From: Hunt Lee (huntl@webcentral.com.au)
Date: Wed May 28 2003 - 04:23:40 GMT-3
Hey Jonathan,
So are my calculations correct? Thanks ;)
H.
Hi guys,
I wrote out the whole thing... So is it the case where as soon as there is
a 1, I put a 1 in the bottom? If so, for LSAP type codes 00, 04, 08, 0C
4 0100 <--- no zeros on last 2 digits
5 0101
6 0110
7 0111
8 1000 <--- no zeros on last 2 digits
9 1001
10 1010 A
11 1011 B
12 1100 C <--- no zeros on last 2 digits
13 1101 D
14 1110 E
15 1111 F
-----------
1100
So would the answer be:
access-list 200 permit 0x0000 0x0C00 (but NOT 0x0000 0x0c0c)
And another eg. if we want to allow only 04 & 06...
4 0100
5 0101
6 0110
7 0111
8 1000
9 1001
10 1010 A
11 1011 B
12 1100 C
13 1101 D
14 1110 E
15 1111 F
-----------
0110
So would the answer be:
access-list 200 permit 0x0000 0x010A
My I correct?
Regards,
H.
-----Original Message-----
From: Jonathan V Hays [mailto:jhays@jtan.com]
Sent: Wednesday, 28 May 2003 3:54 AM
To: ccielab@groupstudy.com
Cc: 'FATHALLAH'; 'lg01'
Subject: RE: Filtering SNA
Since 'C' is 1100 in binary, the first and second (leftmost) bits of a
hex digit are "Don't Care" and can be 1 or 0. The last two (rightmost)
bits must be 0.
And note that 0x0C0C is actually a two-byte, 16-bit mask.
Hope that helps,
Jonathan
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
> Behalf Of FATHALLAH
> Sent: Tuesday, May 27, 2003 11:09 AM
> To: lg01; ccielab@groupstudy.com
> Subject: RE: Filtering SNA
>
>
> 00 04 08 0B all are multiple of 4. so 0C0C mean that the
> first and second
> bits must be "0" and Third or/and fourth can be 1 or 0. witch
> give you 00,
> 04, 08,0B.
>
> Said FATHALLAH
>
> -----Message d'origine-----
> De : nobody@groupstudy.com [mailto:nobody@groupstudy.com]De la part de
> lg01
> Envoyi : mardi 27 mai 2003 11:01
> @ : ccielab@groupstudy.com
> Objet : Filtering SNA
>
>
> Hello group,
>
> If anyone can shed some lights on this, that would be greatly
> appreciated.
>
> In an exercise, it asked me to only allow SNA traffic from
> RTA. And it said
> that the SNA ports used will be 00, 04, 08 & 0B.
>
> But somehow... the answwer config gives:
>
> access-list 200 permit 0x0000 0x0C0C
>
> But I don't understand how they dervie / calculate this ACL.
>
> Thanks.
>
> H.
>
>
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