Need some advice on learning networking

[BillyCarpenter]

Let's see if we can get some discussion going on:

Static vs. DHCP Reservation

There's only certain things we want to have static IP addresses: Servers, routers, switches, printers, storage devices and PC that are hosting any type of services. What else?


What are the advantages of DHCP reservations as opposed to static? I have some thoughts but I'll see if anyone else weighs in.

[slimslob]

Let's see if we can get some discussion going on:

Static vs. DHCP Reservation

There's only certain things we want to have static IP addresses: Servers, routers, switches, printers, storage devices and PC that are hosting any type of services. What else?


What are the advantages of DHCP reservations as opposed to static? I have some thoughts but I'll see if anyone else weighs in.

Corporate officers who need to be able to access the fie servers, printers, internet and other Static IP devices as much as possible. I got a call one afternoon from a local VP at a major oil field ser4vice client. It seemed that about half the people in the warehouse office could not print. It only took me a couple of minutes to realize that the computers that had been turned off over night did not get DHCP when they turned on. I called the receptionist to have her contact the local IT person to have him call me so I could tell him what I had found. She called back to tell me that he was too busy to talk to me trying to determine what router(s) were preventing some people from accessing anything. Apparently she then called the West Coast IT office in Seattle because he called me to as what I had found. I told him "no DHCP." Five minutes the receptionist did an announcement for everyone having trouble to reboot their computers. The local "IT" person's severance check was waiting for him when he clocked out that afternoon.

[BillyCarpenter]

Corporate officers who need to be able to access the fie servers, printers, internet and other Static IP devices as much as possible. I got a call one afternoon from a local VP at a major oil field ser4vice client. It seemed that about half the people in the warehouse office could not print. It only took me a couple of minutes to realize that the computers that had been turned off over night did not get DHCP when they turned on. I called the receptionist to have her contact the local IT person to have him call me so I could tell him what I had found. She called back to tell me that he was too busy to talk to me trying to determine what router(s) were preventing some people from accessing anything. Apparently she then called the West Coast IT office in Seattle because he called me to as what I had found. I told him "no DHCP." Five minutes the receptionist did an announcement for everyone having trouble to reboot their computers. The local "IT" person's severance check was waiting for him when he clocked out that afternoon.

Here's one example of an advantage to using DHCP reservation.


Many times the IT guy is managing devices that are at remote locations. That could be another building on a campus or that could be a location in another city/state. It's very easy to make a mistake when assigning a static IP address to a bunch of devices. Suppose the IT person enters the wrong subnet and loses connectivity to a device? What then? He's gonna have to get in his car and drive to the location of the device and change the subnet?

But what if he would have given the device a DHCP reservation? Then if he made a mistake all he would have to do is change the DHCP configuration and the device would get the corrected configuration.

[BillyCarpenter]

This explanation is more clear and to the point:

DHCP Reservations


DHCP stands for Dynamic Host Configuration Protocol, and was created to dynamically configure hosts networking configuration on the fly for easy deployment.


In it’s most simplest explanation, when a computer (or device) that is configured to use DHCP reaches out to the network, the DHCP server will assign and provide an IP address for the computer to use.


In home networks, pretty much every computer and device will get it’s IP address from the DHCP server running on the router.


In business networks, pretty much every computer and device that isn’t hosting services will get it’s IP address from the DHCP server running on one of their servers or routers.


DHCP Servers support something called a “DHCP Reservation”, which essentially allows you to provide a pre-set IP address to a specific client based on it’s physical MAC address. This means that the device will always get the same IP address and it will never change (whereas they typically do on occasion).


I’m surprised I don’t see these used more often, as they can become quite the powerful tool on the IT tool belt when used properly. I’ve listed some pros and cons below.


The Pros:
Manage IP addresses (IP reservations) from a single console
Ability to change IP addresses on the fly easily from a single console without having to log in to the device.
Manage network topology for ROBO (Remote Office, Branch Office) remotely, easily, and efficiently.
Manage IP addresses for 3rd party devices that you don’t normally have access to modify (tell the vendor to set to DHCP), reducing support calls for external services.
Ability to create different PXE boot environments as each reservation can have it’s own PXE boot options assigned.
The Cons:
Device must support DHCP Configuration.
The device MUST RELY on a DHCP Server once set to use DHCP. If the DHCP Server is down, so is the device.
If rogue DHCP servers appear on your network, it may disrupt communication (this can also happen with static IPs and conflicts).
So with the list above, DHCP reservations look pretty powerful. The next question, is where do we use DHCP reservations. Let’s finish off with the devices we’d use them on, and what use case scenarios apply.


Devices:


Wireless Access Points
Printers
2nd Level (non core) Routers and Gateways
IoT Devices
IP Phones
IP PBX Systems (VoIP, Traditional with IP Management, etc).
Thin Clients and Zero Clients
Use Cases:


Remote Offices (remote sites with limited access)
Remote Support environments
Branch Offices
IP Phone Networks
Wireless LAN Access Point VLANs
DHCP Reservation Use Cases
I use DHCP reservations frequently with customers that have remote or branch offices in remote geographical areas. When supporting these users and troubleshooting issues, it’s awesome to be able to just log in to the DHCP server to change IP addresses of printers, phones, and wireless access points.


Also, when configuring, shipping, and deploying new devices to these offices, I can simply log and write down the MAC address, configure the DHCP reservation, and the device will get the IP address I’ve chosen once it’s connected to the network and powered on.


Using DHCP reservations, you can easily make big changes to these remote networks without having to be present. If you were to use Static IPs and something was misconfigured, this might cause a physical visit to the site to resolve.


If by change a vendor directly dropships equipment to the remote site, I can simply call someone at that office to get the MAC address. Most devices with a NIC (printers, MFPs, wireless access points), all usually have their MAC addresses printed on the outside of the box. With this information provided, I can login to the remote server, create a DHCP reservation, configure drivers, and push the device config out to the network.


DHCP reservations add to the whole concept of a centrally managed environment, which further helps ease of maintaining, and supporting it.

[bsm2]

Welcome to the world of networking Duh
Most companies don't use DHCP Reservations only enterprise size companies and it's still rare to see it used.

There are other ways to find devices on the your network lets see if you can figure that out

[BillyCarpenter]

Welcome to the world of networking Duh
Most companies don't use DHCP Reservations only enterprise size companies and it's still rare to see it used.

There are other ways to find devices on the your network lets see if you can figure that out

Calm down before you have a heart attack. In a minute I'm gonna talk about some of the shortcomings of DHCP Reservations when using IPv4 and how IPv6 overcomes those shortcomings. Here's a hint:

Reservations IPv6 DHCP
To get around this, IPv6 uses two different values. The first is the DHCP unique identifier or DUID. This value is a unique value given to all DHCP clients and servers on the network. Just like a serial number, every DHCP client and DHCP server has a different DUID

[BillyCarpenter]

This journey I've taken with networking has been a strange and fun ride thus far. It started out with Ken, slim and others explaining the most basic of networking concepts to me because I knew almost nothing.

But then I decided to study for my CCNA. That's a whole other world. I poured my heart and soul into it for a few months but I had to take a break for my own sanity. Trust me when I tell you that it's a hard and grueling study.

While I took a break from CCNA, I decided to learn more about Server 2019. Hell, I even bought a Dell PowerEdge R620 Server.

The worlds of Windows Server and CCNA are vastly different. Windows Server is much more fun. Routing and switching is fun, too, in a weird sort of way.

While my brief experience with Windows Server was fun and I learned a lot, it's time to get back to CCNA. At some point I'm gonna come back to Windows Server because I love it. However, I don't like starting something and not finishing it. I've invested way too much time and energy in CCNA to stop now....even though I know this knowledge is something that I'll likely never use.

Back to the grind.

[slimslob]

Here's one example of an advantage to using DHCP reservation.


Many times the IT guy is managing devices that are at remote locations. That could be another building on a campus or that could be a location in another city/state. It's very easy to make a mistake when assigning a static IP address to a bunch of devices. Suppose the IT person enters the wrong subnet and loses connectivity to a device? What then? He's gonna have to get in his car and drive to the location of the device and change the subnet?

But what if he would have given the device a DHCP reservation? Then if he made a mistake all he would have to do is change the DHCP configuration and the device would get the corrected configuration.

But if the DHCP server is down when the computer powers up? Go ahead and make the reservation but set an Alternate Configuration with the same IP Address for when DHCP cannot be obtained.

[BillyCarpenter]

But if the DHCP server is down when the computer powers up? Go ahead and make the reservation but set an Alternate Configuration with the same IP Address for when DHCP cannot be obtained.

Yes, sir. That is one downside to DHCP reservations. Another downside is that DHCP Reservations are married to the MAC Address that resides on the NIC card. If the NIC is replaced then there's a problem if changes aren't made on the server side.


I've been reading up on DHCP Reservations using IPv6 and a lot problems associated with IPv4 are not an issue because it doesn't use the MAC address.

[tsbservice]

Yes, sir. That is one downside to DHCP reservations. Another downside is that DHCP Reservations are married to the MAC Address that resides on the NIC card. If the NIC is replaced then there's a problem if changes aren't made on the server side.


I've been reading up on DHCP Reservations using IPv6 and a lot problems associated with IPv4 are not an issue because it doesn't use the MAC address.

IPv6 I tend to disable it on MFP side Just another unused protocol...well maybe future would prove me wrong but for now less not needed protocols less grief.