RE: default route origination in ISIS

From: Scott Morris (swm@emanon.com)
Date: Sun Nov 21 2004 - 16:10:05 GMT-3


ISIS does not generate and outbound 0/0 route.

If you have an L1 adjacency, you'll get whatever intra-area routes you are
supposed to get. When your L1/L2 router connects to another L2 neighbor
THEN all of those same L1 routes to the same L1 router will be sent with an
ATT bit set.

This ATT bit indicates that the advertising router is attached to another
outside area. The receiving router will then create their own 0/0 route
towards the L1/L2 router solely based on receipt of aroute with the ATT bit
set.

So if you want to see this in action, you really need to have three routers.
One L2 (area 1) one L1/L2 (area 2) and one L1 (area 2)...

HTH,

 
Scott Morris, MCSE, CCDP, CCIE4 (R&S/ISP-Dial/Security/Service Provider)
#4713, JNCIP, CCNA-WAN Switching, CCSP, Cable Communications Specialist, IP
Telephony Support Specialist, IP Telephony Design Specialist, CISSP
CCSI #21903
swm@emanon.com
 
 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of mani
poopal
Sent: Sunday, November 21, 2004 2:00 PM
To: ccielab@groupstudy.com
Subject: default route origination in ISIS

Hi Group,
 
I tried to configure RIP and ISIS. My HUB router is R2(runs rip and isis
and redistributes) in the R3 spoke router I am seeing all rip routes and
isis L2 routes. I thought if I could make the is-type for R3 to level 1,
hub router R2 should geneate a default route. I configured
(config-router)#is-type level-1 at R3, this configuration stopped learing of
all L2 routes and I could not see a default route originated by my Hub
router(level1/level2 I even changed the is type to level 2 only). I am
posting my config at R2 and R3, any feed back is appreciated.[IN THIS CONFIG
I REMOVED THE IS-TYPE LEVEL-1 IN R3]
 
thanks
Mani
==========================================
R3(spoke router)
interface Serial1
 ip address 20.1.1.3 255.255.255.0
 ip router isis
!
router isis
 net 11.0000.0000.0003.00
 passive-interface Loopback0
 passive-interface Loopback1
 passive-interface Loopback2
 passive-interface Loopback3
 passive-interface Loopback4
 passive-interface Loopback5
==
R3#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2
       ia - IS-IS inter area, * - candidate default, U - per-user static
route
       o - ODR, P - periodic downloaded static route Gateway of last resort
is not set
     140.4.0.0/24 is subnetted, 2 subnets
C 140.4.1.0 is directly connected, Loopback1
C 140.4.2.0 is directly connected, Loopback2
     20.0.0.0/24 is subnetted, 1 subnets
C 20.1.1.0 is directly connected, Serial1
     111.0.0.0/24 is subnetted, 1 subnets
i L1 111.11.1.0 [115/10] via 20.1.1.2, Serial1
     160.6.0.0/24 is subnetted, 3 subnets
C 160.6.2.0 is directly connected, Loopback4
C 160.6.3.0 is directly connected, Loopback5
C 160.6.1.0 is directly connected, Loopback3
     130.3.0.0/24 is subnetted, 2 subnets
i L2 130.3.1.0 [115/10] via 20.1.1.2, Serial1
i L2 130.3.2.0 [115/10] via 20.1.1.2, Serial1
     10.0.0.0/24 is subnetted, 1 subnets
i L2 10.1.1.0 [115/10] via 20.1.1.2, Serial1
     150.5.0.0/24 is subnetted, 3 subnets
C 150.5.3.0 is directly connected, Loopback0
i L2 150.5.2.0 [115/10] via 20.1.1.2, Serial1
i L2 150.5.1.0 [115/10] via 20.1.1.2, Serial1
======================================================
R1(HUB ROUTER) RUNNING RIP & ISIS AND MUTUAL REDISTRIBUTION:
interface Serial0
 ip address 10.1.1.2 255.255.255.0
 clockrate 56000
!
interface Serial1
 ip address 20.1.1.2 255.255.255.0
 ip router isis
 clockrate 56000
!
router isis
 net 11.0000.0000.0002.00
 redistribute rip
 passive-interface Loopback10
!
router rip
 version 2
 redistribute connected route-map ABC
 redistribute isis level-1-2 metric 3
 network 10.0.0.0
 network 150.5.0.0
 no auto-summary
!
ip classless
no ip http server
!
route-map ABC permit 10
 match interface Serial1
 

B.ENG,A+,CCNA,CCNP,CCNP-VOICE, CSS1,CNA,MCSE
(416)431 9929
MANI_CCIE@YAHOO.COM
                
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