Cisco ONS 15454 Series Multiservice Provisioning Platforms

Field Notice: Cisco ONS Simplex TCC Support Discontinued

Updated April 18, 2002

June 16, 2000

Products Affected



Cisco ONS 15454

All Simplex Configurations running code versions later then 2.0.2.

Problem Description

In a Cisco ONS 15454 system running in simplex TCC, TCC+, TCCi, XC, XCVT or XC10G systems, a TCC or XC reset (all types) or hardware failure may cause a traffic outage. Node connectivity issues are also a known problem of simplex TCC operation which may result in the inability to manage a Network element (NE).


The Cisco ONS 15454 was designed as a duplex system for redundancy and reliability purposes. Background process are run between common equipment in order to ensure the health of the sytem. Although the system will run in simplex mode, Cisco Systems does not perform software verification and reliability testing on non-redundant ONS 15454 systems and therefore cannot endorse simplex configurations.

Problem Symptoms

In networks operating non-redundant TCCs or XCs, a failure of either of these boards can result in a traffic outage.

Simplex TCC Operation

The following are some issues that you can expect to see if running an ONS 15454 using a non-redundance TCC, where the TCC is reset either manually or as a result of a board failure.

  • Intercard communication - Messages sent between cards require an active running TCC and standby TCC. When a single TCC resets for any reason, there could be a period of approximately two minutes when no intercard messages are passed. This can have severe traffic implications if a protection switch needs to occur during this timeframe.

  • No access to the node - If the single TCC is reset for any reason, there is a timeframe of at least two minutes, during which that node cannot report any alarms, receive configuration requests, or communicate other critical processes. This could have a compounding effect for DCC connected nodes since none of their administrative data can be communicated to the resetting node. If the TCC has failed, it will be necessary to physically insert a known good TCC to restore traffic.

  • Software Upgrade - If you encounter a problem during a software upgrade, you may experience significant downtime if operating with a simplex TCC. With dual TCCs, the new load is first activated on the standby TCC, converting the database and verifying the integrity of the release with the database before switching to the standby TCC with the new release. If there is a problem, activation can be aborted before switching, avoiding traffic affecting issues. With a simplex TCC, the boards are activated without this verfication process. If a problem occurs during activation, it may be necessary to physically reset the node to restore traffic.

  • Timing - Since the TCC sources the sync clock to the other cards, during TCC resets the XCON provides the clock. While this is a generally accepted operation, there can be issues with some cards like DS3/DS3E when operating in this mode.

  • E100/E1000 cards - During a TCC reset all E100/E1000 traffic will be down since spanning tree runs on the TCC.

Simplex XC Operation

The problem may occur during a reset of a simplex XC. During the reset an outage will result which may require physical intervention to restore traffic.

  • XC Resets - Some hardware conditions, like out of frame (OOF), can be solved only with an XC switchover and a reboot of the XC card. With a simplex XC, traffic will be lost as the card reboots.

  • XC Soft Resets - While the XC soft resets, no protection (1+1, BLSR and UPSR) may work. If there is a line or path problem during the reset, traffic will be lost.

  • IO Card Reboots - During card reboots bus noise can be present which may cause the XC to switch to its peer. In a simplex system this will result in a traffic outage.

  • Diagnostics - During XC soft resets, diagnostics are run to detect input port lockup problems on the SXC1 and SXC2 (depending on the board). These diagnotics are only run on the standby card to help detect and fix problems. In a simplex sytem, diagnostics are not running, and therefore cannot catch these problems, which may result in a traffic outage.

  • TCC reboot - When a TCC reboots, line degradation can occur because of a loss of timing. On BLSR rings, this will translate to a ring or span switch. Since the TCC is not up and running, intercard communication is not working, which leads to traffic loss.


If you are currently running a Cisco ONS 15454 using a simplex (single) TCC, TCC+, TCCi, XC, XCVT, XC10G, Cisco strongly recommends you upgrade your system to duplex (dual) TCC and XC cards. Upgrading to a duplex configuration can be performed in service without affecting traffic.

Cisco recommends upgrading your system to duplex TCC's (dual TCC's) prior to upgrading to a newer software release. If you would like details on obtaining an upgrade, please contact your Cisco Sales Representative directly or submit your order using Cisco Marketplace Online.

The Technical Assistance Center (TAC) is unable to support simplex configuration or perform root cause analysis on failed simplex configurations. To support this level of analysis an operational standby TCC is a minimal system requirement.

If you need assistance in upgrading your system to duplex TCCs or XCs please refer to the user documentation or contact the TAC for the correct procedure.

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods: