D-Link DGS-1250 User Manual - Page 98

DGS-1250 Series Gigabit Ethernet Smart Managed Switch Web UI Reference Guide Voice VLAN LLDP-MED Device This window is used to view the voice VLAN LLDP-MED device table. To view the following window, click L2 Features > VLAN > Voice VLAN > Voice VLAN LLDP-MED Device, as shown below: Figure 5-34 Voice VLAN LLDP-MED Device Window STP This Switch supports three versions of the Spanning Tree Protocol (STP): IEEE 802.1D-1998 STP, IEEE 802.1D-2004 Rapid STP, and IEEE 802.1Q-2005 MSTP. The IEEE 802.1D-1998 STP standard will be familiar to most networking professionals. However, as IEEE 802.1D-2004 RSTP and IEEE 802.1Q-2005 MSTP have been recently introduced to D-Link managed Ethernet Switches, a brief introduction to the technology is provided below followed by a description of how to set up IEEE 802.1D-1998 STP, IEEE 802.1D-2004 RSTP, and IEEE 802.1Q-2005 MSTP. 802.1Q-2005 MSTP The Multiple Spanning Tree Protocol (MSTP) is a standard defined by the IEEE community that allows multiple VLANs to be mapped to a single spanning tree instance, which will provide multiple pathways across the network. Therefore, these MSTP configurations will balance the traffic load, preventing wide scale disruptions when a single spanning tree instance fails. This will allow for faster convergences of new topologies for the failed instance. Frames designated for these VLANs will be processed quickly and completely throughout interconnected bridges utilizing any of the three spanning tree protocols (STP, RSTP, or MSTP). A Multiple Spanning Tree Instance (MSTI) ID will classify these instances. MSTP will connect multiple spanning trees with a Common and Internal Spanning Tree (CIST). The CIST will automatically determine each MSTP region, its maximum possible extent and will appear as one virtual bridge that runs a single spanning tree instance. Frames assigned to different VLANs will follow different data routes within administratively established regions on the network, continuing to allow simple and full processing of frames, regardless of administrative errors in defining VLANs and their respective spanning trees. Each Switch utilizing the MSTP on a network will share a single MSTP configuration that will have the following three attributes: • A configuration name defined by an alphanumeric string of up to 32 characters (defined in the MST Configuration Identification window in the Configuration Name field). • A configuration revision number (named here as a Revision Level and found in the MST Configuration Identification window) • A 4094-element table (defined here as a VID List in the MST Configuration Identification window), which will associate each of the possible 4094 VLANs supported by the Switch for a given instance. To utilize the MSTP function on the Switch, three steps need to be taken: • The Switch must be set to the MSTP setting (found in the STP Global Settings window in the STP Mode field). • The correct spanning tree priority for the MSTP instance must be entered (defined here as a Priority in the MSTP Port Information window when configuring MSTI ID settings). • VLANs that will be shared must be added to the MSTP Instance ID (defined here as a VID List in the MST Configuration Identification window when configuring an MSTI ID settings). 89