Intel ER8100STUS - Express 8100 Router, Reference Manual

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Reference.bok : Chapter09 80 Wed Apr 22 10:58:08 1998
80
Novell Routing Concept
Novell IPX Routing
Sequenced Packet eXchange (SPX) is equivalent to the Transmission Control
Protocol (TCP) in the IP protocol suite.
SPX Keep-alive packets
When using IPX/SPX protocol, the keep-alive function is taken care of by the
SPX transport protocol, rather than by the IPX network protocol. As with IPX,
SPX uses keep-alive packets to keep sessions alive—when an established session
has not communicated within a predefined time interval, SPX keep-alive packets
are used to determine if the session is still established. If an established session
fails to respond to a predefined number of SPX keep-alive packets, the session is
terminated. Unlike IPX watchdog packets, SPX keep-alive packets can be sent
by all the network devices in the session.
SPX Keep-alive packets
over WAN links
As with IPX watchdog packets, SPX keep-alive packets can cause problems
when communicating over dial-up (switched) WAN links. If a number of SPX
sessions are established over a WAN link, the link may never get the chance to
become inactive and so the operating costs may be high. In addition, if the WAN
link is brought down by some other reason, the SPX sessions may be terminated
prematurely.
1464
WAN
with an on-demand
timecut connection
Network
devices
Network
devices
Session 1 Session 1
Session 2 Session 2
Session 3 Session 3
Router 2 Router 1
SPX Keep-alive Packets
SPX Keep-alive Packets
SPX Keep-alive Packets
SPX Keep-alive Responses
SPX Keep-alive Responses
SPX Keep-alive Responses
#1
#2
LAN WAN 1 WAN 2 System
® Intel Express Router 9200
LAN WAN 1 WAN 2 System
® Intel Express Router 9200