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Status: Reported (1)

RFC4944, "Transmission of IPv6 Packets over IEEE 802.15.4 Networks", September 2007

Source of RFC: 6lowpan (int)

Errata ID: 4359

Status: Reported
Type: Technical

Reported By: Gabriel Montenegro
Date Reported: 2015-05-07

Section 5.1 says:

   ESC:  Specifies that the following header is a single 8-bit field for
      the Dispatch value.  It allows support for Dispatch values larger
      than 127.

It should say:

   ESC:  Specifies that the following header is a single 8-bit field for
      the Dispatch value.  It allows support for Dispatch values larger
      than 63.

Notes:

The (non-ESCaped) Dispatch value is a 6-bit selector. However, it used to be a 7-bit selector, which has a value at most 127. When the field became a 6-bit selector, this maximum became 63, but the referring text was never updated.

For historical reference, see an early version from IETF 67 proposing the Dispatch value within the Dispatch header as a 7-bit field:

http://6lowpan.tzi.org/FrontPage?action=AttachFile&do=view&target=tentative-draft2-ietf-6lowpan-format-07.txt

The dispatch type is defined by a zero-bit as the first bit. The
dispatch type and header is shown here:

1 2 3
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Dispatch | type-specific header
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


Dispatch 7-bit selector. Identifies the type of header
immediately following the Dispatch type.

The relevant slides also show this (slide 8): http://6lowpan.tzi.org/FrontPage?action=AttachFile&do=view&target=6lowpan-header-proposal-2.ppt


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