From: Arun Arumuganainar (aarumuga@hotmail.com)
Date: Tue Aug 23 2005 - 23:51:18 GMT-3
> Your'e told that "as the IS-IS NET address must start and end to one octet
> "<-
I don't think this is a valid statement . !!!
1) Address can be of length 8 to 20 Bytes ( excluding N-Selector )
2) Length of System ID should be same . Cisco convention is 6 Bytes .
3) N-Selector is left to 00 for IS - systems i.e For Routers N-selector will
be always set to 0
Note : If you follow NSAP format first Bytes should be AFI which 2 bytes .
When you are using private NSAP address AFI would be 49.
Cisco Routes understand non-NSAP formats ( that do not mandates single byte
AFI) also .
You can have 3940.0100.0100.0600.00
Here 3940 ==> Area ID
0100.0100.0600==> System ID
00==> Nselector for IS ( Routers )
Hope this helps .
Thanks and Regards
Arun
----- Original Message -----
From: "Hictor Fernandez" <gnakh@telefonica.net>
To: "Stefan Grey" <examplebrain@hotmail.com>; <ccielab@groupstudy.com>
Sent: Tuesday, August 23, 2005 9:27 PM
Subject: Re: ISIS address rule question. IEWB
> Hi again,
>
> It's confusing you... It's not telling you that you're forced to have the
> first byte equal to 00.
> Remember how an NET address is REPRESENTED for human reading:
> AA.aaaa.aaaa.aaaa.aaaa.aaaa.aaaa.ssss.ssss.ssss.NN (AA and NN are 2 bytes
> that are not shown together, are the rest of groups of 16 bits)
> They're telling you they're going to place 3490 beginning in the second
byte
> instead of beginning the NSAP with 34, and that 00 is being used to fill
the
> AA byte.
> That is: instead of using 34.9000.0100.0100.0600.00, use
> 00.3490.0001.0001.0006.00, that's easier to read, it belongs to area
00.3940
> and has 0001.0001.0006 as system ID.
>
> Your'e told that "as the IS-IS NET address must start and end to one octet
> "<- this just refers as how it is represented... , but you've never been
> forced to use 00... in fact, any NSAP address must start and end with one
> octet... isn't it funny?
>
> I'm not English and trying to express myself it's quite hard, I hope this
is
> clear enough.
>
> Regards
>
> Hictor
>
> ----- Original Message -----
> From: "Stefan Grey" <examplebrain@hotmail.com>
> To: <gnakh@telefonica.net>; <ccielab@groupstudy.com>
> Sent: Tuesday, August 23, 2005 5:42 PM
> Subject: Re: ISIS address rule question. IEWB
>
>
> >
> > Look on the brakedown from the IEWB workbook (this appears some times in
> the
> > workbook so it isn't just a mistake)
> >
> > Task: configure the net address as 13456
> >
> > brakedown,explanation:
> >
> > isis network entity title (NET address are in the ISO NSAP format, and
are
> > denoted in hexadecimal format. The above requirement states that
> R1,R3,R4,R5
> > and R6 be configured in IS-IS area 13456. In hexadecimal, this number
> > converts to 3490. However, as the IS-IS NET address must start and end
to
> > one octet, and additional 00 has been added to the beginning of the
> address.
> >
> > Could anybody comment???
> >
> > >From: Hictor Fernandez <gnakh@telefonica.net>
> > >Reply-To: Hictor Fernandez <gnakh@telefonica.net>
> > >To: "Stefan Grey" <examplebrain@hotmail.com>, <ccielab@groupstudy.com>
> > >Subject: Re: ISIS address rule question.
> > >Date: Tue, 23 Aug 2005 17:35:59 +0200
> > >
> > >Hi all,
> > >
> > >1st. time I've heard of that...
> > >Last octet (n-selector) is what makes that NSAP address the NET, 00.
> First
> > >byte, 34 or 49 here, part of the area address (up to 13 bytes).
> > >
> > >I hope this helps
> > >
> > >best regards
> > >Hictor
> > >
> > >REM: NSAP ADDRESS = AreaID (1..13 bytes), SysID (6 bytes), NSEL (1
byte),
> > >and for the NSAP address to be the NET, NSEL=0x00
> > >
> > >----- Original Message -----
> > >From: "Stefan Grey" <examplebrain@hotmail.com>
> > >To: <ccielab@groupstudy.com>
> > >Sent: Tuesday, August 23, 2005 4:27 PM
> > >Subject: ISIS address rule question.
> > >
> > >
> > > > There is a rule that the Net address should start and end with the
> same
> > > > octet. While doing different labs I can't uderstand it.
> > > >
> > > > 1. 3490.0001.0001.0006.00
> > > > 2.490125.0001.0001.0006.00
> > > >
> > > > Why the first address is incorrect. And to correspond to the rule
> above
> > >we
> > > > should use the address 00.3490.0001.0001.0006.00
> > > >
> > > > But the second is correct. I just can't understand it event writing
> this
> > > > addresses in binary.
> > > >
> > > > Could anybody explain?? thanks;)
> > > >
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