OSPF ON DEMAND CIRCUIT SOMETIMES BRINGS UP

From: jfaure@sztele.com
Date: Sat Feb 01 2003 - 07:44:28 GMT-3


Hi Guys!

We are testing OSPF ON DEMAND features in my lab. I'm using it over an ISDN
link with the purpose of backing up the main serial link (it's running
ospf) if it becomes unavailable. Apparently, it's working fine, but i'm
seeing that every 12 hours or so, the on demand circuit brings up after a
message like this:

 %OSPF-5-ADJCHG: Process 1, Nbr 133.1.46.1 on BRI1/0 from FULL to DOWN, Nei
ghbor Down: Too many retransmitions on Demand Circuit

This happens when the ospf adjacency beetween the two sides of the isdn
link goes down (you know ospf on demand suppress hellos and ospf lsa's in a
link type "point-to-point" as i have, then the adjacency must keep alive).
Then, why this adjacency goes down?

There is no topollogical change in the ospf network other than this (the
ospf adjacency trough the isdn link goes down). The error i said is
reported by the end that receives the isdn call (this end musn't call, and
the ond demand feature and dialer maps are configured in the other link)

Anybody knows what this error means in a ospf on demand environment? Am I
missing something about this?

Here you are the configs of the two routers:

R3---------main Frame Relay link------R5
|---------------backup isdn link--------------|

R5 (the router that must call if the main link goes down)

username R3 password 0 CISCO
ip subnet-zero
no ip domain-lookup
isdn switch-type basic-net3

interface Loopback0
 ip address 133.1.5.5 255.255.255.255
!
interface BRI0/0
 description enlace backup
 ip address 133.1.35.5 255.255.255.0
 encapsulation ppp
 ip ospf demand-circuit
 dialer map ip 133.1.35.6 name R3 broadcast 7200
 dialer load-threshold 128 either
 dialer-group 1
 isdn switch-type basic-net3
 no peer neighbor-route
 ppp authentication chap callin

interface Serial1/1
 no ip address
 encapsulation frame-relay
 no arp frame-relay
 no frame-relay inverse-arp

interface Serial1/1.2 multipoint
 description ENLACE R2 Y R3
 ip address 133.1.46.1 255.255.255.0
 ip ospf authentication message-digest
 ip ospf message-digest-key 1 md5 6 CISCO
 ip ospf network point-to-multipoint
 ip ospf hello-interval 50
 ip ospf priority 255
 no arp frame-relay
 frame-relay map ip 133.1.46.1 502 broadcast
 frame-relay map ip 133.1.46.2 502 broadcast
 frame-relay map ip 133.1.46.3 503 broadcast
 no frame-relay inverse-arp

router ospf 1
 router-id 133.1.46.1
 log-adjacency-changes
 area 5 virtual-link 133.1.56.6
 redistribute rip subnets tag 30
 network 133.1.5.5 0.0.0.0 area 0
 network 133.1.35.0 0.0.0.255 area 3
 network 133.1.46.0 0.0.0.255 area 0
 network 133.1.56.0 0.0.0.255 area 5

access-list 101 permit ospf any any
access-list 101 deny ip any host 255.255.255.255
access-list 101 deny ip host 133.1.5.5 any
access-list 101 permit ip any any
dialer-list 1 protocol ip list 101

Related config of R3

username R5 password 0 CISCO
ip subnet-zero
no ip domain-lookup
!
isdn switch-type basic-net3
interface Loopback0
 ip address 133.1.3.3 255.255.255.255

interface Serial0/0
 description AREA 0
 ip address 133.1.46.3 255.255.255.0
 encapsulation frame-relay
 ip ospf authentication message-digest
 ip ospf message-digest-key 1 md5 6 CISCO
 ip ospf network point-to-multipoint
 ip ospf hello-interval 50
 ip ospf priority 0
 no fair-queue
 no arp frame-relay
 frame-relay map ip 133.1.46.1 305 broadcast
 frame-relay map ip 133.1.46.2 305 broadcast
 frame-relay map ip 133.1.46.3 305 broadcast
 no frame-relay inverse-arp

interface BRI1/0
 ip address 133.1.35.6 255.255.255.0
 encapsulation ppp
 dialer idle-timeout 0
 dialer-group 1
 isdn switch-type basic-net3
 no peer neighbor-route
 ppp authentication chap

router ospf 1
 router-id 133.1.46.3
 log-adjacency-changes
 redistribute eigrp 2 subnets tag 25 route-map onlysum
 network 133.1.3.3 0.0.0.0 area 0
 network 133.1.23.0 0.0.0.255 area 3
 network 133.1.35.0 0.0.0.255 area 3
 network 133.1.46.0 0.0.0.255 area 0

I don't include all the config of the 2 routers, only the related to this
issue.

Any help would be apreciated. Regards

Juan Faure Ferrer
email: jfaure@sztele.com

Lmnea de Negocio de Telematica y CC
Ingeniero de Integracisn de Redes y Sistemas
----------------------------------------------------------------------------

SOLUZIONA TELECOMUNICACIONES
Servicios Profesionales de UNION FENOSA
Jerez, 3
28016 MADRID
tel 91 579 30 00 fax 91 350 72 83
---------------------------------------------------------------------------
.



This archive was generated by hypermail 2.1.4 : Sat Mar 01 2003 - 11:06:00 GMT-3