08-18-2013 09:14 PM
I have a no explanation for this. I have multiple subnets at new customers site as seen below. For whatever reason, when I enter in VE68 (10.35.68.1/21) it tells me it is overlapping with ve64 (10.35.64.1/23)... Can someone tell me what the deal is with this.. never seen it before as they are clearly not overlapping subnets. tried it on a cisco box and had same results.
interface ve 1
ip address 10.35.48.2 255.255.248.0
interface ve 56
ip address 10.35.56.1 255.255.248.0
interface ve 64
ip address 10.35.64.1 255.255.254.0
interface ve 67
ip address 10.35.67.1 255.255.255.0
interface ve 68
ip address 10.35.68.1 255.255.248.0 <- this is the overlapping subnet?
interface ve 74
ip address 10.35.74.1 255.255.255.0
08-20-2013 10:45 AM
The subnets are overlapping, if you take the 10.35.68.0/21 subnet and break it down in the calculator, you will find that the root network address is 10.35.64.0/21 (range is 10.35.64.1 to 10.35.71.254 ), therefore your second subnet of 10.35.64.1/23 is part of the overall /21 subnet.
What you should do is choose the 10.35.72.0/23 for your second subnet.
08-20-2013 02:44 PM
Thanks for your response James. I see how it falls under a 10.35.64.0/21 subnet, but why can I make it a /22 and it dosent overlap? I have already moved the Subnets around, but I'm just not seeing this one right .
Just an FYI for first response the switch is an sx800
08-20-2013 03:00 PM
That's correct, if you make it a /22 then your boundaries will be 10.35.64.0/22 and 10.35.68.0/22 and so on.
Think of it like this, you have a finite amount of numbers to use there, but you have to stick to the rules of subnetting. So it does depend on how you break up the IP blocks, but you cant break the bit boundaries. Best way to stay efficient is to use a IP subnetting calculator. It keeps me honest.
08-29-2013 11:13 AM