Table of Contents

TCP Clear Performance Enhancements

TCP Clear Performance Enhancements

The feature provides inbound and outbound performance enhancements to America Online (AOL) users of wholesale dialing services. This feature is first introduced in Cisco IOS Release 12.1(1)AA.

• Feature Overview
  
  
• Supported Platforms
  
  
• Supported Standards, MIBs, and RFCs
  
  
• Configuration Tasks
  
  
• Configuration Example
  
  
• Command Reference
  
  

Feature Overview

Both aspects of the TCP Clear Performance Enhancements feature are enabled using the autocommand-options telnet-faststream command.

• Outbound---provides stream processing, allowing the output data processing to occur at the interrupt level. Being event driven, this removes polling and process switching overhead. In addition, the flow control algorithm is enhanced to handle the higher volume of traffic and to eliminate some out-of-resource conditions that could result in abnormal termination of the session.
  
  
• Inbound---provides stream processing with the same improvements as for outbound traffic. Also, it removes scanning for special escape characters in the data stream; this is very process-intensive and is not required for this application. (In other situations, the escape characters allow for a return to the Privileged Exec mode prompt on the router.) In addition, a Nagle algorithm is used to form the inbound data stream into larger packets, thus minimizing packet-processing overhead.
  
  

This feature is designed to provide more efficiency in the data transfers for AOL users who are using a Cisco network access server to communicate with a wholesale dial carrier.

The Cisco AS5800 access server is required to support all dial-in lines supported by two complete T3 connections (that is, 1344 connections) running TCP clear connections to an internal host. The desired average data throughput for these connections is 6 kbps outbound and 3 kbps inbound.

Benefits

This feature allows the Cisco AS5800 platform to support the maximum number of connections provided by two T3 connections (that is, 1344 connections) running the TCP Clear protocol with typical traffic loads.

Restrictions

This feature has the following restrictions:

Special character processing---No special character processing, including break recognition, is performed on incoming data from the dial shelf. This requires the TCP clear connection to run as the sole connection on the TTY line. And this sole connection is terminated by TTY line termination or TCP connection termination, with no exec session capability for the user. This has been implemented by specifying a new autocommand-options option "telnet-faststream" which in conjunction with an autocommand of "telnet /stream" enables the fast-stream processing. This will also be available for TACACS/RADIUS av-pair processing since this uses the autocommand facility.

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Note The new autocommand-options telnet-faststream command is available only on the Cisco AS5800. See the "Command Reference" section.

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Supported Platforms

Cisco AS5800

Supported Standards, MIBs, and RFCs

Standards

No new standards or MIBs are supported by this feature.

MIBs

Standard Cisco AS5800 MIBs

For descriptions of supported MIBs and how to use MIBs, see the Cisco MIB web site on CCO at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.

RFCs

No new standards or MIBs are supported by this feature.

Configuration Tasks

See the following sections for the configuration tasks for the TCP Clear Performance Enhancements feature:

• Configuring the autocommand telnet /stream Command (Required)
  
  
• Configuring TCP Clear Performance Enhancements (Required)
  
  

Configuring the autocommand telnet /stream Command

Three options for configuring the autocommand telnet /stream command are as follows:

• The autocommand can be configured on the lines.
  
  

On a Cisco AS5800 network access server, this would be implemented as follows:

	Command	Purpose
Step 1	Router(config)#line 1/3/00 1/11/143	Selects the lines to be configured.
Step2	Router(config-line)#autocommand telnet aol-host 5190 /stream	Configures autocommand on the lines.

• The autocommand can be configured using user ID and password.
  
  

On a Cisco AS5800 network access server, this would be implemented as follows:

	Command	Purpose
Step1	Router(config)#username aol password aol	Defines the user ID and password.
Step2	Router(config)#username aol autocommand telnet aol-host 5190 /stream	Configures autocommand on the user ID.

• The autocommand can also be configured at a TACACS/RADIUS server, if the username authentication is to be performed there, rather than on the router. The av-pair processing allows the autocommand to be configured.
  
  

Configuring TCP Clear Performance Enhancements

To enable the TCP Clear performance enhancements, autocommand-options must be configured to enable "telnet-faststream."

On a Cisco AS5800 network access server, this would be implemented as follows:

	Command	Purpose
Step1	Router(config)#line 1/3/00 1/11/143	Selects the lines to be configured.
Step2	Router(config-line)# autocommand telnet-faststream	Enables the TCP Clear performance enhancements on the selected lines.

Verifying Configuration of TCP Clear Performance Enhancements

Use the show line command to see that the feature is correct in the configuration.

Configuration Example

router#sh line 1/4/00 
   Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int 
*   1/4/00 Digital modem - inout     -    -    -      1       0     0/0       - 
  
 
Line 1/4/00, Location: "", Type: "" 
Length: 24 lines, Width: 80 columns 
Status: PSI Enabled, Ready, Connected, Active, No Exit Banner 
  Modem Detected 
Capabilities: Hardware Flowcontrol In, Hardware Flowcontrol Out 
  Modem Callout, Modem RI is CD, Line usable as async interface 
  Hangup on Last Close, Modem Autoconfigure, Telnet Faststream 
Modem state: Ready 
Modem hardware state: CTS DSR  DTR RTS 
modem=1/4/00, vdev_state(0x00000000)=CSM_OC_STATE, bchan_num=(T1 1/2/0:7:20) 
vdev_status(0x00000001): VDEV_STATUS_ACTIVE_CALL. 
 
Group codes:    0, Modem Configured 
Special Chars: Escape  Hold  Stop  Start  Disconnect  Activation 
                ^^x    none   -     -       none 
Timeouts:      Idle EXEC    Idle Session   Modem Answer  Session   Dispatch 
                never         never                        none     not set 
                            Idle Session Disconnect Warning 
                              never 
                            Login-sequence User Response 
                             00:00:30 
                            Autoselect Initial Wait 
                              not set 
Modem type is 9600. 
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 telnet.  Preferred is lat. 
Automatically execute command "telnet 1.100.254.254 2145 /stream" 
No output characters are padded 
No special data dispatching characters 
router# 

NoteNotice that Telnet Faststream is enabled under the Capabilities.

Command Reference

This section documents new or modified commands. All other commands used with this feature are documented in the Cisco IOS Release 12.1 command reference publications.

autocommand-options telnet-faststream

To provide inbound and outbound TCP Clear performance enhancements, use the autocommand-options telnet-faststream line configuration command. To disable these enhancements, use the no form of this command.

Syntax Description

Defaults

No default behavior or values.

Command Modes

Line configuration command

Command History

Usage Guidelines

The autocommand-options telnet-faststream option is relevant only if the Telnet /stream autocommand is selected for the line.

Examples

The following example shows the autocommand-options command using the new telnet-faststream keyword:

Router(config)#line 1/3/00 1/11/143
Router(config-line)#autocommand telnet aol-host 5190 /stream
Router(config-line)#autocommand-options telnet-faststream