Planet Networking & Communication SGS-5240 Series User Manual page 93

Table 12: Recommended STA Path Cost Range
Table 13: Default STA Path Costs
◆Admin Link Type – The link type attached to this interface.

Point-to-Point – A connection to exactly one other bridge.

Shared – A connection to two or more bridges.

Auto – The switch automatically determines if the interface is attached to a point-to-point link or to shared media.
(This is the default setting.)
 Root Guard – STA allows a bridge with a lower bridge identifier (or same identifier and lower MAC address) to take over
as the root bridge at any time. Root Guard can be used to ensure that the root bridge is not formed at a suboptimal
location. Root Guard should be enabled on any designated port connected to low-speed bridges which could potentially
overload a slower link by taking over as the root port and forming a new spanning tree topology. It could also be used to
form a border around part of the network where the root bridge is allowed.
(Default: Disabled)
 Admin Edge Port – Since end nodes cannot cause forwarding loops, they can pass directly through to the spanning tree
forwarding state. Specifying Edge Ports provides quicker convergence for devices such as workstations or servers,
retains the current forwarding database to reduce the amount of frame flooding required to rebuild address tables during
reconfiguration events, does not cause the spanning tree to initiate reconfiguration when the interface changes state, and
also overcomes other STA-related timeout problems. However, remember that Edge Port should only be enabled for ports
connected to an end node device. (Default: Auto)

Enabled – Manually configures a port as an Edge Port.

Disabled – Disables the Edge Port setting.

Auto – The port will be automatically configured as an edge port if the edge delay time expires without receiving
any RSTP or MSTP BPDUs. Note that edge delay time (802.1D-2004 17.20.4) equals the protocol migration time if
a port's link type is point-to-point (which is 3 seconds as defined in IEEE 802.3D-2004 17.20.4); otherwise it equals
the spanning tree's maximum age for configuration messages.
User's Manual of SGS-5240 Series Managed Switch
93