Hello,
the load threshold is based on the transmit and/or receive load of the interface. You can see the load with the command:
1721#show interface bri0
BRI0 is up, line protocol is up (spoofing)
Hardware is BRI
MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,
----------------------------------------------------
reliability 255/255, txload 1/255, rxload 1/255
----------------------------------------------------
Encapsulation PPP, loopback not set
Last input 00:00:02, output never, output hang never
Last clearing of "show interface" counters 1d19h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/1/16 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
Available Bandwidth 48 kilobits/sec
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
15685 packets input, 62743 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
15685 packets output, 62743 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
3 carrier transitions
The load is based on a scale from 1 to 255, where 255 would be 100%. A load threshold of 153 would be 60%.
Once the second B-channel comes up, twice the line capacity is available, and the buffers will be filled up less, accordingly...not sure if that is what you are asking.
Regards,
Georg