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Network Working Group O. Gsenger
Internet-Draft March 2007
Expires: September 2, 2007
Anycast stream relaying
draft-gsenger-anycast-relay-00
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on September 2, 2007.
Copyright Notice
Copyright (C) The IETF Trust (2007).
Gsenger Expires September 2, 2007 [Page 1]
Internet-Draft Anycast stream relaying March 2007
Abstract
The anycast tunneling (anytun) protocol defines a protocol used for
communication between unicast clients and anycast servers. It can be
used for tunneling information between 2 clients over the servers or
in relay mode to transmit data form the client over the servers to a
third party not using the protocol and vice versa.
Gsenger Expires September 2, 2007 [Page 2]
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1. Introduction
anytun defines a Host Anycast Service as defined in rfc1546. It can
be used to build high scalable and redundant tunnel services. It
supports both UDP and TCP connections. Additionally to the
possibility of establashing an unicast TCP connection over an anycast
address as suggested in rfc1546, it supports real anycast TCP
connections with state syncronisation and heuristic state forecast.
It also has a relay mode, that makes it possible, that only one of
the connection endpoints has to use the anytun protocol. This can be
used to make connections through Firewalls or behind a NAT Router
RFC3068 [1] DTD.
Gsenger Expires September 2, 2007 [Page 3]
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2. Operation modes
This section gives an overview of possible operation modes und usage
scenarios. Please note, that the protocols used in the figures are
only examples and that anytun itself does not care about either
transport protocols or encapsulated protocols. Routing and network
address translation is not done by anytun. Each implemetation MAY
choose it's own way of doing this task (e.g. using functions provided
by the operating system). Anytun is used to establish and controll
tunnnels, to encapsulate and encrypt data.
2.1. Tunnel modes
2.1.1. Tunneling Mode
An example of anytun used in tunnel mode
----------- -----------
| RTP | ---------- | RTP |
----------- -> |server 1| -> -----------
| UDP | ---------- | UDP |
----------- -----------
----- | IPv6 | ---------- | IPv6 | -----
| | -> ----------- -> |server 2| -> ----------- -> | |
----- | anytun | ---------- | anytun | -----
##### ----------- ----------- #####
| UDP | ---------- | UDP |
client 1 ----------- -> |server 3| -> ----------- client 2
| IPv4 | ---------- | IPv4 |
----------- -----------
| ... | anycast | ... |
Figure 1
In tunneling mode the payload of the anytun packet is transmitted
from one unicast host to the anycast server. This server makes a
routing descision based on the underlying protocol and transmits a
new anytun package to one or more clients depending on the routing
descition. The server MAY also route the packet to a directly
connected network or a service running on the server, but please
note, that this is only usefull for anycast host services like DNS
and that the services HAVE TO be running on all servers in order to
work.
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2.1.2. Open tunnel mode
An example of anytun used in open tunnel mode
-----------
| RTP | ----------
----------- -> |server 1| ->
| UDP | ---------- -----------
----------- | RTP |
----- | IPv6 | ---------- ----------- -----
| | -> ----------- -> |server 2| -> | UDP* | -> | |
----- | anytun | ---------- ----------- -----
##### ----------- | IPv6* | #####
| UDP | ---------- -----------
client 1 ----------- -> |server 3| -> | ... | host
| IPv4 | ---------- not using
----------- anytun
| ... | anycast
*changed source address
or port
Figure 2
In open tunnel mode only one of two clients talking to each other
over the servers MUST use the anytun protocol. When a client using
the anytun protocol wants to tunnel data, it is building a connection
to the anycast servers using the anytun protocol. The anycast
servers relay the encapsulated packages directly to the destination
without using the anytun protocol. The source address of the
datagramm HAS TO be changed to the anycast address of the server.
The anytun servers act like a source NAT router, therefor for the
destination it saems that it is talking to the client directly.
Gsenger Expires September 2, 2007 [Page 5]
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2.1.3. relay mode
An example of anytun used in relay mode
-----------
----- | RTP | ----------
| | -> ----------- -> |server 1| ->
----- | UDP** | ---------- -----------
##### ----------- | RTP |
| IPv6**| ---------- ----------- -----
host ----------- -> |server 2| -> | UDP* | -> | |
not using | ... | ---------- ----------- -----
anytun | IPv6* | #####
---------- -----------
----------- -> |server 3| | ... | host
----- | anytun | ---------- not using
| | -> ----------- anytun
----- | IPv4 | anycast
##### -----------
connection| ... |
controller
*changed source address or port
**changed destination address or port
Figure 3
In relay mode the anycast serveres directly repaet the packetes of
clients, only the source and destination addresses are changed. The
anytun protocol is only used for controll messages, but not fr
encapsulation.
2.2. Transport modes
Gsenger Expires September 2, 2007 [Page 6]
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2.2.1. anycast udp mode
An example of anytun used with udp transport
----------- -----------
| RTP | ---------- | RTP |
----------- -> |server 1| -> -----------
| UDP | ---------- | UDP |
----------- -----------
----- | IPv6 | ---------- | IPv6 | -----
| | -> ----------- -> |server 2| -> ----------- -> | |
----- | anytun | ---------- | anytun | -----
##### ----------- ----------- #####
| UDP | ---------- | UDP |
client 1 ----------- -> |server 3| -> ----------- client 2
| IPv4 | ---------- | IPv4 |
----------- -----------
| ... | anycast | ... |
Figure 4
In anycast udp mode the data between clients and anycast serveres is
carried by udp packets. Packets are routed by the serveres from one
client to another. Because udp is stateless no inforamtion has to be
syncronised
2.2.2. anycast light udp mode
An example of anytun used with udp transport
----------- -----------
| RTP | ---------- | RTP |
----------- -> |server 1| -> -----------
| UDP | ---------- | UDP |
----------- -----------
----- | IPv6 | ---------- | IPv6 | -----
| | -> ----------- -> |server 2| -> ----------- -> | |
----- | anytun | ---------- | anytun | -----
##### ----------- ----------- #####
|lightUDP | ---------- |lightUDP |
client 1 ----------- -> |server 3| -> ----------- client 2
| IPv4 | ---------- | IPv4 |
----------- -----------
| ... | anycast | ... |
Figure 5
The light UDP mode is neerly the same as the normal UDP mode, the
Gsenger Expires September 2, 2007 [Page 7]
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only difference is, that the udp size is set to the udp header lenght
and not to the length of the full packet and therefor the checksum is
only calculated for the udp header itself. So there is no error
correction or detection done on the payload. This can be usefull if
realtime data is beeing transimittet or the tunneled protocol does
error correction/detection by itself.
2.2.3. Protocol specification
2.2.3.1. Header format
2.2.3.2. Protocol field
The protocol field defines the payload protocol. ETHER TYPE protocol
numerbers are used. http://www.iana.org/assignments/ethernet-numbers
. The values 0000-05DC are reserverd and not used at the moment.
Some exmples for protocol types
HEX
0000 Reserved
.... Reserved
05DC Reserved
0800 Internet IP (IPv4)
6558 transparent ethernet bridging
86DD IPv6
Figure 6
Gsenger Expires September 2, 2007 [Page 8]
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Appendix A. The appan
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3. References
[1] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers",
RFC 3068, June 2001.
Gsenger Expires September 2, 2007 [Page 10]
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Author's Address
Othmar Gsenger
Sporgasse 6
Graz 8010
AT
Phone:
Email: otti@wirdorange.org
URI: http://anytun.org/
Gsenger Expires September 2, 2007 [Page 11]
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Full Copyright Statement
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Gsenger Expires September 2, 2007 [Page 12]
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