From: Don Rogers (drogers@xxxxxxxxxxx)
Date: Thu Dec 20 2001 - 15:43:48 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.
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.
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 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.
a"vr4drvr ." wrote:
> Here's a static routing question that I need answered. I do have
> theories,
> but I need a proof positive answer. Simple scenario.
>
> R2---10.1.1.0/24
> R1----|
> R3---10.1.1.0/24
>
> 3 routers are connected to an ethernet segment. R1 has 2 static routes
> to
> the 10.1.1.0/24 network pointing to the IP address of the next hop
> ethernets
> on R2 and R3, thereby providing load balancing and fault tolerance. My
> question is... if an ethernet interface on R2 was to go down, how does
> that
> affect the routing from R1 to the 10.1.1.0 network? For instance, will
> R1
> drop half the traffic? How does the ARP cache on R1 impact routing, or
> rather, how is routing impacted by the ARP cache? Will the static route
>
> through R2 get dropped so to speak?
>
> TIA.
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:32:45 GMT-3