Junos Asymmetric Routing

Ken Gilmour ken.gilmour at gmail.com
Thu May 27 19:38:11 CDT 2010


Wow, very fast responses, Thanks Larry Sheldon and Ricardo Tavares!

On 27 May 2010 18:07, Ricardo Tavares <curupas at gmail.com> wrote:

> Not sure if I correctly undestand you but default route its the route
> that the packet must follow if it do not have a specific route for the
> destination, so, if the next-hop for the source IP (3.3.3.3) is not in
> the route table then the packet will follow the default route (ISP1).
>

Yes I believe that would be the default if the session was initiated on the
inside, but if it comes from outside on a particular interface which is not
the default route, why would the router then send the packet out another
interface? Should the device not route session-based traffic according to
where it originated?


>
> So, this behavior will be correct if next-hop for 3.3.3.0/24 is not
> installed. Just for troubleshooting purpose install a static route
> like:
>
> set routing-options static route 3.3.3.0/24 next-hop
> <the-correct-gateway-address> (ISP2)
>

Yes sir, this works, but when you change the static route to point
0.0.0.0/0to the next hop on the virtual router for the particular
interface (ISP2) it
starts going over the interface for ISP1 again. I also set
qualified-next-hop for ISP2 in the main routing table to no avail.


> If this works fine then verify the route table, are you using BGP to
> receive such routing info? If you are not filtering the update maybe
> the sender is. Verify the received routes using the "show route
> protocol bgp receive-protocol bgp x.x.x.x" (x.x.x.x is the bgp
> neighbor)
>

Yes sir, I have also gone to the extent of deactivating BGP and using only
static routes.

Thanks for your help!

Regards,

Ken



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