3Com Baseline 2816 User Manual

Also see for 3CBLUG16A - Baseline Switch 2816: User guide User guide

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3Com Baseline 2816 User Manual Manual pdf 46 page image

46 CHAPTER 4: C ONFIGURING THE S WITCHFigure 28 Spanning Tree Tab■ Forward — Spanning tree BPDU packets received ona port are forwarded to all other ports.■ Block and Discard — Spanning tree BPDUs receivedon a port are dropped. The Switch does not forwardBPDUs to other ports.The Switch does not participate as a bridge node in thespanning tree, it can only be configured to forward orblock spanning tree BPDUs. If the Switch is connectedto other bridging devices, such as switches, that arepart of the spanning tree network, set the Switch to"Forward." If the Switch is connected only toworkstations, it can be set to "Block and Discard."802.1p PrioritizationThe Switch has priority queuing enabled, which meansall packets that are received are examined to see if theyhave been priority encoded. If a packet has been priorityencoded, then the Switch will read the priority level anddetermine whether the packet should be directedthrough the normal or high priority channel. Thisfeature can be useful for example during excessive loadswhen one type of traffic may require priority overanother. The Switch is configured to comply with802.1p, VLAN tagged frames.Traffic prioritization ensures that high priority data isforwarded through the Switch without being delayed bylower priority data. It differentiates traffic into classesand prioritizes those classes automatically. Trafficprioritization uses the multiple traffic queues that arepresent in the hardware of the Switch to ensure thathigh priority traffic is forwarded on a different queuefrom lower priority traffic, and is given preference overthat traffic. This ensures that time-sensitive traffic getsthe highest level of service.The 802.1D standard specifies eight distinct levels ofpriority (0 to 7), each of which relates to a particulartype of traffic. The priority levels and their traffic typesare shown in the following table.Priority Level Traffic Type0 Best Effort1 Background