Cabletron Systems CSX1000, CSX1200 manual Compression Options Background Information

USER’S GUIDE

configuration. If this option is disabled, the system will not negotiate compression with any remote device. The default value is enabled.

Note that enable/disable applies to all protocols which support compression.

DEFAULT PER-DEVICE COMPRESSION SETTING

You may enable or disable the per-device compression setting. This is in addition to the global compression enable/disable state described above. The Default Per-Device Compression setting defines the initial value for the per-device state when you add a new device to the on-node device table. Or, if the device is authenticated via an off node server, the device will be given its compression enable/disable state based on this value when no value is delivered by the off-node database.

You may later change a specific device’s enable/disable state.

The per-device compression enable/disable state is only supported for connections using the PPP protocol. The default value is enabled.

STARTING PPP STAC-LZS SEQUENCE NUMBER

Default value is 1. When using PPP Compression with the STAC-LZS protocol, a sequence numbering scheme can be used whose initial value is required to be 1 by the protocol specification. Some devices from other vendors do not start with 1. This results in a resynchronization sequence on the first frame which is exchanged. When the user device fully supports the CCP protocol’s Reset mechanism, this will only result in the minor inconvenience of a lost frame at the beginning of a session. However, if such a device’s resynchronization mechanism is to completely renegotiate CCP, this sequence will repeat infinitely.

This option provides an escape mechanism to allow interworking with such devices by modifying the initial PPP STAC sequence number.

The Starting PPP STAC Sequence Number is maintained for each device. The value which appears on this configuration screen provides the default value for the per-device value. When you add a new device to the on-node device table, that device’s starting sequence number option will be assigned the value which appears on this screen. You can then change this for each individual device. Or, if the device is authenticated via an off node server that does not deliver a value for this configuration item, the device will be given its starting sequence number from the value on this menu

As its name implies, this option only applies to connections which utilize the PPP protocol with STAC-LZS compression and sequence numbers checking.

COMPRESSION OPTIONS BACKGROUND INFORMATION

The system data compression capability allows the system to negotiate compression algorithms with a remote device. This compression can be done using some proprietary bridging protocols and also the PPP CCP protocol.

After successfully negotiating compression, data is compressed by a peer and transmitted to the system. The system decompresses the data, processes the addressing information contained in the device data, and transmits the data as required. The converse is also true, the system can receive data coming from a WAN or LAN, compresses the data before transmitting it to a peer. The net

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