help :giaddr

[Simon Hobson]

I now see what your problem is - you appear to have little 
understanding of IP addressing & routing. A bit like an architect 
having no knowledge of building materials.

And a quick rant before I reply - PLEASE DON'T POST IN HTML THAT 
SCREWS UP THE CONTENT. I fyou want help, then don't leave the people 
offering it to have to edit :
<http://192.168.2.0>192.168.2.0     <http://0.0.0.0>0.0.0.0 
<http://255.255.255.0>255.255.255.0   U         0 0          0 eth1

to :

192.168.2.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1



abhijit khadatare wrote:

>thanks for ur helpfull reply.
>my network topology is as below
>
>client----->layer2-[switch]----->[if0]router[if1]-------[isc]dhcp server
>
>layer2 switch is manager switch----192.168.1.46/24
>router interface0 -----192.168.1.1/24
>router interface 1---192.168.2.5/24
>dhcp server ------192.168.2.1/24
>
>i'm putting giaddr as layer2 switch which is 192.168.1.46
>  PROBLEM  is discover is reached upto the server ,but we dont get any offer
>routing table is as below
>#route -en
>Kernel IP routing table
>192.168.2.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
>192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
>0.0.0.0         192.168.0.1     0.0.0.0         UG        0 0          0 eth0
>
>but when i add static route for 192.168.1.1 on server
>
>#route -en
>Kernel IP routing table
>Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
>192.168.2.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
>192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1
>192.168.0.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
>0.0.0.0         192.168.0.1     0.0.0.0         UG        0 0          0 eth0

You have NOT added a route to 192.168.1.1 here ! That line should read :
192.168.1.0     192.168.2.5     255.255.255.0

>then we got offer we saw on wireshark that
>discover   from 192.168.2.5 to 192.168.2.1
>offer from 192.168.2.1 to 192.168.1.46

That is worrying. The request is from 192.168.2.5 but the reply is to 
192.168.2.46. My guess here is that you have configured both the 
layer2 switch AND the router to do DHCP forwarding. You do NOT need 
to do this, the layer2 switch should be transparent to DHCP requests 
- or if you need it to act as the relay agent (such as to use the 
circuit ID), then you need to configure the router to NOT also mangle 
the packets.


Now, to your DHCP config posted in your first message.

>shared-network 224-29 {
>   subnet 192.168.2.0 netmask 255.255.255.0 {
>   }
>   subnet 192.168.1.0 netmask 255.255.255.0 {
>   }
>   pool {
>
>     allow members of "foo";
>   log(info ,("ur known to me"));
>     range 192.168.1.25 192.168.1.50;
>   }
>
>   pool {
>     deny members of "foo";
>     ignore unknown-clients;
>     range 192.168.2.140 192.168.2.150;
>   }
>  }

192.168.1.0/24 and 192.168.2.0/24 are on different networks separated 
by a router - you do NOT have a shared network.

Also, your pool declarations should be INSIDE the subnet declarations, thus :

subnet 192.168.2.0 netmask 255.255.255.0 {
   pool {
     deny members of "foo";
     ignore unknown-clients;
     range 192.168.2.140 192.168.2.150;
   }
}
subnet 192.168.1.0 netmask 255.255.255.0 {
   pool {
     allow members of "foo";
    log(info ,("ur known to me"));
     range 192.168.1.25 192.168.1.50;
   }
}