RE: IE Lab 20 11.2 Telnet Filtering

From: Prem Anand \(hprem\) (hprem@cisco.com)
Date: Tue Jul 11 2006 - 06:00:37 ART

Hi,
    I too guess that XOR output = 0, for 000,111 and 1 in all other
cases

    But the algo. I sent was for X-NOR; I wrongly mentioned as X-OR.
Actually we are interested in finding the X-NOR for getting the correct
mask.
    So the corrected version is

    XNOR3 of the 3 numbers shud be (A & B & C) XNOR (A | B | C), where
XNOR3 is defined as 1, for 000 and 111 and 0 in all other cases

    If the defnition of XNOR3 contradicts the actual defnition of XNOR
of 3 numbers, then let us have a different name for this function; But
we r interested in finding the output of this function only.

Regards
Prem

________________________________

From: Shanky [mailto:shankyz@gmail.com]
Sent: Tuesday, July 11, 2006 2:17 PM
To: Prem Anand (hprem)
Cc: Leo Leung; ccielab@groupstudy.com
Subject: Re: IE Lab 20 11.2 Telnet Filtering

Hi,

According to the logic in the link below, for XOR Function with 3
inputs, output will be 1 if one or all inputs are 1, so it will be 0 in
case of even no of 1s and in case all are 0 ?

http://www.dst-corp.com/James/LogicPrimer/Gates.html#Xor3

so XOR of 1,1,0 is 0 ...?

I thought XOR output will be 0, if all inputs are equal and 1 if any
input is different ..

so XOR output = 0, for 000,111 and 1 in all other cases.

Any comments?

On 7/11/06, Prem Anand (hprem) <hprem@cisco.com> wrote:

        (A & B & C) will have a bit set to 1 only when all 3 numbers
have that
        bit set to 1
        (A | B | C) will have a bit set to 0 only when all 3 numbers
have that
        bit set to 0

        So the XOR of the 3 numbers shud be (A & B & C) XOR (A | B | C)

        Any comments?

        Regards
        Prem

        -----Original Message-----
        From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf Of
        Shanky
        Sent: Tuesday, July 11, 2006 12:14 PM
        To: Leo Leung
        Cc: ccielab@groupstudy.com
        Subject: Re: IE Lab 20 11.2 Telnet Filtering

        Hi,

        Was wondering if anyone knows a way to use the windows
calculator for
        AND
        , XOR functions for multiple entries ? I know it works for 2
entries
        but
        can we use it for more than 2

        Appreciate if anyone could help.

        Thanks

        Shanky

        On 7/11/06, Leo Leung <leoleung_yh@yahoo.com> wrote:
>
> Group,
>
> The question asks to have one line access-list for these 3 IP
> addresses.
>
> Decimal Binary
>
> 45.194.169.115 00101101 11000010 10101001 01110011
> 61.202.173.243 00111101 11001010 10101101 11110011
> 41.234.41.250 00101001 11101010 00101001 11111010
>
> IP 41 194 41 114
> Mask 20 40 132 137
>
> I came out with the following:
>
> ip access-list 1 permit 41.194.41.114 20.40.132.137
>
> but solution guide shows the access-list with 3 differences
>
> ip access-list 1 permit 41.194.41.112 20.60.134.137
>
> I am wondering if its typo or I miscalculated.
>
> Leo
>
>
>
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