Dragon0x40
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DHCP option 128 for phones
How do ip phone and computers get the correct ip address from the DHCP server?
I know that a string can be put into option 128 and that string tells the phone where the TFTP server with the phone configuration is.
The dhcp server knows what scope to use because of the ip address of the default gateway with the ip helper address assigned? The dhcp packet has the default gateway address so it knows which ip scope to use?
What if the port is a trunk and the phone and data are on different vlans?
The phone and the computer don't know what vlan they belong to so how can you put the phone and data traffic seperate vlans.
I know that a string can be put into option 128 and that string tells the phone where the TFTP server with the phone configuration is.
The dhcp server knows what scope to use because of the ip address of the default gateway with the ip helper address assigned? The dhcp packet has the default gateway address so it knows which ip scope to use?
What if the port is a trunk and the phone and data are on different vlans?
The phone and the computer don't know what vlan they belong to so how can you put the phone and data traffic seperate vlans.
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It is on my avaya ones and my polycom sip conference phones. I can't speak for every brand. Usually you press star or something as it's turning on to setup vlans and static or dhcp and such.
The VLANs settings are usually made at the switch level...
This is how packets get tagged.
This is how packets get tagged.
Unless you are usin the phone as a switch for the computer because the office only has one port. Not the best or easiest setup but many Offices have this requirement for lack of wiring
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is option 128 used for all brands of IP phones or only some brands?
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So if you have a trunk interface with a phone and a computer then the computer uses the native vlan and the phone uses a different vlan because it has been setup to tag the frames with a predetermined vlan tag?
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The vlan tag is set with the buttons on the phone?