Default gw OSPF

[magedis0383]

Hello,

I have a little problem with OSPF and default gw. 

My 2 routeur R1/R2 receive the fullview (BGP) without default route.

I generate a default-route in the OSPF with R1 and R2

QFX1 and QFX2 receive the default route (0.0.0.0/0) 

I want to QFX1 to use R1 as default gateway and R2 as backup gateway

and for QFX2 i want to use R2 as default gateway and R1 as backup gateway. 

Must i use cost on the link ? 

Thks !

[Pawan Raut]

OSPF use cost to select best route.

You can manipulate the OSPF cost using command "ip ospf cost <cost>".

Set lower cost on interface connecting to router for which path should preferred as primary and Set higher cost on interface connecting to router for which path should as backup.

here on R1 set "ip ospf cost 10" on interface  connecting to QFX1 as primary and "ip ospf cost 20" on interface  connecting to QFX2 as backup.

Similarly here on R2 set "ip ospf cost 10" on interface connecting to QFX2 as primary and "ip ospf cost 20" on interface connecting to QFX1 as backup.

You can also do this same changing the Bandwidth of interface resulting changing in cost.

Kindly rate for helpful post.

Regards,

Pawan

[paul driver]

Hello

you don’t have to use cost in this case

just simply advertise your default from the primary with a metric-type 1 

Res

paul

[Harold Ritter]

Hi Paul,

This will not sastify the original requirement, which is that both GW need to be the primary GW for a different internal router.

Regards,

[paul driver]

Hello Harold

You are Correct, I can only apologies to OP , Mis-read the post entirely, it wouldn't work due to each QFX requiring to go its alternate path.

Costing as stated would work and also i guess a non-backbone area between both QFX's and their related backup links still though with advertised type 1 default routes.

res

Paul

[magedis0383]

Hi,

Can i use cost on the QFX ? or i need to use it on R1/R2 ?

Best regards,

[a.alekseev]

You can use cost on QFX only.

However, it would be better to have symmetrical cost on both sides of the link.

[paul driver]

Hello

Has I have stated you could also do the following:

Area 0

QFX1 -R1

QFX2 -R2

Area1

QFX1 -R2

QFX2 -R1

QFX1 -QFX2

Advertise  the default routes as metric-type 1

res

paul