Bridging
2-78 SONET Port Configuration
The ITU, or International Telecommunications Union (formerly known as the
CCITTÑthe Consultative Committee on International Telegraph and Telephone)
incorporated the SONET standard into its Synchronous Digital Hierarchy (SDH)
recommendations, which address differences between the European and North
American transmission standards. The ITU sets standards for international
communications (except for nations adhering to ANSI standards). SDH is a world
standard, and as such, the SONET standard is considered a subset within it.
The SDH transmission hierarchy uses the STM-1 (Synchronous Transfer Module
Level 1) as its basic building block signal (transmitted at 155.52 Mbps). Again,
there are STM-N signals, which are STM-1 signals that have been multiplexed into
a higher signaling rate.
Table 2-1. SONET/SDH Transmission Hierarchies
You should be sure that the operational mode for both the local and remote ends
of the SONET connection is set appropriately for your region. Setting the wrong
operational mode may cause errors to be generated during transmission, since
there are slight differences in framing SONET and SDH signals.
To access the SONET/SDH ConÞguration window from the Bridge Status
window:
1. Click on the desired Port button ( ) to display the Port menu.
2. Click on SONET/SDH Configuration. The SONET/SDH Configuration: Port X
window, Figure 2-25, will appear.
To access the SONET/SDH ConÞguration window from the Chassis View
window:
1. Click on the appropriate port index to access the Port menu.
2. Click on SONET/SDH Configuration. The SONET/SDH Configuration: Port X
window, Figure 2-25, will appear.
SONET Bit Rate SDH
STS-1/OC-1 51.84 Mbps Ñ
STS-3/OC-3 (supports
FE-100Sx and APIM-2x
in SONET operational
mode)
155.52 Mbps STM-1 (supports
FE-100Sx and APIM-2x
in SDH operational
mode)
STS-12/OC-12 622.08 Mbps STM-4
STS-24/OC-24 1244.16 Mbps Ñ
STS-48/OC-48 2588.32 Mbps STM-16
STS-192/OC-192 9953.28 Mbps STM-64