Enterasys csx150 Guida Utente
USER’S GUIDE
328 CyberSWITCH
compression enable/disable state based on this value when no value is delivered by the off-node
database.
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.
protocol. The default value is enabled.
S
TARTING
PPP STAC-LZS S
EQUENCE
N
UMBER
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.
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 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
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.
STAC-LZS compression and sequence numbers checking.
C
OMPRESSION
O
PTIONS
B
ACKGROUND
I
NFORMATION
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.
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
effect is to increase effective interconnect bandwidth by decreasing transmission time. If
negotiation for compression fails, data is transmitted uncompressed.
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
effect is to increase effective interconnect bandwidth by decreasing transmission time. If
negotiation for compression fails, data is transmitted uncompressed.
The compression algorithm implemented is STAC-LZS. This algorithm is used in all of STAC’s data
compression products. This software version is fully compatible with STAC’s data compression
compressor chips including the multi-tasking features. STAC-LZS data compression is performed
by replacing redundant strings in a data stream with shorter tokens. The STAC-LZS uses a
compression history, or sliding window, as opposed to a structured dictionary. This allows greater
flexibility and a greater number of possible string comparisons during compression process. The
compression history automatically discards old information as new information is processed. Both
the device and system must perform compression using the STAC-LZS data compression
compression products. This software version is fully compatible with STAC’s data compression
compressor chips including the multi-tasking features. STAC-LZS data compression is performed
by replacing redundant strings in a data stream with shorter tokens. The STAC-LZS uses a
compression history, or sliding window, as opposed to a structured dictionary. This allows greater
flexibility and a greater number of possible string comparisons during compression process. The
compression history automatically discards old information as new information is processed. Both
the device and system must perform compression using the STAC-LZS data compression