Manuals / 3Com / Computer Equipment / Switch

3Com 3 manual Ports operating at 1000 Mbps support full duplex mode only

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20CHAPTER 2: OPTIMIZING BANDWIDTH

If the devices at either end of a link do not support auto-negotiation, both ends must be manually set to full duplex or half duplex accordingly.

Ports operating at 1000 Mbps support full duplex mode only.

Flow Control All Switch ports support flow control, which is a mechanism that minimizes packet loss during periods of congestion on the network. Packet loss is caused by one or more devices sending traffic to an already overloaded port on the Switch. Flow control minimizes packet loss by inhibiting the transmitting port from generating more packets until the period of congestion ends.

Flow control is supported on ports operating in half duplex mode, and is implemented using the IEEE 802.3x standard on ports operating in full duplex mode.

Auto-negotiationAuto-negotiation allows ports to auto-negotiate port speed, duplex-mode (only at 10 Mbps and 100 Mbps) and flow control. When auto-negotiation is enabled (default), a port “advertises” its maximum capabilities — these capabilities are by default the parameters that provide the highest performance supported by the port.

You can disable auto-negotiation on all fixed ports on the Switch, or on a per port basis. You can also modify the capabilities that a port “advertises” on a per port basis, dependent on the type of port.

For auto-negotiation to work, ports at both ends of the link must be set to auto-negotiate.

Ports operating at 1000 Mbps support full duplex mode only.

If auto-negotiation is disabled, the ports will no longer operate in auto-MDIX mode. Therefore, if you wish to disable auto-negotiation you must ensure you have the correct type of cable, that is cross-over or straight-through, for the type of device you are connecting to. For more information on suitable cable types, please refer to the Getting Started Guide that accompanies your Switch.

Smart Auto-sensingSmart auto-sensing allows auto-negotiating multi-speed ports, such as 10/100 Mbps or 10/100/1000 Mbps, to monitor and detect a high error rate on a link, or a problem in the “physical” interconnection to another

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3Com 3 manual Ports operating at 1000 Mbps support full duplex mode only

Contents

SuperStack 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Contents Using Multicast Filtering Status Monitoring and Statistics IP Addressing About this Guide Conventions List conventions that are used throughout this guide Related DocumentationComments Pddtechpubscomments@3com.com Product Registration Switch Features Page What is Switch FeaturesManagement Software? Switch Features Overview Ports operating at 1000 Mbps only support full duplex mode For more information about multicast filtering, see UsingDuplex Flow Control For more information about STP and RSTP, see Using Resilience Features Event Notification Quality of ServiceFor more information about Quality of Service, see Using For more information about VLANs, see Setting Up Virtual Port Features Ports operating at 1000 Mbps support full duplex mode only Port Features Switch units connected using an aggregated link Aggregated Links Traffic Distribution and Link Failure on Aggregated Links 2 Gbps aggregated link between two Switch units Optimizing Bandwidth Using Multicast Filtering Relevant multicast group Using Multicast Filtering Query Mode Query modeSnooping Mode Igmp v2 protocol That support IPIgmp multicast filtering works as follows Enabling Igmp Multicast Learning Igmp Multicast Filtering Using Multicast Filtering Network Spanning TreeProtocol STP Ieee 802.1w standard What is STP? Traffic flowing through Bridge B Port Speed Link Type Path Cost 802.1D-1998 802.1w Using Resilience Features Port costs in a network Configuration 3 Redundancy for Cabling Error Configuration 1 Redundancy for Backbone LinkConfiguration 2 Redundancy through Meshed Backbone STP configurations Default Behavior Using STP on aNetwork with Multiple VLANs Configuration that separates VLANs Using Resilience Features What is the Switch How SwitchDatabase? Database Entries Switch Database Entry States Databases entries can have three states What is Traffic Prioritization?Available Converged network applications Used by organizations with a 802.1D Priority Levels How Traffic Prioritization Works Your Switch Traffic Prioritization How traffic is processed to provide Quality of Service Configuring traffic prioritization for QoS on a Switch Using Traffic Prioritization That allows you to monitor the traffic of LANs or VLANs What is RMON?Network efficiency and reduce the load on your network It improves your efficiency AlarmsEvents Switch Rmon Low Threshold Statistic High Threshold Recovery Period Low Threshold Statistic High Threshold Recovery Status Monitoring and Statistics Hardware Status Monitoring Example device summary web Setting UP Virtual Lans VLANs ease the movement of devices on networks VLANs provide extra security VLANs help to control traffic Membership Creating an Ieee 802.1Q Tagged Link Two Vlans connected via a router Configuration Using UntaggedConfigure the VLANs Examples Add ports to the VLANs Configure the VLANs on SwitchAdd endstation ports on Switch 1 to the VLANs Add port 12 on Switch 1 to the VLANs Add endstation ports on Switch 2 to the VLANsAdd port 11 on Switch 2 to the VLANs Check the Vlan membership for both switches Configuration How Your Switch Obtains IPInformation How Automatic IP How Automatic IP Configuration Works Considerations Automatic IP configuration featureThat a Switch may change its IP address whilst in use Configuration Rules IP AddressingGlossary IndexPage Configuration Rules Configuration Rules for Gigabit Ethernet Fast Ethernet configuration rules Configuration Rules for Fast Ethernet Appendix a Configuration Rules Network This chapter contains the following sections Segments are connected to the Switch which is positioned Simple NetworkFamily and 4900 family can be used in your network Example Dual Speed Hub Switch Advanced Network ImprovingResilience of Your Network Therefore the overall network performance EnhancingPerformance IP Addresses Simple Overview Obtaining a Registered IP Address IP Address Network Portion Dotted Decimal NotationDecimal value of an octet whose bits are all 1s is Subnet mask Subnet Mask Numbering Extending the Network Prefix Or leave the field blank Glossary Glossary Endstation EthernetEthernet address Fast Ethernet Gateway Half duplexHub Ieee 802.1D Line speed See baud Glossary Rstp See Rapid Spanning Tree Protocol STP See Spanning Tree Protocol STP Page Glossary Index Numbers Igmp multicast filtering 30 Internet Addresses 85 InterNIC Sub-networks. See subnets Switch Database