Solved

/31 subnet

Posted on 2011-09-08
6
474 Views
Last Modified: 2012-05-12
Hi Experts,

Is there a valid need to have a /31 subnet?

For example, if dealing with an IPSEC VPN and one side specifies for the encryption domain 10.10.10.80/31, the only host IP useable would be 10.10.10.81. 10.10.10.80 would not be useable, am I correct?
So why not specify for the encryption domain 10.10.10.81/32.
0
Comment
Question by:trojan81
  • 4
6 Comments
 
LVL 35

Expert Comment

by:Ernie Beek
ID: 36503447
/31 would be useless. The .80 would be the network address and the .81 the broadcast address. So no room for hosts.
0
 
LVL 35

Expert Comment

by:Ernie Beek
ID: 36503462
Oh, /32 would define a single host, you're correct.
0
 
LVL 43

Accepted Solution

by:
JFrederick29 earned 400 total points
ID: 36503480
/31 is just a way of covering the two hosts:

10.10.10.80
10.10.10.81

It isn't being used on an interface so the subnet/broadcast addresses aren't in play.  It simply saves one line of config (having to specify both hosts individually).

/32 would cover two extra hosts which is probably not the intention:

10.10.10.80
10.10.10.81
10.10.10.82
10.10.10.83

0
Windows Server 2016: All you need to know

Learn about Hyper-V features that increase functionality and usability of Microsoft Windows Server 2016. Also, throughout this eBook, you’ll find some basic PowerShell examples that will help you leverage the scripts in your environments!

 
LVL 35

Expert Comment

by:Ernie Beek
ID: 36503498
Yeah, sorry about that. Got mixed up with the translation :-~
In this matter it is a way of defining the hosts, so no bother with network/broadcast addresses.
0
 
LVL 35

Expert Comment

by:Ernie Beek
ID: 36503526
Thx JFrederick29 :)
0
 

Author Closing Comment

by:trojan81
ID: 36505484
I gave it another thought and yes, they probably wanted to just save .80 from being used by something else.
0

Featured Post

PRTG Network Monitor: Intuitive Network Monitoring

Network Monitoring is essential to ensure that computer systems and network devices are running. Use PRTG to monitor LANs, servers, websites, applications and devices, bandwidth, virtual environments, remote systems, IoT, and many more. PRTG is easy to set up & use.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

I wrote this article to help simplify the process of combining multiple subnets. This can be used for route summarization also but there are other better ways to summarize routes, This article is a result of questions I participate in here at Ex…
If you are thinking of adopting cloud services, or just curious as to what ‘the cloud’ can offer then the leader according to Gartner for Infrastructure as a Service (IaaS) is Amazon Web Services (AWS).  When I started using AWS I was completely new…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

929 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

9 Experts available now in Live!

Get 1:1 Help Now