Steve,
That matches the 10.20.4.0 subnet and 10.30.4.0 subnet, but it won't match any
hosts on either subnet, because the last octet is 0 and the wild-card bits are
zero (must match).
I was looking for a wildcard mask of 0.10.0.255 to match all hosts on either
subnet.
If you went further, you could have also come up with 0.255.0.255, to match
10.x.4.x.
-tcs
On 4/12/11 12:15 AM, Di Bias, Steve wrote:
Terry is right, I may have jumped the gun with the inverse mask statement
(although it's mentioned this way in many documents). For Terry's experiment
let's assume we want to match the voice vlan for buildings 20 and 30
(10.20.4.0 and 10.30.4.0). By breaking this down into binary and using AND/OR
logic we can easily come up with our answer
00001010.00010100.00000100.0000000
00001010.00011110.00000100.0000000
----------------------------------
00001010.00010100.00000100.0000000 = 10.20.4.0
00001010.00010100.00000100.0000000
00001010.00011110.00000100.0000000
----------------------------------
00000000.00001010.00000000.0000000 = 0.10.0.0
So the "wildcard" mask to match both buildings would be 0.10.0.0
Cheers!
Thank you.
Steve Di Bias
Network Engineer - Information Systems
Valley Health System - Las Vegas
Office - 702- 369-7594
Cell - 702-241-1801
[email protected]
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Terry Slattery
Sent: Monday, April 11, 2011 6:58 PM
To: Jay Taylor
Cc:<[email protected]>
Subject: Re: [OSL | CCIE_RS] offset-list and wild card mask
Good answer, Jay. For everyone who thinks that the wild-card mask is the
opposite of the subnet mask...
I have a set of subnets that I need to match. The first octet is 10. The second octet is
a building number. The third octet identifies the subnet in each building, and is
"4" for the voice subnet, which is what I want to match.
Build a wild-card mask that matches
10.x.4.x
Is it the inverse of the subnet mask?
-tcs
On 7/22/64 2:59 PM, Jay Taylor wrote:
Offset list is used to increment the metric of certain routes.
In a wildcard mask a binary 0 means the bit must match and a binary 1
means it does not have to match. This is reverse logic compared to a
normal subnet mask. Also, unlike a subnet mask the 1's and 0's do not
need to be contiguous.
On Mon, Apr 11, 2011 at 11:04 AM, Uli<[email protected]> wrote:
Hi Expert,
Does anyone can explain to me about offset-list as I kind of confused
with it. also, in my opinion that wild card mask is reverse of subnet
mask, but someone told me it isn't ?
Regards
_______________________________________________
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--
Terry Slattery CCIE# 1026
_______________________________________________
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