1 Scalable Loop Free BGP FRR Using Repair
1 Scalable Loop Free BGP FRR Using Repair Label draft-bashandy-idr-bgp-repair-label-02 Authors : Ahmed Bashandy, Cisco Systems Burjiz Pithawala, Cisco Systems Jakob Heitz, Ericsson Presenter : Jakob Heitz, Ericsson IETF 81, Jul/2011 Quebec City, Canda draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
2 What do we want to do BGP free core Packets are tunneled between edge routers On loss of primary path, we want to Restore traffic through a pre-calculated repair path • without waiting for control plane convergence, and • avoid loops when restoring traffic draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
3 Possible Solution PE 1 PE 2 VPNPE 2 LDPPE 2 Packet VPNPE 2 Pa ck Packet et Packet t e ck Swap VPNPE 2 with VPNPE 3 Push LDPPE 3 Pa VPNPE 3 LDPPE 3 CE 1 Network X ck Pa Packet et CE 2 VPNPE 3 draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
4 Problem: If CE fails If the CE fails, we have PE 1 PE 2 VPNPE 2 LDPPE 2 Packet VPNPE 2 a loop !!! PE 2 VP N et ck et Pa ck VPNPE 3 LDPPE 3 CE 1 Pa Packet Pa ck et Packet Network X P k c a et N P V 2 PE Packet VPNPE 3 PP D L E 2 CE 2 PE 3 draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
5 Proposed Solution 1. A PE having an external path advertises a “repair” label • Optional non-transitive attribute 2. When repairing a failed NH, the repairing router uses the repair label instead of the primary label advertised by the repair PE 3. The repair PE never repairs repaired traffic: Deliver the packet to the external next hop OR Drop it draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
6 Proposed Solution PE 1 VPNPE 2 LDPPE 2 Packet VPNPE 2 et ck Pa REPPE 3 LDPPE 3 Pa CE 1 Packet ck et Packet PE 2 No Loop Network X CE 2 Packet REPPE 3 draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
Changes from Previous Version Specify forwarding behavior for edge node A packet arrives from the core If there is an external path • Deliver to external path If there is no external path • If there is a repair PE, forward to repair PE • Else – Drop A packet arrives NOT from the core Forward with the regular label draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada 7
8 Q&A draft-bashandy-idr-bgp-repair-label-02 EDCS-875479 IETF 81, Jul/2011, Quebec City, Canada
- Slides: 8