[c-nsp] Limits of STP/RSTP/REP?

[Сергій Халавчук]

> Definitely not more than 20 in a ring.  As far as I know, IOS limits
> the value of max-hops to 20.  This means you can't have a BPDU
> traverse more than 20 hops without being thrown away.  If one pair of
> switches in the ring experienced a total cut, your network would have
> a diameter of 20, end to end.

this is STP limitation: MaxAge is by default 20 hops.
for IOS, you can change this value:

Switch(config)#spanning-tree vlan 1 max-age ?
  <6-40>  maximum number of seconds the information in a BPDU is valid
or for MST
Switch(config)#spanning-tree mst max-age ?
  <6-40>  maximum number of seconds the information in a BPDU is valid

value 40 is maximum bpdu hopcount for 3560 switch, for other models
there can be other upper limit.

--
wbr
sergey khalavchuk