From: enginedrive2002 (enginedrive2002@yahoo.ca)
Date: Wed Oct 23 2002 - 13:29:37 GMT-3
Thank you very much, Adam!
It's getting clearer and clearer now. Based on your explanation, can I say
"the rule of a router is completely within an area is true for TCP/IP, but
false for CLNS"?
I have so little knowledge about CLNS, hope this conclusion doesn't sound
funny to you guys. :-)
E.D.
----- Original Message -----
From: "Adam Crisp" <adam.crisp@totalise.co.uk>
To: "enginedrive2002" <enginedrive2002@yahoo.ca>; <ccielab@groupstudy.com>
Sent: October 23, 2002 12:02 PM
Subject: RE: IS-IS area and process.
>
>
> yes, I see your problem.
>
> the Area Tag is definitely a Process ID.
> this is because if you were to have a router with more than one ISIS
routing
> process, then you would support more that one NSAP Area.
> eg
> !
> router isis 1
> net 49.0001.1111.1111.1111.00
> !
> router isis 2
> net 49.0002.1111.1111.1111.00
> is-type level-1
> !
> Router2#show clns
> Global CLNS Information:
> 0 Interfaces Enabled for CLNS
> NET: 49.0001.1111.1111.1111.00
> NET: 49.0002.1111.1111.1111.00
> Configuration Timer: 60, Default Holding Timer: 300, Packet Lifetime 64
> ERPDU's requested on locally generated packets
> Intermediate system operation enabled (CLNS forwarding allowed)
> IS-IS level-1-2 Router: 1
> Routing for Area: 49.0001
> IS-IS level-1 Router: 2
> Routing for Area: 49.0002
> Router2#
>
>
>
>
> This is all about OSI and network management
> ISIS can router OSI traffic - ie OSI clns
>
> OSI CLNS/CLNP is used in optical network management land, where devices
like
> Optical Add and Drop Multiplexors need to me managed, and the network
> protocol used is OSI - NOT TCP/IP!!
>
> The ADM's route OSI traffic between them using ISIS - and you can imaging
> that physically the devices can be hundreds of miles apart if they're
> connected via optical fibres.
>
> There is a limit to the number of Network Elements in any one Area, (ISIS
L1
> area) -
> The ADM network would therefore be split up into a number of L1 Areas.
>
> At some point the OSI traffic need to get back to a Network management
> center - and there is a gateway to a regular Cisco Router.
> Instead of having one router for every OSI Area (connected together via L2
> links), a Cisco router can support more that one Area (upto 26)
>
> More than one Area -------- More that one ISIS process
>
> hense the "router isis <area_tag>" ==== "router isis <process Id>
>
> In the scenario I've just tried to outline, the Cisco router would have a
L2
> link to the Telco's core network.
> Only one ISIS process can support L2 LSP's
>
> Hope this helps
>
> Adam
>
>
> -----Original Message-----
> From: enginedrive2002 [mailto:enginedrive2002@yahoo.ca]
> Sent: 23 October 2002 16:36
> To: Adam Crisp; ccielab@groupstudy.com
> Subject: Re: IS-IS area and process.
>
>
> Adam,
>
>
> Thanks for your information.
>
> Regarding command "router isis <a_number_here>", my understanding is like
> yours, it's a process number. But if you check the IOS command reference,
> the syntax is "router isis <area_tag>".
>
> This comes with my confusion. The first thing I learn about IS-IS is "a
> router is completely within an area, and the area borders are on links,
not
> on routers". If we could configure several "router isis <area_tag>" on a
> single router, didn't it bread the rule above, which make the area border
on
> the routers? If we both accept the rule is true, would this make process
> equal to area? Or the rule above is wrong in the very beginning?
>
> Thanks!
>
>
> E.D.
>
> ----- Original Message -----
> From: "Adam Crisp" <adam.crisp@totalise.co.uk>
> To: "enginedrive2002" <enginedrive2002@yahoo.ca>; <ccielab@groupstudy.com>
> Sent: October 23, 2002 11:00 AM
> Subject: RE: IS-IS area and process.
>
>
> > should read at bottom of previous post:
> > R1: NSAP net 39.826f.3142.0000.0000.0002.0006.0010.7b38.0001.00
> > R2: NSAP net 39.826f.3142.0000.0000.0002.0007.0010.7b38.0002.00
> > R3: NSAP#1: net 39.826f.3142.0000.0000.0002.0006.0010.7b38.00de.00
> > R3: NSAP#2: net 39.826f.3142.0000.0000.0002.0007.0010.7b38.00de.00
> > R3: NSAP#3: net 49.0001.0006.0010.7b38.00de.00
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > Adam Crisp
> > Sent: 23 October 2002 15:44
> > To: enginedrive2002; ccielab@groupstudy.com
> > Subject: RE: IS-IS area and process.
> >
> >
> > Hi,
> >
> > It is possible to run more than one ISIS routing process on a router.
> > This is a bit like running more that one OSPF process.
> > Actually, you can run more that one ISIS process, but only one process
can
> > generate and maintain a Level-2 database.
> > example:
> >
> > router isis 10
> > !This runs as isis process with a process ID of 10
> > !This is NOT an automonous system number - it's a process ID - and never
> > leaves the router
> > !this is is bit like typing 'router ospf 10'
> >
> > router isis 20
> > !This runs as isis process with a process ID of 10
> >
> > router isis
> > !This runs as isis process with a process ID of NULL - note that you
> can't
> > do this with OSPF
> >
> >
> > The net statement under isis is a long number that is known as an NSAP
> > address. This is a but like an X.500 address.
> > this is described at
> >
>
http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuratio
> > n_guide_chapter09186a008007fd45.html#1012605
> >
> > A very basic description of an NSAP address is:
> >
> > 1. AFI - Format Identifier - How long is the address, where are the byte
> > boundaries atc.
> > 2. IDI DFI AAI - Organisation - an attempt at describing the
> organisation
> > that holds the address
> > 3. Domain - a number, a bit like autonomous system
> > 4. Area - a number, a bit like an OSPF area ID
> > 5. End system ID, a unique ID, can be anything but must be unique,
> Ethernet
> > MAC addresses are frequently used as these are already unique.
> > 6. N-selector - a bit like TCP port number
> >
> > Different AFI's define different lengths, and different content of the
> NSAP
> > address. - ie picked from the list above
> >
> > eg AFI 49 - example 49.0001.0006.0010.7b38.00de.00
> > AFI 49 - 49.aaaa.iiii.iiii.iiii.iiii.nn
> > where a=area, i=systemID, n=N-sel
> >
> > eg AFI 39 - example net
> 39.826f.3142.0000.0000.0002.0006.0010.7b38.00de.00
> > 39 net 39.idi .dfi .afi .dddd.aaaa.iiii.iiii.iiii.nn
> >
> > Does this answer your question?
> >
> > In practice, we are only intesested in two parts of the NSAP address,
> > 1. Area
> > 2. System ID
> >
> > more...
> > Routing protocols - ISIS only exits on two levels
> > Level-1 - can route between System ID's
> > Level-2 - can route between Areas
> >
> > Level-3 - routing between domains.. well this doesn't exist, Cisco or
> > somebody once thought up IDRP - Interdomain Routing Protocol - but this
> was
> > never implemented. - at least I've never seen it in an IOS release. My
> guess
> > is that the MBgp development will sort this out.
> >
> > As ISIS is only L1,L2 aware, we are only interested in AREA and
SYSTEM_ID
> > The area is all the NSAP address that is NOT the system ID. Therefore
> >
> >
> > ISIS sees the NSAP as two parts, Area and System ID:
> > NSAP: 39.826f.3142.0000.0000.0002.0006.0010.7b38.00de.00 will be treated
> as:
> > NSAP: 39.aaaa.aaaa.aaaa.aaaa.aaaa.iiii.iiii.iiii.00
> >
> > Back to level-1 again,
> > In order for ISIS adjecencies to form, the area must be the same.
> >
> > It is possible for three different NSAPS to be configured on the same
> > routing process
> > eg.
> > !
> > router isis
> > net 39.826f.3142.0000.0000.0002.0006.0010.7b38.00de.00
> > net 39.826f.3142.0000.0000.0002.0007.0010.7b38.00de.00
> > net 49.0001.0006.0010.7b38.00de.00
> > !
> >
> > this has the effect of MERGING the areas together, therefore you could
> have:
> > R1---R2----R3, connected together with serial interfaces
> > the following NSAP addresses configured:
> > R1: NSAP net 39.826f.3142.0000.0000.0002.0006.0010.7b38.0001.00
> > R2: NSAP net 39.826f.3142.0000.0000.0002.0006.0010.7b38.0002.00
> > R3: NSAP#1: net 39.826f.3142.0000.0000.0002.0006.0010.7b38.00de.00
> > R3: NSAP#2: net 39.826f.3142.0000.0000.0002.0007.0010.7b38.00de.00
> > R3: NSAP#3: net 49.0001.0006.0010.7b38.00de.00
> >
> > Since r3 above merges the "areas" R1 and R2 WILL form an adjecency.
> >
> >
> > Good luck
> >
> > Adam
> >
> >
> >
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> > enginedrive2002
> > Sent: 23 October 2002 14:41
> > To: ccielab@groupstudy.com
> > Subject: IS-IS area and process.
> >
> >
> > Hi, Group
> >
> >
> > The concept of area and process in IS-IS really bothering me, sometimes
> they
> > look like the same, sometimes they are not. Could someone explain them
to
> > me?
> >
> > Thank you!
> >
> >
> > E.D.
>
> ______________________________________________________________________
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This archive was generated by hypermail 2.1.4 : Tue Nov 05 2002 - 08:35:54 GMT-3