From: Ken.Farrington@barclayscapital.com
Date: Fri Oct 03 2003 - 03:07:55 GMT-3
Hi Fred,
Sorry for another e-mail, but one last question (after looking at rfc 1620)
- Looking for how Cisco could confuse me (maybe others) in the lab.
<----IDP---> <----------------------DSP---------------------------->
<-----------HO-DSP------------>
+-----+-----+-------------------------------+--------------+-------+
| AFI | IDI |Contents assigned by authority identified in IDI field|
+-----+-----+-------------------------------+--------------+-------+
<----------------Area Address--------------> <-----ID-----> <-SEL->
IDP Initial Domain Part
AFI Authority and Format Identifier
IDI Initial Domain Identifier
DSP Domain Specific Part
HO-DSP High-order DSP
ID System Identifier
SEL NSAP Selector
The area can be from 1 to 8 bytes long, and the complete address can be from
8 bytes to 20 bytes long.
Example
If they said config area 47.01 as the area address with the shortet ISIS
address possible, (47.01) this potion would be the same on all router. Then
I would have to make the system ID a minimum of (minus 2 byte areaID plus 1
byte SEL), so the minimum System ID would be 5 bytes.
Is this correct?
Many thx indeed.
-----Original Message-----
From: Ken.Farrington@barclayscapital.com
[mailto:Ken.Farrington@barclayscapital.com]
Sent: 02 October 2003 20:42
To: fingham@cox.net; ccielab@groupstudy.com
Subject: RE: ISIS Network Entity Title
Thats great fred. Sorry I should have looked at the RFC :)
downloading now for a viewing :)
many thx indeed
-----Original Message-----
From: Fred Ingham [mailto:fingham@cox.net]
Sent: 02 October 2003 20:27
To: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
Subject: Re: ISIS Network Entity Title
Ken: Not a dumb question but the answer is in the RFC (hint).
" The ID field may be from one to eight octets in length, but must have
a single known length in any particular routing domain. Each router
is configured to know what length is used in its domain. The SEL
field is always one octet in length. Each router is therefore able
to identify the ID and SEL fields as a known number of trailing
octets of the NSAP address. The area address can be identified as
the remainder of the address (after truncation of the ID and SEL
fields). It is therefore not necessary for the area address to have
any particular length -- the length of the area address could vary
between different area addresses in a given routing domain."
Cisco routers are configured for a 6 octet ID and a 1 octet SEL.
Fred
----- Original Message -----
From: <Ken.Farrington@barclayscapital.com>
To: <fingham@cox.net>; <ccielab@groupstudy.com>
Sent: Thursday, October 02, 2003 2:50 PM
Subject: RE: ISIS Network Entity Title
> so I can configure on my router as you have explained, the first two
> (3
just
> wipes me out)
>
> router isis
> net 47.0000.0000.0001.00
>
> or
>
> router isis
> net 47.0001.0000.0000.0001.00
>
> How does the router know that the router isis process is in area 47 or
> 47.0001.
>
> Sorry if this sounds really dumb.
>
> Thx, Ken
>
>
> -----Original Message-----
> From: Fred Ingham [mailto:fingham@cox.net]
> Sent: 02 October 2003 19:31
> To: Ken.Farrington@barclayscapital.com; ccielab@groupstudy.com
> Subject: Re: ISIS Network Entity Title
>
>
> Ken: The NET can be from 8 to 20 bytes. The SEL and ESI fields are
> always 1 and 6 bytes respectively for cisco routers. Anything in
> front of this is the area id. Refs are Dolye, Vol I, and RFC 1629.
>
> NET must begin with a single octet, the AFI (Authority and Format
> Identifier)
>
> Examples:
> 47.0000.0000.0001.00 is area id 47
> 47.0001.0000.0000.0001.00 is area id 47.0001
> 47.0004.004d.0001.0001.0c11.1111.00 is area id 47.0004.004d.0001
> which can also be read as AFI 47, domain 0004.004d, area 0001
>
> So, to answer your question the area id can be 1 or 3 (or more) bytes.
>
> HTH, Fred
>
> ----- Original Message -----
> From: <Ken.Farrington@barclayscapital.com>
> To: <ccielab@groupstudy.com>
> Sent: Thursday, October 02, 2003 12:29 PM
> Subject: ISIS Network Entity Title
>
>
> > Guys,
> >
> > v.quick one indeed.
> >
> > Lots of examples of NETs on the www. Can I just clarify a couple of
> points
> > (MAINLY THE LENGTH OF THE AREA ID is it 1 byte of 3?) :-
> >
> > I have confiured this
> >
> > router isis ken
> > net 47.1000.5000.0001.0000.00
> >
> > the first xx.xxxx of the net is an area ID - this is a static size
> > and always 3 bytes? the next fields are the system ID (shortest
> > being xxxx.xxxx (4 bytes), longest being
> > xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx.xxxx (16 bytes) the last two are
> > NSAP xx (1 byte)
> >
> > Is this correct??????????????????????????????????
> >
> >
> >
> > Tested below
> > --------------------
> > R6(config-router)#no router isis ken
> > R6(config)#router isis
> > R6(config-router)#net 47.1111.0000.00
> > %IS-IS: Invalid NET length
> > R6(config-router)#net 47.1111.0000.0000.00 R6(config-router)#no
> > router isis R6(config)#router isis
> > R6(config-router)#net
> > 47.0000.1111.1111.1111.1111.1111.1111.1111.1111.1111.00
> >
^
> > % Invalid input detected at '^' marker.
> >
> > R6(config-router)#net
> > 47.0000.1111.1111.1111.1111.1111.1111.1111.1111.00
> > R6(config-router)#
> >
> >
> >
> > --------------------------------------------------------------------
> > ----
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