TMS zl Management and Configuration Guide ST.1.1.100226

9-18
Routing
RIP
Authentication with MD5 is more secure than simple password authentica-
tion. Attackers can intercept a valid RIP packet and read the simple password.
However, message digests are unique to each packet and impossible to
generate without the secret key.
Simple password authentication is most useful for ensuring routers do not
send messages into networks in the wrong area. Just configure a different
simple password for each interface. MD5 authentication, on the other hand,
also protects against hackers.
You configure RIP authentication while enabling RIP on an interface. See page
9-21.
Timing Intervals
RIP specifies certain intervals at which routers must send updates or remove
routes for which they have not received current information. Routers use RIP
timers to regulate these intervals.
Routers broadcast their routing table at the close of every update interval,
which determines the timing for normal, maintenance updates.
The timeout interval determines the amount of time the module will wait
without receiving information about a route before declaring that route
invalid. When the module times out a route, it sends out poison updates for
that route for the next two update cycles. A poison update (metric 16) informs
routers that a route is unusable. Poison updates help speed convergence.
The router does not actually remove a timed-out route from its routing table
until its flush interval expires. The flush interval is the invalid interval plus the
two update intervals in which the router sends out poison updates for the route.
Table 9-5 displays the settings for timing intervals on the TMS zl Module.
Table 9-5. RIP Intervals on the TMS zl Module
Interval Setting in seconds
Update 30
Timeout 180
Poison 120
Flush 120