Spanning Tree - D-Link DGS-1100-16 Reference Manual

D-Link DGS-1100 Series Switch User Manual

Spanning Tree

This Switch supports two versions of the Spanning Tree Protocol: 802.1D-1998 STP, 802.1D-2004
Rapid STP. 802.1D-1998 STP will be familiar to most networking professionals. However, since
802.1D-2004 RSTP has been recently introduced to DGS-1100 switches, a brief introduction to the
technology is provided below followed by a description of how to set up 802.1D-1998 STP, 802.1D-
2004 RSTP.
802.1D-2004 Rapid Spanning Tree
Rapid Spanning Tree Protocol (RSTP) as defined by the IEEE 802.1D-2004 specification and a
version compatible with the IEEE 802.1D-1998 STP. RSTP can operate with legacy equipment
implementing IEEE 802.1D-1998; however the advantages of using RSTP will be lost.
The IEEE 802.1D-2004 Rapid Spanning Tree Protocol (RSTP) evolved from the 802.1D-1998 STP
standard. RSTP was developed in order to overcome some limitations of STP that impede the
function of some recent switching innovations, in particular, certain Layer 3 functions that are
increasingly handled by Ethernet switches. The basic function and much of the terminology is the
same as STP. Most of the settings configured for STP are also used for RSTP. This section
introduces some new Spanning Tree concepts and illustrates the main differences between the two
protocols.
Edge Port
The edge port is a configurable designation used for a port that is directly connected to a segment
where a loop cannot be created. An example would be a port connected directly to a single work-
station. Ports that are designated as edge ports transition to a forwarding state immediately without
going through the listening and learning states. An edge port loses its status if it receives a BPDU
packet, immediately becoming a normal spanning tree port.
Note: If Spanning Tree protocol is used, loopback detection will not be available. If Loopback
Detection is enabled, the Spanning Tree protocol will not be available.
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