Due to the rapid evolution of Internet as well as services over the Internet, including high bandwidth consuming applications like audio and video streaming, it has become need of the day to enhance the Internet infrastructure for bandwidth efficiency.
One of the present day biggest challenges of networks is the audio/video transmission in real time. Developed by the Internet Engineering Task Force, Multiprotocol label Switching (MPLS) allows networks to offer several services on the single network architecture with improved forwarding speed of routers by solving the problem of longest prefix match in IP networks. Internet Protocol datagram encapsulates payload received from above layer and adds to its own header information. Thus each protocol layer adds its own header with the information related to the layer. This is a disadvantage of a bigger packet header size such as IPv4/UDP/RTP header of 40 bytes compared to the payload size which leads to excessive overhead in case of real-time multimedia applications. Bandwidth can be conserved by reducing the amount of redundant IP header transmitted with every packet for the same packet stream through header compression techniques. The header compression mechanisms have several short comings such as a problem that they work on hop-by-hop basis. The packet is compressed by the compressor and decompressed by the decompressor and for header compression to work; these are connected directly not through any intermediate node, not even a layer 3 device such as a router. In addition to this, there is a limit in the number of compressed flows that a router can take.
The objective of this book is to propose header compression technology which can be implemented over MPLS and used as a bandwidth conserving technology. This will solve the problems of hop-by-hop compression/decompression as the compression of packets is not hop-by-hop rather the compression is per Label Switched Path (LSP) of MPLS network from ingress to egress Label Switched Routers. This will also handle packet reordering in addition to allowing numerous flows at the same time. The current work in the area, both standardized as well as ongoing research has been discussed in detail and also the problems that are yet to be addressed are examined. This approach also increases the bandwidth efficiency as well as processing scalability with respect to the maximum number of simultaneous flows.
Table of Contents
1.1 Introduction
1.2 Motivation
1.3 ROHC over MPLS
2.1 Background
2.2 Multi Protocol Label Switching (MPLS)
2.3 Header Compression
2.4 Header Compression Techniques
2.4.1 Van Jacobson Header Compression (VJHC)
2.4.2 Space Communication Protocol Specification (SCPS)
2.4.3 Internet Protocol Header Compression (IPHC)
2.4.4 RTP Header Compression
2.4.5 Extended Compressed Real Time Protocol (ECRTP)
2.4.6 Robust Header Compression (ROHC)
2.5 Header Compression over MPLS
3.1 RObust Header Compression (ROHC)
3.2 Analysis of Protocol Headers
3.2.1 IP Header Fields
3.2.2 UDP Header Fields
3.2.3 RTP header fields
3.2.4 Complete IPv4/UDP/RTP Header
3.3 Functional Analysis of ROHC
3.3.1 Compressor and decompressor finite state machines
3.3.2 Compressor states
3.3.3 Decompressor states
3.3.4 Modes of Operation
3.3.4.1 Unidirectional Mode (U-mode)
3.3.4.1.1 Compressor states and logic (U-mode)
3.3.4.1.2 Decompressor states and logic (U-mode)
3.3.4.2 Bidirectional Optimistic (O-mode)
3.3.4.2.1 Compressor states and logic (O-mode)
3.3.4.2.2 Decompressor states and logic (O-mode)
3.3.4.3 Bidirectional Reliable mode (R-mode)
3.3.4.3.1 Compressor states and logic (R-mode)
3.3.4.3.2 Decompressor states and logic (R-mode)
3.3.5 Mode Transitions
3.4 Data structures, Parameters and Profiles
3.4.1 Per-channel parameters
3.4.2 Per-context parameters
3.4.3 ROHC Profiles
3.5 Encoding Methods
3.5.1 Least Significant Bits (LSB) Encoding
3.5.2 Window-based LSB (WLSB) Encoding
3.5.3 Scaled RTP Timestamp Encoding
3.5.4 Timer-based RTP Timestamp Encoding
3.5.5 IPv4 Identifier (IP-ID) Offset Encoding
3.5 Chapter Conclusion
4.1 Robust Header Compression over MPLS
4.2 Flow Chart for Compressor and Decompressor
4.3 MPLS Pseudo Wires
4.3.1 MPLS Header Compression Pseudowire Setup, Negotiation and Signaling
4.4 Packet Reordering
Objectives and Research Themes
This work addresses the challenge of bandwidth efficiency in modern networks by proposing a novel application of Robust Header Compression (ROHC) over Multiprotocol Label Switching (MPLS) infrastructure. The research aims to mitigate the overhead associated with redundant packet headers in multimedia streaming applications, seeking to optimize network resource utilization, minimize delay, and provide improved scalability compared to traditional hop-by-hop compression methods.
- Bandwidth optimization through header compression in MPLS networks.
- Technical implementation of ROHC within Label Switched Paths (LSPs).
- Overcoming scalability and latency issues inherent in traditional header compression mechanisms.
- Integration of ROHC with MPLS signaling protocols and pseudo-wire emulation.
Excerpt from the Book
1.1 Introduction
The basis of Internet at the beginning was to have interconnection between different universities, however it lead to a paradigm change and evolved into interconnection of Government organizations, business institutions, academics etc. Present day Internet has seen a rapid increase in data which is mostly multimedia (Audio/Video) in nature and thus putting a great pressure on the available bandwidth [1]. This type of traffic requires good bandwidth with minimum delays and negligible network congestion [2]. The major resource of a channel is its bandwidth and multimedia streaming can tolerate packet loss to some extent but timely and orderly delivery is very important in transmission of audio/video streams. Services like voice over IP (VoIP) will drive the future of communication which is being deployed over the packet switched networks. However, the most common issue faced by users is not having enough bandwidth to support the channel which results in coherent delays in the data network by which the audio/video quality over the internet is affected badly [3].
Also, the multimedia streams face another issue over the internet that is of packet reordering [4]. Since the packet switched networks break the information into packets and then these packets are transmitted, it can happen that each packet takes a separate route to the destination from the source resulting in the additional delay in reaching the receiver. The receiver ignores this packet as it has already received the packet which is next in sequence, thereby causing poor audio and video quality. In addition to this, to provide better Quality of Service to the users, the network has to provide minimum error rates [5].
Summary of Chapters
1.1 Introduction: Provides an overview of the growth of Internet multimedia traffic and the resulting pressure on network bandwidth, introducing the necessity for efficient header compression.
1.2 Motivation: Discusses the significant overhead generated by IP/UDP/RTP headers in multimedia streams and justifies the need for compression to improve network reliability and throughput.
1.3 ROHC over MPLS: Explains the technical requirements for integrating Robust Header Compression within existing MPLS network architectures.
2.1 Background: Surveys current Quality of Service (QoS) frameworks and traditional IP forwarding methods, establishing the role of MPLS in modern network architectures.
2.2 Multi Protocol Label Switching (MPLS): Details the architecture, functioning, and advantages of MPLS as a forwarding technology for next-generation packet networks.
2.3 Header Compression: Defines the general concept of header suppression and compression as a method to reduce redundant information in consecutive packets.
2.4 Header Compression Techniques: Provides a comprehensive survey of established compression techniques including VJHC, SCPS, IPHC, RTP Header Compression, ECRTP, and ROHC.
2.5 Header Compression over MPLS: Discusses the implementation of header compression specifically within the context of MPLS LSPs, referencing relevant RFC standards.
Keywords
ROHC, MPLS, Header Compression, Bandwidth Efficiency, VoIP, Real-time Multimedia, Label Switched Path, Packet Overhead, QoS, Network Scalability, Data Transmission, IP Networks, Context Synchronization, RFC, Pseudowires.
Frequently Asked Questions
What is the primary focus of this work?
The work focuses on implementing Robust Header Compression (ROHC) over Multiprotocol Label Switching (MPLS) networks to improve bandwidth efficiency for real-time multimedia services.
What are the central thematic areas?
The main themes include header compression mechanisms, MPLS architecture, network resource optimization, and the integration of compression technology within label-switched environments.
What is the core research objective?
The objective is to propose a technology that moves beyond hop-by-hop compression, enabling more efficient compression per Label Switched Path (LSP) from ingress to egress routers.
Which scientific methodology is employed?
The work utilizes a survey and architectural analysis approach, investigating standardized header compression protocols and proposing their adaptation for the MPLS domain, including flow-chart based logic for compressor/decompressor operations.
What topics are covered in the main section?
The main sections cover the analysis of various protocol headers (IPv4, IPv6, UDP, RTP), the functional analysis of ROHC states and operational modes, and the specific application of these techniques within an MPLS framework.
Which keywords best characterize this work?
Key terms include ROHC, MPLS, Header Compression, Bandwidth Efficiency, VoIP, Label Switched Path, and Network Scalability.
Why is hop-by-hop compression considered suboptimal in MPLS?
Hop-by-hop compression is inefficient because it forces every intermediate router to perform compression/decompression, adding significant latency and computational overhead rather than improving throughput.
How does this approach handle packet reordering?
The approach leverages the inherent ordered delivery provided by MPLS Label Switched Paths and utilizes specific ROHC mechanisms, such as window-based LSB encoding, to manage and maintain packet sequence integrity.
- Citar trabajo
- Mohammad Ahsan Chishti (Autor), Shaima Quershi (Autor), Ajaz Hussain Mir (Autor), 2016, Robust Header Compression (RoHC) over Multiprotocol Label Switching (MPLS) Networks, Múnich, GRIN Verlag, https://www.grin.com/document/379485
