Foundry Networks Switch and Router User Manual

Foundry Switch and Router Installation and Configuration Guide
12 - 2 December 2000
STP Parameters and Defaults
Table 12.1 lists the default STP bridge parameters. The bridge parameters affect the entire VLAN (or the entire
device, if the only port-based VLAN is the default one, VLAN 1).
Table 12.2 lists the default STP port parameters. The port parameters affect individual ports and are separately
configurable on each port.
Notice that the path costs favor 100 Mbps and faster Ethernet ports over Packet over SONET (POS) ports. STP
applies to POS ports only when they are configured for Layer 2 switching. The POS paths are remote (WAN)
Table 12.1: Default STP Bridge Parameters
Parameter Description Default and Valid Values
Forward Delay The period of time a bridge will wait (the listen and learn
period) before beginning to forward data packets.
15 seconds
Possible values: 4 – 30
seconds
Maximum Age The interval a bridge will wait for a hello packet from the
root bridge before initiating a topology change.
20 seconds
Possible values: 6 – 40
seconds
Hello Time The interval of time between each configuration BPDU
sent by the root bridge.
2 seconds
Possible values: 1 – 10
seconds
Priority A parameter used to identify the root bridge in a
spanning tree (instance of STP). The bridge with the
lowest value has the highest priority and is the root.
A higher numerical value means a lower priority; thus,
the highest priority is 0.
32768
Possible values: 0 – 65535
Table 12.2: Default STP Port Parameters
Parameter Description Default and Valid Values
Priority The preference that STP gives this port relative to other
ports for forwarding traffic out of the spanning tree.
A higher numerical value means a lower priority; thus,
the highest priority is 0.
128
Possible values: 0 – 255
Path Cost The cost of using the port to reach the root bridge. When
selecting among multiple links to the root bridge, STP
chooses the link with the lowest path cost and blocks the
other paths. Each port type has its own default STP path
cost.
10 Mbps – 100
100 Mbps – 19
Gigabit – 4
OC-3c – 200
OC-12c – 80
OC-48c – 20
Possible values are 0 –
65535

Foundry Networks Switch and Router Specifications

General

Brand	Foundry Networks
Model	Switch and Router
Category	Switch
Language	English