From: alsontra@hotmail.com
Date: Sun Jul 25 2004 - 20:48:20 GMT-3
Great explanation! Thanks Bob.
Alsontra
----- Original Message -----
From: "Bob Sinclair" <bsin@cox.net>
To: <alsontra@hotmail.com>
Cc: <ccielab@groupstudy.com>
Sent: Sunday, July 25, 2004 10:51 AM
Subject: Re: Redistributing all Level 1 IP routes into the Level 2 process -
by default
> Alsontra,
>
> When you configure two ISIS processes on one router the first one
configured
> becomes an L2 area and routes from the other areas are automatically
> redistributed. The L1 area gets the attached bit set and so has a gateway
> of last resort. Details are below from my home lab. R3 and R5 are
> connected by Ethernet network 172.16.35.0. R5 and R6 are connected by
> Serial on network 172.16.62.0. I configured ISIS area 35 on the Ethernet
> link and area 56 on the Serial. Config, output and comments below:
>
> R3#
>
> router isis 35
> net 35.3333.3333.3333.00
> !
> interface Ethernet0
> ip address 172.16.35.3 255.255.255.0
> ip router isis 35
>
>
> R5#
> router isis 35
> net 35.5555.5555.5555.00
> !
> router isis 56
> net 56.5555.5555.5555.00
> is-type level-1 !NOTE: this command was inserted automatically. I
> configured Area 35 first.
>
> interface Ethernet0
> ip address 172.16.35.5 255.255.255.0
> ip router isis 35
> !
> interface Serial1
> ip address 172.16.62.1 255.255.255.0
> ip router isis 56
> clockrate 64000
>
>
> R6#
> router isis 56
> net 56.6666.6666.6666.00
>
> interface Serial0
> ip address 172.16.62.2 255.255.255.0
> ip router isis 56
>
>
> R3#sh clns is-neighbors
>
> System Id Interface State Type Priority Circuit Id Format
> R5-2511 Et0 Up L1L2 64/64 R5-2511.01 Phase
V
>
> !NOTE: R3 has a L1/L2 adjacency and it has learned about the Serial link
in
> Area 56, on the far side of R5.
>
> R3#sh ip route isis
> 172.16.0.0/24 is subnetted, 4 subnets
> i L2 172.16.62.0 [115/20] via 172.16.35.5, Ethernet0
> R3#
>
> R6#sh clns is-n
>
> System Id Interface State Type Priority Circuit Id Format
> R5-2511 Se0 Up L1 0 00 Phase
V
> R6#sh ip route
>
> Gateway of last resort is 172.16.62.1 to network 0.0.0.0
>
> !NOTE: R6 has an L1 adjacency with R5, and it has a default via the ATT
bit
> from R5
>
> 172.16.0.0/24 is subnetted, 6 subnets
> C 172.16.62.0 is directly connected, Serial0
> C 172.16.14.0 is directly connected, Ethernet0
> C 172.16.106.0 is directly connected, Loopback6
> C 172.16.69.0 is directly connected, Loopback3
> C 172.16.64.0 is directly connected, Loopback0
> C 172.16.65.0 is directly connected, Loopback1
> i*L1 0.0.0.0/0 [115/10] via 172.16.62.1, Serial0
>
> R5-2511#sh clns is-n
>
> Area 35:
> System Id Interface State Type Priority Circuit Id Format
> R3 Et0 Up L1L2 64/64 R5-2511.01 Phase
V
>
> Area 56:
> System Id Interface State Type Priority Circuit Id Format
> R6 Se1 Up L1 0 00 Phase
V
>
>
>
>
>
>
>
> Bob Sinclair
> CCIE #10427, CISSP, MCSE
> www.netmasterclass.net
>
> ----- Original Message -----
> From: <alsontra@hotmail.com>
> To: "Bob Sinclair" <bsin@cox.net>
> Cc: <ccielab@groupstudy.com>
> Sent: Sunday, July 25, 2004 2:40 PM
> Subject: Redistributing all Level 1 IP routes into the Level 2 process -
by
> default
>
>
> > Hi Bob,
> >
> > Will a router with two separate ISIS processes automatically
redistribute
> L1
> > routes?
> >
> > I have always used the multiple net statements to support separate ISIS
> > areas, so I'm unclear about this point. The document you posted seems
to
> > suggest that L1 routers on a single router belonging to two separate
ISIS
> > process will automatically redistribute. Is this correct?
> >
> > Quote -
> >
> > "Redistribution- IP routes learned via Level 1 routing are advertised by
> > default into Level 2. Even when multiple Level 1 processes are
configured
> on
> > the same unit, this fact is still true. No additional configuration is
> > required to redistribute all Level 1 IP routes into the Level 2 process.
"
> >
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/ismarea.htm
> >
> > Thanks,
> > Alsontra
> >
> >
> >
> >
> > Dehong,
> > If you are required to have differet interfaces on the same router in
> > different ISIS areas, then I would suggest two different ISIS processes.
> > This is the approach suggested by Cisco in the link below. When you
> > configure multiple NETs under one process, your database will show a
> single,
> > merged area.
> >
>
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120t/120t5/ismarea.htm
> > Bob Sinclair
> > CCIE #10427, CISSP, MCSE
> > www.netmasterclass.net
> > ----- Original Message -----
> > From: "Wang Dehong-DWANG1" <Dehong.Wang@motorola.com>
> > To: <ccielab@groupstudy.com>
> > Sent: Friday, July 23, 2004 4:37 PM
> > Subject: ISIS mutiple area question..
> >
> > > I have another question for the group. If you are asked to configure
> > multiple areas, say 2, under one router, should you configure two net
> > statements under one router isis or two seperate net statements under
> > different router isis? or it doesn't matter? My thought is two router
isis
> > statements, but I did see case 1 as well, so I would like to clarify it
> with
> > the group..
> > >
> > > Case 1:
> > >
> > > router isis
> > > net 49.area-A.xxxx.xxxx.xxxx.00
> > > net 49.area-B.xxxx.xxxx.xxxx.00
> > >
> > > Case 2:
> > > router isis
> > > net 49.area-A.xxxx.xxxx.xxxx.00
> > >
> > > router isis area-b
> > > net 49.area-B.xxxx.xxxx.xxxx.00
> > >
> > > thanks in advance..
> > >
> > > - Dehong
> > >
> > >
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