Tunnel broker
Encyclopedia
In the context of computer network
ing, a tunnel broker is a service which provides a network tunnel. These tunnels can provide encapsulated connectivity over existing infrastructure to a new infrastructure.
There are a variety of tunnel brokers, though most commonly the term is used to refer to an IPv6
tunnel broker, as defined in RFC:3053, but it can also refer to an IPv4
tunnel broker.
IPv6 tunnel brokers commonly provide IPv6 tunnels to sites or end users. In general tunnel brokers offer so called 'protocol 41' or proto-41 tunnels. These are tunnels where IPv6 is tunneled directly inside IPv4
by having the protocol
field set to '41' (IPv6) in the IPv4 packet. In the case of IPv4 tunnel brokers IPv4 tunnels are provided to users by encapsulating IPv4 inside IPv6 as defined in RFC:2473.
(TSP), or using Tunnel Information Control protocol (TIC). A client capable of this is AICCU
(Automatic IPv6 Connectivity Client Utility). In addition to IPv6 tunnels TSP can also be used to set up IPv4 tunnels.
s. One way around this is to configure the actual endpoint of the tunnel to be the DMZ
on the NAT-utilizing equipment. Another method is to either use AYIYA or TSP
, both of which send IPv6 inside UDP
, which is able to cross most NAT setups and even firewalls.
A problem that still might occur is that of the timing-out of the state in the NAT machine. As a NAT remembers that a packet went outside to the Internet
it allows another packet to come back in from the Internet that is related to the initial proto-41 packet. When this state expires, no other packets from the Internet will be accepted. This therefore breaks the connectivity of the tunnel until the user's host again sends out a packet to the Tunnel Broker.
or Heartbeat, as used by AICCU. In the case of a tunnel broker using TSP, the client automatically restarting the tunnel will cause the endpoint address and port to be updated.
Computer network
A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow sharing of resources and information....
ing, a tunnel broker is a service which provides a network tunnel. These tunnels can provide encapsulated connectivity over existing infrastructure to a new infrastructure.
There are a variety of tunnel brokers, though most commonly the term is used to refer to an IPv6
IPv6
Internet Protocol version 6 is a version of the Internet Protocol . It is designed to succeed the Internet Protocol version 4...
tunnel broker, as defined in RFC:3053, but it can also refer to an IPv4
IPv4
Internet Protocol version 4 is the fourth revision in the development of the Internet Protocol and the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet...
tunnel broker.
IPv6 tunnel brokers commonly provide IPv6 tunnels to sites or end users. In general tunnel brokers offer so called 'protocol 41' or proto-41 tunnels. These are tunnels where IPv6 is tunneled directly inside IPv4
IPv4
Internet Protocol version 4 is the fourth revision in the development of the Internet Protocol and the first version of the protocol to be widely deployed. Together with IPv6, it is at the core of standards-based internetworking methods of the Internet...
by having the protocol
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
field set to '41' (IPv6) in the IPv4 packet. In the case of IPv4 tunnel brokers IPv4 tunnels are provided to users by encapsulating IPv4 inside IPv6 as defined in RFC:2473.
Automated configuration
Configuration of IPv6 tunnels is usually done using the Tunnel Setup ProtocolTunnel Setup Protocol
In computer networking, the Tunnel Setup Protocol is a networking control protocol used to negotiate IP tunnel setup parameters between a tunnel client host and a tunnel broker server, the tunnel end-points. The protocol is defined in RFC 5572...
(TSP), or using Tunnel Information Control protocol (TIC). A client capable of this is AICCU
AICCU
AICCU is a popular cross-platform utility for automatically configuring an IPv6 tunnel. It is free software available under a BSD license. The utility is originally provided for the SixXS Tunnel Broker but it can also be used by a variety of other tunnel brokers.-History and development:AICCU is...
(Automatic IPv6 Connectivity Client Utility). In addition to IPv6 tunnels TSP can also be used to set up IPv4 tunnels.
NAT Issues
proto-41 tunnels (direct IPv6 in IPv4) may not operate well with NATNetwork address translation
In computer networking, network address translation is the process of modifying IP address information in IP packet headers while in transit across a traffic routing device....
s. One way around this is to configure the actual endpoint of the tunnel to be the DMZ
Demilitarized zone (computing)
In computer security, a DMZ is a physical or logical subnetwork that contains and exposes an organization's external services to a larger untrusted network, usually the Internet...
on the NAT-utilizing equipment. Another method is to either use AYIYA or TSP
Tunnel Setup Protocol
In computer networking, the Tunnel Setup Protocol is a networking control protocol used to negotiate IP tunnel setup parameters between a tunnel client host and a tunnel broker server, the tunnel end-points. The protocol is defined in RFC 5572...
, both of which send IPv6 inside UDP
User Datagram Protocol
The User Datagram Protocol is one of the core members of the Internet Protocol Suite, the set of network protocols used for the Internet. With UDP, computer applications can send messages, in this case referred to as datagrams, to other hosts on an Internet Protocol network without requiring...
, which is able to cross most NAT setups and even firewalls.
A problem that still might occur is that of the timing-out of the state in the NAT machine. As a NAT remembers that a packet went outside to the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
it allows another packet to come back in from the Internet that is related to the initial proto-41 packet. When this state expires, no other packets from the Internet will be accepted. This therefore breaks the connectivity of the tunnel until the user's host again sends out a packet to the Tunnel Broker.
Dynamic Endpoints
When the endpoint isn't a static IP address, the user, or a program, has to instruct the tunnel broker to update the endpoint address. This can be done using the tunnel broker's web site or using an automated protocol like TSPTunnel Setup Protocol
In computer networking, the Tunnel Setup Protocol is a networking control protocol used to negotiate IP tunnel setup parameters between a tunnel client host and a tunnel broker server, the tunnel end-points. The protocol is defined in RFC 5572...
or Heartbeat, as used by AICCU. In the case of a tunnel broker using TSP, the client automatically restarting the tunnel will cause the endpoint address and port to be updated.