Administering the ARP Cache | 3Com 2200 specification

Setting Up an IP Interface for Management

3-11

Administering the ARP Cache

	Top-Level Menu
	system
	ethernet	interface
	fddi	route		➧display
	bridge	route		➧display
	bridge	➧arp		remove
	➧ip	rip		flush
	snmp	rip		flush
	snmp	ping
	analyzer	ping
	analyzer	statistics
	script
	logout

The Switch 2200 uses the Address Resolution Protocol (ARP) to ﬁnd the MAC addresses corresponding to the IP addresses of hosts and routers on the same subnets. An ARP cache is a table of known IP addresses and their corresponding MAC addresses.

Displaying the ARP Cache

To display the contents of the ARP cache, enter the following command from the top level of the Administration Console:

ip arp display

The contents of the ARP cache are displayed as shown in this example:

RIP is active.
IP Address	MAC Address	Interface
158.101.1.112	08-00-1e-31-a6-2	1
158.101.1.117	08-00-1e-65-21-07	1

	Top-Level Menu
	system
	ethernet	interface
	fddi	route		display
	bridge	route		display
	bridge	➧arp		➧remove
	➧ip	rip		flush
	snmp	rip		flush
	snmp	ping
	analyzer	ping
	analyzer	statistics
	script
	logout

Removing an ARP Cache Entry

You might want to remove an entry from the ARP cache if the MAC address has changed.

To remove an entry from the ARP cache:

1From the top level of the Administration Console, enter:

ip arp remove

2Enter the IP address you want to remove.

The address is immediately removed from the table. If necessary, the system will subsequently use ARP to ﬁnd the new MAC address corresponding to that IP address.

Image 52

3Com 2200 manual Administering the ARP Cache

Contents

Superstack II Switch Administration Console User Guide 3Com Corporation 5400 Bayfront Plaza Santa Clara, California Contents Administration Console Interface Parameters Remote Access ParametersSetting Up an IP Interface for Management Online Help Setting Passwords Rebooting the SystemAbout Setting Baselines Setting Baselines Setting tmaxLowerBound Setting lerAlarm Setting lerCutoffSetting the Aging Time Starting Port Monitoring Setting the Bridge Priority 10-710-8 10-9 Using Groups in Packet Filters Listing Groups 13-3Opcodes A-1 Destination Address Filter A-9 Access by Modem Support from 3ComWorld Wide Web Site 3ComForum on CompuServe Returning Products for Repair About this Guide IntroductionFamiliarity with communications protocols that are used on Interconnected LANs Switch 2200. The parts of the guide are described in Table How to UseThis Guide Conventions This guide Documentation SwitchDocuments, contact your sales representative for assistance Comments Introduction About Switch Administration Administration OverviewConﬁguration Tasks General System Commands Task Quick Command For Details, See Adjust the console screen height for your terminal To the system, or reset nonvolatile data to defaults Change the factory default baud rate of the Console port Bridging Commands Task Quick Command For Details, See System Management Setup Commands Task Quick CommandConfigurations, and spanning tree configurations Administer bridge port addresses 12-1 and followingDisplay bridge port information Set the multicast packet firewall threshold A summarized or detailed format Ethernet Commands Task Quick Command For Details, See9-2 to Fddi Commands Task Quick Command 8-3 HOW to USE Initial User AccessAccess Levels of User Select access level read, write, administer Password Using Menus to Perform Tasks System-level Functions Menu Hierarchy for Administer Access Fddi Menu Bridge Menu Bridging Menu Hierarchy for Administer Access IP Menu Snmp Menu Analyzer Menu Most abbreviated version of the same command string is Menu options are not case sensitive Entering Values Console Interface AdjustingParameters Disabling Reboot Abort Keys System consoleLock Setting Timeout Interval for Remote Sessions Running Scripts Administration Console TasksEnter the telnet timeout interval 30 minutes to 60 minutes HOW to USE the Administration Console Running Scripts of Administration Console Tasks Help GettingConsole Exiting returns you to the password prompt To exit from the Administration ConsoleExiting There, by pressing the ESC key SYSTEM-LEVEL Functions Page About Access to the SystemManagement Setting Up Console Serial Port Setting Up an IP Interface for Broadcast Address Cost Ports All Directed all 1s in the host fieldBroadcast address Ip interface modify Removing an Interface Timing out Gateway IP AddressTimed out Defining a Static Route Default route is immediately removed from the routing table Administering the ARP Cache Setting the RIP Mode Enter the IP address of the station you want to ping You could receive one of the following responses IP statistics you can view are described in Table Displaying IP StatisticsStatistics are displayed, as shown in this example Displaying Snmp Settings Setting Up Snmp on Your SystemCommunity string settings are displayed as shown here Administering Snmp Trap Reporting Community string length Conﬁguring Trap Reporting Enter an IP address of the Snmp manager destination address This example shows a trap conﬁguration Trap address invalid or unreachable Remote SMT events. On all other Switch 2200s in your network You receive the following prompt Snmp trap smtProxyTraps Environment Example of a Switch 2200 system conﬁguration displayDisplaying System Conﬁguration Setting Passwords Initial passwords Changing the Date and Time Setting the System NameYou are prompted for the name of the system Rebooting About Setting You must disable the baselineBaselines Displaying the Current Baseline Setting Baselines Baselining is automatically enabled when a baseline is setEnabling or Disabling Baselines Message similar to the following appears Working with SAVING, RESTORING, and Resetting Nonvolatile DataNonvolatile Data Saving NV Data Restoring NV DataSaving the NV data Restoration rules described here System nvData restore Examining a Saved NV Data File You are returned to the NV data menu options Resetting NV Data to Defaults You see the following prompt III Ethernet and Fddi ParametersPage Ports DisplayingEthernet Port Information RxDiscards Describes the information provided about an Ethernet port Default is enabled Layer to receive them or because the port was disabledLong and are not configurable Disabled Second long and are not configurable SuccessfullyTransmitted successfully TxPeakByteRate There is no buffer space available Frame is in error TxDiscards TxQOverflows TxFrames Frames delivered to this port Setting the Port State Labeling a Port Resources AdministeringFddi Stations Describes these statistics Can be Thru, Isolated, WrapA, and WrapBConnectPolicy This value can be user-defined Defaults for connecting to a Port M Description of Fields for Fddi Station Attributes TNotifyFrames NIF. This value can be user-defined TraceMaxExp With defaults for connecting to a Port M Normal tree connectionTopology Node may not go to Thru state in CFM Setting Neighbor Notiﬁcation Timer Enabling Disabling Status Reporting Fddi Paths Description of Fields for Fddi Path Attributes MaxTReq RingLatencyTmaxLowBound TraceStatus Current Trace status of the path TvxLowBound To set tvxLowerBound Station, which appears in brackets Fddi MACs Displaying MAC Information Administering Fddi MACs Describes the information provided for the Fddi MAC Error during reception Description of Fields for Fddi MAC Attributes OldDownstreamNeighbor OldUpstream There is no buffer space available Frame is in error Receive Frame Network Setting the Frame Error Threshold Shows the order in which the discard tests are made Setting the Not Copied Threshold Enter the new threshold value. See the following example Enabling Disabling LLC Service Setting MAC Paths Administering Fddi Ports Displaying Port Information Describes the type of information provided for an Fddi port Setting lerCutoff Setting Port Labels Fddi port path About Roving Roving AnalysisAnalysis On a speciﬁc system Roving AnalysisReceive Adding an Analyzer Port Removing an Analyzer Port Starting Port MonitoringYou can start monitoring port activity See the example below for starting port monitoring Stopping Port Monitoring Bridging Parameters Displaying Bridge Information Information about the bridge is displayed Following example shows a display of bridge information Each item in the bridge parameter list is described in Table BridgeFwdDelay Learning states. The default value is 15 secondsRoot. The default value is 2 seconds ForwardDelay Default value is disabled Bridge Attributes Parameter Description MaxAgeIs determined by the root bridge Mode Enabling Disabling IPFragmentation Disabling IPX Setting AddressThreshold Aging Time STP Bridge Enter enabled or disabled at the promptEnabling and Disabling STP on a Bridge Setting the Bridge Maximum Age To conﬁgure the STP bridge priority Forward delay The recommended value is 15 seconds To conﬁgure the forward delay value Setting the STP Group Address Bridge Port Following example shows a bridge port summary display Following example shows a bridge port detail display RxErrorDiscs Port is attachedDesignatedCost BPDUs from the designated bridge for that LAN Bridge Port Attributes Parameter Description RxFrames Management framesRxMcastExcDiscs Exceeded Disabled in which the port is currently operating Disabled The port has been disabled by managementBridge Port Attributes Parameter Description State Blocking The bridge continues to run the Spanning Tree Shows the order in which the discard decisions are made You are prompted for port type Multicast LimitMulticast packet ﬁrewall, see Bridging Extensions STP Bridge Port EnablingDisabling STP On a Port Bridge port stpCost Bridge port stpPriority Administering Port Addresses Listing Addresses From the top level of the Administration Console, enter You are prompted for the port numberEnter the number of the port You are prompted for one or more addresses to add Flushing All Addresses You are prompted for the port numbers Packet Filters Packet Filtering Listing Packet Filters Displaying Packet Filters Creating and Using Packet Filters Describes the instructions and stacks of a packet ﬁlter Basic Elements of a Packet Filter Ethernet and Fddi Packet Fields Packet Filter Operands Description Opcode Packet field PushFieldSize of the field can be 1, 2, 4, or 6 bytes Want the filter to examine a 48-bit address Constant Accept and Reject Instructions Preprocessed and Run-time Storage Creating Packet Filters 12-9 Opcode.size operand... # comment 12-11 Creating and Using Packet Filters Pseudocode translates into the following packet ﬁlter # XNS Filtering Section Enter executable instruction #1 Enter executable instruction #2 Enter executable instruction #3 Enter executable instruction #4Enter executable instruction #5 Enter executable instruction #6 This combination looks like this Only IP pkts w/in socket range Add a not statement to discard any matching packets Maximum length of a packet ﬁlter deﬁnition is 4096 bytes Command are discarded Being editedDelete Previous Ctrl+h Character One position Delete Current Ctrl+d Deleting Packet Filters Editing, CheckingSaving Packet Filters At the Replace existing filter? prompt Loading Packet Filters Bridge packetFilter load Fddi Unassigning Packet Filters from Ports Configuring Address Port Groups to USE Packet Filters Using GroupsUser-deﬁned Packet Filtering in the SuperStack II Switch Address and port groups in packet ﬁlters OR, for port groups, enter the following command To list the currently deﬁned groups, enter this command Enter this command Displaying Groups Creating New Groups Enter the ports in this syntax Address 08-32-45-e3-32-21 Port Ethernet Addresses AddingPorts to Groups Address 08-37-21-65-78-c4 Removing Addresses or Ports from a Group To remove an address from a group, enterOR, to remove a port from a group, enter Enter the ports in the syntax Address 08-42-21-84-78-f1 Loading Groups 13-11 Configuring Address and Port Groups to USE in Packet Filters Appendixes Packet Filter Opcodes OpcodesOpcodes are described in this section Name name PushField.size offset Bytes PushLiteral.size value PushTop Byte PushSAGMByte PushDAGM Byte Byte PushDPGM PushSPGMByte Eq equal Byte Lt less than Ne not equalByte Le less than or equal to Byte Ge greater than or equal to Gt greater thanByte Bit-wise Or bit-wise or Byte Xor bit-wise exclusive-ORByte Not Byte Accept Byte Shiftl shift left RejectByte Shiftr shift right Examples Packet FilterPacket ﬁlter concepts Address To make a copy of the type ﬁeld XNSPage Errors Common Syntax Characters of the number Number with a leading 0x or 0X is treated asHexadecimal Number with a leading 0 is treated as octal Services Variety of services. This appendix describes these servicesOnline Technical Through the following online systems Access by Isdn Press Return to see the 3ComForum main menu Maintenance, application training, and support services Support fromYour Network Supplier U.S. and Canada, call 800 876-3266 for customer service To ﬁnd your authorized service provider3Com Support contracts are available from 3Com Address Resolution Protocol. See ARP address threshold Index3ComFacts B-3 3ComForum B-2 Abort ARP cache ﬂushing 3-12 removing entry Statistics, displaying 10-1bridge port Multicast limit, setting 11-7 Spanning Tree EnablingCost SRFs 8-2 Connection policies, setting PortState Station MAC addresses 11-11Ethernet addressFddi path deﬁned Fddi port Removing from -9, 3-10 status Enabling Le opcode A-5 Name opcode A-1 Naming the Switch 2200 4-3ne opcode A-5 On-line technical services B-1opcodePassword conﬁguring Multicast frames Packet ﬁlters 12-1multicast limit Rlogin Broadcast address 3-4default mode 3-12displaying stateFddi ports 8-19ping IP station Snmp agent Accessing through IP 3-1deﬁned Snmp trap SMT eventSnifﬁng. See roving analysis and analyzer Port LER Condition Port Path Change Switch Deﬁned 8-7 settingTOpr Technical support B-1telnet Packet ﬁlter 12-12, 12-14, A-11 xor opcode A-7