question about null 0 static route

[Dr.X]

hi ,

if i type

ip route 1.1.1.1  255.255.255.0 2.2.2.2

ip route 1.1.1.1  255.255.255.0 null0

ip route 0.0.0.0 0.0.0.0 9.9.9.9

========================

if i typed the same route with two netxt hop ,

one to null0 and the other to next hop ip

Q1

what is the behaviuor of router ??

i mean  what is the sequency the router will look in this mannaer ???

will  the packet to 1.1.1.1/24  droped , or it will be forwarded to 2.2.2.2 ?

Q2

if i removed the route

ip route 1.1.1.1  255.255.255.0 2.2.2.2

and still typing

ip route 1.1.1.1  255.255.255.0 null0

ip route 0.0.0.0 0.0.0.0 9.9.9.9

what is the behaviuor of the router ???

regards

AHmad

[John Blakley]

Ahmad,

Q1:

Because they're equal cost routes, they both get put into the routing table. The test that I did received one response and lost one response proving that it was losing traffic by also hitting the null0 interface:

Routing entry for 32.32.32.0/24

  Known via "static", distance 1, metric 0 (connected)

  Routing Descriptor Blocks:

  * 10.10.35.3

      Route metric is 0, traffic share count is 1

    directly connected, via Null0

      Route metric is 0, traffic share count is 1

R5#ping 32.32.32.32

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 32.32.32.32, timeout is 2 seconds:

!.!.!

Success rate is 60 percent (3/5), round-trip min/avg/max = 20/28/36 ms

R5#

S       32.32.32.0 [1/0] via 10.10.35.3

                   is directly connected, Null0

Q2:

This one will fall under the longest match rule. If you have a host going to 1.1.1.1 it will hit the null0 route, everything else would hit the default route.

HTH,

John