Cisco IOS Software Releases 12.1 Mainline

Cisco IOS Software Release 12.1(1)AA - No. 1079

Product Bulletin No. 1079

Cisco IOS Software Release 12.1(1)AA


This Product Bulletin describes the content and delivery information concerning Cisco IOS(TM) software release 12.1(1)AA. This release is focused on the application of the AS5800 in wholesale dial networks supporting AOL. The features contained in this release specifically address the scalable support of "TCP-Clear' traffic used to carry AOL 4.0 and lower sessions.

The features delivered with this release will be incorporated into the 12.1(3)T release, but 12.1(1)AA represents a release vehicle that provides these features both sooner, and based off the 12.1 mainline IOS train rather than the 12.1T IOS release train. For more information about the Cisco IOS software release process, please see Product Bulletin #537.

New Features in Cisco IOS Release 12.1(1)AA

The following features will be delivered in the initial release of 12.1(1)AA

Table 1: Cisco IOS Release 12.1(1)AA New Features
Release Feature Platform

TCP Clear Performance Enhancements



Round Robin Type DNS Lookup


Detailed Information

12.1(1)AA delivers support for the following features.

TCP Clear Performance Enhancements

TCP Clear Performance Enhancements provide inbound and outbound performance enhancements to America Online (AOL) wholesale dial providers.There are two aspects to the TCP Clear Performance Enhancements feature, and both are enabled using the same config command

autocommand-options telnet-faststream

Outbound: provides stream processing, allowing the output data processing to occur on an event-driven basis at interrupt level. In addition the flow control algorithm is enhanced to handle the higher volume of traffic, and to eliminate some out-of-resource conditions which 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 processor intensive and is not required for this application. In addition a Nagle algorithm is used to coalesce the inbound datastream into larger packets, thus minimising packet processing overhead.

Allow missing Service-Type for PPP/Exec within RADIUS authorization request

A new hidden command is added to the radius-server group:

radius-server authorization permit missing Service-Type

This command allows an access server to fully process Access-Accept responses from RADIUS servers that do not send the Service-Type attribute. Previously, the access server would not process the attributes within an Access-Accept without a Service-Type attribute, which lead to problems on networks where existing RADIUS server infrastructure did not send it. Although this did not affect authorization of the user, it did mean that any other attributes in the Access-Accept response (e.g. application of ACLs) were ignored.

Round robin type DNS lookup

There is a new command

ip domain round-robin

In AOL wholesale dial networks, it is common to use round-robin DNS to load balance TCP-Clear sessions across AOL hosts. The DNS A record for the AOL hostname is configured to return a list of IP addresses. When enabled, this feature causes IOS to round-robin across the list of returned IP addresses when resolving host names. Thus when a new TCP-Clear session begins, that session uses the next IP address on the list returned by the AOL DNS server, effectively spreading the load of TCP-Clear sessions across all of the AOL servers in the list. IOS continues to round-robin across the IP address list until the A record's Time To Live (TTL) value is exhausted.

Life span

12.1AA will be sold until Cisco IOS Software 12.2(1) is released.


Cisco IOS software release 12.1(1)AA follows the standard Cisco support policy as indicated in the following link:

Supported Hardware Platforms

Cisco IOS Software release 12.1(1)AA supports the following platform:

  • Cisco AS5800 universal access server

Product Numbers and Descriptions

Table 2: Cisco IOS Release 12.1(1)AA Feature Sets, Images, and Memory Recommendations
Platform Software Feature Set Product Code Image Flash DRAM

Cisco AS5800 Series IOS IP PLUS



16 MB

128 MB

Download Information

Customers can download Cisco IOS Release 12.1(1)AA software from Cisco Connection Online (CCO) in the Software Image Library. iosplanner.cgi?get_crypto=&data_from=&hardware_name=&software_name=&release_name=12.1.1-AA1&majorRel=12.1&state=:RL