Don't bank on that 4:1. Any compression algorith is highly sensitive
to the nature of the data fed to it, and STAC compression varies all
over the map, sometimes resulting in expansion, not compression. I'm
running STAC compression between two ciscos, and ... well, first
here's what one of them says:
hf1#sh comp
Serial1
uncompressed bytes xmt/rcv 322146882/246678601
1 min avg ratio xmt/rcv 0.875/2.234
5 min avg ratio xmt/rcv 0.455/2.088
10 min avg ratio xmt/rcv 0.507/2.103
no bufs xmt 0 no bufs rcv 0
restarts 0
Additional Stacker Stats:
Transmit bytes: Uncompressed = 552628408 Compressed = 219504205
Received bytes: Compressed = 119881500 Uncompressed = 0
Take these stats with a large grain of salt though; there is clearly a
bug of some sort in their computation, because what one cisco reports
receiving differs widely from what the other reports sending, and both
ends always report having received 0 uncompressed bytes.
Qualitatively, the compression "feels" like it's maybe an effective
average of something less than 2:1 - not really all that much, but
enough to be a big help in extending the life of a 56k to a small POP
while the telcos struggle to get the T1 upgrade working.
-- Dick St.Peters, Gatekeeper, Pearly Gateway, Ballston Spa, NY stpeters@NetHeaven.com Owner, NetHeaven 518-885-1295/800-910-6671 Albany/Saratoga/Glens Falls/North Creek/Lake Placid/Blue Mountain Lake First Internet service based in the 518 area code