D-Link DES-3350SR [39/184] Spanning tree

D-Link DES-3350SR Standalone Layer 3 Switch

Figure 7 - 10. Static Router Ports Settings window

The following fields are displayed:

Parameter Description

VID Displays the name of the VLAN ID the static

router port belongs to.

VLAN Name Displays the name of the VLAN the static

router port belongs to.

Member Ports Each port can be set individually as a router

port by clicking the port’s click-box entry.

Spanning Tree

The Spanning Tree Protocol (STP) operates on two levels: on the switch level, the settings are globally implemented. On the port

level, the settings are implemented on a user-defined Group of ports basis.

802.1w Rapid Spanning Tree

The Switch implements two versions of the Spanning Tree Protocol, the Rapid Spanning Tree Protocol (RSTP) as defined by the

IEEE 802.1w specification and a version compatible with the IEEE 802.1d STP. RSTP can operate with legacy equipment

implementing IEEE 802.1d, however the advantages of using RSTP will be lost.

The IEEE 802.1w Rapid Spanning Tree Protocol (RSTP) evolved from the 802.1d 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

function 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.

Port Transition States

An essential difference between the two protocols is in the way ports transition to a forwarding state and the in the way this

transition relates to the role of the port (forwarding or not forwarding) in the topology. RSTP combines the transition states

disabled, blocking, and listening used in 802.1d and creates a single state: discarding. In either case, ports do not forward packets;

in the STP port transition states disabled, blocking, or listening, or in the RSTP port state discarding, there is no functional

difference, the port is not active in the network topology. Table 5-1 below compares how the two protocols differ regarding the

port state transition.

802.1d STP 802.1w RSTP Forwarding Learning

Disabled Discarding No No

Blocking Discarding No No

Listening Discarding No No

Learning Learning No Yes

Forwarding Forwarding Yes Yes