subnet

Unanswered Question
Aug 19th, 2007
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Hi forum,


How do i use a single mask for the below:


site a) 172.30.x.x & 172.30.64.x - can i use 255.255.128.x for the mask? currently this site is using vlsm.


site b and site c) 172.30.128.x and 172.30.192.x each. can i use 255.255.192.0 as the mask?


Thanks much,

pn



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gng4life Sun, 08/19/2007 - 06:14
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Hello PN,


You'll have to make a few changes. For instance, in Site A, you list it as 172.30.x.x and 172.30.64.x with both having a /17 mask. That is overlapping. It would have to look something like this:


172.30.1.0/17 and 172.30.128.0/17


Site B and C:


172.31.0.0/18 and 17.31.64.0/18


But are sure about this? A /17 mask gives over 32,000 host IPs, do you really need that many? The /18 gives you over 16,000 IPs, that's still quite a bit.


How many hosts are you expecting on a subnet? I have worked on some very large networks and I've never used that many hosts on a single subnet.


Also, this looks like it should move to the LAN/Switching/Routing or WAN Routing/Switching forum. Thanks


Let us know...

paulnigel Sun, 08/19/2007 - 16:12
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Hi gng4life,


Thanks much for the clarification.


Actually within site A, I have mask like 255.255.255.0,255.255.255.224, etc. I just want to summarize them together using like the 17/18 bit mask, is this possible?


Thanks much,

pn

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