DHCP option 184

[soxcamp12]

I'm having trouble getting option 184 to work with sub option 3 (Vlan) and suboption 4 (remote survivability configuration)



Option 3, why is this 4 octets? how do you figure out what goes where, can someone please explain?



Option 4, makes little sense to me could some explain this as well, is this different to the ERL config done on the VCX?

Cheers, Soxcamp

[bmoroney]

Hi,

What DHCP Server are you using? We use a Windows 2000 DHCP server and an iSeries DHCP server, both of which are configured with Option 184, but only with sub option 3.

With sub option 3, we specify it as follows (using VLAN 16):

3

4

0

16

0

1

on the Windows 2000 server.



If you are using a VLAN, we found we needed to add option 184 at the Server level, not just the VLAN scope level.



Regards,



Brad

[Booda88]

The length of the argument that applies to this suboption. For option 184, suboption 3, there are two arguments:

VLAN ID: 2 bytes (possible values: 0 through 4095)

VLAN Enable: 2 bytes (possible values: 1 = enabled and 0 = disabled)







In Thoroughness is Satisfaction

This message was edited by Booda88 on 1-29-09 @ 9:26 AM

[lpatterson]

Option 3 can be a bit tricky since the documentation is not very clear. I am running Windows server 2008 with about 25 scopes 3 of which are for the phones.

You must have option 184 applied to all scopes or globally with the correct VLAN that you want to use. For example.

I have a vlan that has their PC's in 10.10.10.0 and their phones in 172.16.0.0 My callp's are 172.16.0.1 and .2. My vlan for the phones is 4000. Since it gets confusing with option 3. Here is what it will look like. Enter it in this order into the fields for 184

1 (option 1)

4 (4 bytes long(this is where you need to remember that each line in dhcp is 1 byte))

172 (first ip octet)

16 (second ip octet)

0 (third ip octet)

1 (fourth ip octet)

2 (suboption 2 secondary callp if you have one)

4 (length 4 bytes)

172 (first ip octet)

16 (second ip octet)

0 (third ip octet)

2 (fourth ip octet)

3 (suboption 3 vlan ID

4 (length 4 bytes)

0x0f (byte 1 of vlan id note this has to be entered in hex value. 4000 in hex is 0FA0 thus first line is 0f

0xa0(byte 2 of vlan ID.)

0 (byte 1 of enabled)

1 (bye 2 of enabled 1=enabled 0=disabled)



okay option 4 this one can be ugly

it will look like this with fail over string of 8* and ip of 172.16.0.33

6

172

16

0

33

8

0xAA

[voipuser]

lpatterson,



That 4th option should read



4 (suboption 4 - failover gateway)

8 (4 bytes for IP address and 2 bytes for each digit)

172

16

0

33

8

0xAA (or 170 if you're entering in Decimal, both represent character *)

[lpatterson]

According to the 3com documentation from my own VCX it is 6 and not 8. It is 6 because there are only 6 bytes. Each line equals 1 byte. So if the length were 8 I would be short two lines. Why do you say it is 8?

[voipuser]

4 (suboption 4)

8 (length 1+1+1+1+2+2 = 8 bytes)

172 (1 byte)

16 (1 byte)

0 (1 byte)

33 (1 byte)

8 (2 bytes)

0xAA (2 bytes)



Refer to p175-176 of the VCX Installation Guide for suboption 4.



In 3Com's example, the dial string is 91* which is one more digit than the example you've given, therefore length for their suboption 4 is actually 10 bytes.



IMHO the whole DHCP option 184 is quite confusing and I wish it can be integrated into the VCX itself!

[Ed Holt]

bump up for reference

3Com Certified IP Telephony VCX/NBX Expert

[SHANEADAMS]

Somewhat related - I'm trying to use a 3Com 3000 series router for providing DHCP and option 184.  Unfortunately, it appears the entries are limited on the 3000 series router for adding subfields to opt 184.  The latest firmware is from 2005, so it won't recognize the voice-config command either.

Has anyone had any luck with trying to get option 184 to work properly on a 3Com 3000 series router by chance?

[Inge_Suzzy]

I'm trying with switch 8800 acting as the dhcp server, the telephones obtain ip but a message is displayed on phone screen says that server is unreachable.

what can i do, to solve this

[IanTomkins]

Regarding option 4 it is actually very straightforward the option works like this:

4

Number of bytes after this, so typically 6

4 Bytes of IP address of the emergency gateway

The emergency route number sequence, for example 9*

Note that the emergency route bytes are simply 0-9 for each digit but 170 for * (It's ascii code).

So for example the sequence for a gateway of 192.168.55.66 with a dialing sequence of 9* would be

4,6,192,168,55,66,9,170

In the event the emergency sequence is longer that two characters then the 6 needs to be adjusted accordingly.

[Justin_Goldberg]

Shane,

Here's a config from a 3Com router:

#Sample Configuration File

ddns-update-style interim;
ignore client-updates;

option sip-server-ip code 184 = string;
option sip-server-ip 01:04:A:E7:16:17:02:04:A:E7:16:22:04:07:A:E7:16:32:9:1:AA;

option sip-callp-ip code 120 = string;
option sip-callp-ip 01:A:E7:16:17:A:E7:16:22:A:A:A:A;

subnet 10.231.22.0 netmask 255.255.255.0 {
option routers 10.231.22.23;
option subnet-mask 255.255.255.0;
range 10.231.022.100 10.231.022.150;
default-lease-time 21600;
max-lease-time 43200;
}

I don't understand that gobblydygook, but copied it from our repository.