Siemens 420 S V6.0 Further Information on Option 43 DHCP Support, XML Configuration Management

XML Configuration Management

Installation

2.4.1.1Further Information on Option 43 (DHCP Support)

As there is no DHCP option for exchanging VLAN information via DHCP, the "Vendor Specific Information" option (43) is used to encapsulate VLAN and download information. 1The follow- ing diagram illustrates the format of the "Vendor Specific" option.

Byte #	0	1	2	3	4	5	6	7	8	9	10	11	12 13 14	15	16	17 18	19 20		21	22	23	24	25
Description	Code	Length	Code	Length	Option 1 data - "Siemens" identifier								Code	Length	Option 2 data - to			Padding	Padding	Padding	Padding	Padding	Code
															be allocated VID
Value	43	20	1	10	’S’	’i’	’e’	’m’	’e’	’n’	’s’	0	0 0 2	4	0	0	VID LO	0	0	0	0	0	255
																VIDHI

Byte 1 contains tag "43", "Option 1 data" contains the "Siemens" identifier. The "VLAN ID" is contained in "Option 2". Five padding bytes (starting at byte 20) and the "Terminate Option 255" tag in byte 25 complete the option frame.

You must enter the server values if you have to specify a configuration download server for the configuration update. You can enter the new option before or after the VLAN information but the five padding bytes (value 0) and the "Terminate Option 255" tag must close the option frame.

Example:

Code: 3

Length: 21

File: ftp://ftp.siemens.com (or https://www.siemens.com, for example)

20	21	22	23	24	25	26	27	28	29	30	31	32	33	34	35	36	37	38	39	40	41	42
Code	Length	Option 1 data - "ftp server address"
3	21	’f’	’t’	’p’	’:’	’/’	’/’	’f’	’t’	’p’	’.’	’s’	’i’	’e’	’m’	’e’	’n’	’s’	’.’	’c’	’o’	’m’

43	44	45	46	47	48
Padding	Padding	Padding	Padding	Padding	Code
0	0	0	0	0	255

The five padding bytes and the "Terminate Option 255" tag now complete the option frame in byte 48.

1.Data is transferred from the application layer to the transport layer, where it is assigned a TPC or UDP header and split into datagrams. The transport layer forwards the datagrams to the network layer which divides them into packets and assigns them headers.

2-8	A31003-J4260-M101-2-76A9, 03-2007
	XML Configuration Management, Administrator Manual