Terms and Definitions
15-36 Configuring Spanning Tree
LoopProtect Lock status for port lag.0.2, SID 56_ is UNLOCKED
Enterasys->show spantree lpcapablepartner port lag.0.2
Link partner of port lag.0.2_is LoopProtect-capable.
Enterasys->show spantree nonforwardingreason port lag.0.2
Port lag.0.2 has been placed in listening or blocking state on SID 0 by the
LoopProtect feature.
Terms and Definitions
Table 15-11 lists terms and definitions used in Spanning Tree configuration.
Table 15-11 Spanning Tree Terms and Definitions
Term Definition
Alternate port Acts as an alternate path to the root bridge than that provided by the root port.
Backup port Acts as an backup for the path provided by a designated port toward the leaves of
the Spanning Tree. Backup ports can exist only where two ports are connected
together in a loopback mode or bridge with two or more connections to a shared LAN
segment.
BID Bridge identification, which is derived from the bridge’s MAC address and bridge
priority. The bridge with the lowest BID becomes the root bridge.
BPDU Bridge Protocol Data Unit messages. Used by STP to exchange information,
including designating a bridge for each switched LAN segment, and one root bridge
for the Spanning Tree.
Bridge Switching device.
Bridge priority Assigns the bridge’s relative priority compared to other bridges.
CIST Common and Internal Spanning Tree created by MSTP to represent the connectivity
of the entire network. This is equivalent to the single Spanning Tree used for STP
and RSTP. Communications between MST regions occurs using the CIST.
CST A Spanning Tree defined in the IEEE 802.1q standard that assumes one Spanning
Tree instance for the entire bridged network, regardless of the number of VLANs.
Designated port A forwarding port within an active topology elected for every switched LAN segment.
Edge port Port on the edge of a bridged LAN.
FID Filter Identifier. Each VLAN is associated to a FID. VLANs are mapped to SIDs using
their FID association.
Forward delay Time interval (in seconds) the bridge spends in listening or learning mode before it
begins forwarding BPDUs.
Hello time Time interval (in seconds) at which the bridge sends BPDUs.
ISL Inter-Switch Link.
IST A Spanning Tree instance that extends the CST inside the MST region and
represents the entire MST region as a single CST virtual bridge to the outside world.
Loop Protect Prevents or short circuits loop formation in a network with redundant paths by
requiring ports to receive type 2 BPDUs (RSTP/MSTP) on point-to-point inter-switch
links (ISLs) before their states are allowed to become forwarding.
Master port The MSTI port whose connecting CIST port is root port for an entire MST region.
To Next Page
Loading...
Need help?
General