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Table Of Contents
8.2.2 Synchronization Status Messaging
Security and Timing
This chapter provides information about Cisco ONS 15454 users and SONET timing. To provision security and timing, refer to the Cisco ONS 15454 Procedure Guide.
Chapter topics include:
8.1 Users and Security
The CISCO15 user provided with each ONS 15454 can be used to set up other ONS 15454 users. You can add up to 500 users to one ONS 15454. Each ONS 15454 user can be assigned one of the following security levels:
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Retrieve users can retrieve and view CTC information but cannot set or modify parameters.
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Table 8-1 shows the actions that each user can perform in node view.
Each ONS 15454 user has a specified amount of time that he or she can leave the system idle before the CTC window is locked. The lockouts prevent unauthorized users from making changes. Higher-level users have shorter idle times, as shown in Table 8-2.
Table 8-2 ONS 15454 User Idle Times
Superuser
15 minutes
Provisioning
30 minutes
Maintenance
60 minutes
Retrieve
Unlimited
You can perform ONS 15454 user management tasks from network or node view. In network view, you can add, edit, or delete users from multiple nodes at one time. If you perform user management tasks in node view, you can only add, edit, or delete users from that node.
Note
8.2 Node Timing
SONET timing parameters must be set for each ONS 15454. Each ONS 15454 independently accepts its timing reference from one of three sources:
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You can set ONS 15454 timing to one of three modes: external, line, or mixed. If timing is coming from the BITS pins, set ONS 15454 timing to external. If the timing comes from an OC-N card, set the timing to line. In typical ONS 15454 networks:
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You can set three timing references for each ONS 15454. The first two references are typically two BITS-level sources, or two line-level sources optically connected to a node with a BITS source. The third reference is the internal clock provided on every ONS 15454 TCC+ card. This clock is a Stratum 3 (ST3). If an ONS 15454 becomes isolated, timing is maintained at the ST3 level.
Caution
8.2.1 Network Timing Example
Figure 8-1 shows an ONS 15454 network timing setup example. Node 1 is set to external timing. Two timing references are set to BITS. These are Stratum 1 timing sources wired to the BITS input pins on the Node 1 backplane. The third reference is set to internal clock. The BITS output pins on the backplane of Node 3 are used to provide timing to outside equipment, such as a Digital Access Line Access Multiplexer.
In the example, Slots 5 and 6 contain the trunk cards. Timing at Nodes 2, 3, and 4 is set to line, and the timing references are set to the trunk cards based on distance from the BITS source. Reference 1 is set to the trunk card closest to the BITS source. At Node 2, Reference 1 is Slot 5 because it is connected to Node 1. At Node 4, Reference 1 is set to Slot 6 because it is connected to Node 1. At Node 3, Reference 1 could be either trunk card because they are equal distance from Node 1.
Figure 8-1 An ONS 15454 timing example
8.2.2 Synchronization Status Messaging
Synchronization Status Messaging (SSM) is a SONET protocol that communicates information about the quality of the timing source. SSM messages are carried on the S1 byte of the SONET Line layer. They enable SONET devices to automatically select the highest quality timing reference and to avoid timing loops.
SSM messages are either Generation 1 or Generation 2. Generation 1 is the first and most widely deployed SSM message set. Generation 2 is a newer version. If you enable SSM for the ONS 15454, consult your timing reference documentation to determine which message set to use. Table 8-3 and Table 8-4 show the Generation 1 and Generation 2 message sets.
Posted: Mon Feb 25 15:34:44 PST 2008
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