Key and Sequence Number Extensions to GRE
RFC 2890
Document | Type |
RFC - Proposed Standard
(September 2000; No errata)
Updates RFC 2784
Was draft-dommety-gre-ext (individual)
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Author | Gopal Dommety | ||
Last updated | 2013-03-02 | ||
Stream | Legacy | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | Legacy state | (None) | |
Consensus Boilerplate | Unknown | ||
RFC Editor Note | (None) | ||
IESG | IESG state | RFC 2890 (Proposed Standard) | |
Telechat date | |||
Responsible AD | (None) | ||
Send notices to | (None) |
Network Working Group G. Dommety Request for Comments: 2890 Cisco Systems Category: Standards Track September 2000 Key and Sequence Number Extensions to GRE Status of this Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (C) The Internet Society (2000). All Rights Reserved. Abstract GRE (Generic Routing Encapsulation) specifies a protocol for encapsulation of an arbitrary protocol over another arbitrary network layer protocol. This document describes extensions by which two fields, Key and Sequence Number, can be optionally carried in the GRE Header [1]. 1. Introduction The current specification of Generic Routing Encapsulation [1] specifies a protocol for encapsulation of an arbitrary protocol over another arbitrary network layer protocol. This document describes enhancements by which two fields, Key and Sequence Number, can be optionally carried in the GRE Header [1]. The Key field is intended to be used for identifying an individual traffic flow within a tunnel. The Sequence Number field is used to maintain sequence of packets within the GRE Tunnel. 1.1. Specification Language The keywords "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 [3]. In addition, the following words are used to signify the requirements of the specification. Dommety Standards Track [Page 1] RFC 2890 Key and Sequence Number Extensions to GRE September 2000 Silently discard The implementation discards the datagram without further processing, and without indicating an error to the sender. The implementation SHOULD provide the capability of logging the error, including the contents of the discarded datagram, and SHOULD record the event in a statistics counter. 2. Extensions to GRE Header The GRE packet header[1] has the following format: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |C| Reserved0 | Ver | Protocol Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Checksum (optional) | Reserved1 (Optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The proposed GRE header will have the following format: 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |C| |K|S| Reserved0 | Ver | Protocol Type | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Checksum (optional) | Reserved1 (Optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Key (optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Sequence Number (Optional) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Key Present (bit 2) If the Key Present bit is set to 1, then it indicates that the Key field is present in the GRE header. Otherwise, the Key field is not present in the GRE header. Sequence Number Present (bit 3) If the Sequence Number Present bit is set to 1, then it indicates that the Sequence Number field is present. Otherwise, the Sequence Number field is not present in the GRE header. The Key and the Sequence Present bits are chosen to be compatible with RFC 1701 [2]. Dommety Standards Track [Page 2] RFC 2890 Key and Sequence Number Extensions to GRE September 2000 2.1. Key Field (4 octets) The Key field contains a four octet number which was inserted by the encapsulator. The actual method by which this Key is obtained is beyond the scope of the document. The Key field is intended to be used for identifying an individual traffic flow within a tunnel. For example, packets may need to be routed based on context information not present in the encapsulated data. The Key field provides this context and defines a logical traffic flow between encapsulator and decapsulator. Packets belonging to a traffic flow are encapsulatedShow full document text