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OSPF routing issue

deypuchka
Beginner
Beginner

Hello Guys,

I have this network where i need if x side is down then the traffic should go from y side. I am using OSPF and have check the routing table but I don't know where did i make a mistake. Can someone please correct me?

configs.PNG

6 Replies 6

default-information originate always

always cause issue here, 
this make Edge router always advertise default route, remove it and check  

@MHM Cisco WorldI cannot remove the default route since I have to advertise the default route which is the routing protocol I have to use if i want to route with the isp.

I dont want to remove information-origin 
I want you to remove "always" keyword from information-origin 

deypuchka
Beginner
Beginner

@MHM Cisco World  Still not working with only this command also

router ospf 1
log-adjacency-changes
network 0.0.0.0 255.255.255.255 area 1
default-information originate

OSPF what the different between use always and not use always 

*always meaning the router advertise the default route whatever if default route found or not in RIB 

**no always meaning the router will advertise the default route IF default route found in RIB if not found then the router will not advertise the default route via OSPF

NOW the failure is two case 
*failure of LINK connect Edge router to ISP 
HERE USE ALWAYS IS make blackhole because it advertise default route even if it LINK to ISP is loss 

**failure of Edge router (Edge router totally down)
HERE USE ALWAYS or NOT use ALWAYS will not effect because the Edge router that advertise the default route via OSPF is totally down...


so  you face failure of LINK and you use ALWAYS you make BLACKHOLE. 
so I recommend not use ALWAYS keyword 
and if you dont have default route add default route.

MHM

paul driver
VIP Expert VIP Expert
VIP Expert

Hello
both rtrs
router ospf 1
no default-information originate always
no default-information originate

router 1
router ospf 1
default-information originate metric-type1

router 2
router ospf 1
default-information originate

Lastly even though it now shown in the rtr configs, I do see a default static in the route rable readouts, probably suggest also to make that default condictinal with some ipsla tracking

Example

ip sla 1
icmp-echo x.x.x.x  source-ip x.x.x.x
timeout 1000
threshold 2000
frequency 15
ip sla schedule 1 start now life forever
track 10 rtr1 reachabilty
ip route 0.0.0.0 0.0.0.0 192.168.182.2 track10 name default-route

 


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Kind Regards
Paul
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