ELSA Lancom DSL/10 Office, Руководство пользователя

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Operating modes and functions
ELSA LANCOM DSL/10 Office
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Which information does the router take from received IP RIP packets?
When the router receives such IP RIP packets, it incorporates them in its dynamic routing
table, which looks something like this:
What do the entries mean?
IP address and network mask identify the destination network, the distance shows the
number of routers between the transmitter and receiver, the last column shows which
router has revealed this route. This leaves the 'Time'. The dynamic table thus shows
how old the relevant route is. The value in this column acts as a multiplier for the
intervals at which the RIP packets arrive. A '1', therefore, stands for 30 seconds, a '5' for
about 2.5 minutes and so on. New information arriving about a route is, of course,
designated as directly reachable and is given the time setting '1'. The value in this
column is automatically incremented when the corresponding amount of time has
elapsed. The distance is set to '16' after 3.5 minutes (route not reachable) and the route
is deleted after 5.5 minutes.
Now if the router receives an IP RIP packet, it must decide whether or not to incorporate
the route contained into its dynamic table. This is done as follows:
K
The route is incorporated if it is not yet listed in the table (as long as there is enough
space in the table).
K
The route exists in the table with a time of '5' or '6'. The new route is then used if
it indicates the same or a better distance.
K
The route exists in the table with a time of '7' to '10' and thus has the distance '16'.
The new route will always be used.
K
The route exists in the table. The new route comes from the same router which
notified this route, but has a worse distance than the previous entry. The route is
discarded.
Interaction: static and dynamic tables
The router uses the static and dynamic tables to calculate the actual IP routing table it
uses to determine the path for data packets. In doing so, it includes the routes from the
dynamic table which it does not know itself or which indicate a shorter distance than its
own (static) route with the routes from its own static table.
IP address IP netmask Time Distance Router
192.168.120.0 255.255.255.0 1 2 192.168.110.1
192.168.130.0 255.255.255.0 5 3 192.168.110.2
192.168.140.0 255.255.255.0 1 5 192.168.110.3