Generic Routing Encapsulation over CLNS Networks
RFC 3147
Document | Type |
RFC - Informational
(July 2001; No errata)
Was draft-christian-gre-over-clnp (individual)
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Author | Philip Christian | ||
Last updated | 2013-03-02 | ||
Stream | Legacy stream | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 3147 (Informational) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group P. Christian Request for Comments: 3147 Nortel Networks Category: Informational July 2001 Generic Routing Encapsulation over CLNS Networks Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard of any kind. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2001). All Rights Reserved. Abstract This document proposes a method for transporting an arbitrary protocol over a CLNS (Connectionless Network Service) network using GRE (Generic Routing Encapsulation). This may then be used as a method to tunnel IPv4 or IPv6 over CLNS. 1. Introduction RFC 2784 Generic Routing Encapsulation (GRE) [1] provides a standard method for transporting one arbitrary network layer protocol over another arbitrary network layer protocol. RFC 1702 Generic Routing Encapsulation over IPv4 networks [2] provides a standard method for transporting an arbitrary network layer protocol over IPv4 using GRE. However no standard method exists for transporting other network layer protocols over CLNS. This causes lack of interoperability between different vendors' products as they provide solutions to migrate from CLNS networks to IP networks. This is a problem specifically in, but not limited to, the context of management networks for SONET and SDH networks elements. Large networks exist for the purpose of providing management communications for SONET and SDH network elements. Standards Bellcore GR-253-CORE [3] and ITU-T G.784 [4] mandate that these networks are based on CLNS. Christian Informational [Page 1] RFC 3147 Generic Routing Encapsulation over CLNS Networks July 2001 Many vendors have already started to offer SONET and SDH products that are managed by IP instead of CLNS and a general migration from CLNS towards IP is anticipated within the industry. Part of any migration strategy from CLNS to IP should provide for the co-existence of both CLNS managed and IP managed network elements in the same network. Such a migration strategy should foresee the need to manage existing CLNS managed network elements that become isolated by a new IP network. Such a scenario may be tackled by tunnelling CLNP PDUs over IP using the existing GRE standard RFC 2784 [1] and informational RFC 1702 [2]. Networks have already been deployed that use this method. Such a migration strategy should also foresee the need to manage new IP managed network elements that are installed on the far side of existing CLNS managed network. Such a scenario requires a method for tunnelling IP over CLNS. 2. GRE over CLNS advantages Using GRE to tunnel IP over CLNS offers some advantages. In the absence of a standard for tunnelling IP over CLNS, GRE as specified in RFC 2784 [1] is the most applicable standard that exists. The move from CLNS to IP comes at a time when IP is itself migrating from IPv4 to IPv6. GRE defines a method to tunnel any protocol that has an Ethernet Protocol Type. Therefore by defining a method for CLNS to transport GRE, a method will then exist for CLNS to transport any other protocol that has an Ethernet Protocol Type defined in RFC 1700 [5]. Thus GRE over CLNS can be used to tunnel both IPv4 and IPv6. GRE is already commonly used to tunnel CLNP PDUs over IP and so using GRE to tunnel IP over CLNS gives a common approach to tunnelling and may simplify software within network elements that initiate and terminate tunnels. The only disadvantage of using GRE is the extra minimum of four bytes that will be used between CLNP header and IP payload packet. Given the large size of CLNP headers this will not make a significant difference to the performance of any network that has IP over CLNP PDUs present on it. Christian Informational [Page 2] RFC 3147 Generic Routing Encapsulation over CLNS Networks July 2001 3. Transporting GRE packets over CLNS. It is suggested that GRE should be transported over CLNS at the lowest layer possible, which is as a transport layer protocol over the network layer. This can be achieved by placing the entire GRE packet inside a CLNP Data Type PDU (DT PDU) as data payload. The GRE packet is a GRE packet as defined in RFC 2784 [1], in other words GRE header plus payload packet. Data payload is the part of a Data PDU that is described as "Data" in the structure of a Data PDU in ISO/IEC 8473-1 [6]. Christian Informational [Page 3]Show full document text