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SONET/SDH VT Controllers
SONET/SDH VT on cOCx/STMx interfaces support these
options:
- A fractional T1 or E1 line
You assign channel groups of timeslots to configure fractional T1 or E1 over SONET/SDH
VT on cOCx/STMx interfaces. A channel group is the fraction of the
T1 or E1 line and comprises up to 24 T1 timeslots or up to 31 E1 timeslots.
The default channel group speed for both T1 and E1 is 64 Kbps; 56
Kbps is also available.
- An unframed E1 line
Unframed E1 lines have no timeslots reserved for
framing. The router creates one channel for an unframed E1 line and
assigns the number one to that channel.
 |
Note:
To configure a whole T1 or E1 line, assign 24 T1 or 31 E1 timeslots
to a channel group or configure an unframed E1 line.
|
To identify a controller over SONET/SDH VT, you
must consider the multiplexing for SONET and SDH virtual
tributaries. In SONET, an STS-1 frame can be divided into
seven virtual tributary (VT) groups. Similarly, for SDH, an STM-0 frame can be divided into seven
tributary units (TUs). Each group or unit contains a number of virtual
tributaries; that number depends on the VT type or TU name. Table 11 lists the VT types and TU names that the
router supports.
Table 11: Tributary
Standards That cOCx/STMx Interfaces Support
|
VT Type (SONET)
|
TU Name (SDH)
|
Number of Tributaries in a Group
|
Signal Standard
|
|
VT1.5
|
TU-11
|
4
|
T1
|
|
Not supported
|
TU-12
|
3
|
E1
|
Figure 9 shows the structure
for SONET, and Figure 10 shows the structure
for SDH.
Figure 9: SONET Multiplexing
Figure 10: SDH Multiplexing
For both SONET/SDH VT configurations, you must
identify the path and controllers above the path layer. Table 12 shows the identifiers for these configurations,
and Table 13 provides definitions for the identifiers.
Table 12: Identifiers
for SONET/SDH VT Controllers
|
Configuration
|
Identifier
|
Example
|
|
Unframed E1
|
pathChannel/pathPayload/tributaryGroup/tributaryNumber/channelNumber
|
10/1/2/2/1
|
|
NOTE: The router automatically assigns
the channel number one to an unframed E1 line.
|
|
Fractional T1 or E1
|
pathChannel/pathPayload/tributaryGroup/tributaryNumber/channelGroup
|
10/1/2/2/1
|
Table 13: Definitions
for Identifiers for SONET/SDH VT Controllers
|
Identifier
|
Definition
|
Value
|
|
pathChannel
|
An STS-1 or STM-1 line
|
A number in the range 1–2147483648
|
|
pathPayload
|
Number of the payload within the path
|
In SONET mode, pathPayload is always 1.
In SDH mode, pathPayload is the number of the TUG-3 group.
|
|
tributaryGroup
|
Number of the tributary group within the path
|
In SONET mode, tributary group is the number
of the VT group. In SDH mode, tributaryGroup is the number of the TUG-2 group.
|
|
tributaryNumber
|
Number of the tributary within the group
|
In SONET mode, tributaryNumber is the number of the VT. In SDH
mode, tributaryNumber is the number of the TUG-1 group or tributary
unit.
|
|
channelGroup
|
A fraction of a T1 or an E1 line
|
A number in the range 1-24 for T1 or 1-31 for E1
|
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