0

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?

Danis Fermi
  • 323
  • 1
  • 3
  • 16
  • 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 06 '16 at 00:33
  • Just so we know we're understanding you correctly, can you give an example of what you mean? – Ron Trunk Sep 06 '16 at 00:37
  • 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? – Danis Fermi Sep 06 '16 at 00:38
  • @RonTrunk Ok for example, 88.62.104.0 88.62.112.0 88.62.120.0 88.62.128.0, these IPs ant be sub netted and the reason is that they are not contiguous. My questions is what happens if I subnet them? – Danis Fermi Sep 06 '16 at 00:44
  • When you say subnet them, do you mean break them into smaller networks? it's not clear to me what you're trying to do. – Ron Trunk Sep 06 '16 at 01:11
  • @RonTrunk I'm just trying to understand subnetting. It's mentioned everywhere that subnetting requires contiguous IP addresses but the reason isn't mentioned anywhere. – Danis Fermi Sep 06 '16 at 02:38
  • 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 06 '16 at 02:56
  • @RonTrunk Yes subnet means dividing. When we subnet a network, we have to make sure that it contains only contiguous addresses right? Why is this so? Correct me if I'm wrong about the contiguity part. – Danis Fermi Sep 06 '16 at 14:30
  • 1
    Your question doesn't make sense. A network is a group of contiguous addresses. – Ron Trunk Sep 06 '16 at 14:48
  • Oh then I'm sorry. I'm new to the field and just thought of it that way. Should I delete the question? – Danis Fermi Sep 06 '16 at 14:50

1 Answers1

0

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.

Danis Fermi
  • 323
  • 1
  • 3
  • 16