1. PIM Assert Message Packing
draft-liu-pim-assert-packing-00
Yisong Liu (Huawei)
Michael McBride (Huawei)
Toerless Eckert(Huawei)
IETF104

2. Use Cases Enterprise Network Video Surveillance Financial Services
IPTV Broadcast Video
Future Backhaul or Fronthaul

3. Problem statement RT2 RT3 RT1 RT4 Switch RT1 RT2 Switch Group Address
PIM Join
PIM Assert
RT1
RT2
PIM Assert Message
Group Address
Source Address
(all 0 means *G)
RPT bit
Metric Preference
Route Metric
PIM Assert
IGMP report
IGMP report
Switch
Receiver1
Receiver2
Receiver3
PIM Assert in Network Side
PIM Assert in Host Side
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.

4. Solution Overview No change to the PIM Assert state machine
PIM Hello Option extension for Assert packing
Negotiation of the assert packing capability
PIM Assert Simple packing solution
PIM Assert Aggregating packing solution

5. PIM Hello Option Extension Format
PIM Hello Message Format
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.
The specific packing mode is determined by the value of the Packing_Type field:
1 : simple packing type;
2 : aggregating packing type;
3-255 : reserved for future

6. PIM Assert Simple Packing Solution
Assert Record Count(N)
Assert Record [1]
Assert Record [2]
… …
Assert Record [N]
Group Address
Source Address
RPT bit
Metric Preference
Route Metric
Solution: 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.
Advantages: simple extension from the original assert packet
Disadvantages: 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/Route Metric field, which wastes the payload of the transmitted message.

7. PIM Assert Simple Packing Format
PIM Assert Packet Format
Each Assert Record Format

8. PIM Assert Aggregating Packing Solution
Source Address
RPT bit = 0
Metric Preference
Route Metric
Group Address Count(N)
Group Address [1]
Group Address [2]
… …
Group Address [N]
Assert Record Count(M)
Assert Record [1]
Assert Record [2]
… …
Assert Record [M]
RP Address
RPT bit = 1
Metric Preference
Route Metric
Group Record Count(O)
Group Record [1]
Group Record [2]
… …
Group Record [O]
Group Address
Source Address Count(P)
Source Address [1]
Source Address [2]
… …
Source Address [P]
Solution: Combine the records related to the same 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.
Advantages: Optimize the payload of the transmitted message by merging the same field content
Disadvantages: Add the complexity of the packet encapsulation and parsing

9. PIM Assert Aggregating Packing Format
PIM Assert Packet Format
Each (*,G) Assert Record Format (RPT bit = 1)
Each Group Record Format
Each (S,G) Assert Record Format (RPT bit = 0)
All 0 in source address means (*,G)

10. Next Step
Any questions or comments are Welcomed
Seeking for feedback