ISDN/PSTN compression on Dial Up

[shovels3]

I've configured a 3725 for Dial-Up ISDN/PSTN access using a E1 PRI card.

We are using Microsoft clients.

I was wondering is it worth putting compression on the Dialer interface or is there any gain from doing this?

Does it improve the performance of the router/client?

Thanks

[makchitale]

Sure compression does have its benefits; you can enable mppc on the 3745 for dialup clients:

http://www.cisco.com/en/US/tech/tk713/tk802/technologies_configuration_example09186a00801c13b3.shtml

http://www.cisco.com/warp/public/cc/pd/iosw/tech/compr_wp.htm

Some key points for MPPC:

• Supports point-to-point connections for Microsoft clients.

• Optimizes bandwidth utilization.

• Operates under Multilink PPP (MLP) and Virtual Private Dial-Up Networks (VPDN). CCP runs under the bundled MLP interfaces. Compression takes place before the packets are handed off to the MLP layer in the transmitter side, and decompression occurs after the MLP layer distributes received packets to each interface in the bundled MLP group; therefore, MPPC is transparent to the MLP layer.

Restrictions

The following restrictions apply to the MPPC feature:

• MPPC is only supported with PPP encapsulation.

• Compression can be processor intensive because it requires a reserved block of memory to maintain the history buffer. Do not enable modem or hardware compression because it may cause performance degradation, compression failure or data expansion.

• Both ends of the point-to-point link must be using the same compression method (STAC, Predictor or MPPC, for example).

Thanks, Mak