draft-ietf-pim-dr-improvement-02.txt   draft-ietf-pim-dr-improvement-03.txt 
PIM WG Zheng. Zhang PIM WG Zheng. Zhang
Internet-Draft Fangwei. Hu Internet-Draft Fangwei. Hu
Intended status: Standards Track BenChong. Xu Intended status: Standards Track BenChong. Xu
Expires: June 8, 2017 ZTE Corporation Expires: December 8, 2017 ZTE Corporation
December 5, 2016 Mankamana. Prasad Mishra
Cisco Systems
June 6, 2017
PIM DR Improvement PIM DR Improvement
draft-ietf-pim-dr-improvement-02.txt draft-ietf-pim-dr-improvement-03.txt
Abstract Abstract
PIM is worldly deployed multicast protocol. This document will PIM is widely deployed multicast protocol. PIM protocol is defined
improve the stability of PIM protocol, decrease the lost of multicast in [RFC4601] and [RFC7761]. As deployment for PIM protocol growing
packets when the PIM DR (Designed Router) is down. day by day, user expect least traffic loss and fast convergence in
case of any network failure. This document provides extension to
existing defined protocol which would improve stability of PIM
protocol with respect to traffic loss and convergence time when the
PIM DR is down.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on June 8, 2017. This Internet-Draft will expire on December 8, 2017.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. PIM hello message format . . . . . . . . . . . . . . . . . . 3 3. PIM hello message format . . . . . . . . . . . . . . . . . . 3
3.1. DR Address Option format . . . . . . . . . . . . . . . . 3 3.1. DR Address Option format . . . . . . . . . . . . . . . . 4
3.2. BDR Address Option format . . . . . . . . . . . . . . . . 4 3.2. BDR Address Option format . . . . . . . . . . . . . . . . 4
4. The Protocol Treatment . . . . . . . . . . . . . . . . . . . 4 4. The Protocol Treatment . . . . . . . . . . . . . . . . . . . 4
4.1. Election Algorithm . . . . . . . . . . . . . . . . . . . 5 4.1. Election Algorithm . . . . . . . . . . . . . . . . . . . 5
4.2. Sending Hello Messages . . . . . . . . . . . . . . . . . 6 4.2. Sending Hello Messages . . . . . . . . . . . . . . . . . 6
4.3. Receiving Hello Messages . . . . . . . . . . . . . . . . 6 4.3. Receiving Hello Messages . . . . . . . . . . . . . . . . 7
4.4. The treatment . . . . . . . . . . . . . . . . . . . . . . 7 4.4. The treatment . . . . . . . . . . . . . . . . . . . . . . 8
5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 8 4.5. Sender side . . . . . . . . . . . . . . . . . . . . . . . 9
6. Deployment suggestion . . . . . . . . . . . . . . . . . . . . 8 5. Compatibility . . . . . . . . . . . . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Deployment suggestion . . . . . . . . . . . . . . . . . . . . 9
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
9. Normative References . . . . . . . . . . . . . . . . . . . . 8 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 9. Normative References . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
Multicast technology is used widely. Many modern technology use PIM Multicast technology is used widely. Many modern technology use PIM
technology, such as IPTV, Net-Meeting, and so on. There are many technology, such as IPTV, Net-Meeting, and so on. There are many
events that will influence the quality of multicast services. The events that will influence the quality of multicast services. The
change of unicast routes will cause the lost of multicast packets. change of unicast routes will cause the lost of multicast packets.
The change of DR cause the lost of multicast packets too. The change of DR cause the lost of multicast packets too.
When a DR on a share-media LAN is down, other routers will elect a When a DR on a share-media LAN is down, other routers will elect a
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When the new router becomes the new BDR, the router will join the When the new router becomes the new BDR, the router will join the
existed multicast groups, import multicast flows from upstream existed multicast groups, import multicast flows from upstream
routers. But the BDR MUST not forward the multicast flows to avoid routers. But the BDR MUST not forward the multicast flows to avoid
the duplicate multicast packets in the share-media LAN. The new the duplicate multicast packets in the share-media LAN. The new
router will monitor the DR. The method that BDR monitors the DR may router will monitor the DR. The method that BDR monitors the DR may
be BFD technology or other ways that can be used to detect link/node be BFD technology or other ways that can be used to detect link/node
failure quickly. When the DR becomes unavailable because of the down failure quickly. When the DR becomes unavailable because of the down
or other reasons, the BDR will forward multicast flows immediately. or other reasons, the BDR will forward multicast flows immediately.
DR / BDR election SHOULD be handled in two ways. Selection of which
procedure to use would be totally dependent on deployment scenario.
1. When new router is added in existing steady state of network, if
the new router notices that it is better to be DR than the existing
DR. It does elect itself as DR as procedure defined in RFC 7761.
This method must be used when user is ok to have transition in
network. This option should be used if deployment requirement is to
adopt with new DR as and when they are available, and intermediate
network transition is acceptable.
2. If the new router notices that it is better to be DR than the
existed DR or BDR, the router will make itself the BDR, and send new
hello message with its IP address as BDR and existed DR. Uses of
this option would have less transition in network. This option
should be used when deployment requirement is to have minimum
transition in network unless there is some failure.
4.1. Election Algorithm 4.1. Election Algorithm
The DR and BDR election is according the rules defined below, the The DR and BDR election is according the rules defined below, the
algorithm is similar to the DR election definition in [RFC2328]. algorithm is similar to the DR election definition in [RFC2328].
(1) Note the current values for the network's Designated Router and (1) Note the current values for the network's Designated Router and
Backup Designated Router. This is used later for comparison Backup Designated Router. This is used later for comparison
purposes. purposes.
(2) Calculate the new Backup Designated Router for the network as (2) Calculate the new Backup Designated Router for the network as
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For example, there is a stable LAN that include RouterA and RouterB. For example, there is a stable LAN that include RouterA and RouterB.
RouterA is the DR which has the best priority. RouterC is a RouterA is the DR which has the best priority. RouterC is a
newcomer. RouterC sends hello packet with the DR and BDR is all set newcomer. RouterC sends hello packet with the DR and BDR is all set
to zero. to zero.
If RouterC cannot send hello packet with the DR/BDR capability, If RouterC cannot send hello packet with the DR/BDR capability,
Router C may send the hello packet according the rule defined Router C may send the hello packet according the rule defined
in[RFC4601] and [RFC7761]. in[RFC4601] and [RFC7761].
If deployment requirement is to adopt with new DR as and when they
are available, a new router with highest priority or best IP address
sends hello packet with DR and BDR all set to zero at first. It
sends hello packet with itself set to DR after it finish join all the
existing multicast groups. Then existed DR compares with the new
router, the new router will be final DR.
4.3. Receiving Hello Messages 4.3. Receiving Hello Messages
When the values of DR and BDR which are carried by hello messages are When the values of DR and BDR which are carried by hello messages are
received is all set to 0x0, the router MUST elect the DR due to the received is all set to 0x0, the router MUST elect the DR using
algorithm of [RFC4601] and [RFC7761] after the hold-timer expires. procedure defined in [RFC4601] and [RFC7761] after the hold-timer
And elect a new BDR which are the best choice except DR. expires. And elect a new BDR which is the best choice except DR.
In case the value of DR which is carried by received hello messages In case the value of DR which is carried by received hello messages
is not 0x0, and the value of BDR is set to 0x0, when the hold-timer is not 0x0, and the value of BDR is set to 0x0, when the hold-timer
expires there is no hello packet from other router is received, the expires there is no hello packet from other router is received, the
router will elect itself to BDR. router will elect itself to BDR.
In case the values of DR and BDR that are carried by received hello In case either of the values of DR and BDR that are carried by
messages are all larger than 0x0. The router will mark the existed received hello messages are larger than 0x0. The router will mark
DR, and compare itself and the BDR in message. When the router the existed DR, and compare itself and the BDR in message. When the
notice that it is better to be DR than existed BDR. The router will router notice that it is better to be DR than existed BDR. The
elect itself to the BDR. router will elect itself to the BDR.
When a router receives a new hello message with the values of DR and When a router receives a new hello message with the values of DR and
BDR are set to 0x0. The router will compare the new router with BDR are set to 0x0. The router will compare the new router with
existed information. If the router noticed that the new router is existed information. If the router noticed that the new router is
better to be DR than itself, or the new router is better to be BDR better to be DR than itself, or the new router is better to be BDR
than the existed BDR, the router will set the BDR to the new router. than the existed BDR, the router will set the BDR to the new router.
When existed DR receives hello packet with DR set larger than zero,
algorithm defined in section 4.1 can be used to select the final DR.
As illustrated in Figure 3, after RouterC sends hello packet, RouterC As illustrated in Figure 3, after RouterC sends hello packet, RouterC
will not elect the DR until hold-timer expired. During the period, will not elect the DR until hold-timer expired. During the period,
RouterC should receive the hello packets from RouterA and RouterB. RouterC should receive the hello packets from RouterA and RouterB.
RouterC accepts the result that RouterA is the DR. In case RouterC RouterC accepts the result that RouterA is the DR. In case RouterC
has the lowest priority than RouterA and RouterB, RouterC will also has the lowest priority than RouterA and RouterB, RouterC will also
accept that Router B is the BDR. In case RouterC has the accept that Router B is the BDR. In case RouterC has the
intermediate priority among the three routers, RouterC will treat intermediate priority among the three routers, RouterC will treat
itself as new BDR after the hold-timer expired. In case RouterC has itself as new BDR after the hold-timer expired. In case RouterC has
the highest priority among the three routers, RouterC will treat the highest priority among the three routers, RouterC will treat
RouterA which is the existed DR as DR, and RouterC will treat itself RouterA which is the existed DR as DR, and RouterC will treat itself
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When the routers receive hello message from a new router, the routers When the routers receive hello message from a new router, the routers
will compare the new router and all the other routers on the LAN. If will compare the new router and all the other routers on the LAN. If
the new router is superior to existed BDR, the new router will be new the new router is superior to existed BDR, the new router will be new
BDR. Then the old BDR will send prune message to upstream routers. BDR. Then the old BDR will send prune message to upstream routers.
As a result, the BDR is the one which has the highest priority except As a result, the BDR is the one which has the highest priority except
DR. Once the DR is elected, the DR will not change until it fails or DR. Once the DR is elected, the DR will not change until it fails or
manually adjustment. After the DR and BDR are elected, the routers manually adjustment. After the DR and BDR are elected, the routers
in the network will store the address of DR and BDR. in the network will store the address of DR and BDR.
4.5. Sender side
DR/BDR function also can be used in source side that multiple routers
and source is in same share-media network. The algorithm is the same
as the receiver side. Only the BDR need not build multicast tree
from downstream router.
5. Compatibility 5. Compatibility
If the LAN is a hybrid network that there are some routers which have If the LAN is a hybrid network that there are some routers which have
DR/BDR capability and the other routers which have not DR/BDR DR/BDR capability and the other routers which have not DR/BDR
capability. In order to avoid duplicated multicast flows in the LAN, capability. In order to avoid duplicated multicast flows in the LAN,
all the routers should go backward to use the algorithm defined in all the routers should go backward to use the algorithm defined in
[RFC4601] and [RFC7761]. [RFC4601] and [RFC7761].
6. Deployment suggestion 6. Deployment suggestion
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For general PIM Security Considerations. For general PIM Security Considerations.
8. IANA Considerations 8. IANA Considerations
IANA is requested to allocate OptionTypes in TLVs of hello message. IANA is requested to allocate OptionTypes in TLVs of hello message.
Include DR and BDR. Include DR and BDR.
9. Normative References 9. Normative References
[HRW] IEEE, "Using name-based mappings to increase hit rates",
IEEE HRW, February 1998.
[RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328,
DOI 10.17487/RFC2328, April 1998, DOI 10.17487/RFC2328, April 1998,
<http://www.rfc-editor.org/info/rfc2328>. <http://www.rfc-editor.org/info/rfc2328>.
[RFC2362] Estrin, D., Farinacci, D., Helmy, A., Thaler, D., Deering,
S., Handley, M., Jacobson, V., Liu, C., Sharma, P., and L.
Wei, "Protocol Independent Multicast-Sparse Mode (PIM-SM):
Protocol Specification", RFC 2362, DOI 10.17487/RFC2362,
June 1998, <http://www.rfc-editor.org/info/rfc2362>.
[RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas, [RFC4601] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM): "Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, Protocol Specification (Revised)", RFC 4601,
DOI 10.17487/RFC4601, August 2006, DOI 10.17487/RFC4601, August 2006,
<http://www.rfc-editor.org/info/rfc4601>. <http://www.rfc-editor.org/info/rfc4601>.
[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I., [RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas, I.,
Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent Parekh, R., Zhang, Z., and L. Zheng, "Protocol Independent
Multicast - Sparse Mode (PIM-SM): Protocol Specification Multicast - Sparse Mode (PIM-SM): Protocol Specification
(Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March (Revised)", STD 83, RFC 7761, DOI 10.17487/RFC7761, March
skipping to change at line 417 skipping to change at page 11, line 19
Email: hu.fangwei@zte.com.cn Email: hu.fangwei@zte.com.cn
BenChong Xu BenChong Xu
ZTE Corporation ZTE Corporation
No. 68 Zijinghua Road, Yuhuatai Distinct No. 68 Zijinghua Road, Yuhuatai Distinct
Nanjing Nanjing
China China
Email: xu.benchong@zte.com.cn Email: xu.benchong@zte.com.cn
Mankamana Prasad Mishra
Cisco Systems
821 Alder Drive,
MILPITAS, CALIFORNIA 95035
UNITED STATES
Email: mankamis@cisco.com
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