PIM Assert Message Packing
draft-liu-pim-assert-packing-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Yisong Liu , Mike McBride , Toerless Eckert | ||
| Last updated | 2019-03-05 | ||
| Replaced by | draft-ietf-pim-assert-packing, RFC 9466 | ||
| RFC stream | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-liu-pim-assert-packing-00
PIM Working Group Yisong Liu
Internet Draft M. McBride
Intended status: Standards Track T. Eckert
Expires: September 6, 2019 Huawei Technologies
March 6, 2019
PIM Assert Message Packing
draft-liu-pim-assert-packing-00
Status of this Memo
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Abstract
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In PIM-SM shared networks, there is typically more than one upstream
router. When duplicate data packets appear on the LAN from different
routers, assert packets are sent from these routers to elect a single
forwarder. The PIM assert packets are sent periodically to keep the
assert state. The PIM assert packet carries information about a
single multicast source and group, along with the metric-preference
and metric of the route towards the source or RP. This document
defines a standard to send and receive multiple multicast source and
group information in a single PIM assert packet in a shared network.
This can be particularly helpful when there is traffic for a large
number of multicast groups.
Table of Contents
1. Introduction ................................................ 2
1.1. Requirements Language .................................. 3
1.2. Terminology ............................................ 3
2. Use Cases ................................................... 3
2.1. Enterprise network ..................................... 3
2.2. Video surveillance ..................................... 3
2.3. Financial Services ..................................... 4
2.4. IPTV broadcast video ................................... 4
3. Solution .................................................... 4
3.1. PIM Assert Packing Hello Option ........................ 5
3.2. PIM Assert Packing Simple Type ......................... 5
3.3. PIM Assert Packing Aggregation Type .................... 5
4. Packet Format ............................................... 5
4.1. PIM Assert Packing Hello Option ........................ 6
4.2. PIM Assert Simple Packing Format ....................... 6
4.3. PIM Assert Aggregation Packing Format .................. 7
5. IANA Considerations ......................................... 9
6. Security Considerations ..................................... 9
7. References .................................................. 9
7.1. Normative References ................................... 9
7.2. Informative References ................................ 10
8. Acknowledgments ............................................ 10
1. Introduction
In PIM-SM shared networks, there is typically more than one upstream
router. When duplicate data packets appear on the LAN, from
different upstream routers, assert packets are sent from these
routers to elect a single forwarder according to [RFC7761]. The PIM
assert packets are sent periodically to keep the assert state. The
PIM assert packet carries information about a single multicast
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source and group, along with the corresponding metric-preference and
metric of the route towards the source or RP.
This document defines a standard to send and receive multiple
multicast source and group information in a single PIM assert packet
in a shared network. It can efficiently pack multiple PIM assert
packets into a single message and reduce the processing pressure of
the PIM routers. This can be particularly helpful when there is
traffic for a large number of multicast groups.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Terminology
RPF: Reverse Path Forwarding
RP: Rendezvous Point
SPT: Shortest Path Tree
RPT: RP Tree
2. Use Cases
PIM Asserts will happen in many services where multicast is used and
not limited to the examples described below:
2.1. Enterprise network
When an Enterprise network is connected through a layer-2 network,
the intra-enterprise runs layer-3 PIM multicast. The different sites
of the enterprise are equivalent to the PIM connection through the
shared network. Depending upon the locations and amount of groups
there could be many asserts on the first hop routers.
2.2. Video surveillance
Video surveillance deployments have migrated from analog based
systems to IP-based systems oftentimes using multicast. In certain
deployments, when there are many cameras streaming to many groups,
there may be issues with many asserts on first hop routers.
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2.3. Financial Services
Financial services extensively rely on IP Multicast to deliver stock
market data and its derivatives, and current multicast solution PIM
is usually deployed. As the number of multicast flows grows, there
are many stock data with many groups may result in many PIM asserts
on a shared network from publisher to the subscribers.
2.4. IPTV broadcast video
PIM DR and BDR deployments are often used in host-side network for
IPTV broadcast video services. Host-side access network failure
scenario may be benefitted by assert packing when many groups are
being used. According to [RFC7761] the DR will be elected to forward
multicast traffic in the shared access network. When the DR recovers
from a failure, the original DR starts to send traffic, and the
current DR is still forwarding traffic. In the situation multicast
traffic duplication maybe happen in the shared access network and
can trigger the assert progress.
In the above scenarios, as the multicast service becomes widely
deployed, the number of multicast entries increases, and a large
number of assert messages may be sent in a very short period when
multicast data packets trigger PIM assert process in the shared
networks. The PIM routers need to process a large number of PIM
assert small packets in a very short time. As a result, the device
load is very large. The assert packet may not be processed in time
or even is discarded, thus extending the time of traffic duplication
in the network.
Additionally, future backhaul, or fronthaul, networks may want to
connect L3 across an L2 underlay supporting Time Sensitive Networks
(TSN). The infrastructure may run DetNet over TSN. These transit L2
LANs would have multiple upstreams and downstreams. This draft is
taking a proactive approach to prevention of possible future assert
issues in these types of environments.
3. Solution
The change to the PIM assert includes two elements: the PIM assert
packing hello option and the PIM assert packing method.
There is no change required to the PIM assert state machine.
Basically a PIM router can now be the assert winner/loser for
multiple packed (S, G)'s in a single assert packet instead of one
(S, G) assert at a time. An assert winner is now responsible for
forwarding traffic from multiple (S, G)'s out of a particular
interface based upon the multiple (S, G)'s packed in a single
assert.
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3.1. PIM Assert Packing Hello Option
The newly defined Hello Option is used by a router to negotiate the
assert packet packing capability. It can only be used when all PIM
routers, in the same shared network, support this capability.
This document defines two packing methods. One method is a simple
merge of the original messages and the other is to extract the
common message fields for aggregation.
3.2. PIM Assert Packing Simple Type
In this type of packing, the original assert message body is used as
a record. The newly defined assert message can carry multiple assert
records and identify the number of records.
This packing method is simply extended from the original assert
packet, but, because the multicast service deployment often uses a
small number of sources and RPs, there may be a large number of
assert records with the same metric preference or route metric
field, which wastes the payload of the transmitted message
3.3. PIM Assert Packing Aggregation Type
When the source or RP addresses, in the actual deployment of the
multicast service, are very few, this type of packing will combine
the records related to the source address or RP address in the
assert message.
* (S, G) assert is aggregated according to the same source address,
and all SPT (S, G) entries corresponding to the source address are
merged into one assert record.
* (*, G) assert is aggregated according to the same RP address, and
all (*, G) and RPT (S, G) entries corresponding to the RP address
are merged into one assert record.
This method can optimize the payload of the transmitted message by
merging the same field content, but will add the complexity of the
packet encapsulation and parsing.
4. Packet Format
This section describes the format of new PIM messages introduced by
this document. The messages follow the same transmission order as
the messages defined in [RFC7761]
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4.1. PIM Assert Packing Hello Option
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OptionType = TBD | OptionLength = 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Packing_Type |
+-+-+-+-+-+-+-+-+
- OptionType: TBD
- OptionLength: 1
- Packing_Type: The specific packing mode is determined by the value
of this field:
1: indicates simple packing type as described in section 2.2
2: indicates aggregating packing type as described in section 2.3
3-255: reserved for future
4.2. PIM Assert Simple Packing Format
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|PIM Ver| Type | Reserved | Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | Number of Assert Records (M) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Assert Record [1] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Assert Record [2] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| . |
. . .
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Assert Record [M] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format of each record is the same as the PIM assert message body
of section 4.9.6 in [RFC7761].
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group Address (Encoded-Group format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|R| Metric Preference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4.3. PIM Assert Aggregation Packing Format
This method also extends PIM assert packets to carry multiple
records. The specific assert packet format is the same as section
3.2, but the records are divided into two types.
The (S, G) assert records are organized by the same source address,
and the specific message format is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Metric Preference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Groups (N) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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| Group Address 1 (Encoded-Group format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group Address 2 (Encoded-Group format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group Address N (Encoded-Group format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The (*, G) assert records are organized in the same RP address and
are divided into two levels of TLVs. The first level is the group
record of the same RP address, and the second level is the source
record of the same multicast group address, including (*, G) and RPT
(S, G), and the specific message format is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RP Address (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Metric Preference |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Group Records(O) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Group Record [1] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Group Record [2] .
. .
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
. . .
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. .
. Group Record [O] .
. .
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| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The format of each group record is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Group Address (Encoded-Group format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Number of Sources (P) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address 1 (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address 2 (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . |
| . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Address P (Encoded-Unicast format) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
5. IANA Considerations
This document requests IANA to assign a registry for PIM assert
packing Hello Option in the PIM-Hello Options. The assignment is
requested permanent for IANA when this document is published as an
RFC. The string TBD should be replaced by the assigned values
accordingly.
6. Security Considerations
For general PIM-SM protocol Security Considerations, see [RFC7761].
TBD
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
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[RFC7761] Fenner, B., Handley, M., Holbrook, H., Kouvelas,
I.,Parekh, R., Zhang, Z., and L. Zheng, "Protocol
IndependentMulticast - Sparse Mode (PIM-SM): Protocol
Specification(Revised)", RFC 7761, March 2016
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, May 2017
7.2. Informative References
TBD
8. Acknowledgments
The authors would like to thank the following for their valuable
contributions of this document:
TBD
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Authors' Addresses
Yisong Liu
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: liuyisong@huawei.com
Mike McBride
Huawei Technologies
2330 Central Expressway
Santa Clara, CA 95055
USA
Email: Michael.mcbride@huawei.com
Toerless Eckert
Huawei Technologies
2330 Central Expy
Santa Clara 95050
USA
Email: tte+ietf@cs.fau.de
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