Pim Fangwei. Hu Internet-Draft Jacni. Qin Intended status: Standards Track Zheng. Zhang Expires: April 26, 2012 BenChong. Xu ZTE Corporation Oct 24, 2011 PIM Route Flap Damping draft-hu-pim-route-flap-damping-00.txt Abstract This document describes the route flap damping functions for PIM-SM [RFC4601], to reduce the processing load caused by the instability of routing peers. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on April 26, 2012. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Hu, et al. Expires April 26, 2012 [Page 1] Internet-Draft PIM Route Flap Damping Oct 2011 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Parameters Definition . . . . . . . . . . . . . . . . . . . . 3 3. PIM Join/Prune message Damping . . . . . . . . . . . . . . . . 3 3.1. (*,*, RP)Join/Prune Message Damping . . . . . . . . . . . 3 3.2. (*, G) Join/Prune Message Damping . . . . . . . . . . . . 7 3.3. (S, G) Join/Prune Message Damping . . . . . . . . . . . . 10 3.4. (S, G, RPT) Join/Prune Message Damping . . . . . . . . . . 14 4. Security Considerations . . . . . . . . . . . . . . . . . . . 17 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18 6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18 6.1. Normative references . . . . . . . . . . . . . . . . . . . 18 6.2. Informative References . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 Hu, et al. Expires April 26, 2012 [Page 2] Internet-Draft PIM Route Flap Damping Oct 2011 1. Introduction The instability of downstream routers, which may include the frequent change of, for instance the unicast routing, the physical state of multicast interfaces etc., will trigger an excessive number of Join/ Prune messages sent upwards to the routing peers where an extra amount of updates of routing state are made. This is referred to herein as "route flap". This document specifies the damping functions to reduce the processing load caused by route flaps on the upstream routers. The damping functions are categorized according to route flaps resulting from different types of Join/Prune messages received. In addition, it should be noted that the original operations and state machines of the PIM protocol are preserved when the design of these damping functions is implemented. 2. Parameters Definition Flap count: It is used to count the times of PIM multicast route item flapping. Damping threshold: This value is expressed as a number of PIM multicast route withdrawals. It is above which a PIM multicast route will be suppressed. Damping reuse threshold: This value is expressed as a number of PIM multicast route withdrawals. It is below which a suppressed item will now be used again. Half life timer: It is a cycle timer. When half life timer is expired, the flap count will be reduced by half if it is bigger than 1. If the flap count is 1, it is reduced to 0. The half life timer is used in the NoDamping and Damping state. Maximum hold timer: This value is the maximum time a suppressed PIM multicast route item should be reuse no matter how unstable it has been prior to this period of stability. 3. PIM Join/Prune message Damping 3.1. (*,*, RP)Join/Prune Message Damping The (*,*, RP) Damping state is shown in figure 1, there are three states: Hu, et al. Expires April 26, 2012 [Page 3] Internet-Draft PIM Route Flap Damping Oct 2011 Idle The damping function isn't enabled yet in this router. Damping The (*,*, RP) state is damped in this router. The (*, *, RP) damping route is in damping list. NoDamping The (*,*, RP) state is not damped in this router. The (*, *, RP) damping route is in damping pending list. The following events can change the (*,*, RP) Join/Prune message damping state: E1: damping function is enabled in the router. E2: damping disable is disabled in the router. E3: The flap count is above the damping threshold. E4: The flap count is below the damping reuse threshold. E5: maximum hold timer is expired. (*,*, RP)damping state machine +------+ E1 +----------+ | Idle |---------------------------> | NoDamping| +------+ <------------------------- +----------+ ^ E2 ^ | | | | | | | E2 | E4 or E5 | | | | | | | | E3 | +-------+ | | +-----------------|Damping|---------+ | +-------+ <----------+ Figure 1 (*, *, RP) state machine for triggered messages in tabular form: Hu, et al. Expires April 26, 2012 [Page 4] Internet-Draft PIM Route Flap Damping Oct 2011 | Event | Idle | Damping | NoDamping | +-------+---------------+----------------+----------------+ | E1 | ->NoDamping | N/A | N/A | | | [Action A1] | | | +-----------------------+----------------+----------------+ | E2 | N/A | -> Idle | -> Idle | | | | [Action A2] | [Action A2] | +-----------------------+----------------+----------------+ | | | | -> Damping | | E3 | N/A | N/A | [Action A3] | +-----------------------+----------------+----------------+ | E4 | N/A | -> NoDamping | N/A | | | | [Action A4] | | +-----------------------+----------------+----------------+ | E5 | N/A | -> NoDamping | N/A | | | | [Action A5] | | +-----------------------+----------------+----------------+ Transitions from Idle state When the (*, *, RP) damping state machine is in Idle state, the following events may trigger transitions: E1:The damping function is enabled in this router. The (*, *, RP)damping state machine enters into NoDamping state Transitions from NoDamping State When the (*, *, RP) damping state machine is in NoDamping state, the following events may trigger transitions: E3: The flap count is used to count the changes of (*, *, RP) route. If the (*, *, RP)item is in Join state and the new Join/Prune message received indicates that the route should be pruned, the flap count should record the change, and vice versa, if the (*, *, RP) route is in delete state and new Join/ Prune message received indicates that the route should be created, the flap count also records it. If the flap count is above the damping threshold, event E3 is triggered, the state machine enters into damping state. Transitions from NoDamping State When the (*, *, RP) damping state machine is in damping state, the following events may trigger transitions: E2: The damping function is disabled in this router. The (*, *, RP) damping state machine enters into Idle state. Hu, et al. Expires April 26, 2012 [Page 5] Internet-Draft PIM Route Flap Damping Oct 2011 E4: The flap count is below the damping reuse threshold, the item in damping list is reused, and the (*, *, RP) damping route state machine enters into NoDamping state. E5: The maximum hold timer is expired. The PIM (*, *, RP) route item in Damping state is reused no matter how unstable it has been prior to this period of stability. The (*, *, RP) damping route state machine enters into NoDamping state. (*,*, RP) damping state machine actions: Action A1: The damping function is enabled in the router. The router is ready to record the times of (*,*, RP) route state changed. If the PIM Join/Prune message is received and a new (*,*, RP) item is required to create, the (*,*, RP) item is added to damping pending list if there is no item for that (*,*, RP) and the state is Join, and the flap count should plus one. If the PIM Join/Prune message is received and a (*,*, RP) item is required to prune from the (*,*, RP) table, the (*,*, RP) item is added to damping pending list if there is no item for that (*,*, RP) and the state is Prune, and the flap count should plus one. The half life timer is started when the (*,*, RP) item is added to the damping pending list. The cycle half life timer is running when the damping pending (*, *, RP) is in NoDamping state. If half life timer is expired, the flap count is reduced by half. If the flap count is reduced to zero, (*, *, RP) route should be recovery based on the state in the damping list. If the state of (*, *, RP) in the damping pending list is Join, the (*, *, RP) route will be added to the multicast routing table. If the damping (*, *, RP) route state in damping list is prune, the (*, *, RP) route will be deleted from the multicast routing table if the (*, *, RP) route is existed in. The damping pending (*, *, RP) is deleted from the damping pending list. Action A2: The damping function is disabled in the router. The state machine enters Idle state. The half life timer is stopping if it runs. The flap count is reset and stop counting the times of (*,*, RP) route state change. Action A3: The PIM (*,*, RP) route state is suppressed and moved from the damping pending list to damping list, and the cycle half life timer for that (*,*,RP) route is started. The maximum holding timer is started if it doesn't run. Hu, et al. Expires April 26, 2012 [Page 6] Internet-Draft PIM Route Flap Damping Oct 2011 Action A4: The suppressed item is reused again. If the damping (*,*, RP) route state in damping list is join, the (*,*, RP) route will be added to the multicast routing table. If the damping (*,*, RP) route state in damping list is prune, the (*,*, RP) route will be deleted from the multicast routing table if the (*,*, RP) route is existed in. The damping (*,*, RP) route is deleted from the damping list. The flap count is reset and stop counting the times of (*, *, RP) damping route state change. The cycle half life timer and maximum hold timer are stopped. Action A5: The maximum hold timer is expired. The (*,*, RP) route state item in Damping state is reused. If the damping (*,*, RP) route state in damping list is join, the (*,*, RP) route will be added to the multicast routing table. If the damping (*,*, RP) route state in damping list is prune, the (*,*, RP) route will be deleted from the multicast routing table if the (*,*, RP) route is existed in. The reuse timer and maximum hold timer are stopped if they run. The damping (*,*, RP) route is deleted from the damping list. The flap count is reset and stop counting the times of (*, *, RP) damping route state changed. The cycle half life timer and maximum hold timer are stopped. 3.2. (*, G) Join/Prune Message Damping The (*, G) Damping state is shown in figure 2, there are three states: Idle The damping function isn't enabled yet in this router Damping The (*, G) state is damped in this router. The (*, G) damping route is in damping list. NoDamping The (*, G) state is not damped in this router. The (*, G) damping route is in damping pending list. The following events can change the (*, G) Join/Prune message damping state: E1: damping function is enabled in the router. E2: damping disable is disabled in the router. E3: The flap count is above the damping threshold. Hu, et al. Expires April 26, 2012 [Page 7] Internet-Draft PIM Route Flap Damping Oct 2011 E4: The flap count is below the damping reuse threshold E5: maximum hold timer is expired. (*,G)damping state machine +------+ E1 +----------+ | Idle |---------------------------> | NoDamping| +------+ <------------------------- +----------+ ^ E2 ^ | | | | | | | E2 | E4 or E5 | | | | | | | | E3 | +-------+ | | +-----------------|Damping|---------+ | +-------+ <----------+ Figure 2 (*, G) state machine for triggered messages in tabular form: | Event | Idle | Damping | NoDamping | +-------+---------------+----------------+----------------+ | E1 | ->NoDamping | N/A | N/A | | | [Action A1] | | | +-----------------------+----------------+----------------+ | E2 | N/A | -> Idle | -> Idle | | | | [Action A2] | [Action A2] | +-----------------------+----------------+----------------+ | | | | -> Damping | | E3 | N/A | N/A | [Action A3] | +-----------------------+----------------+----------------+ | E4 | N/A | -> NoDamping | N/A | | | | [Action A4] | | +-----------------------+----------------+----------------+ | E5 | N/A | -> NoDamping | N/A | | | | [Action A5] | | +-----------------------+----------------+----------------+ Transitions from Idle state When the (*, G) damping state machine is in Idle state, the following events may trigger transitions: E1:The damping function is enabled in this router. The (*, G) damping state machine enters into NoDamping state Hu, et al. Expires April 26, 2012 [Page 8] Internet-Draft PIM Route Flap Damping Oct 2011 Transitions from NoDamping State When the (*, G) damping state machine is in NoDamping state, the following events may trigger transitions: E3: The flap count is used to count the changes of (*, G) route. If the (*, G) item is in Join state and the new Join/ Prune message received indicates that the route should be pruned, the flap count should record the change, and vice versa, if the (*, G) route is in delete state and new Join/ Prune message received indicates that the route should be created, the flap count also records it. If the flap count is above the damping threshold, event E3 is triggered, the state machine enters into damping state. Transitions from NoDamping State When the (*, G) damping state machine is in damping state, the following events may trigger transitions: E2: The damping function is disabled in this router. The (*, G) damping state machine enters into Idle state. E4: The flap count is below the damping reuse threshold, the item in damping list is reused, and the (*, G) damping route state machine enters into NoDamping state. E5: The maximum hold timer is expired. The PIM (*, G) route item in Damping state is reused no matter how unstable it has been prior to this period of stability. The (*,G)damping route state machine enters into NoDamping state. (*, G) damping state machine actions: Action A1: The damping function is enabled in the router. The router is ready to record the times of (*, G) route state change. If the PIM Join/Prune message is received and a new (*, G) item is required to create, the (*, G) item is added to damping pending list if there is no item for that (*, G) and the state is Join, and the flap count should record the change. If the PIM Join/ Prune message is received and a (*, G) item is required to prune from the (*, G) table, the (*, G) item is added to damping pending list if there is no item for that (*, G) and the state is Prune, and the flap count should record the change. The cycle half life timer is started when the (*, G) item is added to the damping pending list. The cycle half life timer is running when the (*, G) is in NoDamping state. If half life timer is expired, the flap count is reduced by half. Hu, et al. Expires April 26, 2012 [Page 9] Internet-Draft PIM Route Flap Damping Oct 2011 If flap count is reduced to zero, (*, G) route should be recovery based on the state in the damping list. If the state of (*, G) in the damping pending list is Join, the (*, G) route will be added to the multicast routing table. If the damping (*, G) route state in damping list is prune, the (*, G) route will be deleted from the multicast routing table if the (*, G) route is existed in. The damping pending (*, G) is deleted from the damping pending list. Action A2: The damping function is disabled in the router. The state machine enters Idle state. The half life timer is stopping if it runs. The flap count is reset and stop counting the times of (*, G) route state flapping. Action A3: The PIM (*, G) route state is suppressed and moved from the damping pending list to damping list, and the cycle half life timer for that (*,G) route is started. The maximum holding timer is started if it doesn't run. Action A4: The suppressed item is reused again. If the damping (*, G) route state in damping list is join, the (*, G) route will be added to the multicast routing table. If the damping (*, G) route state in damping list is prune, the (*, G) route will be deleted from the multicast routing table if the (*, G) route is existed in. The damping (*, G) route is deleted from the damping list. The flap count is reset and stop counting the times of (*, G) damping route state changed. The cycle half life timer and maximum hold timer are stopped. Action A5: The maximum hold timer is expired. The (*, G) route state item in damping state is reused. If the damping (*, G) route state in damping list is join, the (*, G) route will be added to the multicast routing table. If the damping (*, G) route state in damping list is prune, the (*, G) route will be deleted from the multicast routing table if the (*, G) route is existed in. The reuse timer and maximum hold timer are stopped if they run. The (*, G) damping route is deleted from the damping list. The flap count is reset and stop counting the times of (*, G) damping route state changed. The cycle half life timer and maximum hold timer are stopped. 3.3. (S, G) Join/Prune Message Damping The (S, G) damping state is shown in figure 3, there are three states: Hu, et al. Expires April 26, 2012 [Page 10] Internet-Draft PIM Route Flap Damping Oct 2011 Idle The damping function isn't enabled yet in this router Damping The (S, G) state is damped in this router. The(S, G) damping route is in damping list. NoDamping The (S, G) state is not damped in this router. The(S, G)damping route is in damping pending list. The following events can change the (S, G) Join/Prune message damping state: E1: damping function is enabled in the router. E2: damping disable is disabled in the router. E3: the flap count is above the damping threshold. E4: the flap count is below the damping reuse threshold. E5: maximum hold timer is expired. (S,G)damping state machine +------+ E1 +----------+ | Idle |---------------------------> | NoDamping| +------+ <------------------------- +----------+ ^ E2 ^ | | | | | | | E2 | E4 or E5 | | | | | | | | E3 | +-------+ | | +-----------------|Damping|---------+ | +-------+ <----------+ Figure 3 (S, G) state machine for triggered messages in tabular form: Hu, et al. Expires April 26, 2012 [Page 11] Internet-Draft PIM Route Flap Damping Oct 2011 | Event | Idle | Damping | NoDamping | +-------+---------------+----------------+----------------+ | E1 | ->NoDamping | N/A | N/A | | | [Action A1] | | | +-----------------------+----------------+----------------+ | E2 | N/A | -> Idle | -> Idle | | | | [Action A2] | [Action A2] | +-----------------------+----------------+----------------+ | | | | -> Damping | | E3 | N/A | N/A | [Action A3] | +-----------------------+----------------+----------------+ | E4 | N/A | -> NoDamping | N/A | | | | [Action A4] | | +-----------------------+----------------+----------------+ | E5 | N/A | -> NoDamping | N/A | | | | [Action A5] | | +-----------------------+----------------+----------------+ Transitions from Idle state When the (S, G) damping state machine is in Idle state, the following events may trigger transitions: E1:The damping function is enabled in this router. The (S, G) damping state machine enters into NoDamping state Transitions from NoDamping State When the (S, G) damping state machine is in NoDamping state, the following events may trigger transitions: E3: The flap count is used to count the changes of (S, G) route. If (S, G) item is in join state and new Join/Prune message received indicates that the route should be pruned, the flap count should record the change, and vice versa, if the (S, G) route is in delete state and new Join/Prune message received indicates that the route should be created, the flap count also records it. If the flap count is above the damping threshold, event E3 is triggered, the (S, G) damping state machine enters into damping state. Transitions from NoDamping State When the (S, G) damping state machine is in damping state, the following events may trigger transitions: E2: The damping function is disabled in this router. The (S, G) damping state machine enters into Idle state. Hu, et al. Expires April 26, 2012 [Page 12] Internet-Draft PIM Route Flap Damping Oct 2011 E4: The flap count is below the damping reuse threshold, the item in damping list is reused, and the (S, G) damping state machine enters into NoDamping state. E5: The maximum hold timer is expired. The PIM (S, G) route item in Damping state is reused no matter how unstable it has been prior to this period of stability. The (S, G) damping state machine enters into NoDamping state. (S, G) damping state machine actions: Action A1: The damping function is enabled in the router. The router is ready to record the times of (S, G) route state change. If the PIM Join/Prune message is received and a new(S, G) item is required to create, the (S, G) item is added to damping pending list if there is no item for that (S, G) and the state is Join, and the flap count should record the change. If the PIM Join/ Prune message is received and a (S, G) item is required to prune from the (S, G) table, the (S, G) item is added to damping pending list if there is no item for that (S, G) and the state is Prune, and the flap count also record the change. The cycle half life timer is started when the (S, G) item is added to the damping pending list. The cycle half life timer is running when the damping pending (S, G) is in NoDamping state. If it is expired, the flap count is reduced by half. If the flap count is reduced to zero, (S, G) route should be recovery based on the state in the damping list, that is, if the state of (S, G) in the damping pending list is Join, the (S, G) route will be added to the multicast routing table, otherwise, the damping (S, G) route state in damping list is prune, the (S, G) route state will be deleted from the multicast routing table if the (S, G) route is existed in yet. The damping pending (S, G) item is deleted from the damping pending list. Action A2: The damping function is disabled in the router. The state machine enters into Idle state. The half life timer is stopping if it runs. The flap count is reset and stop counting the times of (S, G) route state changed. Action A3: The PIM (S, G) route state is suppressed and moved from the damping pending list to damping list, and the cycle half life timer for that (S,G) route is started. The maximum holding Timer is started if it doesn't run. Hu, et al. Expires April 26, 2012 [Page 13] Internet-Draft PIM Route Flap Damping Oct 2011 Action A4: The suppressed item is reused again. If the damping (S, G) route state in damping list is Join, the (S, G) route will be added to the multicast routing table. If the damping (S, G) route state in damping list is Prune, the (S, G) route will be deleted from the multicast routing table if the (S, G) route is existed in. The damping(S, G) route is deleted from the damping list. The flap count is reset and stop counting the times of (S, G) damping route state flapping. The cycle half life timer and maximum hold timer are stopped. Action A5: The maximum hold timer is expired. The (S, G) route state item in Damping state is reused. If the damping (S, G) route state in damping list is Join, the (S, G) route will be added to the multicast routing table. If the damping (S, G) route state in damping list is Prune, the (S, G) route will be deleted from the multicast routing table if the (S, G) route is existed in. maximum hold timer is stopped if they run. The damping(S, G) route is deleted from the damping list. The flap count is reset and stop counting the times of (S, G) damping route state flapping. The cycle half life timer and maximum hold timer are stopped. 3.4. (S, G, RPT) Join/Prune Message Damping The (S, G, RPT) Damping state is shown in figure 4, there are three states: Idle The damping function isn't enabled yet in this router. Damping The (S, G, RPT) state is damped in this router. The (S, G, RPT) damping route is in damping list. NoDamping The (S, G, RPT) state is not damped in this router. The (S, G, RPT) damping route is in damping pending list. The following events can change the (S, G, RPT) Join/Prune message damping state: E1: damping function is enabled in the router. E2: damping disable is disabled in the router. E3: the flap count is above the damping threshold. Hu, et al. Expires April 26, 2012 [Page 14] Internet-Draft PIM Route Flap Damping Oct 2011 E4: the flap count is below the damping reuse threshold. E5: maximum hold timer is expired. (S,G,RPT)damping state machine +------+ E1 +----------+ | Idle |---------------------------> | NoDamping| +------+ <------------------------- +----------+ ^ E2 ^ | | | | | | | E2 | E4 or E5 | | | | | | | | E3 | +-------+ | | +-----------------|Damping|---------+ | +-------+ <----------+ Figure 4 (S, G, RPT) state machine for triggered messages in tabular form: | Event | Idle | Damping | NoDamping | +-------+---------------+----------------+----------------+ | E1 | ->NoDamping | N/A | N/A | | | [Action A1] | | | +-----------------------+----------------+----------------+ | E2 | N/A | -> Idle | -> Idle | | | | [Action A2] | [Action A2] | +-----------------------+----------------+----------------+ | | | | -> Damping | | E3 | N/A | N/A | [Action A3] | +-----------------------+----------------+----------------+ | E4 | N/A | -> NoDamping | N/A | | | | [Action A4] | | +-----------------------+----------------+----------------+ | E5 | N/A | -> NoDamping | N/A | | | | [Action A5] | | +-----------------------+----------------+----------------+ Transitions from Idle state When the (S, G, RPT) damping state machine is in Idle state, the following events may trigger transitions: E1:The damping function is enabled in this router. The (S, G, RPT) damping state machine enters into NoDamping state Hu, et al. Expires April 26, 2012 [Page 15] Internet-Draft PIM Route Flap Damping Oct 2011 Transitions from NoDamping State When the (S, G, RPT) damping state machine is in NoDamping state, the following events may trigger transitions: E3: The flap count is used to count the changes of (S, G, RPT) route. If the (S, G,RPT) item is in Join state and the new Join/Prune message received indicates that the route should be pruned, the flap count should record the change, and vice versa, if the (S, G, RPT) route is in delete state and new Join/Prune message received indicates that the route should be created, the flap count also records it. If the flap count is above the damping threshold, event E3 is triggered, the state machine enters into damping state. Transitions from NoDamping State When the (S, G, RPT) damping state machine is in damping state, the following events may trigger transitions: E2: The damping function is disabled in this router. The (S, G, RPT) damping state machine enters into Idle state. E4: The flap count is below the damping reuse threshold, the item in damping list is reused, and the (S, G, RPT) damping route state machine enters into NoDamping state. E5: The maximum hold timer is expired. The PIM (S, G, RPT) route item in Damping state is reused no matter how unstable it has been prior to this period of stability. The (S,G, RPT)damping route state machine enters into NoDamping state. (S, G, RPT) damping state machine actions: Action A1: The damping function is enabled in the router. The router is ready to record the times of (S, G, RPT) route state changed. If the PIM Join/Prune message is received and a new (S,G,RPT) item is required to create, the (S,G,RPT) item is added to damping pending list if there is no item for that (S,G,RPT) and the state is Join, and the flap count should plus one. If the PIM Join/Prune message is received and a (S,G,RPT) item is required to prune from the (S,G,RPT) table, the (S,G,RPT) item is added to damping pending list if there is no item for that (S,G,RPT) and the state is Prune, and the flap count should plus one. The half life timer is started when the (S, G, RPT) item is added to the damping pending list. The cycle half life timer is running when the damping pending (S, G, RPT) is in NoDamping state. If half life timer is expired, the flap count is reduced by half. Hu, et al. Expires April 26, 2012 [Page 16] Internet-Draft PIM Route Flap Damping Oct 2011 If flap count is reduced to zero, (S, G, RPT) route should be recovery based on the state in the damping list. If the state of (S, G, RPT) in the damping pending list is Join, the (S, G, RPT) route will be added to the multicast routing table. If the damping (S, G, RPT) route state in damping list is prune, the (S, G, RPT) route will be deleted from the multicast routing table if the (S, G, RPT) route is existed in. The damping pending (S, G, RPT) is deleted from the damping pending list. Action A2: The damping function is disabled in the router. The state machine enters Idle state. The half life timer is stopping if it runs. The flap count is reset and stop counting the times of (S, G, RPT) route state change. Action A3: The PIM (S,G,RPT) route state is suppressed and moved from the damping pending list to damping list, and the cycle half life timer for that (S,G, RPT) route is started. The maximum holding timer is started if it doesn't run. Action A4: The suppressed item is reused again. If the damping (S, G, RPT) route state in damping list is join, the (S, G, RPT) route will be added to the multicast routing table. If the damping (S, G, RPT) route state in damping list is prune, the (S, G, RPT) route will be deleted from the multicast routing table if the (S, G, RPT) route is existed in. The damping (S, G, RPT) route is deleted from the damping list. The flap count is reset and stop counting the times of (S, G, RPT) damping route state flapping. The cycle half life timer and maximum hold timer are stopped. Action A5: The maximum hold timer is expired. The (S, G, RPT) route state item in Damping state is reused. If the damping (S, G, RPT) route state in damping list is join, the (S, G, RPT) route will be added to the multicast routing table. If the damping (S, G, RPT) route state in damping list is prune, the (S, G, RPT) route will be deleted from the multicast routing table if the (S, G, RPT) route is existed in. There reuse timer and maximum hold timer are stopped if they run. The damping(S, G, RPT) route is deleted from the damping list. The flap count is reset and stop counting the times of (S, G, RPT) damping route state flapping. The cycle half life timer and maximum hold timer are stopped. 4. Security Considerations Hu, et al. Expires April 26, 2012 [Page 17] Internet-Draft PIM Route Flap Damping Oct 2011 5. Acknowledgements 6. References 6.1. Normative references [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, "Protocol Independent Multicast - Sparse Mode (PIM-SM): Protocol Specification (Revised)", RFC 4601, August 2006. 6.2. Informative References [RFC2439] Villamizar, C., Chandra, R., and R. Govindan, "BGP Route Flap Damping", RFC 2439, November 1998. Authors' Addresses Fangwei Hu ZTE Corporation 889 Bibo Road Shanghai 201203 China Phone: +86-21-68896273 Email: hu.fangwei@zte.com.cn Jacni Qin ZTE Corporation shanghai China Email: jacni@jacni.com Zheng Zhang ZTE Corporation No.68 Zijinghua Rd.Yuhuatai District Nanjing 210012 China Email: zhang.zheng@zte.com.cn Hu, et al. Expires April 26, 2012 [Page 18] Internet-Draft PIM Route Flap Damping Oct 2011 BenChong Xu ZTE Corporation No.68 Zijinghua Rd.Yuhuatai District Nanjing 210012 China Email: xu.benchong@zte.com.cn Hu, et al. Expires April 26, 2012 [Page 19]