What are the reasons for using only contiguous addresses in subnets? Will something malfunction if we use dis contiguous IP addresses?

I am aware that RIP and IGRP will auto-summarize which results in confusing/incomplete entries in the routers routing tables. I am just curious if there are any additional reason?

  • A subnet won't be discontiguous. A summary of subnets may include some subnets which you don't have, so it may be discontiguous in one sense.
    – Ron Maupin
    Sep 6 '16 at 0:33
  • Just so we know we're understanding you correctly, can you give an example of what you mean?
    – Ron Trunk
    Sep 6 '16 at 0:37
  • Ok but can you tell me why subnets can't have non continuous values? To re frame the question, what goes wrong if we have discontinuous IPs in a subnet? Sep 6 '16 at 0:38
  • 2
    "Subnetting" can mean different things depending on what you're reading. It usually means dividing a network into smaller networks. In that context, your comment about contiguous networks doesn't make sense to me.
    – Ron Trunk
    Sep 6 '16 at 2:56
  • 1
    Your question doesn't make sense. A network is a group of contiguous addresses.
    – Ron Trunk
    Sep 6 '16 at 14:48

Hey I got the answer for this. If we include discontinuous IP addresses in a subnet, there is a chance that destination address will not be a part of the network address in the forwarding table. So it may cause a packet to be forwarded to the wrong output port.

  • You simply cannot include discontiguous addresses in a network.See this question and the excellent answer for why that is not possible.
    – Ron Maupin
    Sep 11 '16 at 22:17

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