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Cisco ONS 15454 Installation and Operations Guide
November 2001
Chapter 6 Circuits and Tunnels
Cross-Connect Card Capacities
6.8.1 VT1.5 Cross-Connects
XCVTs and XC10Gs can map up to 24 STSs for VT1.5 traffic. Because one STS can carry 28 VT1.5s,
the XCVT and XC10G cards can terminate up to 672 VT1.5s, or 336 VT1.5 cross-connects. However,
to terminate 336 VT1.5 cross-connects:
• Each STS mapped for VT1.5 traffic must carry 28 VT1.5 circuits. If you assign each VT1.5 circuit
to a different STS, the XCVT and XC10G VT1.5 cross-connect capacity will be reached after you
create 12 VT1.5 circuits.
• ONS 15454s must be in a bidirectional line switched ring (BLSR). Source and drop nodes in UPSR
or 1+1 (linear) protection have capacity for only 224 VT1.5 cross-connects because an additional
STS is used for the protect path.
Table 6-4 shows the VT1.5 capacities for ONS 15454 cross-connect cards. All capacities assume each
VT1.5-mapped STS carries 28 VT1.5 circuits.
Figure 6-9 shows the logical flow of a VT1.5 circuit through the XCVT/XC10G STS and VT matrices
at a BLSR node. The circuit source is an EC-1 card using STS-1. After the circuit is created:
• Two of the 24 XCVT or XC10G STSs available for VT1.5 traffic are used (one STS for VT1.5 input
into the VT matrix; one STS for VT1.5 output).
• 22 STSs are available for VT1.5 circuits.
• The STS-1 from the EC-1 card has capacity for 27 more VT1.5 circuits.
Table 6-3 XC, XCVT, and XC10G Card STS Cross-Connect Capacities
Card Total STSs STS Cross-connects
XC 288 144
XCVT 288 144
XC10G 1152 576
Table 6-4 XC, XCVT, and XC10G VT1.5 Capacities
Card
Total VT1.5s
(BLSR)
VT1.5 Cross-Connect
Capacity (BLSR)
VT1.5 Cross-Connect Capacity
(UPSR or 1+1)
XC 0 0 0
XCVT 672 336 224
XC10G 672 336 224