Document ID: 9346
Updated: Sep 26, 2005
Contents
Introduction
This document provides example of how local-area transport (LAT) node and service names are used with Cisco IOS®. The examples also demonstrate how LAT connections can be monitored.
Before You Begin
Conventions
For more information on document conventions, see the Cisco Technical Tips Conventions.
Prerequisites
There are no specific prerequisites for this document.
Components Used
This document is not restricted to specific software and hardware versions.
LAT Requirements
In order for a router to automatically be aware of LAT service advertisements from other nodes, it must have the following setup:
-
a Cisco IOS software image that supports LAT
-
LAT enabled on the appropriate interfaces
Examples of these requirements are shown below:
hopper# show version Cisco Internetwork Operating System Software IOS (tm) 2500 Software (C2500-J-L), Version 11.2(12.1), MAINTENANCE INTERIM SOFTWARE Copyright (c) 1986-1998 by cisco Systems, Inc. Compiled Mon 02-Mar-98 15:01 by cuser Image text-base: 0x0303F1BC, data-base: 0x00001000 hopper# show lat service Service Name Rating Interface Node (Address) ALBIE 84 Ethernet0 ALBIE (aa00.0400.0a28) Ident: Welcome to OpenVMS VAX V7.1 ALFIE 67 Ethernet0 ALFIE (aa00.0400.1728) Ident: Welcome to OpenVMS (TM) VAX Operating System, Version V7.1 ALPHIE 71 Ethernet0 ALPHIE (0800.2be6.9ec9) Ident: @sys$manager:announce.txt
Because LAT is a valid input and output transport for the async ports, the router will respond to LAT solicitations directed at the router as long as LAT is configured as a valid transport. An example is shown below:
line 2 3
transport input all
hopper# show line 2
Tty Typ Tx/Rx A Modem Roty AccO AccI Uses Noise Overruns
2 TTY 9600/9600 - - - - - 0 0 0/0
Line 2, Location: "", Type: ""
Length: 24 lines, Width: 80 columns
Baud rate (TX/RX) is 9600/9600, no parity, 2 stopbits, 8 databits
Status: Ready
Capabilities: none
Modem state: Ready
Group codes: 0
Modem hardware state: noCTS noDSR DTR RTS
Special Chars: Escape Hold Stop Start Disconnect Activation
^^x none - - none
Timeouts: Idle EXEC Idle Session Modem Answer Session Dispatch
00:10:00 never none not set
Idle Session Disconnect Warning
never
Modem type is unknown.
Session limit is not set.
Time since activation: never
Editing is enabled.
History is enabled, history size is 10.
DNS resolution in show commands is enabled
Full user help is disabled
Allowed transports are lat pad v120 mop telnet rlogin nasi. Preferred is lat.
No output characters are padded
No special data dispatching characters
Making a LAT Connection
There are two methods of establishing a LAT connection.
Method 1: The device requests a connection to a service based on a service advertisement multicast that has been seen and cached. An example is shown below:
hopper# show lat service Service Name Rating Interface Node (Address) ALBIE 84 Ethernet0 ALBIE (aa00.0400.0a28) Ident: Welcome to OpenVMS VAX V7.1 ALFIE 65 Ethernet0 ALFIE (aa00.0400.1728) Ident: Welcome to OpenVMS (TM) VAX Operating System, Version V7.1 ALPHIE 71 Ethernet0 ALPHIE (0800.2be6.9ec9) Ident: @sys$manager:announce.txt
Method 2: The device solicits a connection to a node name "x", containing a port named "y". In the following example, the VAX has a LAT device (LTA400) defined to connect to node "hopper", port "2".
ALFIE> mc latcp show port lta400 Local Port Name: _LTA400: Local Port Type: Application (Queued) Local Port State: Inactive Connected Link: Target Port Name: 2 Actual Port Name: Target Node Name: HOPPER Actual Node Name: Target Service Name: Actual Service Name:
If a virtual terminal connection is attempted from the VAX, the following displays:
ALFIE> set host/dte lta400 %REM-I-TOQUIT, connection established Press Ctrl/\ to quit, Ctrl/@ for command mode
And this displays:
hopper# debug lat event
LAT event debugging is on
hopper#
hopper#
00:18:06: LAT: Host Initiated connection from ALFIE to :2, sc=1
00:18:06: LAT2: created new inbound session
00:18:06: LAT2: Host-initiated connection complete
00:18:06: LAT2: DataB: +FlowIn +FlowOut Parity 2A Mode Interactive(0) Speed *19200/*19200
00:18:06: LAT2: DataB ignored
hopper# who
Line User Host(s) Idle Location
* 0 con 0 idle 00:00:00
2 TTY 2 idle 00:00:18 ALFIE
9 aux 0 Async interface 00:00:47
As you can see, the router has taken the default node name of "hopper" (LAT is not case-sensitive), which is the host name of the router. You can also assign a different node name to the router using the lat node-name command, as shown below:
hopper# conf terminal Enter configuration commands, one per line. End with CNTL/Z. hopper(config)# lat node-name froggie hopper(config)# ^Z
If the VAX now tries to connect, the router does not respond to the solicit request from the VAX, because the router no longer contains the LAT node name "hopper". The LTA device on the VAX needs to be redefined to point to the node name "froggie" instead of "hopper".
ALFIE> set h/dte lta400 %REM-I-TOQUIT, connection established Press Ctrl/\ to quit, Ctrl/@ for command mode %REM-E-PORTRXERR, port receive error -SYSTEM-F-HANGUP, data set hang-up %REM-S-END, control returned to node ALFIE %SYSTEM-F-HANGUP, data set hang-up ALFIE> hopper# show debug LAT: LAT event debugging is on hopper#
You can define services on the router to avoid the administrative overhead of node names. The configuration for this is shown below:
hopper# conf terminal Enter configuration commands, one per line. End with CNTL/Z. hopper(config)# lat service rodent enab hopper(config)# ^Z
The router will now send out LAT service advertisements for the service "rodent". As shown in the example below, the VAX can see these service advertisements and is able to open connections using the service name:
ALFIE> mc latcp show service Service Name Status Identification ---------------- ----------- ------------------------------------------------- ALBIE Available .Welcome to OpenVMS VAX V7.1 ALFIE Available .Welcome to OpenVMS VAX V7.1 ALPHIE Available @sys$manager:announce.txt PRINTERC Available RODENT Available ALFIE>set h/lat rodent %LAT-S-CONNECTED, session to RODENT on node FROGGIE established %LAT-I-TODISCON, type ^\ to disconnect the session User Access Verification Username: hopper# hopper# 00:26:10: LAT: Host delay = 4 tics 00:26:10: LAT: Got new inbound host connection 00:26:10: LAT10: created new inbound session hopper#
Note: The methods of connection to a service name and to a node/port pair differ. The service connection provides a vty session while the node/port combination provides a TTY connection. This is because a service connection is initiated by the VAX to the access server, but a node/port connection is initiated by the access server as a result of an invitation from the VAX. The VAX actually asks the access server to start a Virtual Circuit from node "x" and port "y" to the VAX.
An example of a service connection is shown below:
hopper# who
Line User Host(s) Idle Location
* 0 con 0 idle 00:00:00
9 aux 0 Async interface 00:00:36
10 vty 0 idle 00:01:05 ALFIE
An example of a node/port combination connection is shown below:
hopper# who
Line User Host(s) Idle Location
* 0 con 0 idle 00:00:00
2 TTY 2 idle 00:01:24 ALFIE
9 aux 0 Async interface 00:00:22
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