Intel ER8100STUS - Express 8100 Router, Справочное руководство

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Reference.bok : Chapter09 74 Wed Apr 22 10:58:08 1998
74
Novell Routing Concept
Novell IPX Routing
The hops are also used to discard packets in case of looping, see “Looping pack-
ets” in “Data Transmission”, p. 76 .
Metrics for RIP and SAP
Separate metrics (tics and hops) are calculated for dynamic routes (established
using IPX RIP) and dynamic services (established using IPX SAP). These met-
rics are calculated automatically by the RIP and SAP protocols.
Metrics for static IPX
routes and services
For static IPX routes and services, the time ticks and hops to networks and ser-
vices cannot be calculated by the router. These parameters must therefore be
manually calculated and defined for each static route and service.
Manually calculating
metrics for static routes
and services
When configuring static IPX routes and services, the best way to obtain the met-
rics for static routes and services is by enabling dynamic routing (using RIP and
SAP) and reading the metrics from the routing and service table for the router,
see
“Establishing static routes and static services” in “Static Routes and Servic-
es”, p. 90 . However, in some cases the metrics for a link may need to be calcu-
lated manually.
Note
The delay for a route or service is the accumulated delays for all the
paths to the route or service.
The metrics can be calculated manually as follows:
Delays (Ticks)
The delay for a link is associated with the speed (baud rate) of the link and can
simply be calculated as:
Link Delay (ticks)
=
1100
/
Link Speed (kbps)
.
For example, a 64 kbps WAN link would have the following delay:
1100 / 64 = 17.2
ticks.
This is only an approximation of the link delay calculated by the router (the rout-
er calculation is more complex and would assign a delay of 18). You should
therefore try to use the delay calculated by the router (for the dynamic route or
service you are trying to replace) wherever possible.
Hops
The hops is simply the number of intermediate networks that must be passed in
order to reach the destination network.