PM7340 S/UNI-IMA-8
PRELIMINARY
INVERSE MULTIPLEXING OVER ATM
DATA SHEET
PMC-2001723
ISSUE 3
INVERSE MULTIPLEXING OVER ATM
12.3 Configuring the S/UNI-IMA-8
12.3.1 Configuring Clock/Data Interface
The Clock/Data interface has 2 major modes, Channelized for E1/T1 traffic and
unchannelized for other traffic types.
Each link should be configured for channelized/unchannelized mode using the
RCAS/TCAS link configuration registers. If configuring channelized links, the
T1/E1 mode should be configured at the same time.
One configured, the links are still disabled. The links must be mapped and
provisioned (enabled)
12.3.1.1
Channelized
When channelized links are chosen, the RCAS/TCAS Framing Bit threshold must
be configured to detect the gap in the clock for the framing bit/byte. This value is
dependent upon frame type T1/E1, serial clock speed and REFCLK frequency.
The Link Disable feature may be used when configuring a link to squelch all data
from a link while it is being provisioned.
For the Tx direction, the data sent in idle timeslots may be selected with the
TCAS Idle Time-slot Fill data.
For T1, all timeslots are used to carry the ATM cell data so all timeslots should be
mapped to the same virtual link. A one-to-one mapping between physical links
and virtual links is recommended.
For E1, timeslots 0 and 16 are used for signaling data and do not contain ATM
cell data. Therefore, timeslots 1-15 and 17-31 must be mapped and provisioned
(enabled) to carry ATM cell data. All of the timeslots in a link should be mapped
to the same virtual link. A one-to-one mapping between physical links and virtual
links is recommended.
For Fractional links, multiple fractional ATM flows may exist on the same physical
link. Each flow should be mapped to a unique virtual link. There is a limit of 8
virtual links for the S/UNI-IMA-8.
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA, INC., AND FOR ITS CUSTOMERS’ INTERNAL USE
259
PMC [ PMC-SIERRA, INC ]
