Routing
Routing

Static route through BGP

2 weeks ago

Hello all,

 

Couple of questions. We currently have a /26 with our ISP that connects to them via BGP with the ISP's provided ASN. We received a /24 from the same ISP with our own ASN and we will eventually remove the /26. For now the /26 needs to remain in service.

 

I know you cannot advertise both the /24 and /26 via BGP to the same ISP peer using different AS numbers. What the ISP told us is that we can advertise the /24 via BGP and statically route the /26 through them.  Do I only need to define the static /26 through policy-options, export it through BGP and define it on an interface?

 

Also, do I need the term 1 statement? Our current edge router was programmed before I arrived and has always had that line (when it was only the /26).

 

policy-options {
    policy-statement bgp-export {
        term 1 {
            from {
                protocol direct;
                route-filter 2.2.2.0/24 exact;
            }
            then accept;
        }
        term 2 {
            from {
                protocol static;
                route-filter 3.3.3.64/26 exact;
            }
            then accept;
        }
    }
}

protocols {
    bgp {
        group isp {
            type external;
            local-address 4.4.4.246;
            export bgp-export;
            peer-as 8888;
            local-as 99999;
            neighbor 4.4.4.245;
        }
    }
}

interfaces {
    reth0 {
        per-unit-scheduler;
        mtu 1514;
        redundant-ether-options {
            redundancy-group 1;
        }
        unit 0 {
            family inet {
                address 4.4.4.246/30;
            }
        }
    }
    reth1 {
        redundant-ether-options {
            redundancy-group 1;
        }
        unit 0 {
            family inet {
                address 2.2.2.1/24 {
                    primary;
                }
                address 3.3.3.65/26;
            }
        }
    }
}
5 REPLIES 5
Routing

Re: Static route through BGP

2 weeks ago

Hello

Do you have the 2.2.2.0/24 route as a direct route on the local router("show route 2.2.2.0" displays [Direct])? If so, it makes sense to configure term 1. 

"Do I only need to define the static /26 through policy-options, export it through BGP and define it on an interface"

I did not understand the static and define on interface requirement. Is this /26 route already present in show route output? 

The static route configuration is as follows

https://www.juniper.net/documentation/en_US/junos/topics/topic-map/policy-static-routing.html

But this is needed only if the route is not present already in the local router. 

 

Routing

Re: Static route through BGP

a week ago

Hello,

 


@knightmese wrote:

What the ISP told us is that we can advertise the /24 via BGP and statically route the /26 through them. 

 

What Your ISP likely means is that ISP needs to define a static /26 route to point to Your border router' interface IP.

You don't point the route for an IP block You own to the upstream/ISP.

 

 


@knightmese wrote:

only need to define the static /26 through policy-options, export it through BGP and define it on an interface?

if Your ISP uses a static /26 route to send traffic back to You, You don't need to do anything at all.

 

HTH

Thx
Alex

 

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Routing

Re: Static route through BGP

a week ago

@aarseniev wrote:

 

What Your ISP likely means is that ISP needs to define a static /26 route to point to Your border router' interface IP.

You don't point the route for an IP block You own to the upstream/ISP.

 



Hi Alex,

 

I didn't word that very well.  I'm wondering how the /26 knows to route through to the ISP.  If it was just the /26 and no BGP, I would add a static route saying 0.0.0.0 then go to 4.4.4.245.  I'm new to BGP so if I add it as a secondary IP on the interface, does it just know to inject it into the route table?

 

This is not something I have in production at the moment so I'm not able to check a live routing table.

Routing
Solution
Accepted by topic author knightmese
a week ago

Re: Static route through BGP

a week ago

You will have to export to BGP if it is a non-BGP route. If you dont have the specific route but contributing routes, you can think of aggregating the route as in the example below

https://www.juniper.net/documentation/en_US/junos/topics/example/policy-aggregate-routes.html

Btw, configured IP on the interface will be a direct route; so you will have to modify policy with that.

set policy-options policy-statement send-direct term 1 from protocol direct
set policy-options policy-statement send-direct term 1 from route-filter x.x.x.x/XX exact
set policy-options policy-statement send-direct term 1 then accept
Routing

Re: Static route through BGP

a week ago

Thank you Alex and Shijot!