Questions

If the DHCP scope if full what would I do...

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0 Votes
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If the DHCP scope if full what would I do...

jagannadh1218
actually my DHCP scope (192.168.100.1 to 252)...

reservaation are crossed more than 252 ..in such a case what would I do

give me solution for this.. on
jagannadh1218@gmail.com
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    ManiacMan

    You should have a fairly reasonable and short lease time and it's also good practice to not set a DHCP scope to use the entire subnet, as I'm sure you have devices like servers and printers with static addresses. If needed, create another subnet and scope and use a DHCP relay agent to service the new subnet.

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    scott_heath

    I like a 24 hour lease time personally. You can also change your subnet mask to increase the overall network size. Depending on your network layout this may be harder or easier than setting up a new scope and relay agent.

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    ManiacMan

    You would have to **** away the scope and recreate it with a new subnet mask. This is a typical gotcha and Microsoft loves to ask this on the certification exams, as most people tend to forget this fact.

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    jagannadh1218

    How do I create another subnet and scope and use a DHCP relay agent to service the new subnet.

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    0 Votes
    ManiacMan

    There's too much to explain and if you don't understand how DHCP works or what relay agents are, you've got bigger problems to tackle like getting yourself up to speed on Windows. With all due respect, we'll help you to a point, but you can't expect TR to be an IT school or training center for you, as you will have to do what we all do, which is to do the legwork yourself and read up on this topic or get the appropriate IT training and certification. If you are tasked to be an admin and you don't know these things, you are kidding yourself by assuming you are the proper person for the job. I don't know how things work in your part of the world, but inexperienced IT professionals in the USA are quickly weeded out and don't get too far if they try to BS their way into a job they lack qualifications for.

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    0 Votes
    scott_heath

    You would need to reconfigure a switch as well. Adding a new subnet is done the same way as you added the first. You have to reconfigure a network device with a new subnet and set up a dhcp relay agent that tells DHCP discovery packets to go to another network.

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    1 Votes
    dseward

    Did I miss the question where he asked how to be a know it all jerk. I agree there needs to be some training, but after 20 years of IT and plenty of certifications, I had to search this topic since I have been running a single subnet domain for the past 11 years and I'm only just now needing to increase the size. This isn't something everyone it IT does everyday and I'm sure there are lessons you've learned that you needed to "brush up on" now and then. First lesson, don't be a troll! We're here to help each other.

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    0 Votes
    Rob Kuhn

    At my last company where there was 50 people and maybe 75 devices, an internal class C was more than sufficient (even with the projected growth of 10-15 more people by the end of the year).

    The 10-15 did come aboad as aforementioned along with another 50+ !!

    The simple and quick fix was to create a few VLANs. At the top I had a Layer 3 switch which fed a bunch of Layer 2 switches. The VLAN was created in the Layer 3 switch.

    Before the rapid growth, I was already in the process of building VLANs. One for WiFi (Public and Private) and I wanted to put various departments into their own LANs; I just had to implement a bit sooner than scheduled. :)

    My only word of caution is to not fall into creating too many VLANs. In other words if a LAN starts to get full it's too convenient to create another VLAN.

    All that said I would suggest you change the subnet to a class B or possibly A before creating VLANs. Or if you do decide to create VLANs create class A/B addressing that way you have the growth without having to create a bunch of class C VLANs.

    HTH.

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    0 Votes

    I doubt ManiacMan is going to see your reply to their almost 5 year old
    comment...you should have just let the zombie sleep, and if you have
    a particular question, ask it as a new Q&A. But that's just my advice.

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    0 Votes
    Rob Kuhn

    You can try shortening the DHCP leases. The shortest I've set mine was 6 hours but generally 12-24 hours tends to suffice (longer if majority of your machines are stationary like desktops). But keep in mind that shortening the DHCP lease is just a temp-fix.

    Someone already suggested chaning the subnet mask. This would be my first suggestion.

    VLANs is also a quick way but it does require a bit more work and you have to ensure that they can route across each other. If you do VLAN seriously consider creating at least a class B for each of the new VLANs that way you have gworth without having to create a ton of class C VLANs.

    There is also another way but I would only suggest it as a "temp" fix and that is to go out and get a small home router. Plug the WAN side of the router into your LAN. Take one of the LAN ports on the back of the router and connect that into another switch (make sure that the switch is NOT already connected to your main LAN!). Use the home router's DHCP services to dish up IPs. You may have to create some routing entries in the home router. This will at least buy you some time so that you can put in proper solution.

    I would also take this time to really plan out your infrastructure.

    Good luck!

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    0 Votes
    CG IT

    The Class C subnet only goes up to 254 so unless one knows how many hosts you've got hard to say what to do.

    If you have more than 254 hosts you need addresses for, then you have to subnet because the Class C 192.X.X.X only can have 254.

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    0 Votes

    You will need another broadband/phone line point so that your DHCP router server can access.

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    0 Votes
    dseward

    @wizard57m-cnet - I know you're right, he/she may never see the comment, but I had to vent. Thanks to everyone else for your advice and if anyone else reads this post as old as it is I would also recommend looking into CIDR (Classless Inter Domain Routing) or supernetting. Again its a temp fix but for a small company that hasn't experienced this much growth in 11 years and isn't projected to have much more, it will buy some time. At this point maybe 5 more years and we'll be dealing with IPv6.

  • +
    0 Votes
    ManiacMan

    You should have a fairly reasonable and short lease time and it's also good practice to not set a DHCP scope to use the entire subnet, as I'm sure you have devices like servers and printers with static addresses. If needed, create another subnet and scope and use a DHCP relay agent to service the new subnet.

    +
    0 Votes
    scott_heath

    I like a 24 hour lease time personally. You can also change your subnet mask to increase the overall network size. Depending on your network layout this may be harder or easier than setting up a new scope and relay agent.

    +
    0 Votes
    ManiacMan

    You would have to **** away the scope and recreate it with a new subnet mask. This is a typical gotcha and Microsoft loves to ask this on the certification exams, as most people tend to forget this fact.

    +
    0 Votes
    jagannadh1218

    How do I create another subnet and scope and use a DHCP relay agent to service the new subnet.

    +
    0 Votes
    ManiacMan

    There's too much to explain and if you don't understand how DHCP works or what relay agents are, you've got bigger problems to tackle like getting yourself up to speed on Windows. With all due respect, we'll help you to a point, but you can't expect TR to be an IT school or training center for you, as you will have to do what we all do, which is to do the legwork yourself and read up on this topic or get the appropriate IT training and certification. If you are tasked to be an admin and you don't know these things, you are kidding yourself by assuming you are the proper person for the job. I don't know how things work in your part of the world, but inexperienced IT professionals in the USA are quickly weeded out and don't get too far if they try to BS their way into a job they lack qualifications for.

    +
    0 Votes
    scott_heath

    You would need to reconfigure a switch as well. Adding a new subnet is done the same way as you added the first. You have to reconfigure a network device with a new subnet and set up a dhcp relay agent that tells DHCP discovery packets to go to another network.

    +
    1 Votes
    dseward

    Did I miss the question where he asked how to be a know it all jerk. I agree there needs to be some training, but after 20 years of IT and plenty of certifications, I had to search this topic since I have been running a single subnet domain for the past 11 years and I'm only just now needing to increase the size. This isn't something everyone it IT does everyday and I'm sure there are lessons you've learned that you needed to "brush up on" now and then. First lesson, don't be a troll! We're here to help each other.

    +
    0 Votes
    Rob Kuhn

    At my last company where there was 50 people and maybe 75 devices, an internal class C was more than sufficient (even with the projected growth of 10-15 more people by the end of the year).

    The 10-15 did come aboad as aforementioned along with another 50+ !!

    The simple and quick fix was to create a few VLANs. At the top I had a Layer 3 switch which fed a bunch of Layer 2 switches. The VLAN was created in the Layer 3 switch.

    Before the rapid growth, I was already in the process of building VLANs. One for WiFi (Public and Private) and I wanted to put various departments into their own LANs; I just had to implement a bit sooner than scheduled. :)

    My only word of caution is to not fall into creating too many VLANs. In other words if a LAN starts to get full it's too convenient to create another VLAN.

    All that said I would suggest you change the subnet to a class B or possibly A before creating VLANs. Or if you do decide to create VLANs create class A/B addressing that way you have the growth without having to create a bunch of class C VLANs.

    HTH.

    +
    0 Votes

    I doubt ManiacMan is going to see your reply to their almost 5 year old
    comment...you should have just let the zombie sleep, and if you have
    a particular question, ask it as a new Q&A. But that's just my advice.

    +
    0 Votes
    Rob Kuhn

    You can try shortening the DHCP leases. The shortest I've set mine was 6 hours but generally 12-24 hours tends to suffice (longer if majority of your machines are stationary like desktops). But keep in mind that shortening the DHCP lease is just a temp-fix.

    Someone already suggested chaning the subnet mask. This would be my first suggestion.

    VLANs is also a quick way but it does require a bit more work and you have to ensure that they can route across each other. If you do VLAN seriously consider creating at least a class B for each of the new VLANs that way you have gworth without having to create a ton of class C VLANs.

    There is also another way but I would only suggest it as a "temp" fix and that is to go out and get a small home router. Plug the WAN side of the router into your LAN. Take one of the LAN ports on the back of the router and connect that into another switch (make sure that the switch is NOT already connected to your main LAN!). Use the home router's DHCP services to dish up IPs. You may have to create some routing entries in the home router. This will at least buy you some time so that you can put in proper solution.

    I would also take this time to really plan out your infrastructure.

    Good luck!

    +
    0 Votes
    CG IT

    The Class C subnet only goes up to 254 so unless one knows how many hosts you've got hard to say what to do.

    If you have more than 254 hosts you need addresses for, then you have to subnet because the Class C 192.X.X.X only can have 254.

    +
    0 Votes

    You will need another broadband/phone line point so that your DHCP router server can access.

    +
    0 Votes
    dseward

    @wizard57m-cnet - I know you're right, he/she may never see the comment, but I had to vent. Thanks to everyone else for your advice and if anyone else reads this post as old as it is I would also recommend looking into CIDR (Classless Inter Domain Routing) or supernetting. Again its a temp fix but for a small company that hasn't experienced this much growth in 11 years and isn't projected to have much more, it will buy some time. At this point maybe 5 more years and we'll be dealing with IPv6.