Author Topic: Multiple DHCP with different Subnet on Mitel 3300 Mxe  (Read 5776 times)

Offline ralph

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Re: Multiple DHCP with different Subnet on Mitel 3300 Mxe
« Reply #15 on: November 15, 2016, 07:58:49 AM »
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Bear in mind that you will need a DHCP offer on the native vlan to tell the phone what VLAN it belongs to.

Sarond is correct.  But if your dataswitch ports are in Access Mode (Cisco) then the native VLAN is your voice vlan.  One thing you might want to try is putting wireshark on your laptop to see what you get when you do a DHCP request. 

Ralph


Offline martyn

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Re: Multiple DHCP with different Subnet on Mitel 3300 Mxe
« Reply #16 on: November 15, 2016, 09:25:43 AM »


Bear in mind that you will need a DHCP offer on the native vlan to tell the phone what VLAN it belongs to.

This isn't required, as CDP or LLDP take care of that.

Offline VinceWhirlwind

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Re: Multiple DHCP with different Subnet on Mitel 3300 Mxe
« Reply #17 on: November 15, 2016, 06:28:44 PM »
Let's summarise how this is meant to work:
 
Switch config:
LLDP enabled
VLAN200 voice
 
Switchport config (Access):
Phones/PCs:
VLAN100 untagged(=access)
VLAN200 tagged
Services (eg DHCP server):
VLAN100 untagged
 
Switchport config (uplink):
VLAN100 tagged
VLAN200 tagged
 
Router/Layer3 Switch config:
VLAN100 IP address 10.1.100.1
VLAN200 IP address 10.1.200.1, IP HELPER: 10.1.100.20
 
Router/L3 Switch physical interface config:
VLAN100 tagged
VLAN200 tagged
 
DHCP config:
Server IP address: 10.1.100.20
Scope 10.1.100.21-199
Scope 10.1.200.21-199, Option125 incl gateway address, QoS, & VLAN

Offline sarond

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Re: Multiple DHCP with different Subnet on Mitel 3300 Mxe
« Reply #18 on: November 16, 2016, 01:56:17 AM »


Bear in mind that you will need a DHCP offer on the native vlan to tell the phone what VLAN it belongs to.

This isn't required, as CDP or LLDP take care of that.

This is assuming CDP/LLDP is being used for voice.

The problem I see is that it may not be desired as you would need different VLANs, not all phones belong in the same VLAN.

I would use helpers on each subnet/vlan to point to the 3300.
Program each DHCP option as you have done but remove the VLAN options in 125.
Program ports as untagged/access for the desired vlan. That you are connecting phones to.

If you offer a VLAN in the DHCP option it will tagged the phones packets and it will fail (I believe)

If you are wanting to connect a device on the PC port then this will be a different setup again.

Offline VinceWhirlwind

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Re: Multiple DHCP with different Subnet on Mitel 3300 Mxe
« Reply #19 on: November 16, 2016, 04:32:11 PM »


The problem I see is that it may not be desired as you would need different VLANs, not all phones belong in the same VLAN.


The general approach is that each Access-layer switch (or switch-stack) has a single Voice VLAN.
That VLAN has the "VLAN ID Voice" command issued against it.
Every phone that is patched to that switch gets the LLDP message to use that switch's Voice VLAN.
 
On a different switch, a different VLAN is configured and called "voice" and phones on that switch join that VLAN.
 
The basic principle of VLAN design is to have as few VLANs per switch as possible and they are not spanned across multiple switches.
VLANs are not a security mechanism (except inasmuch as they assist in managing availability risk), they are a convenience to improve efficient management.
 
Sadly, networking textbooks *still* explain VLANs as a way to security-separate functional business units, an approach that was made obsolete in about 1994 when Windows NT came out.


 

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