The PA-MC-STM-1 is a high-speed, single-port multichannel STM-1 port adapter. You can configure the PA-MC-STM-1 as a multichannel E1 STM-1 port, which can be configured into 63 individual E1 links. Each E1 link can carry a single channel at full or fractional rates, or it can be broken down into multiple DS0 rates. However, the maximum number of channels is limited to 256 per PA-MC-STM-1.The PA-MC-STM-1 supports up to three TUG-3/AU-3 transport slots numbered 1 to 3. You can configure each TUG-3/AU-3 to carry 21 SDH TU-12s. Each SDH TU-12 is capable of carrying a channelized E1 frame, which can be unchannelized to n 64-Kbps time slots.