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  • Extending Subnet issue

    Hello team,

    I have a subnet 192.168.9.0 255.255.254.0 192.168.9.1

    I add a second subnet 192.168.8.0 255.255.254.0 192.168.9.1

    the .8 subnet access the .9 fine.. but the .9 cannot see the .8 sub.

    what did I do wrong?

    please help.

    Thanks,

  • #2
    Re: Extending Subnet issue

    They should be able to see each other....
    Can you post an ipconfig/all from a PC on each subnet and maybe we can troubleshoot a bit more

    Where are they getting IPs from?
    Tom Jones
    MCT, MCSE (2000:Security & 2003), MCSA:Security & Messaging, MCDBA, MCDST, MCITP(EA, EMA, SA, EDA, ES, CS), MCTS, MCP, Sec+
    PhD, MSc, FIAP, MIITT
    IT Trainer / Consultant
    Ossian Ltd
    Scotland

    ** Remember to give credit where credit is due and leave reputation points where appropriate **

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    • #3
      Re: Extending Subnet issue

      Those networks are on the same subnet so they should be able to see each other directly though ARP as routing isnt needed.


      192.168.8.0/23 = 192.168.8.0 - 192.168.9.255


      With a /23 the subnets would increment by 2 in the third octet.


      192.168.8.0

      192.168.10.0

      192.168.12.0

      etc....
      Last edited by auglan; 8th June 2012, 14:20.
      CCNA, CCNA-Security, CCNP
      CCIE Security (In Progress)

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      • #4
        Re: Extending Subnet issue

        see the attachment..
        I have one client configure the .99 sub which cannot see the .98

        and i have one client configure the .98 sub and it see the .99 sub fine.
        Attached Files

        Comment


        • #5
          Re: Extending Subnet issue

          Both hosts are on the same layer 3 subnet as I previously stated. The first host has a /23 subnet mask configured and the second host has a /24. You need to change the subnet mask on the second host to a /23.


          These are not separate subnets. The range is 192.168.98.0/23 === 192.168.98.0 - 192.168.99.255


          Like I previously stated they should be able to resolve layer 3 to layer 2 (ARP) directly with no routing involved.
          Last edited by auglan; 8th June 2012, 15:08.
          CCNA, CCNA-Security, CCNP
          CCIE Security (In Progress)

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          • #6
            Re: Extending Subnet issue

            yes.. that is what I did.. change the 2nd host to /23. is it not resolving because my switch still using /24?


            Originally posted by auglan View Post
            Both hosts are on the same layer 3 subnet as I previously stated. The first host has a /23 subnet mask configured and the second host has a /24. You need to change the subnet mask on the second host to a /23.


            These are not separate subnets. The range is 192.168.98.0/23 === 192.168.98.0 - 192.168.99.255


            Like I previously stated they should be able to resolve layer 3 to layer 2 (ARP) directly with no routing involved.

            Comment


            • #7
              Re: Extending Subnet issue

              As long as they are on the same subnet they should be able to reach each other directly as they are on the same Layer 3 network. I assume they are also on the same Layer 2 network (same vlan) but I dont what switch you are using or what the configuration is.
              CCNA, CCNA-Security, CCNP
              CCIE Security (In Progress)

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              • #8
                Re: Extending Subnet issue

                sorry for stupid question..

                how do I know my network is Layer 2 or 3.

                the 192.168.99.x cannot see 192.168.98.x is it because it's on Class C sub?

                EDIT: it's working now.. the reason I couldnt ping the .98 because the windows firewall blocked the ping
                thanks for everyone help

                Originally posted by auglan View Post
                As long as they are on the same subnet they should be able to reach each other directly as they are on the same Layer 3 network. I assume they are also on the same Layer 2 network (same vlan) but I dont what switch you are using or what the configuration is.
                Last edited by Humannetwork; 8th June 2012, 20:26.

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                • #9
                  Re: Extending Subnet issue

                  sorry for stupid question..

                  how do I know my network is Layer 2 or 3.

                  the 192.168.99.x cannot see 192.168.98.x is it because it's on Class C sub?

                  Not a stupid question at all. By Layer 3 I mean the same ip subnet. Those networks encompass the 192.168.98.0/23 subnet so from a Layer 3 prospective they are on the same subnet.


                  By Layer 2 I mean the same vlan. Most unmanaged switches only let you have 1 vlan on the switch which is vlan 1. Cisco and other managed switches allow you to create multiple vlans on the switch. Now typically your Layer 3 subnets will be in their own Layer 2 network (There own vlan per ip subnet). So it really depends on what switches you are using and what configurations are on them.
                  CCNA, CCNA-Security, CCNP
                  CCIE Security (In Progress)

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                  • #10
                    Re: Extending Subnet issue

                    EDIT: it's working now.. the reason I couldnt ping the .98 because the windows firewall blocked the ping
                    thanks for everyone help

                    Originally posted by auglan View Post
                    Not a stupid question at all. By Layer 3 I mean the same ip subnet. Those networks encompass the 192.168.98.0/23 subnet so from a Layer 3 prospective they are on the same subnet.


                    By Layer 2 I mean the same vlan. Most unmanaged switches only let you have 1 vlan on the switch which is vlan 1. Cisco and other managed switches allow you to create multiple vlans on the switch. Now typically your Layer 3 subnets will be in their own Layer 2 network (There own vlan per ip subnet). So it really depends on what switches you are using and what configurations are on them.

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                    • #11
                      Re: Extending Subnet issue

                      Any reason why you are using Static IPs instead of running trouble free DHCP assigned Dynamic IPs?
                      1 1 was a racehorse.
                      2 2 was 1 2.
                      1 1 1 1 race 1 day,
                      2 2 1 1 2

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                      • #12
                        Re: Extending Subnet issue

                        I set static IP for testing purpose.. I will be using DHCP for all the clients..

                        Thanks again for everyone help..

                        HN

                        Originally posted by biggles77 View Post
                        Any reason why you are using Static IPs instead of running trouble free DHCP assigned Dynamic IPs?

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