Now we will look at how to design an address plan for a simple campus. We will be using our campus from the fiber pricing exercise. As you can see on the screen we have six buildings with a server LAN and a core and border router. The following table shows you the host allocation for each part of that campus as you can see on the screen the border route of the core router contains two devices the server network contains 23 devices the signed buildings contains 120 devices and so on to the wireless network which contains 350 devices the university will be using the following ip address space it will be using 172.16.0.0.16 for its ipv4 address block and 2 0 0 1 colon db 8 column 8 slash 48 for its ipv6 address lock you will now use this attracts blocks to design an ipv4 and ipv6 address plan for the campus using the previous table we'll add a column to show the subnet sizes for each function for the border to core router you see the number of devices is 2 that means the subnet size needed is a slash 30. for the server network you have 23 devices that means you need a slash 27 for the subnet size remember that the slash 27 will give you 32 ib addresses and you can only have 30 usable addresses in that prefix for this server network you are only allowed to add seven additional devices in case it's needed in the future so when you're planning you also have to make room for devices that might be needed for that network in future and for the science building you have 120 devices in this case we're using a slash 25 which will give you 120 possible ip addresses with 126 ip addresses that will be usable so for the science building you can see that they will only have an additional six devices that they can add to the network in future for the arts building you have 52 devices and you're going to have a prefix size of slash 26 remember slash 26 will give you 64 ip addresses for the engineering building you have 200 devices and we're using a slash 24 prefix which will give you 256 ip addresses for the library you're going to have 80 devices in which case we're using a slash 25 will give you a possible number of 128 devices on that network administration building you have 40 devices which will also use the slash 26 languages building 30 which will need a prefix of slash 26 in this case slash 26 is also going to give you 64 ip addresses so the question here is if we need 30 devices on the network why are we allocating a slash 26 remember that if we allocate a slash 27 we will have 32 ip addresses and 2 out of them are not usable so you only have 30 ip is available so that means for the languages building you will not be able to add any single device if you use a slash 27 prefix so this is the reason why epic prefixes are located for the languages building for the staff interested in hostile you have 60 devices so you're going to have a slash 25 which will give you possible 128 devices on the network which is 126 usable ib addresses and for the wireless network you have 350 devices which will give you a slash 23 this is 512 devices available now let's assign the ib address blocks accordingly for the border to core router you have two devices we are locating the first slash 3d prefix which is 172.16.0.0.30 for the server network which is has 23 devices we are allocating 27 as shown previously the ipaddress prefix assigned is 172.16.0.32 27. for the science building we have 120 devices and we are located as slash 25 and we're using the prefix 172.16.5.0.25 for the arts building we have 52 devices and we're using a slash 26 prefix which is 172.6 for the engineering building which has 200 devices we're using a slash 24 and the prefix allocated is 172.16.10 the library building has 80 devices and it's using the prefix 172.16.4.0.25 the administration building which has 40 devices and was allocated a slash 26 prefix it's using 172.16.0.192.26 and the language is building which has 30 devices is using the prefix 172.16.5.192 and the staff and certain host cell which has 60 devices is using 172.16.4.128.25 and the wireless network is using 172.16.2.0 23. i guess you're going to be wondering how did we come up with all of these prefix allocations we're going to give you the ipv4 plan explanation we're going to use the first slash 24 prefix for infrastructure and administration network so we're going to use 172.16.0.0.24 for infrastructure and administrative network the border router to core router gets 172.16.0.0.30 remember that's the slideshow needed for that network the server network gets the prefix 172.16.0.32 27 which is the first available slash 27 prefix in that range after the border router to core out of assignment remember that you can use any slash 27 prefix in that range the administration building gets 172.16.192 26 prefix which is also a free slash 26 prefix in that range how do we assign prefixes we're going to start by assigning the biggest subnets first so since wireless has the biggest network we're going to assign that prefix first so wireless is going to get 172.16.2.0.23 prefix which has a range of 172.16.2.0 all the way to 172.16.3.255. remember that is slash 23 free fix is equivalent to 2 24 prefixes so the first available slash 23 prefix is 172.16.2.0.23 you can also use any free slash 23 prefix in the 172.16.0.0 16.4 we will next assign the slash 24 prefix which is the next biggest subnet this goes to the engineering building which will have 172.16.1.0.24 remember that prefix was available after the administration and infrastructure network was assigned so this is the first free brief slash 24 prefix and we're assigning it to the engineering building we'll then move on to the slash 25 so we have three of them so we'll assign the first prefix to 172.16.4.0.25 which is the first free available prefix after the wireless network and you're going to have 172.16.4.120 25 which is going to the staff understood in hostel the first one went to the library building and then you have the last slash 25 prefix which is the 172.16.5.0.25 which goes to the science building finally we assign the remaining slash 26 which is two of them the arts building gets 172.16.5.128 26. and the languages building gets 172.16.5.192 26. Remember it's easier to do the big pieces first and then fill in the gaps with the smaller subnets. Use of the aggregation tree concept that we covered previously is very helpful in the creation of an IPv4 address plan. In conclusion we have addressed our network using 172.16.0.0 through to 172.16.5.255. This is contained within the 172.16.0.0.21 address block. This is an example of an efficient use of an IPv4 address space. Remember we talked about aggregation. This is very useful when you're aggregating your network.
© Produced by Philip Smith and the Network Startup Resource Center, through the University of Oregon.
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