.. SPDX-License-Identifier: GPL-2.0

batman-adv COMPAT\_VERSION
==========================

COMPAT\_VERSION in packet.h is used to identify an incoming packet and
check if it can processed by the current version. The packet structure
should be identified by this version. The stuff which appears in a
packet jumps a little bit with each version because we change stuff in
trunk/main and in next and import those changes to the packet
structure out-of-order.

Following changes were identified and documented.

+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Version   | Releases                                    | Changes                                                                                                                                                                  |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 1         | (development only)                          | Initial definitions of batman\_packet, icmp\_packet, unicast\_packet, bcast\_packet, ethernet type 0x0842                                                                |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 5         | (development only)                          | information in batman\_packet was reordered, tq, old\_orig and hnas were added                                                                                           |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 6         | v0.1                                        | vis\_packet type added, version fields added to each packet, ethernet type changed to 0x4305                                                                             |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 7         | (development only)                          | unused gw flags removed, reordered icmp and batman packet                                                                                                                |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 8         | v0.2, v0.2.1, v2010.0.0                     | source field introduced in vis packets                                                                                                                                   |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 9         | (development only)                          | Gateway flags added to batman\_packet, primaries\_first\_hop flag added for bonding, special icmp messages for route record added                                        |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 10        | (development only)                          | 32 bit sequence numbers added/changed, ttl were added to broadcasts                                                                                                      |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 11        | v2010.1.0                                   | gateway flags were removed                                                                                                                                               |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 12        | v2011.0.0, v2011.1.0, v2012.2.0             | unicast fragmentation added, gateway flags were readded                                                                                                                  |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 13        | v2010.2.0                                   | gateway flags were removed                                                                                                                                               |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 14        | v2011.3.0 until (and including) v2013.4.0   | 3-byte common header, tt queries and related fields added, roam adv packet added                                                                                         |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| 15        | v2014.0.0 and later                         | TVLV (backward compatibility), packet alignment (\_\_packed), vlan aware tt, crc32 checksums for tt, fragmentation v2, packet type prefix and BATADV\_TT\_CLIENT\_TEMP   |
+-----------+---------------------------------------------+--------------------------------------------------------------------------------------------------------------------------------------------------------------------------+

(\* means future version with already defined feature set)

There is a special COMPAT\_VERSION 200 which is only used by saxnet.
This version is v6 with bcast seqno protection added.