Network Working Group Q. Xie
Internet-Draft Motorola
Intended status: Experimental R. Stewart
Expires: September 29, 2008 Cisco Systems, Inc.
M. Stillman
Nokia
M. Tuexen
Muenster Univ. of Applied Sciences
A. Silverton
Motorola, Inc.
March 28, 2008
Endpoint Handlespace Redundancy Protocol (ENRP)
draft-ietf-rserpool-enrp-19.txt
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Abstract
The Endpoint Handlespace Redundancy Protocol (ENRP) is designed to
work in conjunction with the Aggregate Server Access Protocol (ASAP)
to accomplish the functionality of the Reliable Server Pooling
(RSerPool) requirements and architecture. Within the operational
scope of RSerPool, ENRP defines the procedures and message formats of
a distributed, fault-tolerant registry service for storing,
bookkeeping, retrieving, and distributing pool operation and
membership information.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 5
2. ENRP Message Definitions . . . . . . . . . . . . . . . . . . . 6
2.1. ENRP_PRESENCE message . . . . . . . . . . . . . . . . . . 6
2.2. ENRP_HANDLE_TABLE_REQUEST message . . . . . . . . . . . . 8
2.3. ENRP_HANDLE_TABLE_RESPONSE message . . . . . . . . . . . . 8
2.4. ENRP_HANDLE_UPDATE message . . . . . . . . . . . . . . . . 10
2.5. ENRP_LIST_REQUEST message . . . . . . . . . . . . . . . . 12
2.6. ENRP_LIST_RESPONSE message . . . . . . . . . . . . . . . . 13
2.7. ENRP_INIT_TAKEOVER message . . . . . . . . . . . . . . . . 14
2.8. ENRP_INIT_TAKEOVER_ACK message . . . . . . . . . . . . . . 14
2.9. ENRP_TAKEOVER_SERVER message . . . . . . . . . . . . . . . 15
2.10. ENRP_ERROR message . . . . . . . . . . . . . . . . . . . . 16
3. ENRP Operation Procedures . . . . . . . . . . . . . . . . . . 17
3.1. Methods for Communicating amongst ENRP Servers . . . . . . 17
3.2. ENRP Server Initialization . . . . . . . . . . . . . . . . 17
3.2.1. Generate a Server Identifier . . . . . . . . . . . . . 17
3.2.2. Acquire Peer Server List . . . . . . . . . . . . . . . 18
3.2.3. Download ENRP Handlespace Data from Mentor Peer . . . 19
3.3. Server Handlespace Update . . . . . . . . . . . . . . . . 21
3.3.1. Announcing Addition or Update of PE . . . . . . . . . 21
3.3.2. Announcing Removal of PE . . . . . . . . . . . . . . . 22
3.4. Maintaining Peer List and Monitoring Peer Status . . . . . 23
3.4.1. Discovering New Peer . . . . . . . . . . . . . . . . . 23
3.4.2. Server Sending Heartbeat . . . . . . . . . . . . . . . 23
3.4.3. Detecting Peer Server Failure . . . . . . . . . . . . 23
3.5. Taking-over a Failed Peer Server . . . . . . . . . . . . . 24
3.5.1. Initiating Server Take-over Arbitration . . . . . . . 24
3.5.2. Take-over Target Peer Server . . . . . . . . . . . . . 25
3.6. Handlespace Data Auditing and Re-synchronization . . . . . 26
3.6.1. Auditing Procedures . . . . . . . . . . . . . . . . . 26
3.6.2. PE Checksum Calculation Algorithm . . . . . . . . . . 27
3.6.3. Re-synchronization Procedures . . . . . . . . . . . . 28
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3.7. Handling Unrecognized Message or Unrecognized Parameter . 28
4. Variables and Thresholds . . . . . . . . . . . . . . . . . . . 29
4.1. Variables . . . . . . . . . . . . . . . . . . . . . . . . 29
4.2. Thresholds . . . . . . . . . . . . . . . . . . . . . . . . 29
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
5.1. A New Table for ENRP Message Types . . . . . . . . . . . . 30
5.2. A New Table for Update Action Types . . . . . . . . . . . 30
5.3. Port numbers . . . . . . . . . . . . . . . . . . . . . . . 31
5.4. SCTP payload protocol identifier . . . . . . . . . . . . . 31
6. Security Considerations . . . . . . . . . . . . . . . . . . . 32
6.1. Summary of Rserpool Security Threats . . . . . . . . . . . 32
6.2. Implementing Security Mechanisms . . . . . . . . . . . . . 33
6.3. Chain of trust . . . . . . . . . . . . . . . . . . . . . . 34
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 36
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 37
8.1. Normative References . . . . . . . . . . . . . . . . . . . 37
8.2. Informative References . . . . . . . . . . . . . . . . . . 38
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
Intellectual Property and Copyright Statements . . . . . . . . . . 41
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1. Introduction
ENRP is designed to work in conjunction with ASAP
[I-D.ietf-rserpool-asap] to accomplish the functionality of RSerPool
as defined by its requirements [RFC3237].
Within the operational scope of RSerPool, ENRP defines the procedures
and message formats of a distributed fault-tolerant registry service
for storing, bookkeeping, retrieving, and distributing pool operation
and membership information.
Whenever appropriate, in the rest of this document we will refer to
this RSerPool registry service as ENRP handlespace, or simply
handlespace because it manages all pool handles.
1.1. Definitions
This document uses the following terms:
Operational scope: The part of the network visible to pool users by
a specific instance of the reliable server pooling protocols.
Pool (or server pool): A collection of servers providing the same
application functionality.
Pool handle: A logical pointer to a pool. Each server pool will be
identifiable in the operational scope of the system by a unique
pool handle.
Pool element: A server entity having registered to a pool.
Pool user: A server pool user.
Pool element handle (or endpoint handle): A logical pointer to a
particular pool element in a pool, consisting of the pool handle
and a destination transport address of the pool element.
Handle space: A cohesive structure of pool handles and relations
that may be queried by an internal or external agent.
ENRP client channel: The communication channel through which an ASAP
User (either a PE or PU) requests ENRP handlespace service. The
client channel is usually defined by the transport address of the
home server and a well-known port number.
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ENRP server channel: Defined by a list of IP addresses (one for each
ENRP servers in an operational scope) and a well known port
number. All ENRP servers in an operational scope can send "group-
cast" messages to other servers through this channel. In a
"group-cast", the sending server sends multiple copies of the
message, one to each of its peer servers, over a set of point-to-
point SCTP associations between the sending server and the peers.
The "group-cast" may be conveniently implemented with the use of
the "SCTP_SENDALL" option on an one-to-many style SCTP socket
[I-D.ietf-tsvwg-sctpsocket].
Home ENRP server: The ENRP server to which a PE or PU currently
belongs. A PE MUST only have one home ENRP server at any given
time and both the PE and its home ENRP server MUST keep track of
this master/slave relationship between them. A PU SHOULD select
one of the available ENRP servers as its home ENRP server, but the
ENRP server does not need to know, nor does it need to keep track
of this relationship.
1.2. Conventions
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 RFC2119 [RFC2119].
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2. ENRP Message Definitions
In this section, we define the format of all ENRP messages. These
are messages sent and received amongst ENRP servers in an operational
scope. Messages sent and received between a PE/PU and an ENRP server
are part of ASAP and are defined in [I-D.ietf-rserpool-asap]. A
common format, that is defined in [I-D.ietf-rserpool-common-param],
is used for all ENRP and ASAP messages.
Most ENRP messages contains a combination of fixed fields and TLV
parameters. The TLV (Type-Length_value) parameters are also defined
in [I-D.ietf-rserpool-common-param]. If a nested TLV parameter is
not ended on a 32-bit word boundary, it will be padded with all '0'
octets to the next 32-bit word boundary.
All messages, as well as their fields/parameters described below,
MUST be transmitted in network byte order (a.k.a. Big Endian,
meaning the most significant byte is transmitted first).
For ENRP, the following message types are defined in this section:
Type Message Name
----- -------------------------
0x00 - (reserved by IETF)
0x01 - ENRP_PRESENCE
0x02 - ENRP_HANDLE_TABLE_REQUEST
0x03 - ENRP_HANDLE_TABLE_RESPONSE
0x04 - ENRP_HANDLE_UPDATE
0x05 - ENRP_LIST_REQUEST
0x06 - ENRP_LIST_RESPONSE
0x07 - ENRP_INIT_TAKEOVER
0x08 - ENRP_INIT_TAKEOVER_ACK
0x09 - ENRP_TAKEOVER_SERVER
0x0a - ENRP_ERROR
0x0b-0xff - (reserved by IETF)
Figure 1
2.1. ENRP_PRESENCE message
This ENRP message is used to announce (periodically) the presence of
an ENRP server, or to probe the status of a peer ENRP server. This
message is either send on the ENRP server channel or point-to-point
to another ENRP server.
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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 = 0x01 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: PE Checksum Param :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Server Information Param (optional) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sending Server's ID: 32 bit (unsigned integer)
This is the ID of the ENRP server which sent this message.
Receiving Server's ID: 32 bit (unsigned integer)
This is the ID of the ENRP server to which this message is
intended. If the message is not intended for an individual
server (e.g., the message is group-casted to a group of
servers), this field MUST be sent with all 0's. If the message
is send point-to-point this field MAY be sent with all 0's.
PE Checksum Parameter:
This is a TLV that contains the latest PE checksum of the ENRP
server who sends the ENRP_PRESENCE. This parameter SHOULD be
included for handlespace consistency auditing. See
Section 3.6.1 for details.
Server Information Parameter:
If this parameter is present, it contains the server
information of the sender of this message (Server Information
Parameter is defined in [I-D.ietf-rserpool-common-param]).
This parameter is optional. However, if this message is sent
in response to a received "reply required" ENRP_PRESENCE from a
peer, the sender then MUST include its server information.
Note, at startup an ENRP server MUST pick a randomly generated, non-
zero 32-bit unsigned integer as its ID and MUST use this same ID
until the ENRP server is rebooted.
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2.2. ENRP_HANDLE_TABLE_REQUEST message
An ENRP server sends this message to one of its peers to request a
copy of the handlespace data. This message is normally used during
server initialization or handlespace re-synchronization.
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 = 0x02 |0|0|0|0|0|0|0|W| Message Length = 0xC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
W (oWn-children-only) flag: 1 bit
Set to '1' if the sender of this message is only requesting
information about the PEs owned by the message receiver.
Otherwise, set to '0'.
Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
2.3. ENRP_HANDLE_TABLE_RESPONSE message
The PEER_NAME_TABLE_RESPONSE message is sent by an ENRP server in
response to a received PEER_NAME_TABLE_REQUEST message to assist peer
server initialization or handle-space synchronization.
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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 = 0x03 |0|0|0|0|0|0|M|R| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: Pool entry #1 (optional) :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: ... :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: :
: Pool entry #n (optional) :
: :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
M (More_to_send) flag: 1 bit
Set to '1' if the sender of this message has more pool entries
to send in subsequent ENRP_HANDLE_TABLE_RESPONSE messages.
Otherwise, set to '0'.
R (Reject) flag: 1 bit
MUST be set to '1' if the sender of this message is rejecting a
handlespace request. In this case, pool entries MUST not be
included. This might happen if the sender of this message is
in the middle of initializing its database or it is under high
load.
Message Length: 16 bits (unsigned integer)
Indicates the entire length of the message including the header
in number of octets.
Note, the value in Message Length field will NOT cover any
padding at the end of this message.
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Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
Pool entry #1-#n:
If the R flag is set to '0', at least one pool entry SHOULD be
present in this message. Each pool entry MUST start with a
Pool Handle parameter as defined in section 3.9 of
[I-D.ietf-rserpool-common-param], and is followed by one or
more Pool Element parameters in TLV format, as shown below:
+---------------------------+
: Pool handle :
+---------------------------+
: PE #1 :
+---------------------------+
: PE #2 :
+---------------------------+
: ... :
+---------------------------+
: PE #n :
+---------------------------+
2.4. ENRP_HANDLE_UPDATE message
The PEER_NAME_UPDATE message is sent by the home ENRP server of a PE
to all peer servers to announce registration, re-registration, or de-
registration of the PE in the handle-space.
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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 = 0x04 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Update Action | (reserved) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Handle Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool Element Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Message Length: 16 bits (unsigned integer)
Indicates the entire length of the message including the header
in number of octets.
Note, the value in Message Length field will NOT cover any
padding at the end of this message.
Update Action: 16 bits (unsigned integer)
This field indicates the requested action of the specified PE.
The field MUST be set to one of the following values:
0x0000 - ADD_PE: Add or update the specified PE in the ENRP
handlespace
0x0001 - DEL_PE: Delete the specified PE from the ENRP
handlespace.
0x0002 - 0xFFFF: Reserved by IETF.
Other values are reserved by IETF and MUST not be used.
Reserved: 16 bits
This field MUST be set to all 0's by sender and ignored by the
receiver.
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Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
Pool handle:
Specifies to which the PE belongs.
Pool Element:
Specifies the PE.
2.5. ENRP_LIST_REQUEST message
The PEER_LIST_REQUEST message is sent to request a current copy of
the ENRP server list. This message is normally sent from a newly
activated ENRP server to an established ENRP server as part of the
initialization process.
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 = 0x05 |0|0|0|0|0|0|0|0| Message Length = 0xC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
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2.6. ENRP_LIST_RESPONSE message
The PEER_LIST_RESPONSE message is sent in response from an ENRP
server that receives a PEER_LIST_REQUEST message to return
information about known ENRP servers.
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 = 0x06 |0|0|0|0|0|0|0|R| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Server Information Parameter of Peer #1 :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: ... :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Server Information Parameter of Peer #n :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
R (Reject) flag: 1 bit
This flag MUST be set to '1' if the sender of this message is
rejecting a PEER_LIST_REQUEST message. If this case occurs,
the message MUST NOT include any Server Information Parameters.
Message Length: 16 bits (unsigned integer)
Indicates the entire length of the message in number of octets.
Note, the value in Message Length field will NOT cover any
padding at the end of this message.
Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
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Server Information Parameter of Peer #1-#n:
Each contains a Server Information Parameter of a peer known to
the sender. The Server Information Parameter is defined in
[I-D.ietf-rserpool-common-param].
2.7. ENRP_INIT_TAKEOVER message
The ENRP_INIT_TAKEOVER message is sent by an ENRP server (the
takeover initiator) to announce its intention of taking over a
specific peer ENRP server. It is send to all its peers.
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 = 0x07 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Targeting Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
Targeting Server's ID: 32-bit (unsigned integer)
This is the ID of the peer ENRP that is the target of this
takeover attempt.
2.8. ENRP_INIT_TAKEOVER_ACK message
The PEER_INIT_TAKEOVER_ACK message is sent in response to a takeover
initiator to acknowledge the reception of the PEER_INIT_TAKEOVER
message and that it does not object to the takeover.
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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 = 0x08 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Targeting Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
Targeting Server's ID:
This is the ID of the peer ENRP that is the target of this
takeover attempt.
2.9. ENRP_TAKEOVER_SERVER message
The PEER_TAKEOVER_REGISTRAR message is sent by the takeover initiator
to declare the enforcement of a takeover to all active peer ENRP
servers.
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 = 0x09 |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Targeting Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
Targeting Server's ID:
This is the ID of the peer ENRP that is the target of this
takeover operation.
2.10. ENRP_ERROR message
The ENRP_ERROR message is sent by a registrar to report an
operational error to a peer ENRP server.
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 = 0x0a |0|0|0|0|0|0|0|0| Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sending Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiving Server's ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Operational Error Parameter :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Sending Server's ID:
See Section 2.1.
Receiving Server's ID:
See Section 2.1.
Operational Error Parameter:
This parameter, defined in [I-D.ietf-rserpool-common-param],
indicates the type of error(s) being reported.
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3. ENRP Operation Procedures
In this section, we discuss the operation procedures defined by ENRP.
An ENRP server MUST follow these procedures when sending, receiving,
or processing ENRP messages.
Many of the RSerPool events call for both server-to-server and PU/
PE-to-server message exchanges. Only the message exchanges and
activities between an ENRP server and its peer(s) are considered
within the ENRP scope and are defined in this document.
Procedures for exchanging messages between a PE/PU and ENRP servers
are defined in [I-D.ietf-rserpool-asap].
3.1. Methods for Communicating amongst ENRP Servers
Within an RSerPool operational scope, ENRP servers need to
communicate with each other in order to exchange information such as
the pool membership changes, handlespace data synchronization, etc.
Two types of communications are used amongst ENRP servers:
o point-to-point message exchange from one ENPR server to a specific
peer server, and
o announcements from one server to all its peer servers in the
operational scope.
Point-to-point communication is always carried out over an SCTP
association between the sending server and the receiving server.
Announcements are sent out via "group-casts" over the ENRP server
channel.
3.2. ENRP Server Initialization
This section describes the steps a new ENRP server needs to take in
order to join the other existing ENRP servers, or to initiate the
handlespace service if it is the first ENRP server started in the
operational scope.
3.2.1. Generate a Server Identifier
A new ENRP server MUST generate a non-zero, 32-bit server Id that is
as unique as possible among all the ENRP servers in the operational
scope and this server Id MUST remain unchanged for the lifetime of
the server. Normally, a good 32-bit random number will be good
enough as the server Id (RFC4086 [RFC4086] provides some information
on randomness guidelines).
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Note, there is a very remote chance (about 1 in about 4 billion) that
two ENRP servers in an operational scope will generate the same
server Id and hence cause a server Id conflict in the pool. However,
no severe consequence of such a conflict has been identified.
Note, the ENRP server Id space is separate from the PE Id space
defined in [I-D.ietf-rserpool-asap].
3.2.2. Acquire Peer Server List
At startup, the ENRP server (initiating server) will first attempt to
learn all existing peer ENRP servers in the same operational scope,
or to determine that it is alone in the scope.
The initiating server uses an existing peer server to bootstrap
itself into service. We call this peer server the mentor server.
3.2.2.1. Finding the mentor server
If the initiating server is told about one existing peer server
through some administrative means (such as DNS query, configuration
database, startup scripts, etc), the initiating server MUST then use
this peer server as its mentor server.
If multiple existing peer servers are specified, the initiating
server MUST pick one of them as its mentor server and keep the others
as its backup mentor servers.
If no existing peer server is specified, the initiating server MUST
assume that it is alone in the operational scope, and MUST skip the
procedures in Section 3.2.2.2 and Section 3.2.3 and MUST consider its
initialization completed and start offering ENRP services.
3.2.2.2. Request complete server list from mentor peer
Once the initiating server finds its mentor peer server (by either
discovery or administrative means), the initiating server MUST send
an ENRP_LIST_REQUEST message to the mentor peer server to request a
copy of the complete server list maintained by the mentor peer (see
Section 3.4 for maintaining server list).
The initiating server SHOULD start a MAX-TIME-NO-RESPONSE timer every
time it finishes sending an ENRP_LIST_REQUEST message. If the timer
expires before receiving a response from the mentor peer, the
initiating server SHOULD abandon the interaction with the current
mentor server and send a new server list request to a backup mentor
peer, if one is available.
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Upon the reception of this request, the mentor peer server SHOULD
reply with an ENRP_LIST_RESPONSE message and include in the message
body all existing ENRP servers known by the mentor peer.
Upon the reception of the ENRP_LIST_RESPONSE message from the mentor
peer, the initiating server MUST use the server information carried
in the message to initialize its own peer list.
However, if the mentor itself is in the process of startup and not
ready to provide a peer server list (for example, the mentor peer is
waiting for a response to its own ENRP_LIST_REQUEST to another
server), it MUST reject the request by the initiating server and
respond with an ENRP_LIST_RESPONSE message with the R flag set to
'1', and with no server information included in the response.
In the case where its ENRP_LIST_REQUEST is rejected by the mentor
peer, the initiating server SHOULD either wait for a few seconds and
re-send the ENRP_LIST_REQUEST to the mentor server, or if there is a
backup mentor peer available, select another mentor peer server and
send the ENRP_LIST_REQUEST to the new mentor server.
3.2.3. Download ENRP Handlespace Data from Mentor Peer
After a peer list download is completed, the initiating server MUST
request a copy of the current handlespace data from its mentor peer
server, by taking the following steps:
1. The initiating server MUST first send a ENRP_HANDLE_TABLE_REQUEST
message to the mentor peer, with W flag set to '0', indicating
that the entire handlespace is requested.
2. Upon the reception of this message, the mentor peer MUST start a
download session in which a copy of the current handlespace data
maintained by the mentor peer is sent to the initiating server in
one or more ENRP_HANDLE_TABLE_RESPONSE messages (Note, the mentor
server may find it particularly desirable to use multiple
ENRP_HANDLE_TABLE_RESPONSE messages to send the handlespace when
the handlespace is large, especially when forming and sending out
a single response containing a large handlespace may interrupt
its other services).
If more than one ENRP_HANDLE_TABLE_RESPONSE message are used
during the download, the mentor peer MUST use the M flag in each
ENRP_HANDLE_TABLE_RESPONSE message to indicate whether this
message is the last one for the download session. In particular,
the mentor peer MUST set the M flag to '1' in the outbound
ENRP_HANDLE_TABLE_RESPONSE if there is more data to be
transferred and MUST keep track of the progress of the current
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download session. The mentor peer MUST set the M flag to '0' in
the last ENRP_HANDLE_TABLE_RESPONSE for the download session and
close the download session (i.e., removing any internal record of
the session) after sending out the last message.
3. During the downloading, every time the initiating server receives
an ENRP_HANDLE_TABLE_RESPONSE message, it MUST transfer the data
entries carried in the message into its local handlespace
database, and then check whether or not this message is the last
one for the download session.
If the M flag is set to '1' in the just processed
ENRP_HANDLE_TABLE_RESPONSE message, the initiating server MUST
send another ENRP_HANDLE_TABLE_REQUEST message to the mentor peer
to request for the next ENRP_HANDLE_TABLE_RESPONSE message.
4. When unpacking the data entries from a ENRP_HANDLE_TABLE_RESPONSE
message into its local handlespace database, the initiating
server MUST handle each pool entry carried in the message using
the following rules:
A. If the pool does not exist in the local handlespace, the
initiating server MUST create the pool in the local
handlespace and add the PE(s) in the pool entry to the pool.
When creating the pool, the initiation server MUST set the
overall member selection policy type of the pool to the
policy type indicated in the first PE.
B. If the pool already exists in the local handlespace, but the
PE(s) in the pool entry is not currently a member of the
pool, the initiating server MUST add the PE(s) to the pool.
C. If the pool already exists in the local handlespace AND the
PE(s) in the Pool entry is already a member of the pool, the
initiating server SHOULD replace the attributes of the
existing PE(s) with the new information. ENRP will make sure
that the information keeps up to date.
5. When the last ENRP_HANDLE_TABLE_RESPONSE message is received from
the mentor peer and unpacked into the local handlespace, the
initialization process is completed and the initiating server
SHOULD start to provide ENRP services.
Under certain circumstances, the mentor peer itself may not be able
to provide a handlespace download to the initiating server. For
example, the mentor peer is in the middle of initializing its own
handlespace database, or it has currently too many download sessions
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open to other servers.
In such a case, the mentor peer MUST reject the request by the
initiating server and respond with an ENRP_HANDLE_TABLE_RESPONSE
message with the R flag set to '1', and with no pool entries included
in the response.
In the case where its ENRP_HANDLE_TABLE_REQUEST is rejected by the
mentor peer, the initiating server SHOULD either wait for a few
seconds and re-send the ENRP_HANDLE_TABLE_REQUEST to the mentor
server, or if there is a backup mentor peer available, select another
mentor peer server and send the ENRP_HANDLE_TABLE_REQUEST to the new
mentor server.
A handlespace download session that has been started may get
interrupted for some reason. To cope with this, the initiating
server SHOULD start a timer every time it finishes sending an
ENRP_HANDLE_TABLE_REQUEST to its mentor peer. If this timer expires
without receiving a response from the mentor peer, the initiating
server SHOULD abort the current download session and re-start a new
handlespace download with a backup mentor peer, if one is available.
Similarly, after sending out an ENRP_HANDLE_TABLE_RESPONSE, and the
mentor peer set the M-bit to 1 to indicate that it has more data to
send, it SHOULD start a session timer. If this timer expires without
receiving another request from the initiating server, the mentor peer
SHOULD abort the session, cleaning out any resource and record of the
session.
3.3. Server Handlespace Update
This includes a set of update operations used by an ENRP server to
inform its peers when its local handlespace is modified, e.g.,
addition of a new PE, removal of an existing PE, change of pool or PE
properties.
3.3.1. Announcing Addition or Update of PE
When a new PE is granted registration to the handlespace or an
existing PE is granted a re-registration, the home ENRP server uses
this procedure to inform all its peers.
This is an ENRP announcement and is sent to all the peer of the home
ENRP server. See Section 3.1 on how announcements are sent.
An ENRP server MUST announce this update to all its peers in a
ENRP_HANDLE_UPDATE message with the Update Action field set to
ADD_PE, indicating the addition of a new PE or the modification of an
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existing PE. The complete new information of the PE and the pool its
belongs to MUST be indicated in the message with a PE parameter and a
Pool Handle parameter, respectively.
The home ENRP server SHOULD fill in its server Id in the Sending
Server's ID field and leave the Receiving Server's ID blank (i.e.,
all 0's).
When a peer receives this ENRP_HANDLE_UPDATE message, it MUST take
the following actions:
1. If the named pool indicated by the pool handle does not exist in
its local copy of the handlespace, the peer MUST create the named
pool in its local handlespace and add the PE to the pool as the
first PE. It MUST then copy in all other attributes of the PE
carried in the message.
When the new pool is created, the overall member selection policy
of the pool MUST be set to the policy type indicated by the PE.
2. If the named pool already exists in the peer's local copy of the
handlespace AND the PE does not exist, the peer MUST add the PE
to the pool as a new PE and copy in all attributes of the PE
carried in the message.
3. If the named pool exists AND the PE is already a member of the
pool, the peer MUST replace the attributes of the PE with the new
information carried in the message.
3.3.2. Announcing Removal of PE
When an existing PE is granted de-registration or is removed from its
handlespace for some other reasons (e.g., purging an unreachable PE,
see 3.5 in [I-D.ietf-rserpool-asap]), the ENRP server MUST uses this
procedure to inform all its peers about the change just made.
This is an ENRP announcement and is sent to all the peer of the home
ENRP server. See Section 3.1 on how announcements are sent.
An ENRP server MUST announce the PE removal to all its peers in an
ENRP_HANDLE_UPDATE message with the Update Action field set to
DEL_PE, indicating the removal of an existing PE. The complete
information of the PE and the pool its belongs to MUST be indicated
in the message with a PE parameter and a Pool Handle parameter,
respectively.
The sending server MUST fill in its server ID in the Sending Server's
ID field and leave the Receiving Server's ID blank (i.e., set to all
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0's).
When a peer receives this ENRP_HANDLE_UPDATE message, it MUST first
find pool and the PE in its own handlespace, and then remove the PE
from its local handlespace. If the removed PE is the last one in the
pool, the peer MUST also delete the pool from its local handlespace.
If the peer fails to find the PE or the pool in its handlespace, it
SHOULD take no further actions.
3.4. Maintaining Peer List and Monitoring Peer Status
An ENRP server MUST keep an internal record on the status of each of
its known peers. This record is referred to as the server's "peer
list"
3.4.1. Discovering New Peer
If a message of any type is received from a previously unknown peer,
the ENRP server MUST consider this peer a new peer in the operational
scope and add it to the peer list.
The ENRP server MUST send an ENRP_PRESENCE message with the Reply-
required flag set to '1' to the source address found in the arrived
message. This will force the new peer to reply with its own
ENRP_PRESENCE containing its full server information (see
Section 2.1).
3.4.2. Server Sending Heartbeat
Every PEER-HEARTBEAT-CYCLE seconds, an ENRP server MUST announce its
continued presence to all its peer with a ENRP_PRESENCE message. In
the ENRP_PRESENCE message, the ENRP server MUST set the
'Replay_required' flag to '0', indicating that no response is
required.
The arrival of this periodic ENRP_PRESENCE message will cause all its
peers to update their internal variable "peer_last_heard" for the
sending server (see Section 3.4.3 for more details).
3.4.3. Detecting Peer Server Failure
An ENRP server MUST keep an internal variable "peer_last_heard" for
each of its known peers and the value of this variable MUST be
updated to the current local time every time a message of any type
(point-to-point or announcement) is received from the corresponding
peer.
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If a peer has not been heard for more than MAX-TIME-LAST-HEARD
seconds, the ENRP server MUST immediately send a point-to-point
ENRP_PRESENCE with 'Reply_request' flag set to '1' to that peer.
If the send fails or the peer does not reply after MAX-TIME-NO-
RESPONSE seconds, the ENRP server MUST consider the peer server dead
and SHOULD initiate the takeover procedure defined in Section 3.5.
3.5. Taking-over a Failed Peer Server
In the following descriptions, we call the ENRP server that detects
the failed peer server and initiates the take-over the "initiating
server" and the failed peer server the "target server." This allows
PE to continue to operate in case of a failure of their Home ENRP
server.
3.5.1. Initiating Server Take-over Arbitration
The initiating server SHOULD first start the take-over arbitration
process by sending a ENRP_INIT_TAKEOVER message to all its peer
servers. See Section 3.1 on how announcements are sent. In the
message, the initiating server MUST fill in the Sending Server's ID
and Targeting Server's ID. The goal is that only one ENRP server
takes over the PE from the target.
After announcing the ENRP_INIT_TAKEOVER message (group-casting to all
known peers, including the target server), the initiating server
SHOULD wait for an ENRP_INIT_TAKEOVER_ACK message from each of its
known peers, except of the target server.
Each peer receiving an ENRP_INIT_TAKEOVER message from the initiating
server MUST take the following actions:
1. If the peer server determines that itself is the target server
indicated in the ENRP_INIT_TAKEOVER message, it MUST immediately
announce an ENRP_PRESENCE message to all its peer ENRP servers in
an attempt to stop this take-over process. This indicates a
false failure detection case by the initiating server. The
initiating server MUST stop the takeover operation by marking the
target server as "active" and taking no further takeover actions.
2. If the peer server finds that it has already started its own
take-over arbitration process on the same target server, it MUST
perform the following arbitration:
A. If the peer's server ID is smaller in value than the Sending
Server's ID in the arrived ENRP_INIT_TAKEOVER message, the
peer server MUST immediately abort its own take-over attempt
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by taking no further takeover actions of its own. Moreover,
the peer MUST mark the target server as "not active" on its
internal peer list so that its status will no longer be
monitored by the peer, and reply the initiating server with
an ENRP_INIT_TAKEOVER_ACK message.
B. Otherwise, the peer MUST ignore the ENRP_INIT_TAKEOVER
message.
3. If the peer finds that it is neither the target server nor is in
its own take-over process, the peer MUST: a) mark the target
server as "not active" on its internal peer list so that its
status will no longer be monitored by this peer, and b) MUST
reply to the initiating server with an ENRP_INIT_TAKEOVER_ACK
message.
Once the initiating server has received the ENRP_INIT_TAKEOVER_ACK
message from all of its currently known peers (except for the target
server), it MUST consider that it has won the arbitration and MUST
proceed to complete the take-over, following the steps described in
Section 3.5.2.
However, if it receives an ENRP_PRESENCE from the target server at
any point in the arbitration process, the initiating server MUST
immediately stop the take-over process and mark the status of the
target server as "active".
3.5.2. Take-over Target Peer Server
The initiating ENRP server MUST first send, via an announcement, an
ENRP_TAKEOVER_SERVER message to inform all its active peers that the
take-over is enforced. The target server's ID MUST be filled in the
message. The initiating server SHOULD then remove the target server
from its internal peer list.
Then it SHOULD examine its local copy of the handlespace and claim
ownership of each of the PEs originally owned by the target server,
by following these steps:
1. mark itself as the home ENRP server of each of the PEs originally
owned by the target server;
2. send a point-to-point ASAP_ENDPOINT_KEEP_ALIVE message, with the
'H' flag set to '1', to each of the PEs. This will trigger the
PE to adopt the initiating sever as its new home ENRP server;
When a peer receives the ENRP_TAKEOVER_SERVER message from the
initiating server, it SHOULD update its local peer list and PE cache
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by following these steps:
1. remove the target server from its internal peer list;
2. update the home ENRP server of each PE in its local copy of the
handlespace to be the sender of the message, i.e., the initiating
server.
3.6. Handlespace Data Auditing and Re-synchronization
Message losses or certain temporary breaks in network connectivity
may result in data inconsistency in the local handlespace copy of
some of the ENRP servers in an operational scope. Therefore, each
ENRP server in the operational scope SHOULD periodically verify that
its local copy of handlespace data is still in sync with that of its
peers.
This section defines the auditing and re-synchronization procedures
for an ENRP server to maintain its handlespace data consistency.
3.6.1. Auditing Procedures
A checksum covering the data which should be the same is exchanged to
figure out if the data is the same or not.
The auditing of handlespace consistency is based on the following
procedures:
1. An ENRP server SHOULD keep a separate PE checksum (a 32-bit
integer internal variable) for each of its known peers and for
itself. For an ENRP server with 'k' known peers, we denote these
internal variables as "pe_checksum_pr0", "pe_checksum_pr1", ...,
"pe_checksum_prk", where "pe_checksum_pr0" is the server's own PE
checksum. The list of what these checksums cover and a detailed
algorithm for calculating them is given in Section 3.6.2.
2. Each time an ENRP server sends out an ENRP_PRESENCE, it MUST
include in the message its current PE checksum (i.e.,
"pe_checksum_pr0").
3. When an ENRP server (server A) receives a PE checksum (carried in
an arrived ENRP_PRESENCE) from a peer ENRP server (server B),
server A SHOULD compare the PE checksum found in the
ENRP_PRESENCE with its own internal PE checksum of server B
(i.e., "pe_checksum_prB").
4. If the two values match, server A will consider that there is no
handlespace inconsistency between itself and server B and should
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take no further actions.
5. If the two values do NOT match, server A SHOULD consider that
there is a handlespace inconsistency between itself and server B
and a re-synchronization process SHOULD be carried out
immediately with server B (see Section 3.6.3).
3.6.2. PE Checksum Calculation Algorithm
When an ENRP server (server A) calculate an internal PE checksum for
a peer (server B), it MUST use the following algorithm.
Let us assume that in server A's internal handlespace there are
currently 'M' PEs that are owned by server B. Each of the 'M' PEs
will then contribute to the checksum calculation with the following
byte block:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: Pool handle string of the pool the PE belongs (padded with :
: zeros to next 32-bit word boundary if needed) :
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PE Id (4 octets) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Note, these are not TLVs. This byte block gives each PE a unique
byte pattern in the scope. The 16-bit PE checksum for server B
"pe_checksum_prB" is then calculated over the byte blocks contributed
by the 'M' PEs one by one. The PE checksum calculation MUST use the
Internet algorithm described in [RFC1071].
Server A MUST calculate its own PE checksum (i.e., "pe_checksum_pr0")
in the same fashion, using the byte blocks of all the PEs owned by
itself.
Note, whenever an ENRP finds that its internal handlespace has
changed (e.g., due to PE registration/deregistration, receiving peer
updates, removing failed PEs, downloading handlespace pieces from a
peer, etc.), it MUST immediately update all its internal PE checksums
that are affected by the change.
Implementation Note: when the internal handlespace changes (e.g., a
new PE added or an existing PE removed), an implementation needs not
to re-calculate the affected PE checksum; it can instead simply
update the checksum by adding or subtracting the byte block of the
corresponding PE from the previous checksum value.
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3.6.3. Re-synchronization Procedures
If an ENRP server determines that there is inconsistency between its
local handlespace data and a peer's handlespace data with regarding
to the PEs owned by that peer, it MUST perform the following steps to
re-synchronize the data:
1. The ENRP server SHOULD first "mark" every PE it knows about that
is owned by the peer in its local handlespace database;
2. The ENRP server SHOULD then send an ENRP_HANDLE_TABLE_REQUEST
message with W flag set to '1' to the peer to request a complete
list of PEs owned by the peer;
3. Upon reception of the ENRP_HANDLE_TABLE_REQUEST message with W
flag set to '1', the peer server SHOULD immediately respond with
an ENRP_HANDLE_TABLE_RESPONSE message listing all PEs currently
owned by the peer.
4. Upon reception of the ENRP_HANDLE_TABLE_RESPONSE message, the
ENRP server SHOULD transfer the PE entries carried in the message
into its local handlespace database. If an PE entry being
transferred already exists in its local database, the ENRP server
MUST replace the entry with the copy found in the message and
remove the "mark" from the entry.
5. After transferring all the PE entries from the received
ENRP_HANDLE_TABLE_RESPONSE message into its local database, the
ENRP server SHOULD check whether there are still PE entries that
remain "marked" in its local handlespace. If so, the ENRP server
SHOULD silently remove those "marked" entries.
Note, similar to what is described in Section 3.2.3, the peer may
reject the ENRP_HANDLE_TABLE_REQUEST or use more than one
ENRP_HANDLE_TABLE_RESPONSE message to respond.
3.7. Handling Unrecognized Message or Unrecognized Parameter
When an ENRP server receives an ENRP message with an unknown message
type or a message of known type that contains an unknown parameter,
it SHOULD handle the unknown message or the unknown parameter
according to the unrecognized message and parameter handling rules
defined in Sections 3 and 4 in [I-D.ietf-rserpool-common-param].
According to the rules, if an error report to the message sender is
needed, the ENRP server that discovered the error SHOULD send back an
ENRP_ERROR message with proper error cause code.
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4. Variables and Thresholds
4.1. Variables
peer_last_heard - the local time that a peer server was last heard
(via receiving either a group-cast or point-to-point message from
the peer).
pe_checksum_pr - the internal 32-bit PE checksum that an ENRP server
keeps for a peer. A separate PE checksum is kept for each of its
known peers as well as for itself.
4.2. Thresholds
PEER-HEARTBEAT-CYCLE - the period for an ENRP server to announce a
heartbeat message to all its known peers. (Default=30 secs.)
MAX-TIME-LAST-HEARD - pre-set threshold for how long an ENRP server
will wait before considering a silent peer server potentially
dead. (Default=61 secs.)
MAX-TIME-NO-RESPONSE - pre-set threshold for how long a message
sender will wait for a response after sending out a message.
(Default=5 secs.)
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5. IANA Considerations
[NOTE to RFC-Editor:
"RFCXXXX" is to be replaced by the RFC number you assign this
document.
]
This document (RFCXXX) is the reference for all registrations
described in this section. All registrations need to be listed on an
RSerPool specific page.
5.1. A New Table for ENRP Message Types
ENRP Message Types have to be maintained by IANA. Ten initial values
should be assigned by IANA as described in Figure 1. This requires a
new table "ENRP Message Types":
Type Message Name Reference
----- ------------------------- ---------
0x00 (reserved by IETF) RFCXXXX
0x01 ENRP_PRESENCE RFCXXXX
0x02 ENRP_HANDLE_TABLE_REQUEST RFCXXXX
0x03 ENRP_HANDLE_TABLE_RESPONSE RFCXXXX
0x04 ENRP_HANDLE_UPDATE RFCXXXX
0x05 ENRP_LIST_REQUEST RFCXXXX
0x06 ENRP_LIST_RESPONSE RFCXXXX
0x07 ENRP_INIT_TAKEOVER RFCXXXX
0x08 ENRP_INIT_TAKEOVER_ACK RFCXXXX
0x09 ENRP_TAKEOVER_SERVER RFCXXXX
0x0a ENRP_ERROR RFCXXXX
0x0b-0xff (reserved by IETF) RFCXXXX
For registering at IANA an ENRP Message Type in this table a request
has to be made to assign such a number. This number must be unique.
The "Specification Required" policy of RFC2434 [RFC2434] MUST be
applied.
5.2. A New Table for Update Action Types
Update Types have to be maintained by IANA. Two initial values
should be assigned by IANA. This requires a new table "Update Action
Types":
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Type Update Action Reference
------------- -------------------- ---------
0x0000 ADD_PE RFCXXXX
0x0001 DEL_PE RFCXXXX
0x0002-0xffff (reserved by IETF) RFCXXXX
For registering at IANA an Update Action Type in this table a request
has to be made to assign such a number. This number must be unique.
The "Specification Required" policy of RFC2434 [RFC2434] MUST be
applied.
5.3. Port numbers
The references for the already assigned port numbers
enrp-udp 9901/udp
enrp-sctp 9901/sctp
enrp-sctp-tls 9902/sctp
should be updated to RFCXXXX.
5.4. SCTP payload protocol identifier
The reference for the already assigned ENRP payload protocol
identifier 12 should be updated to RFCXXXX.
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6. Security Considerations
We present a summary of the threats to the RSerPool architecture and
describe security requirements in response to mitigate the threats.
Next we present the security mechanisms, based on TLS, that are
implementation requirements in response to the threats. Finally, we
present a chain of trust argument that examines critical data paths
in RSerPool and shows how these paths are protected by the TLS
implementation.
6.1. Summary of Rserpool Security Threats
Threats Introduced by RSerPool and Requirements for Security in
Response to Threats [I-D.ietf-rserpool-threats] describes the threats
to the RSerPool architecture in detail lists the security
requirements in response to each threat. From the threats described
in this document, the security services required for the RSerPool
protocol are enumerated below.
Threat 1) PE registration/deregistration flooding or spoofing
-----------
Security mechanism in response: ENRP server authenticates the PE
Threat 2) PE registers with a malicious ENRP server
-----------
Security mechanism in response: PE authenticates the ENRP server
Threat 1 and 2 taken together results in mutual authentication of the
ENRP server and the PE.
Threat 3) Malicious ENRP server joins the ENRP server pool
-----------
Security mechanism in response: ENRP servers mutually authenticate
Threat 4) A PU communicates with a malicious ENRP server for handle
resolution
-----------
Security mechanism in response: The PU authenticates the ENRP server
Threat 5) Replay attack
-----------
Security mechanism in response: Security protocol which has
protection from replay attacks
Threat 6) Corrupted data which causes a PU to have misinformation
concerning a pool handle resolution
-----------
Security mechanism in response: Security protocol which supports
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integrity protection
Threat 7) Eavesdropper snooping on handlespace information
-----------
Security mechanism in response: Security protocol which supports data
confidentiality
Threat 8) Flood of ASAP_ENDPOINT_UNREACHABLE messages from the PU to
ENRP server
-----------
Security mechanism in response: ASAP must control the number of ASAP
endpoint unreachable messages transmitted from the PU to the ENRP
server.
Threat 9) Flood of ASAP_ENDPOINT_KEEP_ALIVE messages to the PE from
the ENRP server
-----------
Security mechanism in response: ENRP server must control the number
of ASAP_ENDPOINT_KEEP_ALIVE messages to the PE
To summarize the threats 1-7 require security mechanisms which
support authentication, integrity, data confidentiality, protection
from replay attacks.
For RSerPool we need to authenticate the following:
PU <---- ENRP Server (PU authenticates the ENRP server)
PE <----> ENRP Server (mutual authentication)
ENRP server <-----> ENRP Server (mutual authentication)
6.2. Implementing Security Mechanisms
We do not define any new security mechanisms specifically for
responding to threats 1-7. Rather we use an existing IETF security
protocol, specifically [RFC3237], to provide the security services
required. TLS supports all these requirements and MUST be
implemented. The TLS_RSA_WITH_AES_128_CBC_SHA ciphersuite MUST be
supported at a minimum by implementors of TLS for RSerPool. For
purposes of backwards compatibility, ENRP SHOULD support
TLS_RSA_WITH_3DES_EDE_CBC_SHA. Implementers MAY also support any
other IETF approved ciphersuites.
ENRP servers, PEs, PUs MUST implement TLS. ENRP servers and PEs must
support mutual authentication. ENRP servers must support mutual
authentication among themselves. PUs MUST authenticate ENRP servers.
ENRP servers and PEs SHOULD possess a site certificate whose subject
corresponds to their canonical hostname. PUs MAY have certificates
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of their own for mutual authentication with TLS, but no provisions
are set forth in this document for their use. All RSerPool elements
that support TLS MUST have a mechanism for validating certificates
received during TLS negotiation; this entails possession of one or
more root certificates issued by certificate authorities (preferably
well-known distributors of site certificates comparable to those that
issue root certificates for web browsers).
Implementations MUST support TLS with SCTP as described in [RFC3436]
or TLS over TCP as described in [RFC4346]. 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.
Threat 8 requires the ASAP protocol to limit the number of
ASAP_ENDPOINT_UNREACHABLE messages (see Section 3.5 in
[I-D.ietf-rserpool-asap]) to the ENRP server.
Threat 9 requires the ENRP protocol to limit the number of
ASAP_ENDPOINT_KEEP_ALIVE messages from the ENRP server to the PE (see
3.5 in [I-D.ietf-rserpool-asap]).
6.3. Chain of trust
Security is mandatory to implement in RSerPool and is based on TLS
implementation in all three architecture components that comprise
RSerPool -- namely PU, PE and ENRP server. We define an ENRP server
that uses TLS for all communication and authenticates ENRP peers and
PE registrants to be a secured ENRP server.
Here is a description of all possible data paths and a description of
the security.
PU <---> secured ENRP Server (authentication of ENRP server;
queries over TLS)
PE <---> secured ENRP server (mutual authentication;
registration/deregistration over TLS)
secured ENRP server <---> secured ENRP server (mutual authentication;
database updates using TLS)
If all components of the system authenticate and communicate using
TLS, the chain of trust is sound. The root of the trust chain is the
ENRP server. If that is secured using TLS, then security will be
enforced for all ENRP and PE components that try to connect to it.
Summary of interaction between secured and unsecured components: If
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the PE does not use TLS and tries to register with a secure ENRP
server, it will receive an error message response indicated as error
due to security considerations and the registration will be rejected.
If an ENRP server which does not use TLS tries to update the database
of a secure ENRP server, then the update will be rejected. If an PU
does not use TLS and communicates with a secure ENRP server, it will
get a response with the understanding that the response is not secure
as the response can be tampered with in transit even if the ENRP
database is secured.
The final case is the PU sending a secure request to ENRP. It might
be that ENRP and PEs are not secured and this is an allowable
configuration. The intent is to secure the communication over the
Internet between the PU and the ENRP server.
Summary:
RSerPool architecture components can communicate with each other to
establish a chain of trust. Secured PE and ENRP servers reject any
communications with unsecured ENRP or PE servers.
If the above is enforced, then a chain of trust is established for
the RSerPool user.
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7. Acknowledgments
The authors wish to thank John Loughney, Lyndon Ong, Walter Johnson,
Thomas Dreibholz, Frank Volkmer, and many others for their invaluable
comments and feedback.
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8. References
8.1. Normative References
[RFC1071] Braden, R., Borman, D., Partridge, C., and W. Plummer,
"Computing the Internet checksum", RFC 1071,
September 1988.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 2434,
October 1998.
[RFC2960] Stewart, R., Xie, Q., Morneault, K., Sharp, C.,
Schwarzbauer, H., Taylor, T., Rytina, I., Kalla, M.,
Zhang, L., and V. Paxson, "Stream Control Transmission
Protocol", RFC 2960, October 2000.
[RFC3237] Tuexen, M., Xie, Q., Stewart, R., Shore, M., Ong, L.,
Loughney, J., and M. Stillman, "Requirements for Reliable
Server Pooling", RFC 3237, January 2002.
[RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport
Layer Security over Stream Control Transmission Protocol",
RFC 3436, December 2002.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.1", RFC 4346, April 2006.
[I-D.ietf-rserpool-common-param]
Stewart, R., Xie, Q., Stillman, M., and M. Tuexen,
"Aggregate Server Access Protocol (ASAP) and Endpoint
Handlespace Redundancy Protocol (ENRP) Parameters",
draft-ietf-rserpool-common-param-16 (work in progress),
March 2008.
[I-D.ietf-rserpool-asap]
Stewart, R., Xie, Q., Stillman, M., and M. Tuexen,
"Aggregate Server Access Protocol (ASAP)",
draft-ietf-rserpool-asap-18 (work in progress),
November 2007.
[I-D.ietf-rserpool-threats]
Stillman, M., Gopal, R., Guttman, E., Holdrege, M., and S.
Sengodan, "Threats Introduced by RSerPool and Requirements
for Security in Response to Threats",
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draft-ietf-rserpool-threats-09 (work in progress),
October 2007.
[I-D.ietf-tsvwg-sctpsocket]
Stewart, R., Xie, Q., Corp, T., Poon, K., Tuexen, M., and
V. Yasevich, "Sockets API Extensions for Stream Control
Transmission Protocol (SCTP)",
draft-ietf-tsvwg-sctpsocket-16 (work in progress),
February 2008.
8.2. Informative References
[RFC4086] Eastlake, D., Schiller, J., and S. Crocker, "Randomness
Requirements for Security", BCP 106, RFC 4086, June 2005.
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Authors' Addresses
Qiaobing Xie
Motorola, Inc.
1501 W. Shure Drive, 2-F9
Arlington Heights, IL 60004
US
Phone:
Email: Qiaobing.Xie@motorola.com
Randall R. Stewart
Cisco Systems, Inc.
4875 Forest Drive
Suite 200
Columbia, SC 29206
USA
Phone:
Email: rrs@cisco.com
Maureen Stillman
Nokia
127 W. State Street
Ithaca, NY 14850
US
Phone:
Email: maureen.stillman@nokia.com
Michael Tuexen
Muenster Univ. of Applied Sciences
Stegerwaldstr. 39
48565 Steinfurt
Germany
Email: tuexen@fh-muenster.de
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Aron J. Silverton
Motorola, Inc.
1301 E. Algonquin Road
Room 2246
Schaumburg, IL 60196
USA
Phone: +1 847-576-8747
Email: aron.j.silverton@motorola.com
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Full Copyright Statement
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contained in BCP 78, and except as set forth therein, the authors
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Xie, et al. Expires September 29, 2008 [Page 41]
