Routing

Hi All,

Is there anyway to achieve BGP Next-Hop tracking that was available in Cisco. Quite useful for L3VPN services with dual-home PE.

http://www.cisco.com/en/US/docs/ios/12_4t/ip_route/configuration/guide/brbadv.html#wp1109430

Hello there,

The link You supplied refers to how to disable BGP nexthop tracking in IOS. Do you wish to also disable it in JUNOS?

AFAIAA, JUNOS BGP implementation is event-driven: BGP nexthop change is immediately acted upon by JUNOS rpd and this behaviour cannot be disabled.

Rgds

Alex

Hi Alex,

The BGP Next-Hop address tracking features in IOS is to minimize the “Dataplaneconvergence”time for BGP prefixes for the dual-home environment where in any case that on of link is down, (in IOS) all the impacted BGP FIB enteries will be redirected to a valid path without requiring per FIB entry operation i.e. IGP convergence and later BGP NOTIFICATION to update change in next-hop. Insted, IOS BGP NEXT-HOP TRACKING monitor the loopbacks and trigger immediately BGP NOTIFICATION without waiting for IGP convergence.

I'm not fluent in rpd JUNOS but have  you try simulate the dual homing scenario using Juniper devices. Does JUNOS rpd for BGP still inherit the BGP scanner scan-time/Hold time - 60seconds?

Hello there,

JUNOS rpd does not have BGP scanner by design. All nexthop changes are acted upon "as they come in".

That being said, you may see a slight delay - in order of 1 sec - when rpd reacts to "link down" event - if you have an older PIC which isn't sending an interrupt to RE upon losing a link but is being periodically polled by RE instead.

Rgds

Alex

Thank you for the explanation Alex