IP over DVBS Encapsulation Comparison

1
IP over DVB-S Encapsulation Comparison

• ULE vs. MPE

2
Outline

• DVB-S Basics
• Overview
• MPEG-2 Multiplexing
• IP packet Multiplexing
• Packing vs. Padding
• Multi-protocol Encapsulation (MPE)
• Unidirection Lightweight Encapsulation (ULE)
• Experiments
• Transmission Efficiency Comparison
• Processing comparison
• Performance Comparison
• Packing Threshold
• Conclusions

3
DVB-S Basics

• Initials Digital Video Broadcasting on Satellite
• ETSI Standard
• Developed for Digital Television
• Broadcast Transmission
• High Power Transmission Small antennas

4
DVB-S Basics

• TV program Video, Audio, Data
• MPEG-2 codec for Video
• IP over DVB-S ability
• Last Mile
• Common in East Europe and Middle-East
• Destination MAC address for each Receiver
• Upload link
• SCPC
• Not symmetric
• Terrestrial or satellite

5
MPEG-2 Mux

• Each Channel PID (Packet Identification)
• TDM for all Channels
• TS Packets - Fixed size Timeslot (188B)

6
IP Packets Mux

• Protocol Data Unit (PDU) variable Size
• Normally IPv4 could be IPv6, Ethernet or MPLS
• Sub Network Data Unit (SNDU) OHPDUCRC
• SNDU fragmented into MPEG-2 Transport stream

7
Packing vs. Padding

• Fragmentation Variable Packets ? Fixed Frames
• Padding - filling Free space with no Data
• Packing filling Free space with next packet
• Padding is simpler
• Packing improves Transmission efficiency
• More Significant in Small packets
• Packing Threshold Period

8
Multi-Protocol Encapsulation (MPE)

• ETSI Standard
• Widespread use
• Properties
• Mandatory Destination MAC address for Receiver
• Padding for Fragmented Packets
• Complex than most convergence protocols

9
MPE shortcomings

• Mandatory Destination MAC Address
• No optional Source MAC Address
• Absence of a next header type field
• IPv6, MPLS, Ethernet requires LLC/SNAP header
  (8B)
• No support of Packing
• Difficult Implementation High Processing
  requirements
• Absence of flow control specifications

10
Unidirection Lightweight Encapsulation (ULE)

• New encapsulation protocol - Alternative to MPE
• IETF Standard
• Advantages
• Source Destination Address (both optional)
• next header type field for IPv6, MPLS, Ethernet
• Support of both Padding and Packing
• Simpler - Easy implementation Low Processing
• Less overhead
• Flexibility through extension headers

11
Transmission Efficiency Comparison

• Satellite Bandwidth is Very Expensive
• Overhead Comparison
• Reduce Overhead of 4-10 for IPv4 Packets

12
Transmission Efficiency Comparison

• Packing vs. Padding
• Depends significantly on Packet size
• Packing Reduce overhead
• up to 80 for small packets
• up to 30 for long packets

13
Performance Analysis

• IP Traffic captured from DVB-S link
• Packing increase Transmission by 20-30
• For D (VoIP) improvement by packing is much
  higher than for A-C (TCP)
• Padding is Equal for both ULE MPE
• Packing Threshold Period is not Significant

14
Processing Analysis

• Implementation of ULE based software compared to
  MPE hardware solution
• No Difference in Performance
• MPE needs more CPU cycles for
• Filtering
• Reassembly
• Forwarding

15
Packing Threshold

• VoIP simulation (PT40ms, PS252B)
• Packing Threshold 20ms ? TE 63, no Jitter
• Packing Threshold 100ms ? TE 95 and Jitter
  100ms

16
Packing Threshold

• TCP Traffic When Packing Threshold is Larger
• Reduce the overhead gt Increase the TE
• Increase the RTT gt Decrease the TE
• Packing Threshold of 10-40ms is optimal

17
Conclusion

• ULE has lot of advantages over MPE
• Less Overhead and Better Transmission Efficiency
• IPv6, MPLS, Ethernet compatibility
• MAC addresses are optional
• Extension Mechanism
• Low Processing
• Fragmentation Methods - Packing is Better
• Packing Threshold for TCP should be 10-40ms
• Packing Threshold for VoIP should be lt PT

18
Encapsulation
Back