Asante Technologies 3500 Series user manual Flow Control, Auto-Negotiation

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7.3.2 Flow Control

With a link operating at a high data rate, a switch may experience occasional limitations in the buffer space used to store Ethernet frames before forwarding them. In this situation, if the sending station continues to send frames, the switch will have no option but to discard the frames. This may quickly lead to unacceptable delays in upper-level protocols.

In order to avoid unnecessarily dropping frames, a switch may implement Flow Control. Flow control is a feature that allows the switch to recognize when the buffer space is limited, and to send an Ethernet PAUSE frame to its link partner to cease transmission for a specified period. As with a full duplex link, both ends of the link must understand flow control for the mechanism to operate properly.

7.3.3 Auto-Negotiation

As discussed above, you need to make sure that both ends of a link agree about the duplex and flow control settings to be used (as well as the speed of the connection). In even a mid-sized network, making sure that all the links agree on all these parameters would be too big a job if the network manager had to configure every connection manually.

To make configuration as automatic as possible, the IEEE has defined standards so that most connections can be automatically configured by the hardware, without manual intervention. Devices can agree on the speed, duplex mode and flow control settings for each individual connection. The possible links states are ranked:

1000Mbps/Full Duplex 1000Mbps/Half Duplex (never used) 100Mbps/Full Duplex 100Mbps/Half Duplex 10Mbps/Full Duplex 10Mbps/Half Duplex

With auto-negotiation, the link partners will configure the link to operate at the highest speed and duplex state that both support.

Auto-negotiation is supported on IntraCore switches on all UTP ports.

Note: If an Ethernet device that is capable of auto-negotiation is connected to a port that has auto- negotiation turned off, the auto-negotiating device will default to half duplex mode. If the port that is not using auto-negotiation is set to full duplex, the link will have a duplex mismatch, and will so slow that it may be unusable. If you configure an Ethernet port to operate in full duplex mode, you must also configure the link partner to operate in full duplex. It is almost always better to let auto-negotiation take care of this for you.

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Contents IntraCore 3500 Series Quick Start Guide Gigabit Ethernet Switches User’s Manual IntraCore 3500 SeriesTable of Contents Page Package Contents IntroductionLEDs 1 IC3524 Models2 IC3548-2GT 4810/100Front and Back Panel Descriptions #49Management and Configuration Web-Based Interface Console InterfaceSnmp Management Installation Overview Hardware Installation and SetupSafety Overview Installation into an Equipment Rack Recommended Installation ToolsPower Requirements Environmental RequirementsGbic Interfaces Installing a GbicEquipment Rack Guidelines Installing Optional Hardware Modules Connecting PowerRemoving a Gbic Gbic Care and HandlingConnecting to the Network 1 10/100BaseT Ports Cabling ProceduresGigabit Ethernet Ports Cabling Procedures SetupConnecting to a Console Connecting Via the Web Browser Changing the PasswordConnecting Via Telnet IP Assignment Snmp ManagementUsing the Stacking Feature IC3524 only Toggle Stacking Enable/Disable Accessing a Submenu ConfigurationLogging General Information Configuration MenuExiting a Submenu System Administration Configuration Changing System Administration InfoBootstrap Configuration System IP ConfigurationChanging System IP Information Snmp Configuration Changing Community StringsAdding or Updating a Trap Receiver Enabling Authentication TrapsDeleting a Trap Receiver Port Configuration Basic Port Configuration Menu appearsConfiguring Auto-Negotiation Enabling or Disabling a PortConfiguring a Port Manually Configuring 1000BaseX PortsToggling Port Link Speed Toggling Half to Full DuplexSetting Port Class of Service Advanced Port ConfigurationEnabling or Disabling 802.3x Flow Control Setting Port Default Priority Global Port ConfigurationUnicast Forwarding Database Configuration Displaying the Forwarding DatabaseSetting the MAC Address Age-Out Time Searching for a MAC AddressPort Mirroring Configuration Security ManagementVlan Management IP Multicast Traffic ManagementSetting the Monitor Port File Up/Downloading ConfigurationImage Downloading through Tftp Serial Downloading Configuration Performing a Software Upgrade at RuntimeResetting the Switch System Reset ConfigurationPerforming a Software Upgrade Scheduling a System Reset System LogUser Interface Configuration Clearing the System LogSetting Console Idle Time-out Period Setting Telnet Idle Time-out PeriodSystem Utility Changing the PasswordEnabling or Disabling the Web Server Viewing Statistics Configuring Spanning Tree Parameters Advanced ManagementSpanning Tree Protocol Enabling and Disabling STPSpanning Tree Port Configuration Setting Port Priority and Path CostDuplicated IP Detection and Trap Snmp and Rmon ManagementRmon Management Enabling and Disabling Station Movement Trap Enabling and Disabling Duplicated IP DetectionEnabling and Disabling Duplicated IP Trap Viewing a List of Duplicated IP AddressesConfiguring Port Security Configuring Port New Node Detection TrapConfiguring Security Level 2 or Level Configuring Port Lock and Intruder LockSetting the Intruder Trap Vlan Specifications for the IntraCore 3500 Series Resetting Security to DefaultsOther Vlan Features of the switch Inserting/Modifying a Port Trusted MAC AddressConfiguring Static Vlan Groups Kkxxxxxx KxxxxxxxAdvanced Static Vlan Configuration Setting the Port Vlan ID Configuring Vlan Port AttributesSpecifying Tagging or No Tagging for a Port Configuring Port Receive Frame Type Displaying a Summary of Vlan GroupsDisplaying a Vlan Port Summary Adding and Deleting VLANs from the PortResetting Vlan Configuration to Defaults Multicast AddressesConfiguring IP Multicast Traffic Management Igmp SnoopingEnabling and Disabling Igmp Snooping Displaying a Summary of Group AddressesIP Multicast Forwarding Database Configuration Adding Ports to the Selected AddressInserting a Multicast Group Address Removing a Multicast Group Address To remove an addressAccessing with a Web Browser Web-Based ManagementFront Panel Button Genl Info General Information ButtonStatistics Button Port Config Port Configuration Button Span Tree Spanning Tree Button Snmp Button Addr Address Table ButtonVlan Button Port Configuration Creating or Modifying a Vlan Vlan ConfigurationAdding and Deleting Port Members Page Security Button Duplicate IP Button Snmp Management Operations Snmp ManagementSnmp Protocol Community Name and Security MIB TreeName Space Path MIB Groups SupportedPage Switching Concepts VLANsPort-Based VLANs Vlan ID and Tagged FramesHow It Works Port Vlan IDSpanning Tree Parameters Forward Delay Full Duplex, Flow Control and Auto-negotiationFull Duplex Port PriorityFlow Control Auto-NegotiationAppendix A. Troubleshooting Problem Possible SolutionsFeatures Appendix B. Features and SpecificationsSpecifications Physical Characteristics Technical Support and WarrantyEnvironmental Range Standards ComplianceFCC Compliance Statement Important Safety Instructions Appendix C. FCC Compliance and Warranty StatementsIntraCare Warranty Statement Page Pin Number Signal Name Appendix D. Console Port Pin OutsAppendix E. Online Warranty Registration Appendix F. BootP Configuration Bootstrap ConfigurationImage Banks Loading Software Locally
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