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Subnet Question

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  • 22-02-2011 5:43pm
    #1
    Cork24
    Closed Accounts Posts: 2,663 ✭✭✭


    I am giving a Task to do, i have a ip of 172.170.0.0/16

    R2 & R3 both need 15 host R5 Needs 7 LANs and R6 Needs 5 LANs

    its being awhile since i Have done Subnetting VLSM.

    so i am giving a Class B, should i subnet first for the Lans, So R5 will have

    172.170.1.0 to 172.170.7.0 and R6 172.170.8.0 to 172.170.12.0

    which will allow me to subnet a Class C address for the Hosts which would be
    172.170.13.0/24

    should i start with the Links ? R1 have 3 Serial Links to be address, R3 & R2 have 1 link each to be address and R4 has 2 Serial Links,

    Or should i take the 15 hosts first would would give me by off the top of my head giving it a Max 30 host

    R2 172.170.13.1 - 172.170.13.32
    R3 172.170.13.33 - 172.170.13.65

    and then take the ip address for the Links ?

    really stuck here..


Comments

  • Options
    #2
    trebor28
    Registered Users Posts: 1,051 ✭✭✭trebor28


    im no expert but i think you are supposed to start with the biggest block of addresses and work down.

    usually the serials only require two addresses so something like a /30 would do for them.
    so its better to leave them til the end.


  • Options
    #3
    Cork24
    Closed Accounts Posts: 2,663 ✭✭✭Cork24


    thanks for the post, i done the Link addresses first /30 then the host IP,

    Not to sure about the Lans on how they are done so i left them off for a while. I need to use OSPF for the routing Protocols, but dont advertise the ISP and dont know how else are the routers going to ping the Loopback 0 address.


  • Options
    #4
    Shamo
    Registered Users Posts: 802 ✭✭✭Shamo


    Is this a theory question or something you've been asked to do on a job? Just wondering as the requirements are very vague, especially 7 LANs on R5 for example. Do they want you to randomly pick a subnet mask for each of the 7 LANs?


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