PW MUX PWE – 71st IETF 10 March 2008 Yaakov (J) Stein

ACs and PWs ACs PWs RFC 3985 states that PWs connect forwarders PSN RFC 3985 states that PWs connect forwarders The ingress forwarder selects into which PW to inject traffic based on the AC payload content configured forwarding information Thus the forwarder function can be used for PW protection AC protection PW load balancing and inverse mux When the mapping of PW to AC is not one-to-one we will call the forwarder function - a PW MUX

Are there enough labels? There are only 220 unique PW labels If we assign multiple PW labels for each AC won't we run out of labels ? This question is ill-posed When using multiple PWs for protection or load balancing these PWs will not be in the same tunnel RFC3985 mentions that the PW label MAY be unique per PE but it only MUST be unique per tunnel In theory, we could even use the same PW label for all the PWs associated with the same AC So using multiple PWs does not lead to label space exhaustion

1+1 PW Protection AC PSN PW MUX active PW AC PSN PW MUX PW MUX needs to map the AC to the appropriate PWs PW set up protocol associates multiple PW labels with the single AC Ingress forwarder needs to replicate packets Egress forwarder needs to detect and reject duplicate packets

1:1 PW Protection AC PSN PW MUX active PW backup PW AC PSN PW MUX PW MUX needs to map the AC to the appropriate PW(s) PW set up protocol associates multiple PW labels with the single AC Ingress forwarder labels traffic with label of the active PW Egress forwarder extracts traffic from active PW Use VCCV to monitor continuity of active PW Use LDP status message to trigger switch from active to backup PW May revert to original PW when fault is rectified

1+1 AC Protection PSN ACs native service MUX PW MUX PW MUX needs to map one PW to multiple ACs PW setup protocol associates multiple ACs with a single PW label Ingress forwarder needs to select highest quality AC and encapsulate Egress forwarder needs to map PW label to both ACs

1:1 AC Protection PSN ACs native service MUX PW MUX PW MUX needs to map one PW to multiple ACs PW setup protocol associates multiple ACs with a single PW label Ingress forwarder needs to extract traffic from active AC and encapsulate with the PW label Egress forwarder needs to copy PW traffic to active AC Native OAM needs to monitor active AC Native protection mechanisms used to switch between ACs

PW load-balancing and inverse mux balancing PW AC AC PSN PW MUX PW MUX PW MUX needs to map the AC to the appropriate PW(s) PW set up protocol needs to associate multiple PWs with the single AC Ingress forwarder makes a per-packet decision as to which PW to use Egress forwarder needs to collect packets from all PWs in use

Proposal PWE3 should select a single method for handling PW protection AC protection Load balancing and inverse mux This means a unified mechanism should be used for associating PW labels to AC identifiers designating PW status (active, backup, balancing) signaling between forwarders (when needed)