.bix seems to be the firmware file format which is used by Accton-powered switches. It has been spotted on 3com (3812/3824/3848, 3870), EdgeCore (ES3526, ES4649, etc.) and Foundry (EdgeIron 24GS, 48GS) so far.

This research has been mainly based on 3com 3812/3824/3848 firmware images, files from other vendors suggest that they are using something similar.


There are 3 times of .BIX files. Runtime, Diag and Multiple Image.

Runtime and Diag contain a single gzipped datablob. Multiple Image can contain multiple modules (runtimes), each with their own 32-byte header, for instance if the ES4649 where the MPC8245 on the main board and the MPC8241 on the 10GE expansion board each run their own runtime.

Some devices just use a regular runtime, others use the multiple image.

Header and Datablob are checksummed seperatly..


Multiple Image headerEdit

Multiple Image Header
offset comment
00-03h 9A 8B 7C 6D
04-13h ???
14-17h Firmware Version
18-1Bh module 1 version
1C-1Fh module 1 filesize
20-23h module 2 version
24-27h module 2 filesize

Runtime/Diag headerEdit

Runtime/Diag header
offset comment
00-03h 1A 2B 3C 4D
04-07h Image checksum
08-0Bh Firmware Version
0C-0Fh filesize
10-11h ???
12h 00
13-17h 01 01 04 0C 16
18h 00
19-1Bh ???
1C-1Fh File Header Checksum
20-end gzipped datablob