Cisco alternative for Juniper static route no-install statement

[vivsingh]

Hi Community,

This is my first post here. I am looking for alternative feature in Cisco for the Juniper static route no-install statement.

Objective is to redistribute static routes without installing in the router's forwarding table. 

Thank you in advance !

[MHM Cisco World]

What protocol you use ?

Is static route is defualt route ?

MHM

[vivsingh]

@MHM Cisco World - Thank you for your response. I am not using static default route, I am summarizing RFC1918 using static Null0 prefixes and redistributing via eBGP to an internet router.

Now,All the private segment (for instance: 192.168.0.0/16) are not in the same AS and need to be send to different AS.

Adding a static route with AD 255 will not install it in route table. Hence, will not redistribute via BGP.

Adding a static route with less AD well will take precendence in routing table and silently drop the packet.

Juniper gives an option add route to the routing table but not to install in forwarding table.

I am trying to achieve the same here.

[MHM Cisco World]

So I understand there is 192.168.0.0/ge 16 in your rib' 

Router dont send to null0 and drop traffic if there is longest match

I.e.

192.168.0.0 /24 in your Rib 

And you advertise 192.168.0.0/16

When traffic come the router check rib and find that 192.168.0.0/24 is longest match and forward traffic and not drop it.

I think you need only do summary your prefix correctly and the  you can free use it in static route to null0 and advertise via ebgp.

MHM

[Harold Ritter]

Hi @vivsingh ,

> Adding a static route with less AD well will take precedence in routing table and silently drop the packet.

I am not sure I understand. If you have the aggregate route to null0 and more specific routes, the traffic will match the more specific routes and will therefore not be dropped.

Or do you need a less specific route than the route to null0 to be used for forwarding?

Regards,

[vivsingh]

Hi Harold,

Router is learning aggregate routes from another neighbour via OSPF.
I do not wish to redistribute OSPF to BGP.
I prefer using static2bgp but do not wish to install those static routes in the frwding table.

[Harold Ritter]

Hi @vivsingh ,

If you want the traffic to be forwarded via the OSPF path, installing the static route in the RIB would not work (even if you could prevent the installation in the FIB) as it would be preferred over the OSPF route.

I would recommend to either redistribute the OSPF aggregate routes to BGP using a route-map or have the static routes to point to the appropriate neighbor. The other option would be to receive the more specific routes via OSPF instead of the aggregate routes and redistribute the aggregate static route to null 0 into BGP.

Regards,

[MHM Cisco World]

three solution 
1- use summary with mask less than original prefix learn from OSPF 
192.168.0.0/15 
2- redistribute ospf into bgp but using route-map with redistribute
redistribute ospf xx route-map MHM
!
route-map MHM permit 10 
match ip address prefix 192.168.0.0
!
ip prefix-list 192.168.0.0 seq 5 permit 192.168.0.0/16

3- use aggragate address under bgp with keyword summary-only 

that it 

[Giuseppe Larosa]

Hello @vivsingh ,

you may try to use AD = 255 in a floating static route and to test what happens.

ip route <network> <mask> <next-hop> 255

Hope to help

Giuseppe

[Joseph W. Doherty]

I had the same thought.  Also unsure redistribution will pick it up with a 255.

I could try it in Packet Tracer or CML (as I don't have any access to real hardware [BTW what's the target platform?]).

Or perhaps @MHM Cisco World would lab it up (as he is a lab demon).

[MHM Cisco World]

Sure I can but I need to know what Routing protocol he use and if he talk about defualt or static route.

MHM

[Harold Ritter]

Hi @Joseph W. Doherty ,

A route with an administrative distance of 255 will simply not be installed in the RIB and would therefore not be available for redistribution.

Regards,

[vivsingh]

Hi there,

Thanks for your response, but I dont think this will solve the problem. With AD = 255 will not install the route in routing table and hence will not restribute via BGP.

[Harold Ritter]

Hi @vivsingh ,

In IOS, we can only filter out BGP routes from the FIB. This is understandable, as devices such as a route reflector (RR) might hold lots of routes in the RIB, but you do not necessarily want to install them in the FIB if the RR is not in the forwarding path.

If you can explain why it is important for this static route not to be installed in the FIB, we might be able to come up with a suitable solution.

Regards,

[Harold Ritter]

Hi @vivsingh ,

I can't really think of a way to do that for static routes in IOS. It can be done for BGP routes using a table-map, but this does not apply to static routes.

Can you explain a bit more about your setup and why it is important for the static route to be installed in the RIB, but not in the FIB?

Regards,