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Re: [Fwd: RFC: Draft for ROHC over DVB]
Hi All et al :)
Quick comments and questions...
> 4.1. ROHC Channel Parameters Negotiation Protocol (RCPNP)
> The approach presented in this section can only work if compressor site
> and decompressor site are connected through two dedicated unidirectional
> DVB links, with a unidirectional link originating from each of the
> sites, configured to form a bidirectional network link between the two
> sites.
* Why such a limitation? Is there already a preferred where the secondary
link is bidirectional or can not be relied upon at all?
> 4.1.1. Compressor Advertisement
...
> Compressor site should send this message periodically to advertise the
> availability of compressor. Care should be taken as not to send too many
> advertisements.
* What about indicating from, compressor or decompressor, when such a
heartbeat should be expected (Sorry if it was there but I missed this). At
least the interval/period would limit the "promiscuous listing" to one
period only, afterwards the decompressor can "sleep more". Apart from
altruistic energy saving reasons, any mobile application is going to want as
many opportunities to preserve power as possible.
Some argumentation needs making at the very least oin this mail list, but
preferably also in the I-D (maybe as an annex for easy removal later if it
gets adopted).
* What are the alternatives to this scheme based on ROHC?
* How similar to other ROHC profiles is this? Does it break or invent some
new semantic or is it exactly parallel to some existing RFC?
* Is there any effect on header compression at higher layers? E.g. If the
spec interferes with using RTP/UDP/IP ROHC, then any efficiencies could be
lost in the inability for the compression of heaver headers. Likewise, it
makes sense to keep this ULE part isolated if possible so that authors of
any other or future ROHC compression schemes aren't required to know about
this spec while still allowing ULE implementers to benefit from ULE and
higher layer ROHC together.
Cheers, Rod.
PS Good timing of the email Gorry - I was doing my 2-monthly stroll through
IETF mails :)
On 2/17/08 10:26 PM, "ext Gorry Fairhurst" <gorry@erg.abdn.ac.uk> wrote:
>
> I am forwarding this to the list, for comments and discussion.
>
> best wishes,
>
> Gorry Fairhurst
> (as ipdvb Chair)
>
> -------- Original Message --------
> Subject: RFC: Draft for ROHC over DVB
> Date: Sun, 17 Feb 2008 20:39:12 +0800
> From: Ang Way Chuang <wcang@nav6.org>
> To: Gorry Fairhurst <gorry@erg.abdn.ac.uk>
>
> Hi Dr. Fairhurst and members of IP over DVB charter,
> We are from Network Research Group of Universiti Sains Malaysia
> (http://nrg.cs.usm.my/satellite.htm). We would like to seek for your
> comments (and corrections) regarding our draft. Attached is the draft.
> Do note that the most of content in Terminologies section was copied
> from other Internet Drafts and RFCs. I think they are still incomplete.
>
> I tried to sent an email to ipdvb@erg.abdn.ac.uk, but I received
> no such email. I'm guessing the mailing list is not working properly.
>
>
> Thank you very much.
>
> Regards,
> Ang Way Chuang
>
>
>
> Tat-Chee Wan
> Chee-Hong Teh
> Way-Chuang
> Ang
>
> Robust Header Compression over Unidirectional Lightweight Encapsulation (ULE)
> and MPEG2-TS frames
>
> Status of This Memo
>
> This memo defines an Experimental Protocol for the Internet
> community. It does not specify an Internet standard of any kind.
> Discussion and suggestions for improvement are requested.
> Distribution of this memo is unlimited.
>
> Intellectual Property Right
>
> By submitting this Internet-Draft, each author represents that any
> applicable patent or other IPR claims of which he or she is aware
> have been or will be disclosed, and any of which he or she becomes
> aware will be disclosed, in accordance with Section 6 of BCP 79.
>
> Internet-Drafts are working documents of the Internet Engineering
> Task Force (IETF), its areas, and its working groups. Note that other
> groups may also distribute working documents as Internet-Drafts.
>
> Internet-Drafts are draft documents valid for a maximum of six months
> and may be updated, replaced, or obsoleted by other documents at any
> time. It is inappropriate to use Internet-Drafts as reference
> material or to cite them other than as "work in progress."
>
> The list of current Internet-Drafts can be accessed at
> http://www.ietf.org/1id-abstracts.html
>
> The list of Internet-Draft Shadow Directories can be accessed at
> http://www.ietf.org/shadow.html
>
> Abstract
>
> This paper introduces approach to carry ROHC packets over ULE and MPEG2-TS
> frames. For completeness, ROHC channel parameters negotiation protocol is
> also
> presented.
>
> Table of Contents
>
> 1. Introduction
> 2. Terminology
> 3. Packet Format of ROHC Packet
> 3.1. ROHC over ULE
> 3.1.1. Dedicated EtherType Fields for ROHC Compressed Packet
> 3.1.1. Dedicated EtherType Fields for ROHC Compressed Packet
> 3.1.2. ROHC Compressed Packet as Payload of Ethernet Packet
> 3.2. ROHC over MPEG2-TS
> 4. Establishing ROHC Channel
> 4.1. ROHC Channel Negotiation Protocol
> 4.1.1. Compressor Advertisement
> 4.1.2. Compressor Solicitation
> 4.1.3. Request
> 4.1.4. Reply
> 4.1.4.1. Medium Information
> 4.1.4.1.1. MPEG2-TS Medium
> 4.1.4.1.2. ULE Medium
> 4.1.5. Acknowledgement/Negative Acknowledgement
> 4.1.6 Compressor Shutdown
> 4.1.7 Decompressor Shutdown
> 4.2. Interaction of ROHC Channel Parameters Negotiation Protocol
> 4.3 Bidirectional ROHC Channels
> 5. IANA Consideration
> 6. References
>
> 1. Introduction
>
> 2. Terminology
> The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
> document are to be interpreted as described in RFC 2119.
>
> DVB
> Digital Video Broadcast. A framework and set of associated
> standards published by the European Telecommunications Standards
> Institute (ETSI) for the transmission of video, audio, and data
> using the ISO MPEG-2 Standard [ISO-MPEG2].
>
> MAC
> Medium Access Control [IEEE-802.3]. A link-layer protocol defined
> by the IEEE 802.3 standard (or by Ethernet v2 [DIX]).
>
> MPEG-2
> A set of standards specified by the Motion Picture Experts
> Group (MPEG) and standardized by the International Standards
> Organisation (ISO/IEC 13818-1) [ISO-MPEG2], and ITU-T (in H.222
> [ITU-H222]).
>
> PDU
> Protocol Data Unit. Examples of a PDU include Ethernet frames,
> IPv4 or IPv6 datagrams, and other network packets.
>
> Receiver
> Equipment that processes the signal from a TS Multiplex and
> performs filtering and forwarding of encapsulated PDUs to the
> network-layer service (or bridging module when operating at the
> link layer).
>
> Transmitter
> Router or host that sends data.
>
> SNDU
> SubNetwork Data Unit. An encapsulated PDU sent as an MPEG-2
> Payload Unit.
>
> TS
> Transport stream (TS) is a format specified in MPEG-2 Part 1,
> Systems (ISO/IEC standard 13818-1). Its design goal is to allow
> multiplexing of digital video and audio and to synchronize the
> output. Transport stream offers features for error correction for
> transportation over unreliable media, and is used in broadcast
> applications such as DVB and ATSC.
>
> ULE Stream
> An MPEG-2 TS Logical Channel that carries only ULE encapsulated
> PDUs. ULE Streams may be identified by definition of a
> stream_type in SI/PSI [ISO-MPEG2].
>
> ROHC
> Robust Header Compression. A framework of compression headers of IP
> packet as defined in [RFC 3095]
>
> ROHC channel
> A logical unidirectional point-to-point channel carrying ROHC packets
> from one compressor to one decompressor, optionally carrying ROHC
> feedback information on the behalf of another compressor-decompressor
> pair operating on a separate ROHC channel in the opposite direction.
>
> ROHC profile
> A ROHC profile is a compression protocol, which specifies how to
> compress
> specific header combinations. A ROHC profile may be tailored to handle a
> specific set of link characteristics, e.g., loss characteristics,
> reordering between compression points, etc. ROHC profiles provide the
> details of the header compression and each compression profile is
> associated with a unique ROHC profile identifier.
>
> MRRU
> Maximum Reconstructed Reception Unit as defined in [RFC 3095].
>
> DVB
> Digital Video Broadcast. A framework and set of associated standards
> published by the European Telecommunications Standards Institute (ETSI)
> for the transmission of video, audio, and data using the ISO MPEG-2
> Standard [ISO-MPEG2].
>
> Context Identifier
> [RFC 3095] provides a definition for context identifiers.
>
> MSB
> Most significant bit.
>
> LSB
> Least significant bit.
>
> ACK
> Acknowledgement.
>
> NACK
> Negative acknowledgement.
>
> CID
> Context Identifier.
>
> 3. Packet Format of ROHC Packet
>
> 3.1. ROHC over ULE
> The packet format for ROHC packet encapsulated can be in one the following
> two formats:
>
> 3.1.1. Dedicated EtherType Fields for ROHC Compressed Packet
> +-+--------+---------+---------------+------------------------+--------+
> |D| Length |Type=ROHC| Dest Address* | ROHC compressed packet | CRC-32 |
> +-+--------+---------+---------------+------------------------+--------+
> Figure 1: ROHC compressed packet encapsulated using dedicated EtherType
>
> The semantics of D-bit, Length, Type, Destination Address and CRC-32 fields
> are defined in section 4 of [RFC 4326]. However, the Type fields requires
> a new IANA assigned EtherType value to indicate the presence of ROHC
> compressed packet in PDU.
>
> In the absence of multiple receivers, a transmitter can send an SNDU
> without
> Destination Address Field (D bit marked). However, when multiple receivers
> are listening to the same transmitter, destination address must be included
> in SNDU.
>
> 3.1.2. ROHC Compressed Packet as Payload of Ethernet Packet
>
>
> +---+--------+----------+----------+------------+--------------+--------------
> ----------+--------+
> |D=1| Length |Type=Ether| Dest MAC | Source MAC |EtherType=ROHC| ROHC
> compressed packet | CRC-32 |
>
> +---+--------+----------+----------+------------+--------------+--------------
> ----------+--------+
> Figure 2: ROHC compressed packet encapsulated in SNDU bridged frame
>
> This packet format should be used when there are multiple transmitters and
> receivers over a DVB link. The value of EtherType field is similar to Type
> Field in section 3.1.1.
>
> 3.2. ROHC over MPEG2-TS
> This encapsulation format is the smallest packet format in terms of packet
> size. The format of SNDU is the following format:
>
> +------+------------------------+--------+
> |Length| ROHC compressed packet | CRC-32 |
> +------+------------------------+--------+
> Figure 3:
>
> The meaning of each fields is specified below:
>
> Length: This field indicates the ROHC compressed packet field only. This
> field can be either 1 or 2 octets depending on the the most significant
> bit.
> If the most significant bit is cleared, the length of this field is 1 octet
> and may represents values from 0 until 127. Otherwise, the length of this
> field is 2 octets and may represents values from 128 until 61566.
>
> ROHC Compressed Packet: ROHC compressed packet as defined in section 5.2
> of
> [RFC 3095].
>
> CRC-32: The 32-bit CRC is calculated over Length filed and ROHC compressed
> packet. The polynomial used to calculate the CRC is 0x104C11DB7.
>
> Like ULE, ROHC over MPEG2-TS also supports packing and padding mode. The
> mechanism of encapsulating this SNDU is similar to encapsulation of ULE
> packet within MPEG2-TS. This approach requires that separate PID dedicated
> to a ROHC channel.
>
> 4. Establishing ROHC Channel
> This standard presents two approaches to setup a ROHC channel over a DVB
> link. The first approach is to setup ROHC channel manually. This requires
> that the operators at the every transmitters and receivers to manually
> configure the ROHC channel parameters. When the size of network is small,
> this approach is favourable.
>
> But the former approach becomes nonviable if the network is dynamic and is
> not scalable as the size of the network grows. Henceforth, we presents a
> negotiation protocol to create ROHC channel in the next section.
>
> 4.1. ROHC Channel Parameters Negotiation Protocol (RCPNP)
> The approach presented in this section can only work if compressor site
> and decompressor site are connected through two dedicated unidirectional
> DVB links, with a unidirectional link originating from each of the
> sites, configured to form a bidirectional network link between the two
> sites. This protocol works through ULE packets only. It is possible to
> extend this protocol to work over Generic Stream Encapsulation [GSE] in the
> future. While it is possible to extend this protocol to work over
> asymmetrical link, this draft doesn't try to address this issue. Since new
> EtherType is allocated, this protocol can be extended to asymmetrical link
> via Link-Layer Tunneling Mechanism [RFC 3077] with little modifications.
>
> The basic format of ULE SNDU packet is as such:
>
> +---+--------+------------+----------+--------+
> |D=1| Length |Type=ROHCNeg| Body | CRC-32 |
> +---+--------+------------+----------+--------+
> Figure 4: Minimal format of RCPNP message
>
>
> +---+--------+----------+----------+------------+-----------------+------+----
> ----+
> |D=1| Length |Type=Ether| Dest MAC | Source MAC |EtherType=ROHCNeg| Body |
> CRC-32 |
>
> +---+--------+----------+----------+------------+-----------------+------+----
> ----+
> Figure 5: RCPNP message encapsulated in bridged frame.
>
> Type field requires a new separate IANA assigned EtherType number for ROHC
> Channel Negotiation Protocol. The types of message in this protocol is
> defined in the Body field. The following subsections will explain the type
> of messages for this protocol. Compressor Advertisement and Compressor
> Solicitation uses packet format depicted in Figure 4. While other forms of
> messages uses packet format depicted in Figure 5.
>
> The basic format for these messages is depicted is as such:
>
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version | Operation | X |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 6: Basic format of RCPNP Body field.
>
> Currently, version number is 0. Operation field defines the type of message
> contained in the Body field. The content of X-bit depends on operation
> type.
>
> 4.1.1. Compressor Advertisement
>
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=0 | X |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> ~ Address (6 octets) ~
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 7: Format of Compressor Advertisement message.
>
> Compressor site should send this message periodically to advertise the
> availability of compressor. Care should be taken as not to send too many
> advertisements. The decompressor site will use the value specified in the
> Address field when addressing compressor site. X-bit is unused and should
> be
> ignored.
>
> 4.1.2. Compressor Solicitation
>
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=1 | X |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 8: Format of Compressor Solicitation message.
>
> Instead of waiting for compressor site to advertise itself, decompressor
> site
> may opt to solicit for compressor(s) by sending compressor site
> solicitation
> message. Upon receiving solicitation, compressor site should send an
> advertisement. X-bit is unused and should be ignored. Decompressor site
> should rate-limit the frequency of solicitation if it is doesn't receive
> any advertisement to avoid flooding DVB link.
>
> 4.1.3. Request
>
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=2 | X |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Maximum CID +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> ~ MRRU (4 octets) ~
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Num of profiles +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Profile ID 1 +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Profile ID 2 +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Profile ID N +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 9: Format of Request message.
>
> This message is sent by decompressor site to compressor site. The meaning
> of each fields in the message are described below:
>
> Maximum CID: Maximum Context Identifier tolerated by decompressor.
>
> MRRU: Maximum Reconstructed Reception Unit tolerated by decompressor. Value
> of 0 indicates the negotiated channel doesn't allow for segmentation of
> ROHC
> compressed packet.
>
> Number of profiles: Number of profiles supported by decompressor.
>
> Profile IDs: ROHC Profile IDs supported by decompressor. Each profile
> ID occupy 2 octets.
>
> X-bit is unused and should be ignored.
>
> 4.1.4. Reply
>
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=3 | X |
> +===============================================+
> | |
> + Maximum CID +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> ~ MRRU (4 octets) ~
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Num of profiles |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Profile ID 1 +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Profile ID 2 +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | |
> + Profile ID N +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 10: Format of Reply message.
>
> This message is sent by compressor site to decompressor site in response to
> request message sent by decompressor site. The meaning of each fields in
> the
> message are described below:
>
> Maximum CID: Maximum CID tolerated by compressor. This value of this field
> should be less than or equal to its counterpart in request message.
> Decompressor site should send a NACK if it receives Maximum CID that is
> higher than the initial negotiated value.
>
> MRRU: Maximum Reconstructed Reception Unit tolerated by compressor.
> Likewise,
> decompressor site should send a NACK if it is receives higher MRRU than
> what
> it requested.
>
> Number of profile IDs: Note that this field is 1 octet instead of 2 because
> there can be only 256 active profiles at any given ROHC channel.
> Decompressor
> site should send a NACK if it receives more profile IDs than it can
> support.
>
> Profile IDs: Profile Identifiers of the ROHC profiles that will be used for
> the negotiated ROHC channel. Decompressor site should send a NACK if it
> receives any profile ID that it doesn't support.
>
> X-bit is unused and should be ignored.
>
> 4.1.4.1. Medium Information
> The following notation depicted in the previous figure 10 indicates the
> presence of medium information.
>
> +===============================================+
>
> Medium information conveys how compressor is to send ROHC compressed
> packets
> to decompressor. Currently only 2 media are supported, namely MPEG2-TS and
> ULE. The details of packet format for ROHC over MPEG2-TS/ULE is described
> in section 3. Medium type is conveyed by Medium field. Other media may be
> supported in the future and the support for these media will specified in
> other documents. Decompressor receiving unsupported medium type should send
> a NACK.
>
> 4.1.4.1.1. MPEG2-TS Medium
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Medium=0 | |
> +-----+-----+-----+ PID +
> | |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 11: Medium information for ROHC over MPEG2-TS.
>
> PID: Packet Identifier of MPEG2-TS frames that will carry ROHC compressed
> packet.
>
> 4.1.4.1.2. ULE Medium
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Medium=1 | ULE Type | Reserved |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 12: Medium information for ROHC over ULE.
>
> ULE Type:
>
> 0: No MAC address will be sent in ULE packets. This option should only be
> used if the compressor site is certain that there is only one receiver and
> one transmitter over DVB link.
>
> 1: Only destination MAC address will be sent in ULE packets that carry ROHC
> compressed packet. This means that Destination Absent bit in ULE header
> will
> be cleared. This option is used only if there is one transmitter and many
> receivers listening to that transmitter via DVB link.
>
> 2: ROHC packets will be encapsulated in Ethernet bridged frame. This option
> is used when there multiple transmitters and receivers over a DVB link.
>
> 3: Not used. Receiver should treat it as corrupted packet, silently
> discard the message and wait for a valid Reply message or until a timeout
> occur at which the decompressor site will start the negotiation afresh by
> sending a Request message.
>
> Reserved field is not used and should be ignored.
>
> 4.1.5. Acknowledgement
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=4 | Ack |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 13: Format of Acknowledgement message.
>
> Decompressor site should send either an acknowledgement or negative
> acknowledgement if it receives a valid Reply message. If Ack bit is set,
> then the message is an acknowledgement. Otherwise, it is a negative
> acknowledgement. If compressor site doesn't receive ACK nor NACK within a
> reasonable interval, it should discard any information of negotiated ROHC
> channel parameters. An acknowledgement must be sent to decompressor site
> when
> compressor site receives Decompressor Shutdown message.
>
> 4.1.6 Compressor Shutdown
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=5 | X |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 14: Format of Compressor Shutdown message.
>
> This message is sent by the compressor site to notify the decompressor site
> that it is about to stop compressing IP packets. Upon receiving this
> message, decompressor should release all resources that are being held.
>
> Compressor must wait for an acknowledgement from decompressor site before
> freeing its resource. If it doesn't an acknowledgement within a reasonable
> interval, it should keep sending a shutdown message for a number of times
> before freeing its resource.
>
> X-bit is unused and should be ignored.
>
> 4.1.7 Decompressor Shutdown
> MSB LSB
> 0 1 2 3 4 5 6 7
> +-----+-----+-----+-----+-----+-----+-----+-----+
> | Version=0 | Operation=6 | X |
> +-----+-----+-----+-----+-----+-----+-----+-----+
> Figure 15: Format of Decompressor Shutdown message.
>
> This message is sent by the decompressor site to notify the compressor
> that it is about to stop decompressing IP packets. Upon receiving this
> message, compressor should release all resources that are being held and
> stop
> sending compressed IP packets.
>
> Decompressor must wait for an acknowledgement from compressor site before
> freeing its resource. If it doesn't an acknowledgement within a reasonable
> interval, it should keep sending a shutdown message for a number of times
> before freeing its resource.
>
> X-bit is unused and should be ignored.
>
> 4.2. Interaction of RCPNP
> The following diagram depicts a possible interaction between compressor
> site
> and decompressor site in negotiating ROHC channel parameters.
>
> Compressor Site Decompressor Site
> |<------------ Solicit (optional) ----------------|
> | |
> |------------------- Advertise ------------------>|
> | |
> |<------------------- Request --------------------|
> | |
> |--------------------- Reply -------------------->|
> | | Create
> instance
> | | of
> decompressor
> Create |<-------------------- ACK -----------------------|
> compressor | |
> | |
> | ==== (Compression can begin at this point) === |
> | |
> | |
> Destroy |<------------ Decompressor Shutdown -------------|
> compressor | |
> |--------------------- ACK ---------------------->| Destroy
> | | decompressor
>
> Figure 15: Packets flow of RCPNP
>
>
> 4.3 Bidirectional ROHC Channels
> While establishing bidirectional ROHC channels allows for the use of ROHC
> bidirectional optimistic mode and bidirectional reliable mode, RCPNP
> doesn't
> concern itself with the establishment of bidirectional ROHC channels.
> Therefore, it is up to implementers of this protocol to support
> bidirectional ROHC channels. The implementation should be as
> straightforward
> as mapping correct pair of ROHC channels.
>
> 5. IANA Consideration
> Two EtherTypes should be assigned. One of it is for RCPNP and the other is
> to indicate the presence of ROHC compressed packet.
>
> 6. References
> [RFC 3095] Bormann, C. et al, "RObust Header Compression (ROHC):
> Framework and four profiles: RTP, UDP, ESP, and uncompressed",
> RFC 3095, 2001
>
> [RFC 4326] Fairhurst, G. and Collini-Nocker, B., "Unidirectional
> Lightweight Encapsulation (ULE) for Transmission of IP
> Datagrams
> over an MPEG-2 Transport Stream (TS)", RFC 4326, 2005
>
> [GSE] Digital Video Broadcasting, "Generic Stream Encapsulation
> (GSE)
> Protocol", DVB Document A116, 2007
>
> [RFC 3077] Duros, E. et al, "A Link-Layer Tunneling Mechanism for
> Unidirectional Links", RFC 3077, 2001
>
> [ISO-MPEG2] IS 13818-1, "Information technology -- Generic coding of
> moving
> pictures and associated audio information -- Part 1: Systems",
> International Standards Organisation (ISO), 2000.
>
>
> Authorsâ?? Addresses
> Tat-Chee Wan
> School of Computer Sciences,
> Universiti Sains Malaysia,
> 11800 USM, Penang, Malaysia.
> Email: tcwan@cs.usm.my
> Web: http://nrg.cs.usm.my/~tcwan
>
> Chee-Hong Teh
> School of Computer Sciences,
> Universiti Sains Malaysia,
> 11800 USM, Penang, Malaysia.
> Email: chteh@nav6.org
>
> Way-Chuang Ang
> School of Computer Sciences,
> Universiti Sains Malaysia,
> 11800 USM, Penang, Malaysia.
> Email: wcang@nav6.org
>
>
>