ARP

[treiher]

Schemas

• Fixed-size field systematization-binary-schemas#1
• Field type: unsigned integer systematization-binary-schemas#20 (ar$hln, ar$pln)
• Field type: enumeration systematization-binary-schemas#22 (ar$hrd, ar$pro, ar$op)
• Fixed field type defined by value of other field with redundant length field systematization-binary-schemas#44 (ar$sha, ar$spa, ar$tha, ar$tpa)

In theory, the length fields (ar$hln and ar$pln) are redundant,
since the length of a protocol address should be determined by
the hardware type (found in ar$hrd) and the protocol type (found
in ar$pro). It is included for optional consistency checking,
and for network monitoring and debugging

Specification

https://tools.ietf.org/html/rfc826
https://en.wikipedia.org/wiki/Address_Resolution_Protocol