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New Member

Default route in OSPF

Hello,

I want to create a Default route in 30 of our Site.We have OSPF running in our Network. I Know there are couple of ways to create a default route in OSPF.

1) to create a static defualt route and redistribute  into ospf  but it will not advertise in ospf table 2)is to use default-information originate always to create a default.

But this will not work for me:

So Scenario is:

we Have R1,R2 &R3 working as a Core Route(they all are in differnt location).R4 working as a site Router(we have more than 50 sites).

If i create default-information originate in R2 & R3(ABR) it will create default route in R4 but it will also create default route in R1 which i dont want.

IF i apply any route map to deny default-route in R1 it will not only deny any default route coming from R2 & R3 but also deny deny any routes coming from internet as well.

so What i want is:

Only my Site R4 should contain a default route no default route in any of R2,R3,R1.

I have attacheda diagram for refrence.

Help should be appreciated..


7 REPLIES
Hall of Fame Super Blue

Default route in OSPF

It's not clear from your diagram which routers are in which areas ?

But if R2/R3 are ABRs that suggest R4 is in a different area than R1. Can you not just make R4's area a stub or totally stubby area and then the ABRs would generate a default route into that area for you.

Jon

New Member

Default route in OSPF

lab.jpg

I have put a diagram here R2/R3 are acting as ABR here.You can considerd R2 and R3 as two Different Data Centre

Problem is We are preffering R2 as primary Path path and R3 as secondry path.

Some of the applications are coonecting to R2 and some Conencting R3 by creating stub/totaly stub we have default route but towards priamry path only.So if traffic want to use R3 datacentre apps it will take R2 as prefered path which i dont want so in our case stub/totaly stub wont work.

Hall of Fame Super Blue

Default route in OSPF

Not sure i understand.

A stub area receives both a default route but also type 3 LSAs. So it would still have more specific routes to get the R3's

DC apps as well as having a default route.

Jon

New Member

Default route in OSPF

yes but a default route wont help me here For example:

R4(see route and tracert of R4)

Routes before Stub applied for R4

Tunnel 11 is Primary Tunnel 15 is Seconday

O IA     10.204.0.0/26 [110/25] via 10.220.101.25, 1d18h, Tunnel11

O        10.220.152.0/24 [110/42] via 10.220.108.133, 1w0d, Tunnel15

O E2     192.168.2.2 [110/20] via 10.220.108.133, 1w0d, Tunnel15

Routes AFTER Stub applied on R4

Gateway of last resort is 10.220.101.25 to network 0.0.0.0


O*IA  0.0.0.0/0 [110/21] via 10.220.101.25, 00:00:33, Tunnel11

O IA     10.204.0.0/26 [110/25] via 10.220.101.25, 1d18h, Tunnel11

O        10.220.152.0/24 [110/42] via 10.220.108.133, 1w0d, Tunnel15

See tracert for above 3 routes and compare with applying beofre and after stubb

1)   hhhNR101#traceroute 10.204.1.0(internal Roue NO ISSUES)(apps is in R2 DC)

      VRF info: (vrf in name/id, vrf out name/id)

      1 10.220.101.25 96 msec *  92 msec(Passing to R2)

2)    hhNR101#traceroute10.220.152.0Internal Roue No issues)((apps is in R3 DC)

  1 10.220.108.133 84 msec 76 msec 72 msec(passing through R3)

  2 abcns-core1-rb-lan_0-0.network.ibechtel.com (10.220.168.10) 72 msec 76 msec 88 msec

  3 abcn-wlc1.network.ibechtel.com (10.220.152.17) 88 msec 88 msec 76 msec

Problem came when we have E2 type route because of Stub:

before Stub

O E2     192.168.2.2 [110/20] via 10.220.108.133, 1w0d, Tunnel15

(compare hop of both routes applied before and after stub(see above)

3)  hhhR101#traceroute 192.168.1.1 (this is our E2 route)

after stub

VRF info: (vrf in name/id, vrf out name/id)

  1 10.220.101.25 96 msec 92 msec 96 msec

  2 abcnr001-tu5.network.ibechtel.com (10.220.55.65) 144 msec 140 msec 140 msec

  3 abcns-core1-rb-lan_0-0.network.ibechtel.com (10.220.168.10) 140 msec 140 msec 144 msec

  4  *  *  *

  5  *  *

let me know if u need any more info

Hall of Fame Super Blue

Default route in OSPF

IF i apply any route map to deny default-route in R1 it will not only deny any default route coming from R2 & R3 but also deny deny any routes coming from internet as well.

Where is the default route from the internet coming from then ? 

Presumably we are only seeing a bit of the topology in your network ?

Jon

New Member

Default route in OSPF

Its coming from R1 is the Main DC(all major APPS iNTERNET coming from There)

Hall of Fame Super Blue

Re: Default route in OSPF

Okay, i'm not understanding this. If R1 is receiving a default route from the internet then why not have it do the default-information originate and then it would send a default route to R2/R3 who would then send it to R4.

Jon

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