DHCP Help

AY400AY400 Posts: 1Registered Users ■□□□□□□□□□
W70bd


Basically what I've done is configured all of my DHCP pools on R1, one for 192.168.1.0, 192.168.2.0 and one for 192.168.3.0. The routers are interconnected with OSPF and each of the routers FA 0/0 port has an address of 192.168.x.1. The problem that I'm running into is the fact that all of the switches are receiving and forwarding an address from the 192.168.1.0 range. I assumed that the helper-address would fix this, but either I was wrong or placed it in the wrong place, or missed a step somewhere. Can anyone help me out here or at least give me a hint/ point me in the general direction of what I'm looking for.

P.S.
I have this set on three actual Cisco routers and Switches, I just made a replica of the network in PT.

Comments

  • rob42rob42 Posts: 423Member
    You may find it a help to others if you make the CPT file available for download from somewhere (i.e a Dropbox link).

    B.t.w, why not use a DHCP Server and leave the Routers to do what they were designed to do; Routing. I'm new this stuff myself, but to my mind, I'd use Servers and Routers to do the jobs that they're designed for. Just an observation...
    No longer an active member
  • DCDDCD Posts: 449Member
    Base on what you have given you miss configured it but if you give the proper show commands or upload it to Dropbox or gmail then we can give you some direction.
  • dontstopdontstop Posts: 578Member ■■■■□□□□□□
    Definitely need more information. Please upload the CPT file to something like Free File Hosting - Online Storage; Upload Mp3, Videos, Music. Backup Files
  • Moldygr33nb3anMoldygr33nb3an Posts: 241Member
    rob42 wrote: »
    You may find it a help to others if you make the CPT file available for download from somewhere (i.e a Dropbox link).

    B.t.w, why not use a DHCP Server and leave the Routers to do what they were designed to do; Routing. I'm new this stuff myself, but to my mind, I'd use Servers and Routers to do the jobs that they're designed for. Just an observation...

    For SOHO networks, it's acceptable to let your Router provide DHCP services. It's when you have large networks, where it's beneficial to have a dedicated server providing DHCP services.
    Current: OSCP

    Next: CCNP (R&S and Sec)

    Follow my OSCP Thread!
  • rob42rob42 Posts: 423Member
    For SOHO networks, it's acceptable to let your Router provide DHCP services. It's when you have large networks, where it's beneficial to have a dedicated server providing DHCP services.
    Thanks for that: Yes, I understand that, as you say, "for SOHO...". The reason for my comment was that fact that AY400's post suggests a much bigger setup; multiple Routers, multiple networks, OSPF... Would it not be better to have one DCHP server per network? I only ask in the interests of furthering not only my own knowledge, but also for anyone else trying to learn. I look forward to reading your thoughts.
    No longer an active member
  • Uriah7Uriah7 Posts: 45Member ■■□□□□□□□□
    rob42 wrote: »
    Thanks for that: Yes, I understand that, as you say, "for SOHO...". The reason for my comment was that fact that AY400's post suggests a much bigger setup; multiple Routers, multiple networks, OSPF... Would it not be better to have one DCHP server per network? I only ask in the interests of furthering not only my own knowledge, but also for anyone else trying to learn. I look forward to reading your thoughts.

    The op is likely focused on a certification (CCNA or CCENT) and is using the routers, multiple subnets and OSPF for that purpose. As someone else mentioned, a DHCP server is really not ideal for this situation.
  • txn41655txn41655 Posts: 53Member ■■□□□□□□□□
    AY400 wrote: »
    W70bd


    Basically what I've done is configured all of my DHCP pools on R1, one for 192.168.1.0, 192.168.2.0 and one for 192.168.3.0. The routers are interconnected with OSPF and each of the routers FA 0/0 port has an address of 192.168.x.1. The problem that I'm running into is the fact that all of the switches are receiving and forwarding an address from the 192.168.1.0 range. I assumed that the helper-address would fix this, but either I was wrong or placed it in the wrong place, or missed a step somewhere. Can anyone help me out here or at least give me a hint/ point me in the general direction of what I'm looking for.

    P.S.
    I have this set on three actual Cisco routers and Switches, I just made a replica of the network in PT.

    Correct me if I am wrong icon_cool.gif. According to my CCNA study you must set the correct default-router address on each pool and the ip helper address must the on the interface that receive the broadcast :

    default-router 192.168.1.1 and network 192.168.1.0 (R1 1st pool)
    default-router 192.168.2.1 and network 192.168.2.0 (R1 2nd pool)
    default-router 192.168.3.1 and network 192.168.3.0 (R1 3rd pool)

    Place helper address on the interfaces receiving broadcast.
    * ip-helper-address [Interface Address that receives the DHCP requests on the router providing DHCP OR Address of DHCP server]


    Example :according to your case if R2 is connected to R1's serial interface S0/0/0 (address of 192.168.1.254 255.255.255.252) then you should place ip helper-address 192.168.1.254 on the gateways that requires dhcp help. AND if R3 is connected to R1's S0/0/0/1(address of 192.168.100.254 255.255.255.252) then the ip helpder-address would be 192.168.100.254 .
  • PhilipJayyFryPhilipJayyFry Posts: 3Registered Users ■□□□□□□□□□
    txn41655 wrote: »
    Correct me if I am wrong icon_cool.gif. According to my CCNA study you must set the correct default-router address on each pool and the ip helper address must the on the interface that receive the broadcast :

    default-router 192.168.1.1 and network 192.168.1.0 (R1 1st pool)
    default-router 192.168.2.1 and network 192.168.2.0 (R1 2nd pool)
    default-router 192.168.3.1 and network 192.168.3.0 (R1 3rd pool)

    Place helper address on the interfaces receiving broadcast.
    * ip-helper-address [Interface Address that receives the DHCP requests on the router providing DHCP OR Address of DHCP server]


    Example :according to your case if R2 is connected to R1's serial interface S0/0/0 (address of 192.168.1.254 255.255.255.252) then you should place ip helper-address 192.168.1.254 on the gateways that requires dhcp help. AND if R3 is connected to R1's S0/0/0/1(address of 192.168.100.254 255.255.255.252) then the ip helpder-address would be 192.168.100.254 .

    This sounds correct to me. I would assume the default-router command was miss-configured among the pools and is not giving out ip's from the correct one.
Sign In or Register to comment.