From: vr4drvr . (adrian36@xxxxxxxxxxx)
Date: Thu Dec 20 2001 - 16:18:48 GMT-3
>Many Cisco routers are used to route traffic without using routing
>protocols.
>All routes are static routes. Routes are not learned or advertised.
>However,
>a routing protocol is required for load balancing."
A dynamic routing protocol is not required for load balancing, rather its
sole purpose is to dynamically build a (loop free) routing table as quickly
as possible, which best reflects the network topology even during topology
changes. Although some routing protocols can support unequal cost paths (a
form of load balancing) if configured accordingly.
>An IP routing protocol on R1 is required to get both static routes in the
>IP
>routing table. If you enter two static routes for the same network and you
>are not using a routing protocol, then the first static route goes in the
>routing table. The second will replace the first in the routing table, if
>the
>first goes away.
Having two equal cost routes (paths) will not inhibit the router in any way
from keeping both routes. There is no replacement unless you specify
different metrics or AD's.
>The IP routing protocol performs the load balancing. No routing protocol,
>then no load balancing. When the routing protocol discovers that it no
>longer
>has a route to the next hop, it removes the route from the routing table.
The route lookup (read: the routing table) allows for load balancing (ie.
multiple paths), not the routing protocol. When packets are propogated by
the routing function this is done independently of the routing protocol.
The routing function couldn't care less how the table was built.
>The default timeout on a Cisco router for an arp table is four hours.
>If you are not running a routing protocol between R1, R2, and R3, then it
>may
>take a while for R1 to discover that R2 or R3 has gone away.
ARP timeout is configurable, but yes it is 4 hours by default.
Congrats, you have come to one of the fundamentals of my question!
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:32:45 GMT-3