Presentation on theme: "Pseudowire freeze mechanism draft-jin-pwe3-pw-freeze-00 Lizhong Jin Bhumip. Khasnabish."— Presentation transcript:
Pseudowire freeze mechanism draft-jin-pwe3-pw-freeze-00 Lizhong Jin Bhumip. Khasnabish
Requirements Several PW high availability mechanism –Pseudowire redundancy mechanism –PSN tunnel protection technology For the PW control plane failure, using above high availability methods will bring: –Additional resources to backup –High provisioning cost –For the case when many PWs are down due to signaling failure which is coursed by sharing same fate of signaling session: It is a burden or pressure for the network to switch all affected PWs to the backup at the same time. MPLS-TP is required that the data and control planes are both logically and physically separated.
Problem statement (I) In some network of deploying PW, the signaling path is different from the data transmission path. See the figure above, T-LDP session has different path with TE-Tunnel path (setup by strict ERO). In this case, the failure of T-LDP session should not influence the pseudowire data traffic. PE1PE2CE1CE2 T-LDP Session Router TE-Tunnel AC PW
Problem statement (II) Problem statement –According to the LDP procedure [RFC5036], if the T- LDP session is DOWN, the corresponding traffic is interrupted. –When graceful restart [RFC3478] is enabled on this T-LDP session, PE will not interrupt the PW traffic for a time within the time of "reconnect time. The maximum value of "reconnect time" is seconds, or 49.7 days, not infinite. –Sometimes, operators need more flexible configuration, and only want some of the PWs not to be influenced by T-LDP session status, so as to provide different availability level of service.
Problem statement (III) The PW freeze mechanism aims to: –Provide a function for PW not to be influenced by the turbulence of control plane. When the PW supports freeze" function and is operational UP: –It will not be influenced by the turbulence of control plane.
PW freeze status encoding PW freeze status is encoded in PW status TLV: 0x (to be assigned by IANA). –When the PW freeze bit is set, it indicates that the PW supports "freeze" function, and will be in "freezed" state. –When the PW freeze bit is cleared, it indicates that the PW will be in "unfreeze" state. When the PW is configured as "freeze, PE SHOULD advertise the capability when: –Sending label mapping message carrying the PW status TLV with "PW freeze bit" set –Sending LDP notification message carrying the PW status TLV with "PW freeze bit" set.
PW freeze status signaling When one of the PW endpoint signals PW status with PW freeze bit cleared –both of the two endpoints should unfreeze the PW. When PW is already in "freeze" state –the PW status should be transmitted through G-ACH, as defined in [I-D. draft-ietf-pwe3-static-pw-status-00].
PE operation If PW supports "freeze" function through negotiation: –When PW is operational UP PW will enter into the freezed state. The PE should locally store the PW information that received from the peer node, including PW type, PW label and etc. –When T-LDP session is DOWN, the PE should continue the PW data forwarding.
Next steps Need comments from work group Thank you