Black Box LGB2118A, LGB2124A manual Flow Control, Ethernet parameters for half-duplex mode

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Chapter 4: Basic Concepts and Management

Table 4-5. Ethernet parameters for half-duplex mode.

Parameter Value/LAN

10BASE

100BASE

1000BASE

 

 

 

 

Max. collision domain DTE to DTE

328 feet (100 m)

328 feet (100 m) for UTP

328 feet (100 m) for UTP

1351.7 feet (412 m) for fiber

1043.3 feet (316 m) for fiber

 

 

 

 

 

 

Max. collision domain with repeater

8202.1 feet (2500 m)

672.6 feet (205 m)

646.1 feet (200 m)

 

 

 

 

Slot time

512 bit times

512 bit times

512 bit times

 

 

 

 

Interframe gap

9.6 µs

0.96 µs

0.096 µs

 

 

 

 

Attempt Limit

16

16

16

 

 

 

 

Backoff Limit

10

10

10

 

 

 

 

Jam size

32 bits

32 bits

32 bits

 

 

 

 

Max. frame size

1518

1518

1518

 

 

 

 

Min. frame size

64

64

64

 

 

 

 

Burst limit

Not applicable

Not applicable

65536 bits

 

 

 

 

Figure 4-5. Full-duplex mode.

In full-duplex operation mode, both transmitting and receiving frames are processed simultaneously. This doubles the total bandwidth. Full-duplex is much easier than half-duplex because it does not involve media contention, collision, retransmission schedule, and padding bits for short frames. It functions according to the IEEE 802.3 specification. The minimum inter-frame gap requirement between successive frames and frame formats is the same as that in the half-duplex operation.

No collision will happen in full-duplex operation. What happens if the receiving device is busy and a frame is coming at the same time? Can it use “backpressure” to tell the source device? A flow control function is introduced in full-duplex operation.

4.4 Flow Control

Flow control is a mechanism that tells the source device to stop sending frames for a specified period of time designated by a target device until the PAUSE time expires. It does this by sending a PAUSE frame from the target device to the source device. When the target is not busy and the PAUSE time is expired, it will send another PAUSE frame with zero time-to-wait to the source device. After the source device receives the PAUSE frame, it will again transmit frames immediately. The PAUSE frame is identical in the form of the MAC frame with a pause-time value and with a special destination MAC address 01-80-C2-00-00-01. As per the specification, PAUSE operation can not be used to inhibit the transmission of a MAC control frame.

Normally, in 10-Mbps and 100-Mbps Ethernet, only symmetric flow control is supported. However, the Gigabit Smart Switch Eco Fanless supports not only symmetric, but also asymmetric flow control for the special application. In Gigabit Ethernet, both symmetric flow control and asymmetric flow control are supported. Asymmetric flow control only allows transmitting a PAUSE frame in one way from one side; the other side is not transmitted. Instead the switch receives and discards the flow control information. Symmetric flow control allows both two ports to transmit PAUSE frames to each other simultaneously.

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Contents Supports http and Snmp interface for switch management Trademarks Used in this Manual Trademarks Used in this ManualFCC and IC RFI Statements NOM Statement Table of Contents Table of Contents Specifications General SpecificationsVlan Supports Port-based Vlan and Tag-based Ieee 802.1Q Vlan Management Software SpecificationsFeatures OverviewOverview Introduction What’s Included Not shown in -1 or LGB2118A componentsLGB2118A LED functions 2 24-Port Gigabit Smart Switch Eco Fanless LGB2124ANot shown in -3 or LGB2124A LED functions LGB2124A componentsFront view of 1000BASE-SX/LX LC, SFP Fiber Transceiver Optional Modules for LGB2118A and LGB2124AInstallation Installation Starting Up the SwitchHardware and Cable Installation Cabling Requirements 100BASE-TX TP Fiber supported by the switchVlan Attribute-based Vlan diagram Installation Address Assignment Login screen for the WebInstallation Prefix Length Typical Applications Copper cables Fiber cable RJ-45 Gigabit Smart SwitchMedia ConverterCopper cables RJ-45 Financial Copper cables RJ-45 Gigabit Smart SwitchBasic Concepts and Management Basic Concepts and ManagementEthernet MAC sub layer in physical layer in OSI model Logical Link Control LLCSsap address field Options Media Access Control MAC MAC AddressingEthernet Frame Format 0x8137 0x0835Gigabit Ethernet Frame Flow Control Ethernet parameters for half-duplex modeBasic Concepts and Management Collision Basic Concepts and Management How Does a Switch Work? Virtual LAN Ethernet switch Printer Workstations Ethernet switch MiniMini Computer frameRouter 1a2a Ethernet switchBasic Concepts and Management VID Link Aggregation LGB2118A Only Basic Concepts and Management Operation of Web-based Management Operation of Web-based ManagementWeb Management Home Overview Main menu function tree for Web interface System Information ConfigurationOperation of Web-based Management Port Configuration Operation of Web-based Management Vlan Group Configuration Vlan Mode ConfigurationFunction name Vlan Mode Setting Media supportedTag-VLAN Mode 10. Port-Based Vlan Configuration Function name Port Isolation Configuration Vlan Port Isolation ConfigurationAggregation LGB2118A Only Mirroring Configuration Function name Igmp Snooping ConfigurationIgmp Snooping Snmp 15. Mirror ports configurationOperation of Web-based Management Loop Detection Broadcast Storm Protection Operation of Web-based Management Quality of Service QoS Configuration Operation of Web-based Management Statistics Overview MonitoringDetailed Statistics Operation of Web-based Management Igmp Status Ping Status Warm Restart MaintenanceFactory Default Software UpgradeConfiguration File Transfer Logout Troubleshooting Resolving a No Link Condition TroubleshootingQuestions and Answers Contacting Black BoxAppendix MIB Specifications Appendix MIB SpecificationsBlackbox.com Blackbox.com Black Box Tech Support FREE! Live /7