From: Scott Morris (swm@emanon.com)
Date: Sun Jun 05 2005 - 09:10:20 GMT-3
And what did you see on different routers? You'll find a pattern as far as
how the metrics work. They're treated the same by default, at least for
adding metrics!
Scott
-----Original Message-----
From: san [mailto:san.study@gmail.com]
Sent: Sunday, June 05, 2005 3:58 AM
To: swm@emanon.com
Cc: Group Study
Subject: Re: isis basic question
Thanks Scott.
After further experiment, i have taken the below notes on ISIS...May be
useful for beginners. I have another question below.
Question 1:
----------------
One more basic question in "sh isis database detail".....Metric for Same
routes for L1 is different from L2 in the database. (example:
130.1.26.0 network in the below output ) Can you comment ?
Rack1R6#sh isis data deta
IS-IS Level-1 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
Rack1R6.00-00 * 0x0000000F 0xFF9C 716 1/0/0
Area Address: 66
NLPID: 0xCC
Hostname: Rack1R6
IP Address: 180.1.8.8
Metric: 10 IP 130.1.26.0 255.255.255.0 <<<<<<<<<metric 10
??
Metric: 10 IP 180.1.8.0 255.255.255.0
IS-IS Level-2 Link State Database:
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL
Rack1R1.00-00 0x00000027 0x2D62 979 0/0/0
Area Address: 12
NLPID: 0xCC
Hostname: Rack1R1
IP Address: 130.1.12.1
Metric: 10 IS Rack1R2.02
Metric: 10 IP 170.1.2.0 255.255.255.0
Metric: 0 IP-External 130.1.13.0 255.255.255.0
Metric: 10 IP 130.1.12.0 255.255.255.0
Metric: 20 IP 130.1.26.0 255.255.255.0
<<<<<<<<metric 20 ??
Metric: 20 IP 150.1.2.0 255.255.255.0
Metric: 0 IP-External 150.1.1.0 255.255.255.0
/SAN
Notes:
--------
Formating used.
- Main section
-- sub section
--- sub-sub section
Topology:
(nw z) R6---------isis-nw A-----R2---------(nw B)isis------------R1------(nw
C)ospf--------R3
Net26 net 12
net12
- Sh clns neighbor (to check neighbor relationship is at L1 or L2 of
L1/2)
- Sh isis database detail (to check how routes are learnt ? or learnt
? )
- "clns routing" is not necessary for ip routing.
- Router-isis# Passive-interface loop 1 , neighbor will see the
route as i L1 route.
- Redistribute-connected under isis, will redistbute the route as i
L2 route to isis neighbors
-- If nw B needs to be redistributed by R1 to R3 (isis to
ospf)..use "redistribute connected"
-- If nw C needs to be redistribute...simply redistribute ospf.into
isis.
Summary under isis-process
--------------------------------------------
- Router-isis# Summary-address x.x.x.x mask ,.will summary only at
the output of ISIS engine.so only isis neighbors will know about
it...So, if you are redistributing isis into OSPF, (ospf neighbor
will still see all the individual routes.so, need another summary route for
the same network under the ospf process, where redistribution is done).
Within ISIS to ISIS neighbors (no redistribution).
-------------------------------------------------------------
- External routes through redistribution (sh isis database level-2
detail show external)
--If the peer connection is L2, all routes learnt from neighbor is
L2
--If the peer connection is L1L2,
--- L1 routes or connected routes of peer is L1 routes here (ex: nw
A treated as L1 at R1)
--- L2 routes of Peer is L2 routes here (ex: nw Z treated as L2 at
R1)
Redistribute ospf into isis
------------------------------------
- Router-isis# Redistribution ospf/connected will redistribute as
only l2 ((if needed change the options in redistrib cmd))...((R1 & R2 has
both L1/2 relation.))
-- Level-1 => Routing tables sees as only L1 at R2, R1 routing
table sees as "ospf"
--- R1 sees in L1 & L2 database: L1 database as external, L2
database as just a route may be because of L1L2 relation ship between
R1 & R2)
--- (R2 sees in L1 & L2 database: L1 database as external, L2
database as just a route because of L1L2 relation ship between R1 &
R2)
-- Default / manually level-2 => By default when redistributing into
isis protocol, it only redistribute as Level-2, unless specified. (ex:
routing table R2 sees as I L2, R1 sees as "o"
because R1 is also running ospf )
--- R1 sees in L2 database: L1 database as ----, L2 database as
external
--- (R2 sees in L2 database: L1 database as ----, L2 database as
external
-- Level-1-2 => Routing table sees as only L1 at R2 (l1 is
preferred over L2), R1 sees as ospf
--- R1 sees in L2 database: L1 database as external, L2 database
as external
--- R2 sees in L2 database: L1 database as external, L2 database
as external
redistribute isis into ospf
--------------------------------
- Router-ospf# redistribute isis level-xxxxxx subnets ((ospf
learns as 0 E2 metric 20 ))
-- Level-1 => it does redistribute level-1 only from its local
database
-- Default => By default when redistributing into another protocol,
it only redistribute Level-2, unless specified
-- Level-1-2 => both level-1-2 redistrbuted.
On 6/3/05, Scott Morris <swm@emanon.com> wrote:
> Clns routing is not necessary for ISIS in the method that we use it
> for the IP environment. If you actually have a CLNS network and are
> passing CLNS information as well, then you'll need it. For ISIS-IP
> routing, you do not need it.
>
> As for your redistribution, what do you see in the OSPF database when
> you do it the way you have described there? :)
>
> Scott
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of san
> Sent: Friday, June 03, 2005 4:40 AM
> To: Group Study
> Subject: isis basic question
>
> 1. When do we need to enable "clns routing" for isis ?
>
> 2. quote: below
> By default when redistributing into another protocol, it only
> redistribute Level-2, unless specified
>
> router ospf 1
> redistribute isis level-1 subnet tag 22110
> redistribute connected subnet tag 22000
>
> Assuming the above config, does it redistribute level-2 also ? or Do
> i need to specify "redistribute isis level-1-2 subnet" ?
>
>
>
> Thanks in Advance
> SAN
>
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