Routing

Hello i have configured  a routing instance as  vrf type.And configured this:

interface-routes {
   rib-group inet InstanceA;

rib-groups {
   InstanceA {
       import-rib [ InstanceA.inet.0 inet.0 ];

Which caused all the interface routes to be imported to the  Routing instance routing table and then configured this :

route 10.0.0.0/24 next-table InstanceA.inet.0;

To be able to ping inside the vrf from the default routing instance.
My question is how can i put inside InstanceA just a default route and not the interfaces routes?

Thank you

It's easy to put a default route inside a routing-instance:

set routing-instance InstanceA routing-options static route x.x.x.x/x next-hop y.y.y.y

However, if the next-hop points to an interface which is not bound to the InstanceA routing-instance you the route is not going to become active.

This is typically why you would configure a rib-group and configure your interface-routes to be mirrored in the routing-instance and inet.0.  Or if the interface is bound to inet.0 then you could simply create a default route inside the InstanceA routing-instance and point it to a next-table of inet.0.

Can you give us more specifics to what you are trying to accomplish?

I just want to to configure in the routing instance 4 interfaces that will go outside the routing instanceto the internet  by default route.

I have all ready configured a static route pointing to "next table" for 1 isubnet and i cannot do the same from the routing instance for a default route because Junos wont let me due to a loop might be created.How do you suggest to configure a default route from the routing instance pointing to inet.0?

@Stefan

How many way we can communicate between different routing instance .

Could you please explain the benefit and better usage of each one

Thanks

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@ssuet wrote:

@Stefan

 

How many way we can communicate between different routing instance .

 

Could you please explain the benefit and better usage of each one

 

 

Thanks

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Basically, the methods for communicating between routing instances are as follows:

• static route with a next-hop of next-table pointing to the appropriate routing table which contains more accurate information
• rib-groups to mirror routing information from one route-table to another.  However, in many cases, in order to make this work, interface-routes also need to be mirrored.  RIB Group policy can be used to constrain the routing information
• instance-import and instance-export statements configured within the individual routing-instances to leak routes from one table to another.  Again, policy can be used here to constrain the routing information.  This method is more straightforward than the rib-group method
• A final approach is to use physical interfaces or logical-tunnels to stitch routing-instances and use a routing protocol or static routes across this connection between the two routing-instances.

This sounds like it could be worthy of a blog post 🙂

Stefan

Thank really appreciated  .Im looking for more help from your side

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@seaweed wrote:

 

I have all ready configured a static route pointing to "next table" for 1 isubnet and i cannot do the same from the routing instance for a default route because Junos wont let me due to a loop might be created.

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This is a kind of insurance policy to prevent you from "shooting self in the foot" - TTL is _NOT_ decremented for packets travelling between routing-instances.

To allow bidirectional routing of packets between RI, use static route(s) with "next table" _AND_ FBF together, e.g. static(s) in inet.0 and FBF in your custom RI. You can use FBF in FW filter assigned to interface or in forwarding table filter.

HTH

Rgds

Alex