Subscription Option - Extended Packet Sequence Numbering
related documents:
Description of Option
This facility allows packets to contain sequence numbers operating modulo
128 (as opposed to modulo 8).
This facility allows the possibility of a greater throughput on a logical
channel with extended packet sequence numbering, because more packets can be
transmitted without waiting for an acknowledgement.
This facility is indicated by bits 5 and 6 in the GFI and it requires an extra
byte in the packet header of DATA,RR,RNR and REJ packets to hold the sequence
numbers.
UK(a) - this facility is not supported.
UK(b) - this facility is technically possible, although it does not provide
any benefit since packet level acknowledgements are local in UK(b). UK(b) supports
standard (modulo 8) and extended (modulo 128) packet sequence numbering, the
numbering scheme is dependent on link configuration. Only one sequence scheme
may be used during the subscription period.
+--------------------------------------------------------------------------------------------+
| X.2 LEVEL 3 PER USER SUBSCRIPTION | X.2 (1984) | UK(a) | UK(b) |interworking|
| OPTIONS | REF CLASS | now | now |R5a|R5b| R6 | |
+-------------------------------------+-------------+--------+-----+---+---+----+------------|
| Extended packet sequence numbering..| 1.1 A | . |
