Simplex TCC, TCC+, TCCi, XC, XCVT and XC10G Configurations Are Unsupported

Revised April 18, 2002

June 16, 2000

---

Products Affected

Product	Comments
Cisco ONS 15454	(All Simplex configurations running code versions later than 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 can cause a traffic outage. Node connectivity issues are also a known problem of simplex TCC operation and can result in the inability to manage a network element (NE).

Background

The ONS 15454 was designed as a duplex system for redundancy and reliability purposes. Background processes are run between common equipment in order to ensure the health of the system. Although the system can run in simplex mode, Cisco does not perform software verification and reliability testing on nonredundant ONS 15454 systems. Therefore, Cisco cannot endorse simplex configurations.

Problem Symptoms

In networks that operate nonredundant TCCs or XCs, a failure of either of these boards can result in a traffic outage.

Simplex TCC Operation

These are some issues that you can expect to see if you run an ONS 15454 with a nonredundance TCC, where the TCC is reset 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 can be a period of approximately 2 minutes when no intercard messages are passed. This can have severe traffic implications if a protection switch needs to occur during this time frame.

No access to the node-If the single TCC is reset for any reason, there is a time frame of at least 2 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 because none of the administrative data can be communicated to the resetting node. If the TCC has failed, you need to physically insert a known good TCC to restore traffic.

Software Upgrade-If you encounter a problem during a software upgrade, you can experience significant downtime if you operate 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 verification process. If a problem occurs during activation, you may need to physically reset the node to restore traffic.

Timing-Since the TCC sources the synchronization 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, such as DS3/DS3E, when you operate in this mode.

E100/E1000 cards-During a TCC reset, all E100/E1000 traffic is down because spanning tree runs on the TCC.

Simplex XC Operation

The problem can occur during a reset of a simplex XC. During the reset, an outage results that can 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 is lost as the card reboots.

XC Soft Resets-While the XC soft resets, there is the possibility that no protection (1+1, BLSR and UPSR) works. If there is a line or path problem during the reset, traffic is lost.

IO Card Reboots-During card reboots, bus noise can be present that can cause the XC to switch to the peer. In a simplex system, this results 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 diagnostics are only run on the standby card to help detect and fix problems. In a simplex system, diagnostics do not run, and therefore, cannot catch these problems. This 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 translates to a ring or span switch. Since the TCC is not up and running, intercard communication does not work, which leads to traffic loss.

Workaround/Solution

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

Cisco recommends upgrading your system to duplex TCCs (dual TCCs) prior to upgrading to a newer software release. For details on how to obtain an upgrade, contact your Cisco Sales Representative directly or submit your order using Cisco Marketplace.

Cisco Technical Support 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, refer to the user documentation or contact Cisco Technical Support 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:

• Open a service request on Cisco.com
• By email
• By telephone

Receive Email Notification For New Field Notices

Product Alert Tool - Set up a profile to receive email updates about reliability, safety, network security, and end-of-sale issues for the Cisco products you specify.

---