draft-ietf-ipv6-compression-nego-v2-02.txt   rfc5172.txt 
IPv6 Working Group S.Varada (Editor) Network Working Group S. Varada, Ed.
Internet Draft Transwitch Request for Comments: 5172 Transwitch
Obsoletes: RFC 2472 (if approved) February 2008
Category: Standards track
Negotiation for IPv6 datagram compression using IPv6 Control Protocol
<draft-ietf-ipv6-compression-nego-v2-02.txt>
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Copyright (C) The IETF Trust (2008). This document specifies an Internet standards track protocol for the
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Abstract Abstract
The Point-to-Point Protocol (PPP) provides a standard method of The Point-to-Point Protocol (PPP) provides a standard method of
encapsulating Network Layer protocol information over encapsulating network-layer protocol information over point-to-point
point-to-point links. PPP also defines an extensible Link Control links. PPP also defines an extensible Link Control Protocol, and
Protocol, and proposes a family of Network Control Protocols proposes a family of Network Control Protocols (NCPs) for
(NCPs) for establishing and configuring different network-layer establishing and configuring different network-layer protocols.
protocols.
The IPv6 Control Protocol (IPV6CP), which is an NCP for a PPP The IPv6 Control Protocol (IPV6CP), which is an NCP for a PPP link,
link, allows for the negotiation of desirable parameters for an allows for the negotiation of desirable parameters for an IPv6
IPv6 interface over PPP. interface over PPP.
This document defines the IPv6 datagram compression option that This document defines the IPv6 datagram compression option that can
can be negotiated by a node on the link through the IPV6CP. be negotiated by a node on the link through the IPV6CP.
Table of Contents Table of Contents
1. Introduction...................................................2 1. Introduction ....................................................2
1.1 Specification of Requirements..............................3 1.1. Specification of Requirements ..............................2
2. IPV6CP Configuration Options...................................3 2. IPV6CP Configuration Options ....................................3
2.1 IPv6-Compression-Protocol..................................3 2.1. IPv6-Compression-Protocol ..................................3
3. Security Considerations........................................5 3. Security Considerations .........................................4
4. IANA Considerations............................................5 4. IANA Considerations .............................................5
5. Acknowledgments................................................6 5. Management Considerations .......................................5
6. References.....................................................6 6. Acknowledgments .................................................5
6.1 Normative References.......................................6 7. References ......................................................5
6.2 Informative References.....................................6 7.1. Normative References .......................................5
Editor's Address..................................................7 7.2. Informative References .....................................6
IPR Notice ......................................................7
Copyright Notice and Disclaimer...................................8
1. Introduction 1. Introduction
PPP [1] has three main components: PPP [1] has three main components:
1) A method for encapsulating datagrams over serial links. 1) A method for encapsulating datagrams over serial links.
2) A Link Control Protocol (LCP) for establishing, configuring, 2) A Link Control Protocol (LCP) for establishing, configuring,
and testing the data-link connection. and testing the data-link connection.
3) A family of Network Control Protocols (NCPs) for establishing 3) A family of Network Control Protocols (NCPs) for establishing
and configuring different network-layer protocols. and configuring different network-layer protocols.
In order to establish communications over a point-to-point link, In order to establish communications over a point-to-point link, each
each end of the PPP link must first send LCP packets to end of the PPP link must first send LCP packets to configure and test
configure and test the data link. After the link has been the data link. After the link has been established and optional
established and optional facilities have been negotiated as facilities have been negotiated as needed by the LCP, PPP must send
needed by the LCP, PPP must send NCP packets to choose and NCP packets to choose and configure one or more network-layer
configure one or more network-layer protocols. Once each of the protocols. Once each of the chosen network-layer protocols has been
chosen network-layer protocols has been configured, datagrams configured, datagrams from each network-layer protocol can be sent
from each network-layer protocol can be sent over the link. The over the link. The link will remain configured for communications
link will remain configured for communications until until explicit LCP or NCP packets close the link down, or until some
explicit LCP or NCP packets close the link down, or until some external event occurs (power failure at the other end, carrier drop,
external event occurs (power failure at the other end, carrier etc.).
drop, etc.).
In the IPv6 over PPP specification [2], the NCP, or IPV6CP, for In the IPv6 over PPP specification [2], the NCP, or IPV6CP, for
establishing and configuring IPv6 over PPP is defined. The establishing and configuring IPv6 over PPP is defined. The same
same specification defines the Interface Identifier parameter, specification defines the Interface Identifier parameter, which can
which can be used to generate link-local and global unique IPv6 be used to generate link-local and globally unique IPv6 addresses,
addresses, for negotiation. for negotiation.
In this specification, the compression parameter for use in IPv6 In this specification, the compression parameter for use in IPv6
datagram compression is defined. Together with RFC 5072 [2], this datagram compression is defined. Together with RFC 5072 [2], this
document obsoletes RFC 2472 [13]. However, no protocol changes document obsoletes RFC 2472 [13]. However, no protocol changes have
have been introduced over RFC 2472. been introduced over RFC 2472.
1.1 Specification of Requirements 1.1. Specification of Requirements
In this document, several words are used to signify the In this document, several words are used to signify the requirements
requirements of the specification. of the specification.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
"OPTIONAL" in this document are to be interpreted as described document are to be interpreted as described in [3].
in [3].
2. IPV6CP Configuration Options 2. IPV6CP Configuration Options
IPV6CP Configuration Options allow negotiation of desirable IPv6 IPV6CP Configuration Options allow negotiation of desirable IPv6
parameters. IPV6CP uses the same Configuration Option format as parameters. IPV6CP uses the same Configuration Option format as
defined for LCP [1] but with a separate set of Options. If a defined for LCP [1] but with a separate set of Options. If a
Configuration Option is not included in a Configure-Request Configuration Option is not included in a Configure-Request packet,
packet, the default value for that Configuration Option is the default value for that Configuration Option is assumed.
assumed.
The only IPV6CP option defined in this document is the IPv6- The only IPV6CP option defined in this document is the IPv6-
Compression-Protocol. The Type field for this IPV6CP Option is as Compression-Protocol. The Type field for this IPV6CP Option is as
follows: follows:
2 IPv6-Compression-Protocol 2 IPv6-Compression-Protocol
Note that the up-to-date values of the IPV6CP Option Type field Note that the up-to-date values of the IPV6CP Option Type field are
are specified in the on-line database of "Assigned Numbers" specified in the on-line database of "Assigned Numbers" maintained by
maintained at IANA [7]. IANA [7].
2.1 IPv6-Compression-Protocol 2.1. IPv6-Compression-Protocol
Description
This Configuration Option provides a way to negotiate the use of a This Configuration Option provides a way to negotiate the use of a
specific IPv6 packet compression protocol. The specific IPv6 packet compression protocol. The IPv6-Compression-
IPv6-Compression-Protocol Configuration Option is used to indicate Protocol Configuration Option is used to indicate the ability to
the ability to receive compressed packets. Each end of the link receive compressed packets. Each end of the link MUST separately
MUST separately request this option if bi-directional compression request this option if bidirectional compression is desired. By
is desired. By default, compression is not enabled. default, compression is not enabled.
IPv6 compression negotiated with this option is specific to IPv6 IPv6 compression negotiated with this option is specific to IPv6
datagrams and is not to be confused with compression resulting datagrams and is not to be confused with compression resulting from a
from a compression method negotiated via the PPP Compression compression method negotiated via the PPP Compression Control
Control Protocol (CCP) [12], which potentially affects all Protocol (CCP) [12], which potentially affects all datagrams.
datagrams.
A summary of the IPv6-Compression-Protocol Configuration Option A summary of the IPv6-Compression-Protocol Configuration Option
format is shown below. The fields are transmitted from left to format is shown below. The fields are transmitted from left to
right. right.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | IPv6-Compression-Protocol | | Type | Length | IPv6-Compression-Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 4, line 28 skipping to change at page 4, line 4
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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | IPv6-Compression-Protocol | | Type | Length | IPv6-Compression-Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data ... | Data ...
+-+-+-+-+ +-+-+-+-+
Type Type
2 2
Length Length
>= 4 >= 4
IPv6-Compression-Protocol IPv6-Compression-Protocol
The IPv6-Compression-Protocol field is two octets and indicates The IPv6-Compression-Protocol field is two octets and
the compression protocol desired. Values for this field are indicates the compression protocol desired. Values for this
always the same as the PPP Data Link Layer Protocol field field are always the same as the PPP Data Link Layer Protocol
values for that same compression protocol. field values for that same compression protocol.
IPv6-Compression-Protocol field values have been assigned in IPv6-Compression-Protocol field values have been assigned in
[14] for IPv6 Header Compression (004f), [4, 5] for IP Header [4, 5] for IP Header Compression (0061), and in [6] for Robust
Compression (0061), and [6] for Robust Header compression Header Compression (ROHC) (0003). Other assignments can be
(ROHC) (0003). Other assignments can be made in documents that made in documents that define specific compression algorithms.
define specific compression algorithms.
Data Data
The Data field is zero or more octets and contains additional The Data field is zero or more octets and contains additional
data as determined by the particular compression protocol. data as determined by the particular compression protocol.
Default The default (in the absence of negotiation of this option) is to have
no IPv6 compression protocol enabled.
No IPv6 compression protocol enabled.
3. Security Considerations 3. Security Considerations
Lack of proper link security, such as authentication, prior to Lack of proper link security, such as authentication, prior to data
data transfers may enable man-in-the middle attacks transfers may enable man-in-the middle attacks resulting in the loss
resulting in the loss of data integrity and confidentiality. The of data integrity and confidentiality. The mechanisms that are
mechanisms that are appropriate for ensuring PPP link security appropriate for ensuring PPP link security are addressed below
are addressed below together with the reference to a generic together with the reference to a generic threat model.
threat model.
The mechanisms that are appropriate for ensuring PPP link The mechanisms that are appropriate for ensuring PPP link security
Security are: 1) Access Control Lists that apply filters on are: 1) Access Control Lists that apply filters on traffic received
traffic received over the link for enforcing admission policy, 2) over the link for enforcing admission policy, 2) an authentication
an Authentication protocol that facilitates negotiations between protocol that facilitates negotiations between peers [8] to select an
peers [8] to select an authentication method (e.g., MD5 [9]) for authentication method (e.g., MD5 [9]) for validation of the peer, and
validation of the peer, and 3) an Encryption control protocol 3) an encryption control protocol that facilitates negotiations
that facilitates negotiations between peers to select encryption between peers to select encryption algorithms (or crypto-suites) to
algorithms (or, crypto-suites) to ensure data confidentiality ensure data confidentiality [10]).
[10]).
There are certain threats associated with peer interactions on a There are certain threats associated with peer interactions on a PPP
PPP link even with one or more of the above security measures in link even with one or more of the above security measures in place.
place. For instance, using the MD5 authentication method [9] For instance, using the MD5 authentication method [9] exposes one to
exposes one to replay attacks, in which an attacker could replay attacks, in which an attacker could intercept and replay a
intercept and replay a station's identity and password hash to station's identity and password hash to get access to a network. The
get access to a network. The user of this specification is user of this specification is advised to refer to [8], which presents
advised to refer to [8], which presents a generic threat model, a generic threat model, for an understanding of the threats posed to
for an understanding of the threats posed to the security of a the security of a link. The reference [8] also gives a framework to
link. The reference [8] also gives a framework to specify specify requirements for the selection of an authentication method
requirements for the selection of an authentication method for a for a given application.
given application.
4. IANA Considerations 4. IANA Considerations
There are no specific recommendations for the IANA on the No specific action is needed for the assignment of a value for the
assignment of values for the Type field of the IPv6 datagram Type field of IPv6 datagram compression option specified in this
compression option specified in section 2.1 of this document. The specification. The current assignment is up-to-date in the registry
current assignment is up-to-date at [7]. "PPP IPV6CP CONFIGURATION OPTIONS" for item IPv6-Compression-Protocol
(2) at [7]. However, the RFC reference for that item has been
changed to 5172.
No action is needed either for the assignment of the No action is needed either for the assignment of the IPV6-
IPv6-Compression-Protocol values, as such values have already Compression-Protocol values, as such values have already been defined
been defined by other documents listed in the Section 2.1. Values by other documents listed in Section 2.1. Values for this field are
for this field are always the same as the PPP Data Link Layer always the same as the PPP Data Link Layer Protocol field values for
field values for that same compression protocol. As a result, that same compression protocol. As a result, future allocation of
future allocation of these values is governed by RFC 3818 [11] these values is governed by RFC 3818 [11] that requires IETF
that requires IETF consensus process. Consensus. Current values are in the registry "IPv6-Compression-
Protocol Types". However, the RFC reference for that registry has
been changed to 5172.
5. Acknowledgments 5. Management Considerations
From an operational point of view, the status of the negotiation and
the compression algorithm on the link should be observable by an
operator managing a network. There is no standard management
interface that covers this at the time of the writing of this
specification.
6. Acknowledgments
The editor is grateful to Jari Arkko for the direction provided on The editor is grateful to Jari Arkko for the direction provided on
this draft and James Carlson for helpful suggestions. this document and James Carlson for helpful suggestions.
Acknowledgements are also due to D. Haskins and E. Allen for the Acknowledgments are also due to D. Haskin and E. Allen for the
specification work done in RFC 2023 and RFC 2472. specification work done in RFC 2023 and RFC 2472.
6. References 7. References
6.1 Normative References 7.1. Normative References
[1] Simpson, W., "The Point-to-Point Protocol", STD 51, RFC 1661, [1] Simpson, W., Ed., "The Point-to-Point Protocol (PPP)", STD 51,
July 1994. RFC 1661, July 1994.
[2] Allen, E., Haskin, D., and, S. Varada, Ed., "IPv6 over PPP", [2] Varada, S., Ed., Haskin, D., and E. Allen, "IP Version 6 over
RFC 5072, September 2007. PPP", RFC 5072, September 2007.
[3] Bradner, S., "Key words for use in RFCs to Indicate Requirement [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[4] Degermark M., B. Nordgren, and S. Pink, "IP Header Compression", [4] Degermark, M., Nordgren, B., and S. Pink, "IP Header
RFC 2507, February 1999. Compression", RFC 2507, February 1999.
[5] Koren T., S. Casner, and C. Bormann, "IP Header Compression Over [5] Koren, T., Casner, S., and C. Bormann, "IP Header Compression
PPP", RFC 3544, July 2003. over PPP", RFC 3544, July 2003.
[6] Bormann C., "Robust Header Compression (ROHC) over PPP", RFC [6] Bormann, C., "Robust Header Compression (ROHC) over PPP", RFC
3241, April 2002. 3241, April 2002.
6.2 Informative References 7.2. Informative References
[7] IANA, "Assigned Numbers", http://www.iana.org/numbers.html [7] IANA, http://www.iana.org.
[8] Aboba, R., Blunk, L., Vollbrecht, J., Carlson, J., and [8] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
H. Levkowetz,Ed., "Extensible Authentication Protocol", RFC Levkowetz, Ed., "Extensible Authentication Protocol (EAP)", RFC
3748, June 2004. 3748, June 2004.
[9] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, April [9] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321, April
1992. 1992.
[10] Meyer, G., "The PPP Encryption Control Protocol (ECP)", RFC [10] Meyer, G., "The PPP Encryption Control Protocol (ECP)", RFC
1968, June 1996. 1968, June 1996.
[11] Schryver, V., "IANA Considerations for the Point-to-Point [11] Schryver, V., "IANA Considerations for the Point-to-Point
Protocol (PPP)", RFC 3818, June 2004. Protocol (PPP)", BCP 88, RFC 3818, June 2004.
[12] Rand, D., "The PPP Compression Control Protocol(CCP)", RFC 1962, [12] Rand, D., "The PPP Compression Control Protocol(CCP)", RFC 1962,
June 1996. June 1996.
[13] Haskin D., and E. Allen, "IP Version 6 over PPP", RFC 2472, [13] Haskin, D. and E. Allen, "IP Version 6 over PPP", RFC 2472,
December 1998. December 1998.
[14] Haskin D., and E. Allen, "IP Version 6 over PPP", RFC 2023,
October 1996.
Editor's Address Editor's Address
Srihari Varada Srihari Varada
TranSwitch Corporation TranSwitch Corporation
3 Enterprise Dr. 3 Enterprise Dr.
Shelton, CT 06484. US. Shelton, CT 06484
US
Phone: +1 203 929 8810 Phone: +1 203 929 8810
EMail: varada@ieee.org EMail: varada@ieee.org
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