On 02/26/2014 07:28 AM, Jatin Davey wrote:
> Hi All
>
> I have two hosts. Host A and Host B
>
> Host A routing table
> ------------------------
> [root@localhost ~]# route -n
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use
> Iface
> 172.29.110.0 172.29.109.1 255.255.255.0 UG 0 0 0 eth0
> 172.29.109.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
> 169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
> 0.0.0.0 172.29.109.1 0.0.0.0 UG 0 0 0 eth0
>
> HOST A IP address : 172.29.109.254
>
>
>
> Host B routing table
> -------------------------
> [jatin@localhost ~]$ route -n
> Kernel IP routing table
> Destination Gateway Genmask Flags Metric Ref Use
> Iface
> 172.29.110.0 0.0.0.0 255.255.255.0 U 1 0 0 eth0
> 20.20.20.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
> 169.254.0.0 0.0.0.0 255.255.0.0 U 1002 0 0 eth0
> 0.0.0.0 172.29.110.1 0.0.0.0 UG 0 0 0 eth0
>
> HOST B Ip address : 172.29.110.93
>
>
> Host B basically houses some simulated devices which are configured in
> the ip address range of 20.20.20.1 to 20.20.20.254. The netmask being
> used here is 255.255.255.0
>
> I want to configure a static route on HOST A so that they can reach the
> simulated devices running on HOST B which are in the ip address range
> 20.20.20.1-20.20.20.254 , I am trying the following command but it does
> not configure the static route for me.
>
> [root@localhost ~]# route add -net 20.20.20.0 netmask 255.255.255.0 gw
> 172.29.110.93
> SIOCADDRT: Network is unreachable
>
On B first add route to A's subnet:
route add -net 172.29.109.0 netmask 255.255.255.0 gw 172.29.110.1
Also, 172.29.109.1 and 172.29.110.1 must know how to find each other.
Use ping and traceroute to test availability for every subnet between you.
And see if they can ping each other. Once ping works, your route should
have looked like this:
route add -net 20.20.20.0 netmask 255.255.255.0 gw 172.29.109.1 (always
the first gateway on your way to some IP/subnet!)
BUT considering 172.29.109.1 is ALREADY your DEFAULT gateway, there is
no need to added above route, but fix the other side, that HOST B can
see/ping HOST A.
Consider routing as sending package by mail. You do write destination
address on the package, but you do not carry it yourself. You take it to
closest Post office, clerk looks at the address, finds closest post
office/depot in that direction and sends it on it's way THERE, so
another clerk (router) there looks for closest post office/depo in the
direction of the destination address. BUT, no post clerk/ router only
needs to know NEXT office/depot to sent it to.
Important to take care of is that same applies to returning packet,
routers need to know where the to return the package, NEXT router at the
time.
--
Ljubomir Ljubojevic
(Love is in the Air)
PL Computers
Serbia, Europe
StarOS, Mikrotik and CentOS/RHEL/Linux consultant
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