(just for network purposes I know I can use other methods)

Hey guys, I am trying to ping pc1 pc2 pc3 pc4 (on r1-r5 respectively) to pc5 and vice versa but it does not seem to work please could someone help me I cant see how to fix the problem.

Below is a diagram and configuration of how I hope the network to look! enter image description here

If anyone can see where I am going wrong or help with anything that would be appreciated thankyou.

  • BTW, have you got a bit more info on this 'netkit' you are using: the interweb is full of 'netkit' products, distros & companies.
    – DutchUncle
    Feb 21 '11 at 17:54
  • yes its a virtual environment (in Linux) that I am using to simulate my network. ( I have used the static routing lab provided by netkit but I am trying to implement 5 routers instead of 2)
    – donok
    Feb 21 '11 at 18:04
  • OK, so this 'netkit' is part of the packages on your linux distro? If so, what distro and what's the package name?
    – DutchUncle
    Feb 21 '11 at 18:12
  • 1
    distro: ubuntu and the package name is based on User Mode Linux it can be found on wiki.netkit.org sorry is that what you meant?
    – donok
    Feb 21 '11 at 18:20
  • Donok: as you know, I put some effort into one of your earlier questions that was very similar. Are we just doing your networking homework for you? Community, you might want to look at serverfault.com/questions/238180/… and serverfault.com/questions/237902/… in the context of this question.
    – MadHatter
    Feb 21 '11 at 19:46

Edited to include 4 possible errors I found

`1. There is a route missing on R2, it does not know how to access the subnet Try adding on R2:

route add -net netmask gw dev eth3

(but please check this previous line first yourself)

`2. on R2, you don't need to explicity add the route to, but you need to add a route to the net behind R4, On R2 again type:

route add -net netmask gw dev eth2

(again, check this previous line!)

`3. on R5: the broadcast address on R5/eth1 seems to be wrong, it should be 2 00. 3.3.11 .

`4. on R4: on eth1, broadcast should be 100.2.2. 11 .

  • Thanks I have added what is mentioned yet I am still at square one I even added on r5 route add -net gw yet I still cannot get anywhere, Thanks alot for your help btw.
    – donok
    Feb 21 '11 at 20:28

Are the "routers" Linux PC's?

If your answer was "yes", then is the output of

# cat /proc/sys/net/ipv4/ip_forward

1 ?

If you have a "0" there, then no packet forwarding will be done. Try doing

echo 1 > /proc/sys/net/ipv4/ip_forward

If these are not Linux routers then forget this answer.

  • I forgot to mention there is no firewalls etc Ive allowed all to be set to 1 so they can all communicate my question is I think I have not set a default gateway on one of the routers but I just cant seem to see where.
    – donok
    Feb 21 '11 at 17:27
  • they are virtual machines by the way.
    – donok
    Feb 21 '11 at 17:28
  • I just need to get my rep up by one so I can show you the diagram of what I mean.
    – donok
    Feb 21 '11 at 17:30
  • 1
    I've done you +5. Now let's see a diagram at last :-)
    – DutchUncle
    Feb 21 '11 at 17:51
  • @UnisoftDesign thank you just uploaded the diagram :).
    – donok
    Feb 21 '11 at 17:52

The broadcast address on R5/eth1 seems to be wrong, it should be 2 00. 3.3.11.

Similarly on R4: on eth1 broadcast should be 100.2.2. 11 .

  • my pc5 can ping pc1- pc4 but it does not receive the reply, do you have any idea why? so it can partially ping.
    – donok
    Feb 21 '11 at 18:29
  • The problem lies with r5 as it does not have a clue how to access r1 and r3 r4r2 but I dont know what I need to set as a gateway on r5.
    – donok
    Feb 21 '11 at 18:56
  • No, I don't think so, see my new answer below.
    – rems
    Feb 21 '11 at 19:25
  • @rems: You have 3 answers to this question. You may want to edit them all into one as the site randomises the way they are displayed if they all have equal votes and they get out of sequence.
    – user9517
    Feb 21 '11 at 20:21
  • Ok, put together in the previous one.
    – rems
    Feb 22 '11 at 9:45

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