From: Michael Snyder (msnyder@revolutioncomputer.com)
Date: Fri Feb 13 2004 - 19:48:49 GMT-3
Here's an example from last week.
In hex,
40E0.1E5D.9587
40E0.1E5D.9547
40E0.1E5D.95C7
40E0.1E5D.9527
Just working with the last octet (hex mode) windows calc
(0x87&0x47&0xC7&0x27) = 0x07 (common)
(0x87|0x47|0xc7|0x27) = 0xe7 (scope)
0x07 nor 0xe7 = e0 (offset wildcard)
Mask value= ff-wild = 0xff-0xe0 =0x1f
Answer
dlsw icanreach mac-address 40E0.1E5D.9507 ffff.ffff.ff1f
It's all mask logic I've used before.
When you `and` a set of values, you get the most common element of the
values.
When you `or` a set of values you get the scope (range) of the elements.
When you `nor` the common against the scope you get the offset
(difference) of the two in wildcard format.
Total possible value - wildcard = mask.
-----Original Message-----
From: Bob Sinclair [mailto:bsinclair@netmasterclass.net]
Sent: Friday, February 13, 2004 4:28 PM
To: Martin D. Fierbaugh
Cc: ccielab@groupstudy.com
Subject: Re: mac-address access-list.
Martin,
I am sure there are guys out there who could do that in HEX in their
heads,
just as some can do decimial IP subnetting in their heads. But I would
take
the approach you suggest. Seems to me it would work just fine.
Bob Sinclair
CCIE #10427, CISSP, MCSE
www.netmasterclass.net
----- Original Message -----
From: "Martin D. Fierbaugh" <marty@networkwv.com>
To: "'Bob Sinclair'" <bsin@cox.net>
Cc: <ccielab@groupstudy.com>
Sent: Friday, February 13, 2004 4:24 PM
Subject: RE: mac-address access-list.
> Bob and all...
>
> What if the requirement was to ask to block several mac addresses
using
> the minimal number of lines to do so?
>
> Example:
>
> Block these mac addresses with the minimal number of acl entries.
> 0040.05bb.bcc2
> 0004.5a9c.b4ac
> 00a0.2a03.64d6
>
>
> Would you convert hex -> binary and then use the same method for
> combining access-lists that has been so clearly gone over many times
on
> this list?
>
> Thanks,
>
> **********************************
> Martin D. Fierbaugh, CCNP
> Manager - IP Routing
> NTELOS Advanced Data Engineering
> (w) 304.353.8916
> (m) 304.415.0427
> **********************************
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Bob Sinclair
> Sent: Friday, February 13, 2004 10:04 AM
> To: R&S Groupstudy
> Cc: ccielab@groupstudy.com
> Subject: Re: mac-address access-list.
>
> YUP!
>
> Please replace 1's with f's in previous post.
>
>
> Thanks!!
>
> Bob Sinclair
> CCIE #10427, CISSP, MCSE
> www.netmasterclass.net
>
> ----- Original Message -----
> From: "R&S Groupstudy" <rsg@synergy-networking.co.uk>
> To: "Bob Sinclair" <bsin@cox.net>
> Sent: Friday, February 13, 2004 10:03 AM
> Subject: RE: mac-address access-list.
>
>
> > isnt that all f's bob.... 0000.0000.ffff ?
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf
Of
> > Bob Sinclair
> > Sent: 13 February 2004 14:51
> > To: Casey, Paul (6822); ccielab@groupstudy.com
> > Subject: Re: mac-address access-list.
> >
> >
> > Paul,
> >
> > You should be able to do this in IOS (router or 3550) with an access
> list
> in
> > the range 700.
> >
> > access-list 701 permit 0000.abcd.0000 0000.0000.1111
> >
> > should work to permit only source mac addresses starting 0000.abcd
> >
> > Hope that is what you are looking for.
> >
> > Bob Sinclair
> > CCIE #10427, CISSP, MCSE
> > www.netmasterclass.net
> >
> >
> > ----- Original Message -----
> > From: "Casey, Paul (6822)" <Paul.Casey@o2.com>
> > To: <ccielab@groupstudy.com>
> > Sent: Friday, February 13, 2004 7:35 AM
> > Subject: mac-address access-list.
> >
> >
> > > Hello
> > >
> > > Can you match match MAC addresses that start with a specific
range.
> > > Exampe can you match 0000.abcd range of mac-addresses.
> > >
> > > kind regards.
> > >
> > >
> > >
> >
>
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