Traffic Management; Frame Discard Capability; Efci - 3Com CoreBuilder 7000 Operation Manual

Traffic
Management
Frame Discard
Capability

EFCI

The CoreBuilder 7000 family ATM switch provides several traffic
management services for handling congestion including:

Frame Discard Capability

EFCI
The CoreBuilder 7000 ATM switch can discard cells at the frame (AAL
protocol data unit) level. The switch detects the frame boundaries by
examining the SDU-type in the payload type field of the ATM cell header.
The CoreBuilder 7000 ATM switch can perform the following:


Pass the frame discard indication towards the network


If indication cannot be transported over the output interface (UNI 3.*)
frame discard is not performed.
Discarding Frames for an SVC
The calling party encodes instructions about frame discard in the framed
discard bit in the SETUP message and the called party does the same in
the CONNECT message. The switch generally passes this information
along to an end user but, in certain circumstances, the switch can choose
to drop frames. This can happen in the circumstances shown in Table 35:
Table 35 Discarding Frames
Message
Received Coding
SETUP The forward frame discard bit
is coded to frame discard
allowed
Indication of backward frame
discard allowed
CONNECT The backward frame discard
indication is coded to frame
discard allowed
The CoreBuilder 7000 family ATM switch supports a rate-based algorithm
with Explicit Forward Congestion Indication (EFCI).

Traffic Management

Action
Pass this indication towards
called party.
Can perform frame discard for
the forward direction of the
connection
Pass this indication towards
called party
Pass this indication towards
calling party
Can perform frame discard for
the backward direction of the
connection
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