HELP!!!

[Sugun]

hi ,
i got a problem with my cisco router 2600 series.
The line is 128kbps VSAT connection.
But it never shows the speed of 128kbps , before that we had 32kbps line which was fine compared to this 128kbps.
When the 128kbps was given the connection showed lightning speeds for 1 week then later on it is running like a turtle.
So can u tell me what could be the problem ?
Sometimes it shows good condition , but most of the times it's slow.
When we complain to the ISP then they told that we are using the complete bandwidth that's why the link is appearing to be slow. But even at times when there is harldy one or two persons working , then also the sam problem appears.
So can any one tell me how to solve this problem?

Thanx in advance...

bye
sugun
sugun123@yahoo.com
sugunakar@mail.recw.ernet.in
sugunakar@recw.ernet.in

Here is the output.

RECWarangal>show int
Ethernet0/0 is up, line protocol is up
Hardware is AmdP2, address is 0003.6b6c.fde0 (bia 0003.6b6c.fde0)
Internet address is 202.141.49.1/24
MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, rely 255/255, load 2/255
Encapsulation ARPA, loopback not set, keepalive set (10 sec)
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
5 minute input rate 25000 bits/sec, 27 packets/sec
5 minute output rate 108000 bits/sec, 20 packets/sec
11392 packets input, 1400975 bytes, 0 no buffer
Received 1825 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
0 input packets with dribble condition detected
8473 packets output, 5852217 bytes, 0 underruns
0 output errors, 1 collisions, 2 interface resets
0 babbles, 0 late collision, 18 deferred
0 lost carrier, 0 no carrier
0 output buffer failures, 0 output buffers swapped out

Serial0/0 is up, line protocol is up
Hardware is PowerQUICC Serial
Description: ## Scpc link of RECWarangal ##
Internet address is 202.41.103.126/30
MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec, rely 255/255, load 87/255
Encapsulation HDLC, loopback not set, keepalive not set
Last input 00:00:08, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: weighted fair
Output queue: 0/1000/64/0 (size/max total/threshold/drops)
Conversations 0/27/256 (active/max active/max total)
Reserved Conversations 0/0 (allocated/max allocated)
5 minute input rate 117000 bits/sec, 21 packets/sec
5 minute output rate 22000 bits/sec, 26 packets/sec
9105 packets input, 6574658 bytes, 0 no buffer
Received 20 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
10194 packets output, 1152055 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
DCD=up DSR=up DTR=up RTS=up CTS=down

 

[svermill]

Looking at your interface statistics, it looks as if you are getting about 117 kbps down and 22 kbps up. So from a pure bits per second perspective, your ISP is correct. You are using all of your bandwidth. However, you need to look deeper. How many of those 117 kbps down are retransmissions? Witch TCP, you have some serious issues to contend with when there is a lot of delay on the line, or, stragely enough, too much bandwidth. The typical *maximum* tcp window size is 64 kbytes. That is the most data that can be "in flight" or "on the wire" without being acknowledged. The formula for determining this is:

datarate in bps / 8 * roundtrip delay.

Some pings will give you your average roundtrip delay. Probably between half a second a full second via satellite. Then, if possible, compare that against your TCP window size.

Of course, this is just one of many possibilities. It is strange that your performance was good for a while and then bad later. My delay theory doesn't really address that issue does it?