4. IPv6 Next Header Compression

LOWPAN_IPHC elides the IPv6 Next Header field when the NH bit is set to 1. This also indicates the use of 6LoWPAN next header compression, LOWPAN_NHC. The value of IPv6 Next Header is recovered from the first bits in the LOWPAN_NHC encoding. The following bits are specific to the IPv6 Next Header value. Figure 11 shows the structure of an IPv6 datagram compressed using LOWPAN_IPHC and LOWPAN_NHC.

+-------------+-------------+-------------+-----------------+--------
| LOWPAN_IPHC | In-line     | LOWPAN_NHC  | In-line Next    | Payload
|   Encoding  |   IP Fields |   Encoding  |   Header Fields |
+-------------+-------------+-------------+-----------------+--------

   Figure 11: Typical LOWPAN_IPHC/LOWPAN_NHC Header Configuration