routing

[dkblee]

hi! i saw a statement in my router

ip route 10.81.2.1 255.255.255.255 10.81.2.254.

what could this statement mean? Only host with the exact ip of 10.81.2.1 will be forwarded to  through gw of 10.81.2.254? it seems to be redundant to me since we already have a static route of /24 for that segment configured.

thx

[John Blakley]

" Only host with the exact ip of 10.81.2.1 will be forwarded to  through  gw of 10.81.2.254?"

Not exactly. In order to get to that host (10.81.2.1) you would need to go through 10.81.2.254 to get to it. The connection would look something like:

10.81.2.50 -> 10.81.2.5 -> 10.81.2.254 -> 10.81.2.1

Above would be a host 10.81.2.50 needing to get to 10.81.2.1. 10.81.2.50's gateway is 10.81.2.5, and it has a connection to 10.81.2.254. 10.81.2.254 knows how to get to 10.81.2.1. Your router needs to know where it needs to send a packet to this particular host. It's HIGHLY possible that in some configurations, you can have something like:

Not redundant:

ip route 10.81.2.0 255.255.255.0 10.81.2.253

ip route 10.81.2.1 255.255.255.255 10.81.2.254

The routers are different, but the host route (the one with  255.255.255.255) is preferred to go over the .254 link.

Redundant:

ip route 10.81.2.0 255.255.255.0 10.81.2.254

ip route 10.81.2.1  255.255.255.255 10.81.2.254

If you have a /24 that is already specified for this network AND the host route is also going to the same destination (10.81.2.254), then you're correct, it's redundant.

HTH,

John

[Ganesh Hariharan]

hi! i saw a statement in my router
ip route 10.81.2.1 255.255.255.255 10.81.2.254.
what
could this statement mean? Only host with the exact ip of 10.81.2.1
will be forwarded to  through gw of 10.81.2.254? it seems to be
redundant to me since we already have a static route of /24 for that
segment configured.
thx

That particular statement means route to the specific host is reachble via 10.81.2.254,If you see the genrall logic for ip route command

Router(config)#ip route network-address subnet-mask {ip-address | exit-interface }

The following parameters are used:

Network-address - Destination network address of the remote network to be added to the routing table
Subnet-mask - Subnet mask of the remote network to be added to the routing table. The subnet mask can be modified to summarize a group of networks.
ip-address - Commonly referred to as the next-hop router's IP address

Hope to Help !!

Ganesh.H

Remember to rate the helpful post