Network Working Group R. R. Stewart
INTERNET-DRAFT Cisco Systems Inc.
Q. Xie
Motorola
M. Stillman
Nokia
expires in six months March 1, 2002
Aggregate Server Access Protocol (ASAP)
<draft-ietf-rserpool-asap-02.txt>
Status of This Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of [RFC2026]. 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.
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
Abstract
Aggregate Server Access Protocol (ASAP) in conjunction with the
Endpoint Name Resolution Protocol (ENRP) [ENRP] provides a high
availability data transfer mechanism over IP networks. ASAP uses a
name-based addressing model which isolates a logical communication
endpoint from its IP address(es), thus effectively eliminating the
binding between the communication endpoint and its physical IP
address(es) which normally constitutes a single point of failure.
In addition, ASAP defines each logical communication destination
as a pool, providing full transparent support for server-pooling
and load sharing. It also allows dynamic system scalability -
members of a server pool can be added or removed at any time
without interrupting the service.
ASAP is designed to take full advantage of the network level
redundancy provided by the Stream Transmission Control Protocol
(SCTP) [SCTP].
The high availability server pooling is gained by combining two
protocols, namely ASAP and ENRP, in which ASAP provides the user
interface for name to address translation, load sharing
management, and fault management while ENRP defines the high
availability name translation service.
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Table Of Contents
1. Introduction...............................................3
1.1 Definitions............................................3
1.2 Organization of this document..........................5
1.3 Scope of ASAP..........................................5
1.3.1 Extent of the Namespace..........................5
2. Conventions................................................5
3. Message Definitions........................................5
3.1 ASAP Parameter Formats.................................6
3.1.1 IPv4 Address Parameter...........................7
3.1.2 IPv6 Address Parameter ..........................7
3.1.3 Pool Element Parameter...........................7
3.1.4 Pool Handle Parameter............................8
3.1.5 Authorization Parameter..........................8
3.2 ASAP Message Formats...................................9
3.2.1 REGISTRATION message.............................10
3.2.2 DEREGISTRATION message...........................10
3.2.3 REGISTRATION_RESPONSE message....................11
3.2.4 NAME_RESOLUTION message..........................11
3.2.5 NAME_RESOLUTION_RESPONSE message.................12
3.2.6 NAME_UNKNOWN message.............................12
3.2.7 ENDPOINT_KEEP_ALIVE message......................12
3.2.8 ENDPOINT_UNREACHABLE message ....................12
3.2.9 SERVER_HUNT message .............................13
3.2.10 SERVER_HUNT_RESPONSE message....................13
4. The ASAP Interfaces........................................13
4.1 Registration.Request Primitive.........................13
4.2 Deregistration.Request Primitive.......................14
4.3 Cache.Populate.Request Primitive.......................14
4.4 Cache.Purge.Request Primitive..........................14
4.5 Data.Send.Request Primitive............................14
4.5.1 Sending to a Pool Handle.........................15
4.5.2 Pool Element Selection...........................16
4.5.2.1 Round Robin Policy.......................16
4.5.2.2 Least Used Policy........................17
4.5.2.3 Least Used with Degradation Policy.......17
4.5.2.4 Weighted Round Robin Policy..............17
4.5.3 Sending to a Pool Element Handle.................17
4.5.4 Send by Transport Address........................18
4.5.5 Message Delivery Options........................18
4.6 Data.Received Notification.............................19
4.7 Error.Report Notification..............................20
4.8 Examples...............................................20
4.8.1 Send to a New Pool Handle........................20
4.8.2 Send to a Cached Pool Handle.....................21
4.9 Handle ASAP to ENRP Communication Failures.............22
4.9.1 SCTP Send Failure................................22
4.9.2 T1-ENRPrequest Timer Expiration..................22
4.9.3 Handle ENDPOINT_KEEP_ALIVE Messages..............22
4.9.4 Home ENRP Server Hunt............................23
5. Variables, Timers, and Constants...........................23
5.1 Timers.................................................23
5.2 Thresholds.............................................23
6. Security Considerations....................................24
7. References.................................................24
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8. Acknowledgements...........................................24
9. Authors' Addresses.........................................24
1. Introduction
Aggregate Server Access Protocol (ASAP) in conjunction with ENRP
[ENRP] provides a high availability data transfer mechanism over IP
networks. ASAP uses a name-based addressing model which isolates a
logical communication endpoint from its IP address(es), thus
effectively eliminating the binding between the communication
endpoint and its physical IP address(es) which normally constitutes
a single point of failure.
When multiple receiver instances exist under the same name, a.k.a, a
server pool, ASAP will select one Pool Element (PE), based on the
current load sharing policy indicated by the server pool, and
deliver the message to the selected PE.
While delivering the message, ASAP monitors the reachability of the
selected PE. If it is found unreachable, before notifying the sender
of the failure, ASAP can automatically select another PE (if one
exists) under that pool and attempt to deliver the message to that
PE. In other words, ASAP is capable of transparent fail-over amongst
instances of a server pool.
ASAP uses the Endpoint Name Resolution Protocol (ENRP) to provide a high
availability name space. ASAP is responsible for the abstraction of
the underlying transport technologies, load distribution management,
fault management, as well as the presentation to the upper layer
(i.e., the ASAP user) a unified primitive interface.
When SCTP [RFC2960] is used as the transport layer protocol, ASAP can
seamlessly incorporate the link-layer redundancy provided by the
SCTP.
This document defines the ASAP portion of the high availability server
pool. ASAP depends on the services of a high availiablity name space
a.k.a. ENRP.
1.1 Definitions
This document uses the following terms:
ASAP User:
Either a PE or PU that uses ASAP.
Operation scope:
The part of the network visible to Pool Users by a specific
instance of the reliable server pooling protocols.
Server pool (or Pool):
A collection of servers providing the same application
functionality.
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Pool handle (or pool name):
A logical pointer to a pool. Each server pool will be
identifiable in the operation scope of the system by a unique
pool handle or "name".
Pool Element (PE):
A server entity having registered to a pool.
Pool User (PU):
A server Pool User.
Pool Element handle (PE handle):
A logical pointer to a particular Pool Element in a pool,
ENRP server:
A server program running on a host that manages the
name space collectively with its peer ENRP servers and
replies to the service requests from any Pool User or
Pool Element.
Home ENRP server:
The ENRP server to which a Pool Element currently uses. A PU
or PE normally chooses the ENRP server on their local host as
the home ENRP server (if one exists). A PU or PE should only
have one home ENRP server at any given time.
ENRP client channel:
The communication channel through which an ASAP User (either a
PE or PU) requests ENRP namespace service. The client channel
is usually defined by the transport address of the
home server and a well known port number.
ENRP server channel:
Defined by a well known multicast IP address and a well
known port number, or a well known list of transport
addresses for a group of ENRP servers spanning an
operational scope. All ENRP servers in an operation scope
can communicate with one another through this channel.
ENRP name domain:
Defined by the combination of the ENRP client channel and the
ENRP server channel in the operation scope.
Network Byte Order:
Most significant byte first, a.k.a Big Endian.
Transport address:
A Transport Address is traditionally defined by Network Layer
address, Transport Layer protocol and Transport Layer port
number. In the case of SCTP running over IP, a transport
address is defined by the combination of an IP address and an
SCTP port number (where SCTP is the Transport protocol).
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1.2 Organization of this document
Chapter 3 details ASAP message formats. In Chapter 4 we give the
details of the ASAP interface, focusing on the communication
primitives between the applications above ASAP and ASAP itself, and
the communications primitives between ASAP and SCTP (or other
transport layer). Also included in this discussion is relevant
timers and configurable parameters as appropriate. Chapter 5
provides settable protocol values.
1.3 Scope of ASAP
The requirements for high availability and scalability do not imply
requirements on shared state and data. ASAP does not provide
transaction failover. If a host or application fails during
processing of a transaction this transaction may be lost. Some
services may provide a way to handle the failure, but this is not
guaranteed. ASAP MAY provide hooks to assist an application in
building a mechanism to share state but ASAP in itself will NOT
share any state.
1.3.1 Extent of the Namespace
The scope of the ASAP/ENRP is NOT Internet wide. The namespace is
neither hierarchical nor arbitrarily large like DNS. We propose a
flat peer-to-peer model. Pools of servers will exist in different
administrative domains. For example, suppose we want to use
ASAP/ENRP. First, the PU may use DNS to contact an ENRP server.
Suppose a PU in North America wishes to contact the server pool in
Japan instead of North America. The PU would use DNS to get the IP
address of the Japanese server pool domain, that is, the address of
an ENRP server(s) in Japan. From there the PU would query the
ENRP server and then directly contact the PE(s) of interest.
2. Conventions
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, NOT RECOMMENDED, MAY, and OPTIONAL, when
they appear in this document, are to be interpreted as described in
[RFC2119].
3. Message Definitions
All messages as well as their fields described below shall be in
Network Byte Order during transmission. For fields with a length
bigger than 4 octets, a number in a pair of parentheses may follow
the filed name to indicate the length of the field in number of
octets.
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3.1 ASAP Parameter Formats
ASAP parameters are defined in a Type-length-value (TLV) format as
shown below.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Parameter Type | Parameter Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: Parameter Value :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Parameter Type: 16 bits (unsigned integer)
The Type field is a 16 bit identifier of the type of parameter.
It takes a value of 0 to 65534.
The value of 65535 is reserved for IETF-defined extensions. Values
other than those defined in specific SCTP chunk description are
reserved for use by IETF.
Parameter Length: 16 bits (unsigned integer)
The Parameter Length field contains the size of the parameter in
bytes, including the Parameter Type, Parameter Length, and
Parameter Value fields. Thus, a parameter with a zero-length
Parameter Value field would have a Length field of 4. The
Parameter Length does not include any padding bytes.
Parameter Value: variable-length.
The Parameter Value field contains the actual information to be
transferred in the parameter.
The total length of a parameter (including Type, Parameter Length and
Value fields) MUST be a multiple of 4 bytes. If the length of the
parameter is not a multiple of 4 bytes, the sender pads the Parameter
at the end (i.e., after the Parameter Value field) with all zero
bytes. The length of the padding is not included in the parameter
length field. A sender SHOULD NOT pad with more than 3 bytes. The
receiver MUST ignore the padding bytes.
The Parameter Types are encoded such that the highest-order two bits
specify the action that must be taken if the processing endpoint does
not recognize the Parameter Type.
00 - Stop processing this ASAP message and discard it, do not process
any further parameters within it.
01 - Stop processing this ASAP message and discard it, do not process
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any further parameters within it, and report the unrecognized
parameter in an 'Unrecognized Parameter Type' error.
10 - Skip this parameter and continue processing.
11 - Skip this parameter and continue processing but report the
unrecognized parameter in an 'Unrecognized Parameter Type'
error.
In the following sections, we define the common parameter formats
used in ASAP.
3.1.1 IPv4 Address Parameter
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x1 | Length = 8 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv4 Address: 32 bits (unsigned integer)
Contains an IPv4 address of the sending endpoint. It is binary
encoded.
3.1.2 IPv6 Address Parameter
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x2 | Length = 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IPv6 Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 Address: 128 bit (unsigned integer)
Contains an IPv6 address of the sending endpoint. It is binary
encoded.
3.1.3 Pool Element Parameter
This parameter is used in multiple ASAP message to represent an ASAP
endpoint (i.e., a PE in a pool) and the associated information, such
as its transport address(es), load control, and other operational
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status information of the PE.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x3 | Length=variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SCTP Port | Number of IP addrs=k |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: IP addr param #0 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: IP addr param #1 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: ..... :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: IP addr param #k :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Load Policy Type | Policy Value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Registration Life |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Each of the IP address parameters in a PE parameter can be either
an IPv4 or IPv6 address parameter.
3.1.4 Pool Handle Parameter
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x4 | Length=variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: Pool Handle :
: :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This parameter holds a pool handle that is a NULL terminated ASCII
string.
3.1.5 Authorization Parameter
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x5 | Length=variable |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: Authorization Signature :
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: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This parameter is used to hold an authorization signature. The
signature is signed over the entire ASAP message and uses a
preconfigured public/private key pair. The receiver of a message
which includes this parameter can validate the message is
from the sender by comparing the signature to one generated
using the peers public key.
3.2 ASAP Message Formats
The figure below illustrates the common format for all ASAP
messages. Each message is formatted with a Message
Type field, a message-specific Flag field, a Message Length field,
and a Value field.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type | Msg Flags | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: Message Value :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Message Type: 8 bits (unsigned integer)
This field identifies the type of information contained in the
Message Value field. It takes a value from 0 to 254. The value
of 255 is reserved for future use as an extension field.
Message Types are encoded such that the highest-order two bits
specify the action that must be taken if the message receiver
does not recognize the Message Type.
00 - Stop processing this message and discard it.
01 - Stop processing this message and discard it, and report the
unrecognized message in an 'Unrecognized Parameter Type'
error.
10 - reserved.
11 - reserved.
Message Flags: 8 bits
The usage of these bits depends on the message type as given by
the Message Type. Unless otherwise specified, they are set to
zero on transmit and are ignored on receipt.
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Message Length: 16 bits (unsigned integer)
This value represents the size of the message in bytes including
the Message Type, Message Flags, Message Length, and Message
Value fields. Therefore, if the Message Value field is
zero-length, the Length field will be set to 4. The Message
Length field does not count any padding.
Message Value: variable length
The Message Value field contains the actual information to be
transferred in the message. The usage and format of this field
is dependent on the Message Type.
The total length of a message (including Type, Length and Value
fields) MUST be a multiple of 4 bytes. If the length of the
message is not a multiple of 4 bytes, the sender MUST pad the
message with all zero bytes and this padding is not included in the
message length field. The sender should never pad with more than 3
bytes. The receiver MUST ignore the padding bytes.
3.2.1 REGISTRATION message
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x1 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The pool handle parameter field specifies the name to be registered.
The PE Parameter field shall be filled in by the registrant
endpoint to declare its transport addresses, server pooling
policy and value, and other operation preferences.
3.2.2 DEREGISTRATION message
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type = 0x2 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter :
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The PE sending the DEREGISTRATION shall fill in the pool handle
and the PE Parameter in order to allow the ENRP server to verify
the identity of the endpoint.
3.2.3 REGISTRATION_RESPONSE message
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 = 0x3 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Action code | Result code | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Action: (8 bits)
The message that this results code is in response to:
0x0 -- registration
0x1 -- de-registration
Result code: (8 bits)
0x0 -- request granted
0x1 -- request denied, unspecifed
0x2 -- request denied, authorization failure
0x3 -- request denied, invalid values
Reserved: (16 bits)
Ignored by the receiver and set to 0 by the sender.
3.2.4 NAME_RESOLUTION message
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 = 0x4 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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3.2.5 NAME_RESOLUTION_RESPONSE message
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 = 0x5 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter 1 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter N :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.6 NAME_UNKNOWN message
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 = 0x6 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.7 ENDPOINT_KEEP_ALIVE message
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 = 0x8 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.8 ENDPOINT_UNREACHABLE message
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 = 0x9 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter :
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.9 SERVER_HUNT message
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 = 0xa |0|0|0|0|0|0|0|0| Message Length :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
3.2.10 SERVER_HUNT_RESPONSE message
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 = 0xb |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Authorization Parameter (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
4. The ASAP Interfaces
This chapter will focus primarily on the primitives and
notifications that form the interface between the ASAP-user and the
ASAP and that between ASAP and its lower layer transport protocol
(e.g., SCTP).
Appropriate timers and recovery actions for failure detection and
management are also discussed.
An ASAP User passes primitives to the ASAP sub-layer to
request certain actions. Upon the completion of those actions or
upon the detection of certain events, the ASAP will notify the
ASAP user.
4.1 Registration.Request Primitive
Format: registration.request(poolHandle)
where the poolHandle parameter contains a NULL terminated ASCII
string of fixed length.
The ASAP user invokes this primitive to add itself to the
namespace, thus becoming a Pool Element of a pool. The ASAP user
must register itself with the ENRP server by using this primitive
before other ASAP users using the namespace can send message(s) to
this ASAP user by pool handle or by PE handle (see Sections 4.5.1
and 4.5.2).
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In response to the registration primitive, the ASAP layer will send
a REGISTRATION message to the home ENRP server (See section 3.2.1),
and start a T2-registration timer.
If the T2-registration timer expires before receiving a
REGISTRATION_RESPONSE message, or a SEND.FAILURE notification is
received from the SCTP layer, the ASAP layer shall start the Server
Hunt procedure (see Section 4.9.4) in an attempt to get service
from a different ENRP server.
4.2 Deregistration.Request Primitive
Format: deregistration.request(poolHandle)
The ASAP PE invokes this primitive to remove itself from the
Server Pool. This should be used as a part of the graceful shutdown
process by the application.
A DEREGISTRATION message will be sent by ASAP layer to the home ENRP
server (see Section 3.2.2).
4.3 Cache.Populate.Request Primitive
Format: cache.populate.request(destinationAddress, typeOfAddress)
If the address type is a Pool handle and a local name
translation cache exists, the ASAP layer should initiate a mapping
information query by sending a NAME.RESOLUTION message on the Pool
handle and update it local cache when the response comes back from
the ENRP server.
The destinationAddress field contains the address for which the
cache needs to be populated. The typeOfAddress indicates the address
type. Allowable types are Pool handle and Pool Element handle. In
the case of a Pool Element handle, the Pool handle is extracted from
the Pool Element handle and used to form a NAME.RESOLUTION
message (see Section 3.5).
4.4 Cache.Purge.Request Primitive
Format: cache.purge.request(destinationAddress, typeOfAddress)
If the address type is a Pool handle and local name
translation cache exists, the ASAP layer should remove the mapping
information on the Pool handle from its local cache.
4.5 Data.Send.Request Primitive
Format: data.send.request(destinationAddress, typeOfAddress,
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message, sizeOfMessage, Options);
This primitive requests ASAP to send a message to some specified
Pool or Pool Element within the current Operational scope.
Depending on the address type used for the send request, the
sender's ASAP layer may perform address translation and Pool Element
selection before sending the message out.
The data.send.request primitive can take different forms of
address types as described in the following sections.
4.5.1 Sending to a Pool Handle
In this case the destinationAddress and typeOfAddress together
indicates a pool handle.
This is the simplest form of send.data.request primitive. By
default, this directs ASAP to send the message to one of the Pool
Elements in the specified pool.
Before sending the message out to the pool, the sender's ASAP layer
MUST first perform a pool handle to address translation. It may
also need to perform Pool Element selection if multiple Pool
Elements exist in the pool.
If the sender's ASAP implementation does not support a local cache
of the mapping information or if it does not have the mapping
information on the pool in its local cache, it will transmit a
NAME.RESOLUTION message to the current home ENRP server, and
MUST hold the outbound message in queue while awaiting the response
from the ENRP server (any further send request to this pool before
the ENRP server responds SHOULD also be queued).
Once the necessary mapping information arrives from the ENRP server,
the sender's ASAP will:
A) map the pool handle into a list of transport addresses of the
destination PE(s),
B) if multiple PEs exist in the pool, ASAP will choose
one of them and transmit the message to it. In that case, the
choice of the PE is made by ASAP layer of the sender based on
the server pooling policy as discussed in section 4.5.2.
C) if no transport association exists towards the destination PE,
ASAP will establish a new transport association,
NOTE: if the underlying SCTP implementation supports implicit
association setup, this step is not needed (see [SCTPAPI]).
D) send out the queued message(s) to the SCTP association using the
SEND primitive (see [RFC2960]), and,
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E) if the local cache is implemented, append/update the local cache
with the mapping information received in the ENRP server's
response. Also, record the local SCTP association id, if a new
association was created.
For more on the ENRP server request procedures see [ENRP].
Optionally, the ASAP layer of the sender may return a Pool Element
handle of the selected PE to the application after sending the
message. This PE handle can then be used for future transmissions to
that same PE (see Section 4.5.3).
Section 4.5.5 defines the fail-over procedures for cases where the
selected PE is found unreachable.
4.5.2 Pool Element Selection
Each time an ASAP user sends a message to a pool that contains
more than one PE, the sender's ASAP layer must select one of
the PEs in the pool as the receiver of the current
message. The selection is done according to the current server
pooling policy of the pool to which the message is sent.
Note, no selection is needed if the ASAP_SEND_TOALL option is set
(see Section 4.5.5).
When joining a pool, along with its registration each
PE specifies its preferred server pooling policy for receiving
messages sent to this pool. But only the server pooling
policy specified by the first PE joining the pool will
become the current server pooling policy of the group.
Moreover, together with the server pooling policy, each PE can
also specify a Policy Value for itself at the registration time. The
meaning of the policy value depends on the current server pooling
policy of the group. A PE can also change its policy value
whenever it desires, by re-registering itself with the namespace
with a new policy value. Re-registration shall be done by simply
sending another REGISTRATION to its home ENRP server.
Note, if this first PE removes itself from the pool
(e.g., by de-registration from the name space) and the remaining
PEs have specified conflicting server pooling policies at
their corresponding registrations, it is implementation specific to
determine the new current server pooling policy.
Four basic server pooling policies are defined in ASAP, namely the
Round Robin, Least Used, Least Used Degrading and Weighted Round
Robin. The following sections describes each of these policies.
4.5.2.1 Round Robin Policy
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When a ASAP endpoint sends messages by Pool Handle and Round-Robin
is the current policy of that Pool, the ASAP layer of the sender
will select the receiver for each outbound message by round-Robining
through all the registered PEs in that Pool, in an attempt to
achieve an even distribution of outbound messages. Note that in a
large server pool, the ENRP server may NOT send back all PEs
to the ASAP client. In this case the client or PU will be
performing a round robin policy on a subset of the entire Pool.
4.5.2.2 Least Used Policy
When the destination Pool is under the Least Used server pooling
policy, the ASAP layer of the message sender will select the PE that
has the lowest policy value in the group as the receiver of the
current message. If more than one PE from the group share the same
lowest policy value, the selection will be done round Robin amongst
those PEs.
It is important to note that this policy means that the same PE will
be always selected as the message receiver by the sender until the
load control information of the pool is updated and changed in the
local cache of the sender (see section ?).
4.5.2.3 Least Used with Degradation Policy
This policy is the same as the Least Used policy with the exception
that, each time the PE with the lowest policy value is selected from
the Pool as the receiver of the current message, its policy value is
incremented, and thus it may no longer be the lowest value in the
Pool.
This provides a degradation of the policy towards round Robin policy
over time. As with the Least Used policy, every local cache update
at the sender will bring the policy back to Least Used with
Degradation.
4.5.2.4 Weighted Round Robin Policy
[TBD]
4.5.3 Sending to a Pool Element Handle
In this case the destinationAddress and typeOfAddress together
indicate an ASAP Pool Element handle.
This requests the ASAP layer to deliver the message to the PE
identified by the Pool Element handle.
The Pool Element handle should contain the poolHandle and a
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destination transport address of the destination PE or the
poolHandle and the SCTP 'association id'.
The ASAP layer shall use the transport address to identify the
SCTP association (or to setup a new one if necessary) and then
invoke the SCTP SEND primitive to send the message to the PE.
In addition, if a local translation cache is supported the
endpoint will:
A) send out the message to the transport address (or association
id) designated by the PE handle.
B) determine if the pool handle is in the local cache.
If it is NOT, the endpoint will:
i) ask the home ENRP server for name resolution on pool handle
by sending a NAME.RESOLUTION message, and
ii) use the response to update the local cache.
If the pool handle is in the cache, the endpoint will only
update the pool handle if the cache is stale. A stale cache is
indicated by it being older than the protocol parameter
'stale.cache.value'.
Section 4.5.5? defines the fail-over procedures for cases where
the PE pointed to by the Pool Element handle is found unreachable.
Optionally, the ASAP layer may return the actual Pool Elment handle
to which the message was sent (this may be different from the Pool
Element handle specified when the primitive is invoked, due to the
possibility of automatic fail-over).
4.5.4 Send by Transport Address
In this case the destinationAddress and typeOfAddress together
indicate an SCTP transport address.
This directs the sender's ASAP layer to send the message out to the
specified transport address.
No endpoint fail-over is support when this form of send request is
used. This form of send request effectively by-passes the ASAP
layer.
4.5.5 Message Delivery Options
The Options parameter passed in the various forms of the above
data.send.request primitive gives directions to the sender's ASAP
layer on special handling of the message delivery.
The value of the Options parameter is generated by bit-wise
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"OR"ing of the following pre-defined constants:
ASAP_USE_DEFAULT: 0x0000
Use default setting.
ASAP_SEND_FAILOVER: 0x0001
Enables PE fail-over on this message. In case where the first
selected PE or the PE pointed to by the PE handle is found
unreachable, this option allows the sender's ASAP layer to
re-select an alternate PE from the same pool if one exists, and
silently re-send the message to this newly selected endpoint.
Endpoint unreachable is normally indicated by the SCTP
COMMUNICATION.LOST or SEND.FAILURE notification.
ASAP_SEND_NO_FAILOVER: 0x0002
This option prohibits the sender's ASAP layer from re-sending the
message to any alternate PE in case that the first selected PE or
the PE pointed to by the PE handle is found unreachable. Instead,
the sender's ASAP layer shall notify its upper layer about the
unreachability with an Error.Report and return any unsent data.
ASAP_SEND_TO_LAST: 0x0004
This option requests the sender's ASAP layer to send the message to
the same PE in the pool that the previous message destined to this
pool was sent to.
ASAP_SEND_TO_ALL: 0x0008
When sending by Pool Handle, this option directs the sender's ASAP
layer to send a copy of the message to all the PEs, except for the
sender itself if the sender is a PE, in that pool.
ASAP_SEND_TO_SELF: 0x0010.
This option only applies in combination with ASAP_SEND_TO_ALL option.
It permits the sender's ASAP layer also deliver a copy of the
message to itself if the sender is a PE of the pool (i.e., loopback).
ASAP_SCTP_UNORDER: 0x1000
This option instructs the SCTP transport layer to send the current
message using un-ordered delivery.
4.6 Data.Received Notification
Format: data.received(messageReceived, sizeOfMessage, senderAddress,
typeOfAddress)
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When a new user message is received, the ASAP layer of the receiver
uses this notification to pass the message to its upper layer.
Along with the message being passed, the ASAP layer of the receiver
should also indicate to its upper layer the message sender's
address. The sender's address can be in the form of either an SCTP
association id, or a ASAP Pool Element handle.
A) If the name translation local cache is implemented at the
receiver's ASAP layer, a reverse mapping from the sender's IP
address to the pool handle should be performed and if the mapping is
successful, the sender's ASAP Pool Element handle should be
constructed and passed in the senderAddress field.
B) If there is no local cache or the reverse mapping is not
successful, the SCTP association id should be passed in the
senderAddress field.
4.7 Error.Report Notification
Format: error.report(destinationAddress, typeOfAddress,
failedMessage, sizeOfMessage)
An error.report should be generated to notify the ASAP user about
failed message delivery as well as other abnormalities (see Section
? for details).
The destinationAddress and typeOfAddress together indicates to whom
the message was originally sent. The address type can be either a
ASAP Pool Element handle, association id, or a transport address.
The original message (or the first portion of it if the message is
too big) and its size should be passed in the failedMessage and
sizeOfMessage fields, respectively.
4.8 Examples
4.8.1 Send to a New Pool
This example shows the event sequence when a Pool User sends the
message "hello" to a pool which is not in the local
translation cache (assuming local caching is supported).
ENRP Server PU new-name:PEx
| | |
| +---+ |
| | 1 | |
| 2. NAME_RESOLUTION +---+ |
|<-------------------------------| |
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| +---+ |
| | 3 | |
| 4. NAME_RESOLUTION_REPONSE +---+ |
|------------------------------->| |
| +---+ |
| | 5 | |
| +---+ 6. "hello1" |
| |---------------->|
| | |
1) The user at PU invokes:
data.send.request("new-name", name-type, "hello1", 6, 0);
The ASAP layer, in response, looks up the pool "new-name" in its
local cache but fails to find it.
2) The ASAP layer of PU queues the message, and sends a
NAME_RESOLUTION request to the ENRP server asking for all
information about pool "new-name".
3) A T1-ENRPrequest timer is started while the ASAP layer is waiting
for the response from the ENRP server.
4) The ENRP Server responds to the query with a
NAME_RESOLUTION_REPONSE message that contains all the information
about pool "new-name".
5) ASAP at PU cancels the T1-ENRPrequest timer and populate its
local cache with information on pool "new-name".
6) Based on the server pooling policy of pool "new-name", ASAP at
PU selects the destination PE (PEx), sets up, if necessary, an
SCTP association towards PEx (explicitly or implicitly), and
send out the queued "hello1" user message.
4.8.2 Send to a Cached Pool Handle
This shows the event sequence when the ASAP user PU sends
another message to the pool "new-name" after what happened in
Section 4.8.1.
ENRP Server PU new-name:PEx
| | |
| +---+ |
| | 1 | |
| +---+ 2. "hello2" |
| |---------------->|
| | |
1) The user at PU invokes:
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data.send.request("new-name", name-type, "hello2", 6, 0);
The ASAP layer, in response, looks up the pool "new-name" in its
local cache and find the mapping information.
2) Based on the server pooling policy of "new-name", ASAP at PU
selects the PE (assume EPx is selected again), and sends out
"hello2" message (assume the SCTP association is already set
up).
4.9 Handle ASAP to ENRP Communication Failures
Three types of failure may occur when the ASAP layer at an endpoint
tries to communicate with the ENRP server:
A) SCTP send failure
B) T1-ENRPrequest timer expiration
C) Registration failure
Registration failure is discussed in section ?.
4.9.1 SCTP Send Failure
This indicates that the SCTP layer failed to deliver a message sent
to the ENRP server. In other words, the ENRP server is currently
unreachable.
In such a case, the ASAP layer should not re-send the failed
message. Instead, it should discard the failed message and start the
ENRP server hunt procedure as described in Section ?.
4.9.2 T1-ENRPrequest Timer Expiration
When a T1-ENRPrequest timer expires, the ASAP should re-send the
original request to the ENRP server and re-start the T1-ENRPrequest
timer. In parallel, a SERVER_HUNT message should be issued per
Section ?.
This should be repeated up to 'max-request-retransmit' times. After
that, an Error.Report notification should be generated to inform the
ASAP user and the ENRP request message associated with the timer
should be discarded.
4.9.3 Handle ENDPOINT_KEEP_ALIVE Messages
At times, an ASAP endpoint may receive ENDPOINT_KEEP_ALIVE messages
(see Section 3.2.7?) from the ENRP server. This message requires
no response and should be silently discarded by the ASAP layer.
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4.9.4 Home ENRP Server Hunt
At its startup, or when it fails to send to (i.e., timed-out on a
service request) with its current home ENRP server, a PE or PU shall
initiate the following home ENRP server hunt procedure to find a
new home server.
The PE or PU shall multicast a SERVER_HUNT message over the ENRP
client channel, and shall repeat sending this message every
<TIMEOUT-SERVER-HUNT> seconds until a SERVER_HUNT_RESPONSE message
is received from an ENRP server.
Then the PE or PU shall pick one of the ENRP servers that have
responded as its new home ENRP server, and send all its subsequent
the namespace service requests to this new home ENRP server.
Upon the reception of the SERVER_HUNT message, an ENRP server shall
always reply to the PE with a SERVER_HUNT_RESPONSE message.
5. Variables, Timers, and Constants
The following is a summary of the variables, timers, and pre-set
protocol constants used in ASAP.
5.1 Timers
T1-ENRPrequest - A timer started when a request is sent by ASAP to
the ENRP server (providing application information is
queued). Normally set to 15 seconds.
T2-registration - A timer started when sending a registration
request to the home ENRP server, normally set to 30 seconds.
T3-registration-reattempt - If the registration cycle does not
complete, this timer is begun to restart the registration
process. Normal value for this timer is 10 minutes.
T4-reregistration - This timer is started after successful
registration into the ASAP name space and is used to cause a
re-registration at a periodic interval. This timer is normally set
to 10 minutes.
5.2 Thresholds
Timeout-registration - pre-set threshold; how long an PE
will wait for the REGISTRATION_RESPONSE from its home ENRP server.
Timeout-server-hunt - pre-set threshold; how long a PE will
wait for the REGISTRATION_RESPONSE from its home ENRP server.
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num-of-serverhunts - The current count of server hunt messages that
have been transmitted.
registration-count - The current count of attempted registrations.
max-reg-attempt - The maximum number of registration attempts to be
made before a server hunt is issued.
max-request-retransmit - The maximum number of attempts to be made
when requesting information from the local ENRP server before a
server hunt is issued.
6. Security Considerations
Due to varying requirements and multiple use cases of Rserpool, we
point out two basic security protocols, IPsec and TLS. We
specifically do not discuss whether one security protocol would be
preferred over the other. This choice will be made by designers
and network architects based on system requirements.
For networks that demand IPsec security, implementations MUST
support [SCTPIPSEC] which describes IPsec-SCTP. IPsec is two
layers below RSerPool. Therefore, if IPsec is used for securing
Rserpool, no changes or special considerations need to be made to
Rserpool to secure the protocol.
For networks that cannot or do not wish to use IPsec and prefer
instead TLS, implementations MUST support TLS with SCTP as
described in [SCTPTLS] or TLS over TCP as described in [RFC2246].
When using TLS/SCTP we must ensure that RSerPool does not use any
features of SCTP that are not available to an TLS/SCTP user. This
is not a difficult technical problem, but simply a
requirement. When describing an API of the RSerPool lower layer we
have also to take into account the differences between TLS and
SCTP. This is also not difficult, but it is in contrast to the
IPsec solution which is transparently layered below Rserpool.
Support for security is required for the ENRP server and the PEs.
Security support for the Rserpool end user is optional. Note that
the end user implementation contains a piece of the Rserpool
protocol -- namely ASAP -- whereby the pool handle is passed for
name resolution to the ENRP server and IP address(es) are
returned.
The argument for optional end user security is as follows: If the
user doesn't require security protection for example, against
eavesdropping for the request for pool handle resolution and
response, then they are free to make that choice. However, if the
end user does require security, they are guaranteed to get it due
to the requirement for security support for the ENRP server. It is
also possible for the ENRP server to reject an unsecured request
from the user due to its security policy in the case that it
requires enforcement of strong security. But this will be
determined by the security requirements of the individual network
design.
7. References
[RFC2026] Bradner, S., "The Internet Standards Process --
Revision 3", BCP 9, RFC 2026, October 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2960] R. Stewart, Q. Xie, K. Morneault, C. Sharp,
H. Schwarzbauer, T. Taylor, I. Rytina, M. Kalla, L. Zhang,
and, V. Paxson, "Stream Control Transmission Protocol," RFC
2960, October 2000.
[ENRP] Q. Xie, R. R. Stewart "Endpoint Name Resolution Protocol",
draft-ietf-rserpool-enrp-02.txt, work in progress.
[SCTPAPI] R. R. Stewart, Q. Xie, L Yarroll, J. Wood, K. Poon,
K. Fujita "Sockets API Extensions for SCTP",
draft-ietf-tsvwg-sctpsocket-01.txt, work in progress.
[SCTPTLS] A. Jungmaier, E. Rescorla, M. Tuexen "TLS over SCTP",
draft-ietf-tsvwg-tls-over-sctp-00.txt, work in progress.
[SCTPIPSEC] S.M. Bellovin, J. Ioannidis, A. D. Keromytis,
R.R. Stewart, "On the Use of SCTP with IPsec",
draft-ietf-ipsec-sctp-03.txt, work in progress.
[RFC2246] T. Dierks, C. Allen "The TLS Protocol - Version 1.0",
RFC 2246, January 1999.
8. Acknowledgements
The authors wish to thank John Loughney, Lyndon Ong, and many
others for their invaluable comments.
9. Authors' Addresses
Randall R. Stewart Phone: +1-815-477-2127
24 Burning Bush Trail. EMail: rrs@cisco.com
Crystal Lake, IL 60012
USA
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Qiaobing Xie Phone: +1-847-632-3028
Motorola, Inc. EMail: qxie1@email.mot.com
1501 W. Shure Drive, 2-F9
Arlington Heights, IL 60004
USA
Maureen Stillman Phone: +1 607 273 0724 62
Nokia EMail: maureen.stillman@nokia.com
127 W. State Street
Ithaca, NY 14850
USA
Expires in six months from Mar. 2002
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