Network Services Header Context Allocation Identifier

Document Type Expired Internet-Draft (individual)
Authors Gunter Van de Velde  , Martin Vigoureux  , Praveen Muley 
Last updated 2017-04-20 (latest revision 2016-10-17)
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The specification of the NSH MD Type 1 header [draft-ietf-sfc-nsh] mandates four Context Headers, 4-byte each, and they MUST be added immediately following the Service Path Header. As direct consequence, an NSH MD Type 1 header is always Length 0x6 (six 4-byte words). As a result, the Length field of the NSH MD Type 1 header provides an information which is known by simply looking at the "MD Type" field. However, while [draft-ietf-sfc-nsh] does not specify the encoding of these Context Headers, other specifications have started to do so. A need to distinguish types of Context Headers therefore arises. This draft proposes to overload the Length field of an NSH MD Type 1 as Meta-Data context allocation identifier and to create a IANA repository for NSH MD Type 1 allocation schemes. The NSH MD Type 1 Length field overload intends to allow universal understanding at any network location and by any network device of the context allocation structure.


Gunter Van de Velde (
Martin Vigoureux (
Praveen Muley (

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