AIS AI2524 user manual Autodetect encapsulation encapsulation-type

Chapter 11: AI2524 Sync PPP Configuration Steps

Configure

Automatic

Detection of

Encapsulation

Type

Configure

Compression of

PPP Data

You can enable a serial or ISDN interface to accept calls and dynami- cally change the encapsulation on the interface when the remote de- vice does not signal the call type. For example, if an ISDN call does not identify the call type in the Lower Layer Compatibility fields and is using an encapsulation that is different from the one configured on the interface, the interface can change its encapsulation type on the fly.

This feature enables interoperation with ISDN terminal adapters that use V.120 encapsulation but do not signal V.120 in the call setup mes- sage. An ISDN interface that, by default, answers a call as synchro- nous serial with PPP encapsulation can change its encapsulation and answer such calls.

Automatic detection is attempted for the first 10 seconds after the link is established or for the first 5 packets exchanged over the link, which- ever is first.

In interface configuration mode, enable automatic detection of encap- sulation type:

autodetect encapsulation encapsulation-type

You can specify one or more encapsulations to detect. Cisco IOS soft- ware currently supports automatic detection of PPP and V.120 encap- sulations.

You can configure point-to-point software compression on serial inter- faces that use PPP encapsulation. Compression reduces the size of a

PPPframe via lossless data compression. The compression algorithm used is a predictor algorithm (the RAND algorithm), which uses a compression dictionary to predict the next character in the frame.

PPPencapsulations support both predictor and Stacker compression algorithms.

Compression is performed in software and might significantly affect system performance. Disable compression if the router CPU load ex ceeds 65%. To display the CPU load, use th show process cpu EXEC command.

If the majority of your traffic is already compressed files, do not us compression.

In interface configuration mode, configure compression over PPP:

1.Enable encapsulation of a single protocol on the serial line. encapsulation ppp

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