Black Box LGB2124A manual Logical Link Control LLC, MAC sub layer in physical layer in OSI model

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Chapter 4: Basic Concepts and Management

Figure 4-2. MAC sub layer in physical layer in OSI model.

This diagram shows the Ethernet architecture, LLC sub-layer and MAC sub-layer, which operate at the Data Link layer, and transceivers, which work at the Physical layer in the OSI model. In this section, we describe the MAC sub-layer.

4.2 Logical Link Control (LLC)

The data link layer consists of both the sub-layers of MAC and MAC-client. The MAC client may be logical link control or the bridge relay entity.

Logical link control supports the interface between the Ethernet MAC and upper layers in the protocol stack, such as Network layer. It can operate over different LAN technologies, such as Token Ring, FDDI, and so on. For the interface to the MAC layer, LLC defines the services with the interface, independent of the medium access technology.

Table 4-1. LLC PDU format.

Parameter

Value

Description

 

 

 

DSAP address

8 bits

Destination service access point address field

 

 

 

SSAP address

8 bits

Source service access point address field

 

 

 

 

 

Control field (16 bits for formats that include

Control

8 or 16 bits

seqeuence numbering, and 8 bits for formats that

 

 

do not)

 

 

 

Information

M*8 bits

Information

 

 

 

* = Multiplication

M = An integer value equal to or greater than 0. (Upper bound of M is a function of the medium access control methodology used.)

Table 4-1 shows the format of LLC PDU. It consists of four fields: DSAP, SSAP, Control, and Information. The DSAP address field identifies one or more service access points that have an I/G bit for an individual or group address. If all bits of DSAP are 1s, it’s a global address. The SSAP address field identifies the specific services indicated by the C/R bit (command or response). The DSAP and SSAP pair with some reserved values indicate some well-known services listed in Table 4-2.

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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 Specifications GeneralManagement Software Specifications Vlan Supports Port-based Vlan and Tag-based Ieee 802.1Q VlanOverview FeaturesOverview Introduction What’s Included LGB2118A components Not shown in -1 or2 24-Port Gigabit Smart Switch Eco Fanless LGB2124A LGB2118A LED functionsLGB2124A components Not shown in -3 or LGB2124A LED functionsOptional Modules for LGB2118A and LGB2124A Front view of 1000BASE-SX/LX LC, SFP Fiber TransceiverInstallation Starting Up the Switch InstallationHardware and Cable Installation Cabling Requirements Fiber supported by the switch 100BASE-TX TPVlan Attribute-based Vlan diagram Installation Login screen for the Web Address AssignmentInstallation Prefix Length Typical Applications Gigabit Smart Switch Copper cables Fiber cable RJ-45Media ConverterCopper cables RJ-45 Gigabit Smart Switch Copper cables RJ-45 FinancialBasic Concepts and Management Basic Concepts and ManagementEthernet Logical Link Control LLC MAC sub layer in physical layer in OSI modelMedia Access Control MAC MAC Addressing Ssap address field OptionsEthernet Frame Format 0x0835 0x8137Gigabit Ethernet Frame Ethernet parameters for half-duplex mode Flow ControlBasic Concepts and Management Collision Basic Concepts and Management How Does a Switch Work? Virtual LAN Ethernet switch MiniMini Computer frame Ethernet switch Printer WorkstationsEthernet switch Router 1a2aBasic 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 Configuration System InformationOperation of Web-based Management Port Configuration Operation of Web-based Management Vlan Mode Configuration Vlan Group ConfigurationFunction name Vlan Mode Setting Media supportedTag-VLAN Mode 10. Port-Based Vlan Configuration Vlan Port Isolation Configuration Function name Port Isolation ConfigurationAggregation LGB2118A Only Function name Igmp Snooping Configuration Mirroring ConfigurationIgmp Snooping 15. Mirror ports configuration SnmpOperation of Web-based Management Loop Detection Broadcast Storm Protection Operation of Web-based Management Quality of Service QoS Configuration Operation of Web-based Management Monitoring Statistics OverviewDetailed Statistics Operation of Web-based Management Igmp Status Ping Status Maintenance Warm RestartSoftware Upgrade Factory DefaultConfiguration File Transfer Logout Troubleshooting Troubleshooting Resolving a No Link ConditionQuestions and Answers Contacting Black BoxAppendix MIB Specifications Appendix MIB SpecificationsBlackbox.com Blackbox.com Black Box Tech Support FREE! Live /7