IPv6 Tunnel Broker with the Tunnel Setup Protocol (TSP)Viagenie2600 boul. Laurier, suite 625QuebecQCG1V 4W1Canada+1-418-656-9254Marc.Blanchet@viagenie.caBeon SolutionsQuebecQCCanada+1 418 353 0857Florent.Parent@beon.ca
Operations
IPv6TunnelTransitionTSP
A tunnel broker with the Tunnel Setup Protocol (TSP) enables the
establishment of tunnels of various inner protocols, such as IPv6 or
IPv4, inside various outer protocols packets, such as IPv4, IPv6 or
UDP over IPv4 for IPv4 NAT traversal. The control protocol (TSP) is
used by the tunnel client to negotiate the tunnel with the broker. A
mobile node implementing TSP can be connected to both IPv4 and IPv6
networks whether it is on IPv4 only, IPv4 behind a NAT or on IPv6
only. A tunnel broker may terminate the tunnels on remote tunnel
servers or on itself. This document describes the TSP protocol within
the model of the tunnel broker model.
This document first describes the TSP framework, the protocol details,
and the different profiles used. It then describes the applicability
of TSP in different environments, some of which were described in the
v6ops scenario documents.
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 .
Tunnel Setup Protocol (TSP) is a signaling protocol to setup tunnel
parameters between two tunnel end-points. TSP is implemented as a tiny
client code in the requesting tunnel end-point. The other end-point
is the server that will setup the tunnel service. TSP uses XML basic messaging over TCP or UDP.
The use of XML gives extensibility and easy option processing.
TSP negotiates tunnel parameters between the two tunnel
end-points. Parameters that are always negociated are:
authentication of the users, using any kind of authentication
mechanism (through SASL ) including
anonymous
Tunnel encapsulation
IPv6 over IPv4 tunnels
IPv4 over IPv6 tunnels
IPv6 over UDP-IPv4 tunnels for NAT traversal
IP address assignment for the tunnel endpoints
DNS registration of the IP end point address (AAAA)
Other tunnel parameters that may be negotiated are:
Tunnel keep-alive
IPv6 prefix assignment when the client is a router
DNS delegation of the inverse tree, based on the IPv6 prefix assigned
Routing protocols
The tunnel encapsulation can be explicitly specified by the client, or
can be determined during the TSP exchange by the broker. The latter is used to
detect the presence of NAT in the path and select IPv6 over UDP-IPv4
encapsulation.
The TSP connection can be established between two nodes, where each
node can control a tunnel end-point.
The nodes involved in the framework are:
the TSP clientclient tunnel end-pointthe TSP serverserver tunnel end-point
1,3 and 4 form the tunnel broker model ,
where 3 is the tunnel broker and 4 is the tunnel server (). The tunnel broker may control one or many
tunnel servers.
In its simplest model, one node is the client configured as a tunnel
end-point (1 and 2 on same node), and the second node is the server
configured as the other tunnel end-point (3 and 4 on same node). This
model is shown in
From the point of view of an operating system, TSP is implemented as a
client application which is able to configure network parameters of
the operating system.
TSP is also used to discover if a NAT is in the path. In this
discovery mode, the client sends a TSP message over UDP, containing
its tunnel request information (such as its source IPv4 address) to
the TSP server. The TSP server compares the IPv4 source address of the
packet with the address in the TSP message. If they differ, one or
many IPv4 NAT is in the path.
If an IPv4 NAT is discovered, then IPv6 over UDP-IPv4 tunnel encapsulation is
selected. Once the TSP signaling is done, the tunnel is established over the
same UDP channel used for TSP, so the same NAT address-port mapping is used
for both the TSP session and the IPv6 traffic. If no IPv4 NAT is detected in
the path by the TSP server, then IPv6 over IPv4 encapsulation is used.
A keep-alive mechanism is also included to keep the NAT
mapping active.The IPv4 NAT discovery builds the most effective tunnel for all
cases, including in a dynamic situation where the client moves.
TSP is used to negotiate IPv6 over IPv4 tunnels, IPv6 over UDP-IPv4
tunnels and IPv4 over IPv6 tunnels. IPv4 over IPv6 tunnels are used
in the Dual Stack Transition Mechanism (DSTM) together with TSP .
When a node moves to a different IP network (i.e. change of its IPv4
address when doing IPv6 over IPv4 encapsulation), the TSP client
reconnects automatically to the broker to re-establish the tunnel
(keep-alive mechanism). On the IPv6 layer, if the client uses user
authentication, the same IPv6 address and prefix are kept and
re-established, even if the IPv4 address or tunnel encapsulation type
changes.
Tunnels established by TSP are static tunnels, which are more secure
than automated tunnels (). No 3rd party relay
required.
Stability of the IP address and prefix, enabling applications needing
stable address to be deployed and used. For example, when tunneling
IPv6, there is no dependency on the underlying IPv4 address.
Prefix assignment supported. Can use provider address space.
Signaling protocol flexible and extensible (XML, SASL)
One solution to many encapsulation techniques: v6 in v4, v4 in v6, v6
over UDP over v4. Can be extended to other encapsulation types, such
as v6 in v6.
Discovery of IPv4 NAT in the path, establishing the most optimized
tunnelling technique depending on the discovery.
In a tunnel broker model, the broker is taking charge of all
communication between tunnel servers (TS) and tunnel clients
(TC). Tunnel clients query brokers for a tunnel and the broker finds a
suitable tunnel server, asks the Tunnel server to setup the tunnel and
sends the tunnel information to the Tunnel Client.
Tunnel Servers are providing the specific tunnel service to a Tunnel
Client. It can receive the tunnel request from a Tunnel Broker (as in
the Tunnel Broker model) or directly from the Tunnel Client. The
Tunnel Server is the tunnel end-point.
The tunnel client is the entity that needs a tunnel for a particular
service or connectivity. A tunnel client can be either a host or a
router. The tunnel client is the other tunnel end-point.
IPv6-over-IPv4 tunnel encapsulation
IPv6-over-UDP-over-IPv4 tunnel encapsulation
IPv4-over-IPv6 tunnel encapsulation
The following diagrams describe typical TSP scenarios. The goal is to establish
a tunnel between Tunnel client and Tunnel server.
The Tunnel Setup Protocol is initiated from a client node to a
tunnel broker. The Tunnel Setup Protocol has three phases:
The Authentication phase is when the tunnel broker/server
advertises its capability to a tunnel client and when a tunnel
client authenticate to the broker/server.
The command phase is where the client requests or updates a
tunnel.
The response phase is where the tunnel client receives the
request response from the tunnel broker/server, and the client
accepts or rejects the tunnel offered.
For each command sent by a Tunnel Client there is an expected response
by the server.
After the response phase is completed, a tunnel is established as
requested by the client. If requested, periodic keep-alive packets can
be sent from the client to the server.
The following sections describes in detail the TSP protocol and the
different phases in the TSP signaling.
TSP signaling can be transported over TCP or UDP, and over IPv4 or
IPv6. The tunnel client selects the transport according to the
tunnel encapsulation to be requested. shows the transport used for TSP
signaling with possible tunnel encapsulation requested.
TSP signaling over UDP/v4 MUST be used if a v6 over UDP over IPv4
(v6udpv4) tunnel is to be requested (e.g., for NAT traversal).
Note that the TSP framework allows for other type of encapsulation
to be defined, such as IPv6 over GRE or IPv6 over IPv6.
TSP over TCP is sent over port number 3653 (IANA assigned). TSP
data used during signaling is detailed in the next sections.
While TCP provides the connection-oriented and reliable data
delivery features required during the TSP signaling session, UDP
does not offer any reliability. This reliability is added inside the
TSP session as an extra header at the beginning of the UDP payload.
The algorithm used to add reliability to TSP packets sent over UDP is
described in section 22.5 in .
The four bit field (0-3) is set to 0xF. This marker is used by
the tunnel broker to identify a TSP signaling packets that is sent
after an IPv6 over UDP is established. This is explained in section
28 bit field. Set by the tunnel client. Value is increased by one for
every new packet sent to the tunnel broker. The return packet from
the broker contains the unaltered sequence number.
32 bit field. Set by the tunnel client. Generated from the client
local time value. The return packet from the broker contains the
unaltered timestamp.
Same as in the TCP/v4 case. Content described in latter sections.
The TSP client builds its UDP packet as described above and sends it
to the tunnel broker. When the tunnel broker responds, the same
values for the sequence number and timestamp MUST be sent back to
the client. The TSP client can use the timestamp to determine the
retransmission timeout (current time minus the packet
timestamp). The client SHOULD retransmit the packet when the
retransmission timeout is reached. The retransmitted packet MUST use
the same sequence number as the original packet so that the server
can detect duplicate packets. The client SHOULD use exponential
backoff when retransmitting packets to avoid network congestion.
The authentication phase has 3 steps :
Client's protocol version identificationServer's capability advertisementClient authentication
When a TCP or UDP session is established to a tunnel
broker, the tunnel client sends the current protocol
version it is supporting. The version number syntax is:
VERSION=2.0.0 CR LF
Version 2.0.0 is the version number of this specification. Version 1.0.0 was
defined in earlier drafts.
If the server doesn't support the protocol version it sends an error message
and closes the session. The server can optionally send a server list that may
support the protocol version of the client.
If the server supports the version sent by the client, then the server sends a
list of the capabilities supported for authentication and tunnels.
CAPABILITY TUNNEL=V6V4 TUNNEL=V6UDPV4
AUTH=ANONYMOUS AUTH=PLAIN AUTH=DIGEST-MD5 CR LF
Tunnel types must be registered with IANA and their profiles are defined in
. Authentication is done using SASL. Each authentication mechanism should be a
registered SASL mechanism. Description of such mechanisms is not in the scope
of this document.
The tunnel client can then choose to close the session if none of the
capabilities fits its needs. If the tunnel client chooses to continue,
it authenticates to the server using one of the advertised mechanism
using SASL. If the authentication fails, the server sends an error
message and closes the session.
The example in shows a failed
authentication where the tunnel client requests an anonymous
authentication which is not supported by the server.
Note that linebreaks and indentation within a "C:" or "S:" are
editorial and not part of the protocol.
shows a successful anonymous
authentication.
Digest-MD5 authentication with SASL follows . shows a successgul digest-md5
SASL authentication.
The base64-decoded version of the SASL exchange is:
Once the authentication succeeds, the server sends a success return
code and the protocol enters the Command phase.
The Command phase is where the tunnel client send a tunnel request
or a tunnel update to the server. In this phase, commands are sent
as XML messages. The first line is a "Content-length" directive
that indicates the size of the following XML message. When the
server sends a response, the first line is the "Content-length"
directive, the second is the return code and third one is the XML
message if any. The "Content-length" is calculated from the first
character of the return code line to the last character of the XML
message, inclusively.
Spaces can be inserted freely.
The example in shows a
client requesting an anonymous v6udpv4 tunnel, indicating that a
keep-alive packet will be sent every 30 seconds. The tunnel broker
responds with the tunnel parameters and indicates its acceptance of
the keepalive period (). Finally, the
client sends an accept message to the server.
Once the accept message has been sent, the server and client
configure their tunnel endpoint based on the negotiated tunnel
parameters.
Once the TSP signaling is completed, a tunnel can be established
on the tunnel server and client node. If a v6v4 tunnel has been
negotiated, then an IPv6-over-IPv4 tunnel is established using the operating system tunneling
interface. On the client node, this is accomplished by the TSP
client calling the appropriate OS commands or system calls.
If a v6udpv4 tunnel is configured, the same source/destination
address and port used during the TSP signaling are used to configure
the v6udpv4 tunnel. If a NAT is in the path between the TSP client
and tunnel broker, the TSP signaling session will have created a UDP
state in the NAT. By reusing the same UDP socket parameters to
transport IPv6, the traffic will flow across the NAT using the same
state.
At any time, a client may re-establish a TSP signaling
session. The client disconnects the current tunnel and starts a
new TSP signaling session as described in . If a NAT is present and the new TSP
session uses the same UDP mapping in the NAT as for the tunnel,
the tunnel broker will need to disconnect the client tunnel before
the client can establish a new TSP session.
A TSP client may select to send periodic keep-alive messages to
the server in order to maintain its tunnel connectivity. This
allows the client to detect network changes and enable automatic
tunnel re-establishment. In the case of IPv6-over-UDP tunnels,
periodic keep-alive can help refresh the connection state in a NAT
if such device is in the tunnel path.
For IPv6-over-IPv4 and IPv6-over-UDP tunnels, the keep-alive
message is an ICMPv6 echo request sent
from the client to the tunnel server. The IPv6 destination address
of the echo message MUST be the address from the 'keepalive'
element sent in the tunnel response during the TSP signaling
(). The echo message is sent
over the configured tunnel.
The tunnel server responds to the ICMPv6 echo requests and can
keep track of which tunnel is active. Any client traffic can also
be used to verify if the tunnel is active. This can be used by the
broker to disconnect tunnels that are no longer in use.
The broker can send a different keep-alive interval from the value
specified in the client request. The client MUST conform to the
broker specified keep-alive interval. The client SHOULD apply a
random "jitter" value to avoid synchronization of keep-alive
messages from many clients to the server . This
is achieved by using an interval value in the range of [0.75T -
T], where T is the keep-alive interval specified by the server.
This section describes the XML messaging used in the TSP signaling
during the command and response phase. The XML elements and
attributes are listed in the DTD ().
The client and server use the tunnel token with an action
attribute. Valid actions for this profile are : 'create',
'delete', 'info', 'accept' and 'reject'.
action used to request a new tunnel or update an existing
tunnel. Sent by the tunnel client.
action used to remove an existing tunnel from the server. Sent by
the tunnel client.
action used to request current properties of an existing
tunnel. This action is also used by the tunnel broker to send tunnel
parameters following a client 'create' action.
action used by the client to acknowledge the server that the tunnel
parameters are accepted. The client will establish a tunnel.
action used by the client to signal the server that the tunnel
parameters offered are rejected and no tunnel will be established.
The tunnel 'lifetime' attribute is set by the tunnel broker and
specifies the lifetime of the tunnel in minutes. The lifetime is an
administratively set value. When a tunnel lifetime is expired, it is
disconnected on the tunnel server.
The 'tunnel' message contains three elements:
Client's informationServer's informationList of other server's
The client element contains 3 sub-elements: 'address', 'router'
and 'keepalive'. These elements are used to describe the client
request and will be used by the server to create the appropriate
tunnel. The client element is the only element sent by a client.
The 'address' element is used to identify the client IP endpoint
of the tunnel. When tunneling over IPv4, the client MUST send
only its IPv4 address to the server. When tunneling over IPv6,
the client MUST only send its IPv6 address to the server.
The broker then returns the assigned IPv6 or IPv4 address
endpoint and domain name inside the 'client' element when the
tunnel is created or updated. If supported by the broker, the
'client' element MAY contain the registered DNS name for the
address endpoint assigned to the client.
Optionally a client MAY send a 'router' element to ask for
a prefix delegation.
Optionally, a client MAY send a 'keepalive' element which
contains the keep-alive time interval requested by the client.
The 'server' element contains 2 elements: 'address' and
'router'. These elements are used to describe the server's
tunnel endpoint. The 'address' element is used to provide both
IPv4 and IPv6 addresses of the server's tunnel endpoint, while
the 'router' element provides information for the routing method
chosen by the client.
The 'broker' element is used by a tunnel broker to provide a
alternate list of brokers to a client in the case where the
server is not able to provide the requested tunnel.
The 'broker' element contains a series of 'address' element(s).
This section presents multiple examples of requests.
A simple tunnel request consist of a 'tunnel' element which
contains only an 'address' element. The tunnel action is
'create', specifying a 'v6v4' tunnel encapsulation type. The
response sent by the tunnel broker is an 'info' action. Note
that the registered FQDN of the assigned client IPv6 address is
also returned to the tunnel client.
A tunnel request with prefix consist of a 'tunnel' element which
contains 'address' element and a 'router' element. The 'router'
element also contains the 'dns_server' element which is used to
request DNS delegation of the assigned IPv6 prefix. The
'dns_server' element lists the IP address of the DNS servers to
be registered for the reverse-mapping zone.
This is similar to the previous 'create' action, but with the
tunnel type is set to 'v4v6'.
If the allocation request is accepted, the broker will acknowledge the
allocation to the client by sending a 'tunnel' element with the
attribute 'action' set to 'info', 'type' set to 'v4v6' and the
'lifetime' attribute set to the period of validity or lease time of
the allocation. The 'tunnel' element contains 'server' and 'client'
elements.
In DSTM
terminology, the DSTM server is the TSP broker and the TEP
is the tunnel server.
When a client is capable of both IPv6 over IPv4 and IPv6 over UDP over
IPv4 encapsulation, it can request the broker, by using the "v6anyv4"
tunnel mode, to determine if it is behind a NAT and to send the
appropriate tunnel encapsulation mode as part of the response. The
client can also explicitly request an IPv6 over UDP over IPv4 tunnel
by specifying "v6udpv4" in its request.
In the following example, the client informs the broker that it
requests to send keep-alives every 30 seconds. In its response, the
broker accepted the client suggested keep-alive interval, and the
IPv6 destination address for the keep-alive packets is specified.
This section describes the applicability of TSP in different networks.
In a provider network where IPv4 is dominant, a tunnelled
infrastructure can be used to provide IPv6 services to the enterprise
customers, before a full IPv6 native infrastructure is built. In
order to start deploying in a controlled manner and to give enterprise
customers a prefix, the TSP framework is used. The TSP server can be
in the core, in the aggregation points or in the PoPs to offer the
service to the customers. IPv6 over IPv4 encapsulation can be used. If
the customers are behind an IPv4 NAT, then IPv6 over UDP-IPv4
encapsulation can be used. TSP can be used in combination of other
techniques.
In a provider network where IPv4 is dominant, a tunnelled
infrastructure can be used to provider IPv6 services to the home/small
office customers, before a full IPv6 native infrastructure is built.
The small networks such as Home/Small offices have a non-upgradable
gateway with NAT. TSP with NAT traversal is used to offer IPv6
connectivity and a prefix to the internal network.
Automation of the prefix assignment and DNS delegation, done by TSP,
is a very important feature for a provider in order to substantially
decrease support costs. The provider can use the same AAA database
that is used to authenticate the IPv4 broadband users. Customers can
deploy home IPv6 networks without any intervention of the provider
support people.
With the NAT discovery function of TSP, providers can use the same TSP
infrastructure for both NAT and non-NAT parts of the network.
In an enterprise network where IPv4 is dominant, a tunnelled
infrastructure can be used to provider IPv6 services to the IPv6
islands (hosts or networks) inside the enterprise, before a full IPv6
native infrastructure is built . TSP can be
used to give IPv6 connectivity, prefix and routing for the
islands. This gives to the enterprise a full control deployment of
IPv6 while maintaining automation and permanence of the IPv6
assignments to the islands.
In a wireless network where IPv4 is dominant, hosts and networks move
and change IPv4 address. TSP enables the automatic re-establishment of
the tunnel when the IPv4 address change.
In a wireless network where IPv6 is dominant, hosts and networks
move. TSP enables the automatic re-establishment of the IPv4 over IPv6
tunnel.
An unmanaged network is where no network manager or staff is available
to configure network devices . TSP is
particularly useful in this context where automation of all necessary
information for the IPv6 connectivity is handled by TSP: tunnel
end-points parameters, prefix assignment, dns delegation, routing.
An unmanaged network may be behind a NAT, maybe not. With the NAT
discovery function, TSP works automatically in both cases.
Mobile hosts are common and used. Laptops moving from wireless, wired
in office, home, ... are examples. They often have IPv4 connectivity,
but not necessarily IPv6. TSP framework enables the mobile hosts to
have IPv6 connectivity wherever they are, by having the TSP client
send updated information of the new environment to the TSP server,
when a change occurs. Together with NAT discovery and traversal, the
mobile host can be always IPv6 connected wherever it is.
Mobile here means only the change of IPv4 address. Mobile-IP mechanisms
and fast hand-off take care of additional constraints in mobile
environments.
Mobile networks share the applicability of the mobile hosts. Moreover,
in the TSP framework, they also keep their prefix assignment and can
control the routing. NAT discovery can also be used.
A tunnel type registry should be setup by IANA. The following strings
are defined in this document:
"v6v4" for IPv6 in IPv4 encapsulation (using IPv4 protocol 41)"v6udpv4" for IPv6 in UDP in IPv4 encapsulation"v6anyv4" for IPv6 in IPv4 or IPv6 in UDP in IPv4 encapsulation"v4v6" for IPv4 in IPv6 encapsulation.
Registration of a new tunnel type can be obtained on a first come
first served policy . A new registration
should provide a point of contact, the tunnel type string, and a brief
description on the applicability.
IANA assigned 3653 as the TSP port number.
Authentication of the TSP session uses the SASL framework, where the authentication mechanism is negotiated between
the client and the server. The framework uses the level of
authentication needed for securing the session, based on the policies.
Static tunnels are created when the TSP negotiation is
terminated. Static tunnels are not open gateways and exhibit less
security issues than automated tunnels. Static IPv6 in IPv4 tunnels
security considerations are described in .
In order to help ensure that the traffic is traceable to its correct
source network, a tunnel server implementation should allow ingress
filtering on the user tunnel .
A customer A behind a NAT can use a large number of (private) IPv4
addresses and/or source ports and request multiple v6udpv4
tunnels. That would quickly saturate the tunnel server capacity. The
tunnel broker implementation should offer a way to throttle and limit
the number of tunnel established to the same IPv4 address.
The Tunnel Setup Protocol (TSP) is applicable in many environments,
such as: providers, enterprises, wireless, unmanaged networks, mobile
hosts and networks. TSP gives the two tunnel end-points the ability
to negotiate tunnel parameters, as well as prefix assignment, dns
delegation and routing in an authenticated session. It also provides
IPv4 NAT discovery function by using the most effective encapsulation.
It also supports the IPv4 mobility of the nodes.
This draft is the merge of many previous drafts about TSP. Octavio
Medina has contributed to an earlier draft (IPv4 in IPv6). Thanks
to the following people for comments on improving and clarifying
this document: Pekka Savola, Alan Ford, Jeroen Massar and
Jean-Francois Tremblay.Key words for use in RFCs to Indicate Requirement LevelsHarvard University1350 Mass. Ave.CambridgeMA 02138- +1 617 495 3864sob@harvard.edu
General
keyword
In many standards track documents several words are used to signify
the requirements in the specification. These words are often
capitalized. This document defines these words as they should be
interpreted in IETF documents. Authors who follow these guidelines
should incorporate this phrase near the beginning of their document:
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
RFC 2119.
Note that the force of these words is modified by the requirement
level of the document in which they are used.
Simple Authentication and Security Layer (SASL)Using Digest Authentication as a SASL MechanismInternet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) SpecificationExtensible Markup Language (XML) 1.0 (Third Edition)Basic Transition Mechanisms for IPv6 Hosts and RoutersGeneric Packet Tunneling in IPv6 SpecificationLucent Technologies Inc.300 Baker AveConcordMA01742-2168USA+1 978 287 2842aconta@lucent.comCisco Systems170 West Tasman DrSan JoseCA95132-1706USA+1-408-527-8213deering@cisco.com
Internet
encapsulateinternet protocol version 6IPv6tunnel
This document defines the model and generic mechanisms for IPv6
encapsulation of Internet packets, such as IPv6 and IPv4. The model
and mechanisms can be applied to other protocol packets as well, such
as AppleTalk, IPX, CLNP, or others.
Ingress Filtering for Multihomed NetworksGuidelines for Writing an IANA Considerations Section in RFCsIBM Corporation3039 Cornwallis Ave.PO Box 12195 - BRQA/502Research Triangle ParkNC 27709-2195919-254-7798narten@raleigh.ibm.comMaxwarePirsenteretN-7005 TrondheimNorway+47 73 54 57 97Harald@Alvestrand.no
General
Internet Assigned Numbers AuthorityIANA
Many protocols make use of identifiers consisting of constants and
other well-known values. Even after a protocol has been defined and
deployment has begun, new values may need to be assigned (e.g., for a
new option type in DHCP, or a new encryption or authentication
algorithm for IPSec). To insure that such quantities have consistent
values and interpretations in different implementations, their
assignment must be administered by a central authority. For IETF
protocols, that role is provided by the Internet Assigned Numbers
Authority (IANA).
In order for the IANA to manage a given name space prudently, it
needs guidelines describing the conditions under which new values can
be assigned. If the IANA is expected to play a role in the management
of a name space, the IANA must be given clear and concise
instructions describing that role. This document discusses issues
that should be considered in formulating a policy for assigning
values to a name space and provides guidelines to document authors on
the specific text that must be included in documents that place
demands on the IANA.
Security Considerations for 6to4IPv6 Tunnel BrokerDual Stack IPv6 Dominant Transition MechanismIPv6 Enterprise Network ScenariosEvaluation of IPv6 Transition Mechanisms for Unmanaged NetworksUnix Network Programming, 3rd editionThe Synchronization of Periodic Routing MessagesLawrence Berkeley LaboratoryLawrence Berkeley Laboratory
Error codes are sent as a numeric value followed by a text message
describing the code, similar to SMTP. The codes are sent from the
broker to the client. The currently defined error codes are showned
below. Upon receiving an error, the client will display the
appropriate message to the user.
New error messages may be defined in the future. For interoperability
purpose, the error code range to use should be from 300 to 599.
The reply code 200 is used to inform the client that an action
successfully completed. For example, this reply code is used in
response to an authentication request and a tunnel creation request.
The server may redirect the client to another broker. The details on
how these brokers are knowned or discovered is beyond the scope of
this document. When a list of tunnel brokers follows the error code
as a referal service, then 1000 is added to the error code.
The predefined values are :
Successful operation
Invalid userid, password or authentication mechanism.
The server has reached its capacity limit.
The client version is not supported by the server.
The server does not provide the requested tunnel type.
Undefined server error.
Received request has invalid syntax or truncated
IPv4 address specified by the client is invalid
IPv6 address specified by the client is invalid
A IPv6-over-IPv4 tunnel already exists using the same IPv4 address
endpoints.
The requested prefix length cannot be allocated on the server
The client tunnel request is being processed by the server. Temporary
error.
Request cannot be process, insufficient resources. Temporary error.