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New Member

do i call it VLSM?

hi,

suppose i have 3 class B networks(2 LANs, 1 WAN).

all of them with the subnet mask 255.255.255.240.

can I say that VLSM is applied here?

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: do i call it VLSM?

Hi

Variable length subnet masking (VLSM) means implementing more than one mask on the same major class of a network.

So, in your scenario vlsm is not applied,

it would be if for example the 2 lans have 222.255.255.240 and the wan link 255.255.255.252 with the same major network.

here is a pretty good link about subneting basics:

http://www.cisco.com/warp/public/701/3.pdf

hope this helps

regards

2 REPLIES
New Member

Re: do i call it VLSM?

Hi

Variable length subnet masking (VLSM) means implementing more than one mask on the same major class of a network.

So, in your scenario vlsm is not applied,

it would be if for example the 2 lans have 222.255.255.240 and the wan link 255.255.255.252 with the same major network.

here is a pretty good link about subneting basics:

http://www.cisco.com/warp/public/701/3.pdf

hope this helps

regards

Hall of Fame Super Silver

Re: do i call it VLSM?

Actually the original post talked about having 3 class B networks and 3 interfaces. In that situation there could never be VLSM - each interface would have its own unique network and its own mask.

The essence of VLSM is variability of the subnet mask. If a given network (class A, or class B, or class C) has subnets with at least two different subnet masks then it is VLSM. If all the subnets of a given network have the same mask then it is traditional subnetting or Fixed Length Subnet Masking (FLSM instead of VLSM).

HTH

Rick

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