Siemens HIPATH 8000 - Manual (Page 39)

Technical Overview
39
VLAN discovery per DHCP
An additional use for DHCP in the phone is the Æ VLAN discovery per
DHCP feature. This allows the phone to discover its VLAN from a DHCP
server in the untagged LAN. After discovering its VLAN the phone starts
its standard DHCP process within that discovered VLAN to configure itself
from the DHCP within that VLAN.
DHCP Support Explanation of Option 43
As no DHCP option exists for the exchange of VLAN information over
DHCP, the Vendor Specific Information option (43) shall be used to encap-
sulate VLAN and download configuration. The following diagram illustrates
the format of the Vendor Specific Option.
Byte 1 contains the tag "43", option 1 data contains the "Siemens" identifier
and the VLAN ID is contained in option 2. Five Padding Bytes starting in
Byte 20 and the terminate option 255 in byte 25 complete the option
frame.
If you have to specify a configuration download server for configuration up-
date ( see Æ page 88) so you have to add the values of the server. You can
place the new option before or after the VLAN information but the five Pad-
ding Bytes (Value 0) and the terminate option 255 have to close the op-
tion frame.
Example:
Code: 3
length: 28
data: sdlp://dls.siemens.com:18443
The five Padding Bytes and the terminate option 255 now completes
the option frame in byte 48.
SIP Server option 120:
Because the phone only reads the first name/IP address supplied in
option 120, the maximum length of the contents has been limited
to 50 octets. Please be aware of this when you are using it.
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
Descrip-
tion
Co
de
Le
ng
th
Co
de
Le
ng
th Option 1 data - "Siemens" identifier
Co
de
Le
ng
th Option 2 data -
to be allocated
VID
P
addi
ng
P
addi
ng
P
addi
ng
P
addi
ng
P
addi
ng
Co
de
Value 43 20 1 10 ’S’ ’i’ ’e’ ’m’ ’e’ ’n’ ’s’ 0 0 0 2 4 0 0
VID HI VID L
O 0 0 0 0 0 255
20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55
Co
de
Le
ngt
h Option 1 data - "dls server address"
P
addin
g
P
addin
g
P
addin
g
P
addin
g
P
addin
g
Co
de
3 28 ’s’ ’d’ ’l’ ’p’ ’:’ ’/’ ’/’ ’d’ ’l’ ’s’ ’.’ ’s’ ’i’ ’e’ ’m’ ’e’ ’n’ ’s’ ’.’ ’c’ ’o’ ’m’ ’:’ ’1’ ’8’ ’4’ ’4’ ’3’ 0 0 0 0 0 255