Rapid STP question

damien2008

STP defines the Max Age timer as 10 times the Hello timer or 20 seconds.
RSTP shortens this timer, defining Max Age as 3 times the Hello timer

Hello timer = 2 secs
RSTP Max Age should be 6 secs

When changed from pvst (default) to rapid-pvst why hasn't the Max Age timer changed ?

d-niet123

It is the default time set on the switch.

damien2008

d-niet123 wrote: »

It is the default time set on the switch.

explain ?

nman99

damien2008 wrote: »

explain ?

The timers that are defaulted for the different versions of spanning tree are just the defaults, you can set the timers for regular stp to be a timer of 2 seconds and max age of 6 seconds if you wanted to.

nman99

[h=3]Protocol Timers[/h] Table 8-2 describes the protocol timers that affect the Rapid PVST+ performance.


Table 8-2 Rapid PVST+ Protocol Timers

[TH] Variable
[/TH]
[TH] Description
[/TH]


Hello timer

Determines how often each switch broadcasts BPDUs to other switches. The default is 2 seconds, and the range is from 1 to 10.



Forward delay timer

Determines how long each of the listening and learning states last before the port begins forwarding. This timer is generally not used by the protocol but is used as a backup. The default is 15 seconds, and the range is from 4 to 30 seconds.



Maximum age timer

Determines the amount of time protocol information received on an port is stored by the switch. This timer is generally not used by the protocol, but it is used when interoperating with 802.1D spanning tree. The default is 20 seconds; the range is from 6 to 40 seconds.

fredrikjj

It's 20 because Max Age isn't used in RSTP for PDU aging on a port. Instead, 3x hello time is used when a hold time is needed.