Thanks Prakash,

 

I've noted this down on my notebook just for reference

 

Cheers!

Antonio

 

From: prakash patel [mailto:[email protected]] 
Sent: Tuesday, 19 May 2009 12:03 AM
To: [email protected]
Subject: RE: [OSL | CCIE_RS] ACL filtering blues

 

Tweaking of words may kill you in ACL.
 
Here is the concept I follow
 
(1) Always put down in binary..separate "common" and "uncommon" per
requirements
 
(2) then check the requirement...How many lines ?
 
(3) if it says one line or two lines ...Always keep that "implied deny" will
take care of so many things"
 
Consider the options to meet # of lines
(1)  2 lines then      deny ..permit...Implied deny
(2) one line then      permit..Implied deny
(3)  2 lines          permit ...permit...Implied deny
 
 
thanks Prakash
 

  _____  

To: [email protected]; [email protected];
[email protected]
From: [email protected]
Date: Mon, 18 May 2009 14:24:32 +0000
Subject: Re: [OSL | CCIE_RS] ACL filtering blues

Antonio,

Check it out: between 10 and 14 we have 1 bit different right? Which bit? It
is the 4 bit right? Since it can be 1 or 0 we "don't care" so it is a 1 in
the mask.

So our mask is 00000100. That is 4 in decimal.

Regards,

Joe Astorino 
CCIE #24347 (R&S)
Sr. Support Engineer - IPexpert, Inc.
URL: http://www.IPexpert.com

  _____  

From: "Antonio Dee Hotmail" 
Date: Mon, 18 May 2009 23:49:09 +0930
To: 'CCIE_RS OnlineStudyList'<[email protected]>
Subject: Re: [OSL | CCIE_RS] ACL filtering blues

 

Hi Prakash,

 

Michael is right, this would filiter only 10 and 14 , and not 13

 

pretty much let say i want 10 and 14, and the answer is 0.0.4.0 ???? still
having hard time grasping it

 

Cheers!

ANtonio

 

 

 

From: prakash patel [mailto:[email protected]] 
Sent: Monday, 18 May 2009 11:35 PM
To: [email protected]; [email protected]
Subject: RE: [OSL | CCIE_RS] ACL filtering blues

 

Addition to previous. 
 
it will allow whole range though.
 
What is the statement says...need more information.
 
We may have to adjust it.
 
 
 
 
 
 
 

  _____  

From: [email protected]
To: [email protected]; [email protected]
Date: Mon, 18 May 2009 09:59:33 -0400
Subject: Re: [OSL | CCIE_RS] ACL filtering blues

 
Hello
 
10=00001010
13=00001101
14=00001110
 
What is the common here ?....00001xxx
 
so xxx vlaues give you 0.0.7.0
 
the fist should be 10.10.8.0
 
so the whole completed is 10.10.8.0 0.0.7.0 
 
if u see logical in 3rd octets  ...8 is starting value and ending 8+7 = 15
 
10.10.8.0 thru 10.10.15.0 
 
makes sense?

  _____  

From: [email protected]
To: [email protected]
Date: Mon, 18 May 2009 23:23:05 +0930
Subject: [OSL | CCIE_RS] ACL filtering blues

Hi All,

 

Need some help on ACL calculation. This is general ACL filtering scenario.

 

I'm just practicing on ACL filtering especially on the non-continuous
wildcards.

 

i've injected this to my test router but i don't seem to get the logic why
it's this wildcard. can somebody enlighten me on this?

 

I know 0 in the wildcard are care bits and 1 don't care, just the opposite
of a subnet mask.

 

Example Scenario:

 

I get this networks from a backbone router:

 

network 10.10.10.0

network 10.10.11.0

network 10.10.12.0

network 10.10.13.0

network 10.10.14.0

network 10.10.15.0

network 10.10.16.0

 

I want to filter on the third octet and allow only 10, 13, 14 to come in

 

been playing with various values on the wildcard, and the working value is
0.0.4.0 , WHY????

 

 

Kind Regards,

Antonio

 

 

 

 

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