arp question - "arp who-has" problem

arp question - "arp who-has" problem

Post by kodg » Fri, 17 Jan 2003 01:05:59



hi

i have a simple test network as follows:

----------   -------         -------   ----------
|        |   |     |---------|     |   |        |
| host 1 |---| rt1 |         | rt2 |---| host 2 |
|        |   |     |---------|     |   |        |
----------   -------         -------   ----------
.27.2         .27.1            .28.1      .28.2
              .15.1            .15.3
              .15.2            .15.4

The machines rt1 and rt2 are routers with 3 interfaces each: 1 to the
local subnet (either 27.0/24 or .28.0/24) and 2 interfaces on the .15.0/24
network (the 2 interfaces on .15.0/24 are necessary since this will
eventually be a load-balancing problem). The 6 interfaces on the 2 routers
plug into 1 hub. host 1 is connected to rt 1 via a crossover cable. A
crossover is also used between host 2 and rt 2.

What i'm trying to do is use a machine on one subnet to ping a machine on
a different subnet, and this doesnt work. eg. I cant use host 2 to ping
rt1 or host 1 to ping host 2. But all machines on the same subnet can
communicate just fine eg. rt2 and host2 can ping one another, and rt1 and
rt2 can ping one another.

The following is an example of the problem i'm having. I use rt1 to ping
host 2. When i do, rt2 gets the following message:

        arp who-has 146.141.28.2 tell 146.141.15.1

I know what this means, but i dont know how to send the hardware address
across to 146.141.15.1. Do i need proxy-arp or some sort of arp
forwarding??? Or should I be doing something completely different?

I just dont know where to start when fixing this problem. Pointers to
documentation are more than welcome.

Thanks in advance

kodge
fali at cs.wits.ac.za

NB: this is the network setup I have to use. i'm not in a position to
change it even if I wanted to.

 
 
 

arp question - "arp who-has" problem

Post by Michael Heimin » Fri, 17 Jan 2003 07:12:16



> hi
> i have a simple test network as follows:
> ----------   -------         -------   ----------
> |        |   |     |---------|     |   |        |
> | host 1 |---| rt1 |         | rt2 |---| host 2 |
> |        |   |     |---------|     |   |        |
> ----------   -------         -------   ----------
> .27.2         .27.1            .28.1      .28.2
>               .15.1            .15.3
>               .15.2            .15.4
> The 6 interfaces on the 2 routers plug into 1 hub.

How should that work out, assuming your "hub" isn't some kind of $$ cisco,
able to handle multiple VLANs.

Michael Heiming
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