Cisco Cisco ONS 15454 SONET Multiservice Provisioning Platform (MSPP) Guía De Diseño

OL-4556-01

 

48

 

288 STS

Ports

 

 
Point-to-multipoint connections are used for drop and continue sites in Path Protection 
Configuration and BLSR nodes.  It is very important to note that when creating point-to-multipoint 
connections, the ratio of ports-to-connections is not 2:1, as it is in point-to-point cross-
connections.  Therefore, when calculating capacities, count terminating STS ports, not 
connections.  When creating a point-to-point circuit, “Connection A,” from Slot 1/Port 3/STS 2 
(1/3/2) to Slot 2/Port 2/STS 4, consumes 2 ports.  Creating a point-to-multipoint circuit, 
“Connection B,” where Slot 2/Port 2/STS 2 maps to Slot 4/Port 4/STS 4 and Slot 5/Port 5/STS 5, 
consumes 3 ports. Subtracting the sum of Connection A (2 ports) and Connection B (3 ports) 
yields 288 – 5 = 283 logical ports remaining on the STS cross-connect.  If these were 
unidirectional flows, Connection A would use 1 port and Connection B would use 1.5 ports.  
Unidirectional connections can be measured in .5 increments, because the cross-connect views a 
bi-directional flow as 2 unidirectional connections.  An STS-1 on any input port can be mapped to 
any output port.  Therefore the STS cross-connect is non-blocking, because it has the capacity to 
switch all 288 ports and STSs to all 288 ports and STSs. 
 

 
The XC-VT has all of the STS cross-connect functions that the XC does, including the Virtual 
Tributary (VT) tunneling.  The XCVT provides non-blocking STS-48 capacity to all of the high-
speed slots and non-bi-directional blocking STS-12 capacity to all multispeed slots.  Any STS-1 
on any port can be connected to any other port, meaning that the STS cross-connections are 
non-blocking. 
 
The STS-1 switch matrix on the XC-VT card consists of 288 bi-directional ports and adds a VT 
matrix that can manage up to 336 bi-directional VT1.5 ports or the equivalent of a bi-directional 
STS-12.  The VT1.5 cross-connect matrix is used when mapping VT1.5 signals from one STS to 
multiple STSs, or performing TSI on the VT1.5s.  The VT1.5 signals can be cross-connected, 
dropped, or rearranged.  The switch matrices are fully cross-point and broadcast supporting.  If