Thanks for all of your help...
When you guys do it, do you start by writing it all out in binary, or
make an educated guess on what groups together? and it is best to start
with the first octet and going forward, or the last going backwards?
Again, Thanks!
Sincerely,
Kim Pedersen
Tyson Scott wrote:
Yes Correct Kim,
194 and 193 can defiantly be matched in one line if all the rest were the
same. In your example none of those could be combined into one line without
matching additional networks.
Regards,
Tyson Scott - CCIE #13513 R&S and Security
Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Cell: +1.248.504.7309
Fax: +1.810.454.0130
Mailto: [email protected]
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-----Original Message-----
From: Kim Pedersen [mailto:[email protected]]
Sent: Monday, June 08, 2009 2:02 PM
To: Tyson Scott
Cc: 'Bryan Bartik'; [email protected]
Subject: Re: [OSL | CCIE_RS] ACL Wildcards
Hi Tyson,
In my example, those 4 bits are just in the first octet alone. So im
assuming we really need to treat the entire address, and not just by octet?
So there's no "set-in-stone" rules to go by, you just sort of have to
group them, see if that matches and go from there?
Finally, in my example, if i add the 193 prefix, I would have 6 bits
of difference, so the closest i could do in one line is by matching 64
nets, and this would give an indication on whether i need to narrow it down?
Sincerely,
Kim
Tyson Scott wrote:
Kim
When it has a large amount of differences you need to find similarities
between them to put them together
194 is 11000010
174 is 10101110
This is 4 bit differences so you would have to have 16 entries to match
them
as one line without matching additional subnets
It is important to also note if they say to not match any additional
networks or if they just say to combine them to as few lines without
specifying that you can't match additional networks as well.
Regards,
Tyson Scott - CCIE #13513 R&S and Security
Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Cell: +1.248.504.7309
Fax: +1.810.454.0130
Mailto: [email protected]
Join our free online support and peer group communities:
http://www.IPexpert.com/communities
IPexpert - The Global Leader in Self-Study, Classroom-Based, Video On
Demand
and Audio Certification Training Tools for the Cisco CCIE R&S Lab, CCIE
Security Lab, CCIE Service Provider Lab , CCIE Voice Lab and CCIE Storage
Lab Certifications.
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Kim Pedersen
Sent: Monday, June 08, 2009 11:28 AM
To: Bryan Bartik
Cc: [email protected]
Subject: Re: [OSL | CCIE_RS] ACL Wildcards
Hi Bryan,
I guess I didnt point out the problem (sounds soo serious :) ), but
what if the question states: "make these into as few entries as
possible", and they are soo different that it might not end up in one
entry (again, with difference in multiple octets).
For example (no logic behind choosing these):
194.64.0.96/27
174.34.87.64/26
193.23.10.8/30
...
Next, imagine 32 addresses just like this :)
How do you go about breaking all of this down?
Sincerely,
Kim Pedersen
Bryan Bartik wrote:
Kim, even if there is more than one octet you still can look at the
number of bits that are different. Example:
192.168.0.0
192.168.0.1
192.168.1.0
192.168.1.1
The above addresses have 2 bits (bit 0 in the 3rd and 4th octets) that
differ and we can combine them in one ACL.
3rd and 4th octets:
0000 0000 | 0000 0000
0000 0000 | 0000 0001
0000 0001 | 0000 0000
0000 0001 | 0000 0001
0000 0000 | 0000 0000 AND
0000 0001 | 0000 0001 XOR
192.168.0.0 0.0.1.1 would be the ACL entry.
-hth
Bryan Bartik
CCIE #23707 (R&S), CCNP
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com
On Mon, Jun 8, 2009 at 7:47 AM, Rodriguez, Jorge
<[email protected]
<mailto:[email protected]>> wrote:
Jeremy this should help you in doing the calculating wildcard mask
http://www.internetworkexpert.com/resources/01700370.htm
http://blog.internetworkexpert.com/2007/12/26/q-how-do-i-compute-complex-wil
dcard-masks-for-access-lists/
Rgds
Jorge
*From:* [email protected]
<mailto:[email protected]>
[mailto:[email protected]
<mailto:[email protected]>] *On Behalf Of
*JEREMY FURR (RIT Student)
*Sent:* Friday, June 05, 2009 10:12 AM
*To:* [email protected]
<mailto:[email protected]>
*Subject:* [OSL | CCIE_RS] ACL Wildcards
Does anyone know of a website or book that explains well how ACL
wildcards work? I have been trying to filter out four blocks from
a bunch of route advertisments but just can't get the three I want
through, this is what I have R2 is originating 192.168.2.0/24
<http://192.168.2.0/24> through 192.168.15.0/24
<http://192.168.15.0/24> in RIP to R1. I want to only accept
blocks 192.168.5.0, 192.168.10.0, 192.168.13.0 and 192.168.14.0
If I use acl with 192.168.10.0 0.0.4.0, I will get 10 and 14 but
not thirteen. For the 5 network I just use the 192.168.5.0
0.0.0.255.
Any thoughts or help would be appreciated.
Jeremy Furr
[email protected] <mailto:[email protected]>
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