draft-ietf-rserpool-tcpmapping-01.txt   draft-ietf-rserpool-tcpmapping-02.txt 
Network Working Group P. Conrad Network Working Group P. Conrad
Internet-Draft University of Delaware Internet-Draft University of Delaware
Expires: June 18, 2004 P. Lei Expires: December 10, 2004 P. Lei
Cisco Systems, Inc. Cisco Systems, Inc.
December 19, 2003 June 11, 2004
TCP Mapping for Reliable Server Pooling Enhanced Mode TCP Mapping for Reliable Server Pooling Enhanced Mode
draft-ietf-rserpool-tcpmapping-01.txt draft-ietf-rserpool-tcpmapping-02.txt
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved. Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract Abstract
This memo defines the shim protocol that maps the requirements of the This memo defines the shim protocol that maps the requirements of the
ASAP protocol [5] to the capabilities of the TCP protocol [7]. In ASAP protocol [5] to the capabilities of the TCP protocol [7]. In
particular, this shim protocol adds the following capabilties that particular, this shim protocol adds the following capabilties that
are required by ASAP, but not provided by TCP: (1) message are required by ASAP, but not provided by TCP: (1) message
orientation, (2) heartbeat messages, (3) multiple streams, and (4) orientation, (2) heartbeat messages, (3) multiple streams, and (4)
undelivered message retrieval (if provided). undelivered message retrieval (if provided).
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Brief overview of RSerPool . . . . . . . . . . . . . . . . . . 3 1.1 Brief overview of RSerPool . . . . . . . . . . . . . . . . 3
1.2 Role of the TCP Mapping Protocol . . . . . . . . . . . . . . . 3 1.2 Role of the TCP Mapping Protocol . . . . . . . . . . . . . 3
1.3 Consistency of Service . . . . . . . . . . . . . . . . . . . . 5 1.3 Consistency of Service . . . . . . . . . . . . . . . . . . 5
2. Conventions Used In This Document . . . . . . . . . . . . . . 6 2. Conventions Used In This Document . . . . . . . . . . . . . . 6
3. Packet Format . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Packet Format . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1 Basic Chunk Format . . . . . . . . . . . . . . . . . . . . . . 6 3.1 Basic Chunk Format . . . . . . . . . . . . . . . . . . . . 6
3.2 DATA Chunk . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3.2 DATA Chunk . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3 INIT Chunk . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.3 INIT Chunk . . . . . . . . . . . . . . . . . . . . . . . . 10
3.4 ACK Chunk . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3.4 ACK Chunk . . . . . . . . . . . . . . . . . . . . . . . . 13
3.5 HEARTBEAT Chunk . . . . . . . . . . . . . . . . . . . . . . . 14 3.5 HEARTBEAT Chunk . . . . . . . . . . . . . . . . . . . . . 14
3.6 HEARTBEAT ACK Chunk . . . . . . . . . . . . . . . . . . . . . 15 3.6 HEARTBEAT ACK Chunk . . . . . . . . . . . . . . . . . . . 15
4. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 16 4. Protocol Operations . . . . . . . . . . . . . . . . . . . . . 16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 17 5. Security Considerations . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
References . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 18 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . 19 Intellectual Property and Copyright Statements . . . . . . . . 19
1. Introduction 1. Introduction
This memo defines the shim protocol that maps the requirements of the This memo defines the shim protocol that maps the requirements of the
ASAP protocol [5] to the capabilities of the TCP protocol [7]. See ASAP protocol [5] to the capabilities of the TCP protocol [7]. See
[6] for details of these mapping requirements. [6] for details of these mapping requirements.
1.1 Brief overview of RSerPool 1.1 Brief overview of RSerPool
skipping to change at page 4, line 12 skipping to change at page 4, line 12
that are present in SCTP, but are lacking in TCP. Specifically, that are present in SCTP, but are lacking in TCP. Specifically,
these are: these are:
(1) Message Orientation. Messages must be framed within the TCP byte (1) Message Orientation. Messages must be framed within the TCP byte
stream to allow for undelivered message retrieval (see below), and stream to allow for undelivered message retrieval (see below), and
so that ASAP transport services can be consistent between SCTP and so that ASAP transport services can be consistent between SCTP and
TCP. TCP.
(2) Heartbeat Messages. Heartbeats are needed so that a failed (2) Heartbeat Messages. Heartbeats are needed so that a failed
connection can be detected in a timely manner, even if that connection can be detected in a timely manner, even if that
connection is idle. The "keepalive" mechanism provided in some TCP connection is idle. The "keepalive" mechanism provided in some
implementations (but not a standard feature of the protocol; see TCP implementations (but not a standard feature of the protocol;
RFC1122) is not sufficient for this purpose. see RFC1122) is not sufficient for this purpose.
(3) Retreival of Undelivered Messages. A PU can request that the ASAP (3) Retreival of Undelivered Messages. A PU can request that the
layer detects when the transport layer association/connection ASAP layer detects when the transport layer association/connection
between that PU and some PE has failed, and automatically failover between that PU and some PE has failed, and automatically failover
to a new PE. In this case, it is necessary for the ASAP layer to to a new PE. In this case, it is necessary for the ASAP layer to
determine which messages were not successfully delivered to the determine which messages were not successfully delivered to the
PE, retrieve them from the transport layer below, and resend them PE, retrieve them from the transport layer below, and resend them
to the new PE. SCTP provides the RETRIEVE_UNSENT primitive to the new PE. SCTP provides the RETRIEVE_UNSENT primitive
(Section 10.1, item (E) of RFC2960) to enable this retrieval. TCP (Section 10.1, item (E) of RFC2960) to enable this retrieval. TCP
has no such facility. has no such facility.
To provide this capability over TCP, the mapping protocol provides To provide this capability over TCP, the mapping protocol provides
another layer of acknowledgements on top of TCP; these acks are another layer of acknowledgements on top of TCP; these acks are
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resent to the new PE. resent to the new PE.
This feature is optional and is NOT required. However, an This feature is optional and is NOT required. However, an
appropriate error code must be returned to the upper layer if this appropriate error code must be returned to the upper layer if this
feature is requested, but is unavailable (not implemented). feature is requested, but is unavailable (not implemented).
(4) Other features present in SCTP. Two other features present in (4) Other features present in SCTP. Two other features present in
SCTP are simulated by the TCP mapping layer, namely the multiple SCTP are simulated by the TCP mapping layer, namely the multiple
streams feature and the protocol payload identifier field (PPID). streams feature and the protocol payload identifier field (PPID).
Strictly speaking these features are not necessary for RSerPool Strictly speaking these features are not necessary for RSerPool
operation. However, it is trivial to provide these features in the operation. However, it is trivial to provide these features in
TCP mapping layer, and providing them offers an important benefit, the TCP mapping layer, and providing them offers an important
without significantly increasing the complexity of the protocol or benefit, without significantly increasing the complexity of the
the on-the-wire overhead. This is discussed further in Section protocol or the on-the-wire overhead. This is discussed further
1.3 in Section 1.3
NOTE: PU-PE communication that is NOT mediated by the RSerPool NOTE: PU-PE communication that is NOT mediated by the RSerPool
framework is allowable when the application layer does not require framework is allowable when the application layer does not require
data channel services. In this case, no mapping for application data channel services. In this case, no mapping for application
layer data is used regardless of the transport protocol used as they layer data is used regardless of the transport protocol used as they
will be tranported over the appropriate application-defined tranport will be tranported over the appropriate application-defined tranport
protocol. protocol.
1.3 Consistency of Service 1.3 Consistency of Service
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Thus, for minimal extra cost, "consistency of service" is preserved Thus, for minimal extra cost, "consistency of service" is preserved
by including multiple streams and the PPID field in the TCP mapping. by including multiple streams and the PPID field in the TCP mapping.
It is RECOMMENDED that any future mappings of RSerPool to other It is RECOMMENDED that any future mappings of RSerPool to other
transport protocols SHOULD follow this model of providing transport protocols SHOULD follow this model of providing
"consistency of service" where possible. "consistency of service" where possible.
2. Conventions Used In This Document 2. Conventions Used In This Document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [2]. document are to be interpreted as described in RFC 2119 [1].
The terms "transmission sequence number" (TSN), "stream number", The terms "transmission sequence number" (TSN), "stream number",
"stream identifier", "stream sequence number", and "payload "stream identifier", "stream sequence number", and "payload
protocol-id(PPID)" are used in this document with meanings analogous protocol-id(PPID)" are used in this document with meanings analogous
to their meanings in RFC2960 [8]; it is assumed that the reader is to their meanings in RFC2960 [8]; it is assumed that the reader is
familiar with these terms as they appear in that document. familiar with these terms as they appear in that document.
Comparisons and arithmetic on TSNs and stream sequence numbers are Comparisons and arithmetic on TSNs and stream sequence numbers are
governed by the rules in Section 1.6 of RFC2960 [8]. governed by the rules in Section 1.6 of RFC2960 [8].
skipping to change at page 10, line 26 skipping to change at page 10, line 26
User Data: variable length User Data: variable length
This is the payload user data. The implementation MUST pad the This is the payload user data. The implementation MUST pad the
end of the data to a 4 byte boundary with all-zero bytes. Any end of the data to a 4 byte boundary with all-zero bytes. Any
padding MUST NOT be included in the length field. A sender MUST padding MUST NOT be included in the length field. A sender MUST
never add more than 3 bytes of padding. never add more than 3 bytes of padding.
3.3 INIT Chunk 3.3 INIT Chunk
The figure below illustrates the field format for the INIT chunk. The The figure below illustrates the field format for the INIT chunk.
INIT chunk is transmitted only once at the beginning of the TCP The INIT chunk is transmitted only once at the beginning of the TCP
connection. The purpose of the INIT chunk is to transmit flags connection. The purpose of the INIT chunk is to transmit flags
indicating which fields will be enabled/disabled in all subsequent indicating which fields will be enabled/disabled in all subsequent
data chunks over the lifetime of the TCP connection. data chunks over the lifetime of the TCP connection.
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 = 1 |reservd |P|S|T| Chunk Length = 4 | | Type = 1 |reservd |P|S|T| Chunk Length = 4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Chunk Type: 8 bits (unsigned integer) Chunk Type: 8 bits (unsigned integer)
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There are no known additional security considerations over what is There are no known additional security considerations over what is
already present for TCP. already present for TCP.
6. IANA Considerations 6. IANA Considerations
[Open Issue TBD: Will there be an enumeration of the various [Open Issue TBD: Will there be an enumeration of the various
transport layer mappings that must be registered with IANA?] transport layer mappings that must be registered with IANA?]
7. Acknowledgements 7. Acknowledgements
References 8 References
[1] Tuexen, M. and Q. Xie, "Architecture for Reliable Server
Pooling", draft-ietf-rserpool-arch-07 (work in progress),
October 2003.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] 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.
[3] Loughney, J., "Comparison of Protocols for Reliable Server [2] Loughney, J., "Comparison of Protocols for Reliable Server
Pooling", draft-ietf-rserpool-comp-07 (work in progress), Pooling", draft-ietf-rserpool-comp-07 (work in progress),
October 2003. October 2003.
[3] Tuexen, M., Xie, Q., Stewart, R., Shore, M. and J. Loughney,
"Architecture for Reliable Server Pooling",
draft-ietf-rserpool-arch-07 (work in progress), October 2003.
[4] Xie, Q., Stewart, R. and M. Stillman, "Enpoint Name Resolution [4] Xie, Q., Stewart, R. and M. Stillman, "Enpoint Name Resolution
Protocol (ENRP)", draft-ietf-rserpool-enrp-07 (work in Protocol (ENRP)", draft-ietf-rserpool-enrp-08 (work in
progress), October 2003. progress), June 2004.
[5] Stewart, R., Xie, Q., Stillman, M. and M. Tuexen, "Aggregate [5] Stewart, R., Xie, Q., Stillman, M. and M. Tuexen, "Aggregate
Server Access Protocol (ASAP)", draft-ietf-rserpool-asap-08 Server Access Protocol (ASAP)", draft-ietf-rserpool-asap-09
(work in progress), October 2003. (work in progress), June 2004.
[6] Conrad, P. and P. Lei, "Services Provided By Reliable Server [6] Conrad, P. and P. Lei, "Services Provided By Reliable Server
Pooling", draft-ietf-rserpool-service-00 (work in progress), Pooling", draft-ietf-rserpool-service-01 (work in progress),
December 2003. June 2004.
[7] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, [7] Postel, J., "Transmission Control Protocol", STD 7, RFC 793,
September 1981. September 1981.
[8] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer, [8] Stewart, R., Xie, Q., Morneault, K., Sharp, C., Schwarzbauer,
H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson, H., Taylor, T., Rytina, I., Kalla, M., Zhang, L. and V. Paxson,
"Stream Control Transmission Protocol", RFC 2960, October 2000. "Stream Control Transmission Protocol", RFC 2960, October 2000.
Authors' Addresses Authors' Addresses
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Phone: +1 302 831 8622 Phone: +1 302 831 8622
EMail: conrad@acm.org EMail: conrad@acm.org
URI: http://udel.edu/~pconrad URI: http://udel.edu/~pconrad
Peter Lei Peter Lei
Cisco Systems, Inc. Cisco Systems, Inc.
8735 W Higgins Rd, Suite 300 8735 W Higgins Rd, Suite 300
Chicago, IL 60631 Chicago, IL 60631
US US
Phone: +1 847 870 7201 Phone: +1 773 695 8201
EMail: peterlei@cisco.com EMail: peterlei@cisco.com
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