859
29.7k21859
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
add a comment |
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
Is that 128 the default bridge priority or the default port priority? I thought bridge priorities are something like 32768 usually (by default) and go in steps of 4096 or something like that?
– ilkkachu
11 hours ago
add a comment |
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