Juniper BGP Convergence Time

Thu May 17 00:00:51 UTC 2018

While we are on ECMP topic...

In L3VPN, when I've learned say, 3 different routes all using different MPLS tags to the 3 remote PE's, is there a way to ECMP hash across all of the paths to load balance?

Aaron

> On May 16, 2018, at 6:32 PM, Thomas Bellman <bellman at nsc.liu.se> wrote:
> 
>> On 2018-05-16 15:22, Adam Kajtar wrote:
>> 
>> I wasn't using per-packet load balancing. I believe juniper default is per
>> IP.
> 
> The Juniper default is to not do ECMP at all.  Only a single route is
> programmed into the FIB for each prefix in your RIB.  If you e.g. have
> routes to 198.51.100.0/24 pointing to ten different ports, all traffic
> to that entire /24 will go out over a single port, unless you have
> explicitly enabled ECMP.
> 
> To enable ECMP, you need this:
> 
>    policy-options {
>    policy-statement ecmp {
>        then {
>        load-balance per-packet;
>        }
>    }
>    }
>    routing-options {
>    forwarding-table {
>        export ecmp;
>    }
>    }
> 
> in your configuration.  Note also that "per-packet" is a mis-nomer; it
> is really "per flow", based on a hash of the L3/L4 headers.
> 
> 'show route forwarding-table destination 198.51.100.0/24' shows if you
> actually have multiple routes in your FIB.
> 
> 
>    /Bellman
> 