Specifications

1-16
Cisco MGX 8850 (PXM45) and MGX 8950 Software Configuration Guide
Release 3, Part Number 78-14788-01 Rev. C0, January 2004
Chapter 1 Preparing for Configuration
Planning for Card and Line Redundancy
Figure 1-8 shows how a single AXSM/FRSM-12 connects to redundant lines.
Figure 1-8 Single AXSM/FRSM-12 Front Card Configuration with Redundant Lines
The redundant lines shown in Figure 1-8 are labeled the working line and the protection line, as defined
in the SONET specification for APS. The working line is the primary communications line, and the
protection line takes over if the working line fails. If the protection line is being used for traffic and fails,
the working line takes over.
Two types of APS communications are supported: 1+1 and 1:1. The 1+1 communications type transmits
data on both the working line and the protection line. The 1:1 communications type transmits data on
either the working line or the protection line.
Notice that both the working line and the protection line connect to the same back card in Figure 1-8.
This configuration is also known as an intracard APS configuration. When planning an intracard APS
configuration, consider the following:
• The working line and the protection line must connect to adjacent ports on the same back card.
• The working line must be assigned to an odd-numbered port. For example, the working line could
be on port 1 and the protection line on port 2.
• The working line must be assigned to a lower numbered port than the protection line. For example,
the working line could be on port 3 and the protection line on port 4. If the protection line is on port
2, do not assign the working line to port 3.
AXSM front card AXSM back cards
Working line B
45055
Midplane
Protection line B
Working line A
Protection line A