Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. If you'd prefer to explore, try our test area to get started. And see here for current known issues.

New Member

Compression 3640

I am using 3 BRI's and digital modem Module. when I dial in (using win2k pro laptop) I can never connect faster than 31.2kbps and detail properties of the connection show no compression even though it is on the dialup client.

The following is the config

interface Group-Async1

ip address x.x.x.x

ip helper-address x.x.x.x

ip directed-broadcast

ip nat inside

encapsulation ppp

ip tcp header-compression passive

async mode interactive

peer default ip address pool default

ppp authentication chap

group-range 65 70

What am I missing?


Re: Compression 3640

To raise the connecting speed of your modems, I would recommend that you upgrade your modem firmware.

We have 3640s running with a PRI and I am able to connect a win2k PC with the use of TCP headercompression. Your config resembles what we are running, execpt that we are using virtual interfaces.

Could be an IOS-issue.

Alltogether it would help in troubleshooting when we know what versions you are using. Could you provide the output of sh ver and of sh modem ver?

New Member

Re: Compression 3640

Here is the show ver

Cisco Internetwork Operating System Software

IOS (tm) 3600 Software (C3640-D-M), Version 12.0(7)XK1, EARLY DEPLOYMENT RELEASE


TAC:Home:SW:IOS:Specials for info

Copyright (c) 1986-2000 by cisco Systems, Inc.

Compiled Thu 16-Mar-00 21:16 by phanguye

Image text-base: 0x600088F0, data-base: 0x609FA000

ROM: System Bootstrap, Version 11.1(20)AA2, EARLY DEPLOYMENT RELEASE SOFTWARE (f


ROM: 3600 Software (C3640-D-M), Version 12.0(7)XK1, EARLY DEPLOYMENT RELEASE SOF

TWARE (fc1)

newyork uptime is 27 weeks, 14 hours, 28 minutes

System returned to ROM by reload

System image file is "flash:c3640-d-mz-120-7.XK1"

cisco 3640 (R4700) processor (revision 0x00) with 27648K/5120K bytes of memory.

Processor board ID 21990196

R4700 CPU at 100Mhz, Implementation 33, Rev 1.0

MICA-6DM Firmware: CP ver 2310 - 6/3/1998, SP ver 2310 - 6/3/1998.

Bridging software.

X.25 software, Version 3.0.0.

Basic Rate ISDN software, Version 1.1.

and sh modem ver

newyork#sh modem ver

Slot 2:MICA-6DM Firmware, Source - IOS

CP ver 2310 - 6/3/1998, CheckSum B4585A04.

SP ver 2310 - 6/3/1998.

MICA 0: HW Version 2.1, Serial Number 21149683.

MICA 1: Not Installed.

MICA 2: Not Installed.

MICA 3: Not Installed.

MICA 4: Not Installed.


Thanks for your assistance


Re: Compression 3640

Note that the 3600 does not support V.90 speeds with 2310; you would need at least 2510; 2940 is the latest and supports V.92, but this will require an IOS upgrade too.

As for compression, I'm not sure if you are referring to V.42bis or VJHC; if it's the former, certainly upgrading the modem code may be prudent. If it's the later, the IOS code could be an issue, although I would first suggest you have a look at "debug ppp neg" to see how header-compression is being negotiated.