Network Working Group O. Gsenger Internet-Draft March 2007 Expires: September 2, 2007 anycast tunneling and relay protocol 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 time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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 tunneling and relay protocol March 2007 Abstract The anycast tunneling and relay protocol (anytun) defines a protocol used for communication between unicast clients and anycast servers. It can be used for tunneling information between 2 clients over the anycast servers or in relay mode to transmit data form the client over the anycast servers to a third party not using the protocol and vice versa. Unlike other tunneling protocols like GRE or IPIP tunnels which indeed will work with anycast as well, anytun directly includes cryptography and authentication. In relay mode it also supports source NAT with integrated NAT transversal. It is intended to deliver a high performance and reliability solution for tunneling and relaying of data over servers, where direct client to client connections are not possible or not wanted. Gsenger Expires September 2, 2007 [Page 2] Internet-Draft anycast tunneling and relay protocol March 2007 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] Internet-Draft anycast tunneling and relay protocol March 2007 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. Gsenger Expires September 2, 2007 [Page 4] Internet-Draft anycast tunneling and relay protocol March 2007 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] Internet-Draft anycast tunneling and relay protocol March 2007 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 2.2.1. anycast udp mode Anytun does not define wich lower layer protocols HAVE TO be used, but it's most likely used on top of udp. This section should only discuss some issues on udp in combination with anycasting and tunnels. Gsenger Expires September 2, 2007 [Page 6] Internet-Draft anycast tunneling and relay protocol March 2007 2.2.2. Using UDP An example of anytun used with udp as 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 When using UDP no flow controll or retransmission is done, neigther by UDP nor anytun. The encapsulated protocol HAS TO take care of this tasks if needed. UDP however has a checksum of the complete udp datagram, so a packet gets discarded if there is a biterror in the payload 2.2.3. Using lightUDP 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 Gsenger Expires September 2, 2007 [Page 7] Internet-Draft anycast tunneling and relay protocol March 2007 The difference between normal UDP and lightUDP is, that the udp size is not set to the length of the full packet, but to the lenght of the data used for the checksum and therefor the checksum is only calculated for that part. When using lightUDP, the lenght HAS tO be set to the udp header length + the anytun header lenght. 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. 2.2.4. Fragmentation The only way of fully supporting fragmentation would be to syncronise fragments between all anycast servers. This is considered to be to much overhead, so there are two non perfect solutions for this problems. Either fragmentation HAS TO be disabled or if not all fragments arrive at the same server the ip datagramm HAS TO be discarded. As routing changes are not expected to occure very frequently, the encapsulated protocol can do a retransmission and all fragments will arrive at the new server. 2.3. Protocol specification 2.3.1. Header format 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] Internet-Draft anycast tunneling and relay protocol March 2007 Appendix A. The appan Gsenger Expires September 2, 2007 [Page 9] Internet-Draft anycast tunneling and relay protocol March 2007 3. References [1] Huitema, C., "An Anycast Prefix for 6to4 Relay Routers", RFC 3068, June 2001. Gsenger Expires September 2, 2007 [Page 10] Internet-Draft anycast tunneling and relay protocol March 2007 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] Internet-Draft anycast tunneling and relay protocol March 2007 Full Copyright Statement Copyright (C) The IETF Trust (2007). 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