Mitel Forums - The Unofficial Source
Mitel Forums => Mitel MiVoice Business/MCD/3300 => Topic started by: pakman on January 18, 2017, 03:48:34 PM
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Hello,
I'm trying to understand more about the phone boot up process and vlans. When I watch a phone boot up it goes through 802.1x, LLDP, DHCP, Vlan 100, Option 125 and Minet before starting up.
In our DHCP options we don't have vlan info set and so I'm wondering how exactly LLDP plays a role in the phone getting on the voice vlan? Ultimately, when troubleshooting some phones I show the phone registering in both our data vlan and voice vlan and I don't get how that's possible.
Thanks,
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LLDP can set priority and vlan. Most phones can take this and move to the assigned vlan. As you see this happens before the DHCP request. In your case they move to vlan 100 and are provided an address and other options contained in the 125 string.
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LLDP may or may not have anything to do with this, the phones could be moving to the desired VLAN in other ways such as Cisco SmartPort as well. The fact they seem to be on two vlans at once is odd... I would start at the switch level and look at the ports and they uplinks to other switches. Hard to say from the given information what the cause could be.
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LLDP is a protocol that runs on various networking devices. It sends regular advertisements out ethernet interfaces which a neighbouring device also running LLDP will receive. These advertisements contain a few details about the device sending it.
For the phones running LLDP, the thing they are looking fo rin the LLDP advertisements from the switch they are connected to is a line to the effect, "VLAN20 VOICE".
The phone sees this and configures its LAN-facing interface to be tagged in VLAN20.
Then, the phone can send a DHCP request out VLAN20 and get assigned an IP address in the Voice VLAN subnet.
Alternatively, if there is no LLDP, the phone will not learn any VLAN ID, so it will send a DHCP request out its LAN-facing interface within untagged frames. This request will go to the Data VLAN DHCP scope, and the phone will be assigned an IP address within the Data subnet. The DHCP offer will contain Option125, including the correct VLAN ID for the Voice VLAN. The phone will assign the Voice VLAN ID to itself and add it as a tagged VLAN to its LAN-facing interface, and then reboot itself, coming up in the Voice VLAN, and then sending a DHCP request off into the Voice VLAN so it can get a Voice VLAN subnet IP address.
If you're seeing the phone in both scopes on the DHCP server, it could be either the second process is what's happening, or your DHCP server is patched to a switchport that is misconfigured with multiple VLANs assigned to it.
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LLDP is cool to get you up and running when your in a time crunch, but if you have time, configure you switchports so you know what is where. That also gives you a good time to document your switchports, so when things go belly up, you have a reference point of what should be where.
-Ian
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LLDP is cool to get you up and running when your in a time crunch, but if you have time, configure you switchports so you know what is where. That also gives you a good time to document your switchports, so when things go belly up, you have a reference point of what should be where.
-Ian
pffffftttt documentation.... if it was hard to put in it should be hard to troubleshoot.
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LLDP is cool to get you up and running when your in a time crunch, but if you have time, configure you switchports so you know what is where. That also gives you a good time to document your switchports, so when things go belly up, you have a reference point of what should be where.
-Ian
I think you are thinking of Cisco VTP. Don't use Cisco VTP.
LLDP doesn't configure your switchports - it configures your phone. You don't want to manually configure every single handset to tell it what its Voice VLAN is. You can let DHCP configure your phone, but the phone will need to boot up twice to get onto the Voice VLAN if you do it that way, so LLDP is better.
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Virtual Trunking Protocol (VTP) shouldn't be in the discussion ;) . I know LLDP deals with Network Discovery, along the same lines of CDP. I may have described VTP, my point being is that I do not want either a Cisco Protocol (CDP) or an open-source Protocol (LLDP) telling my VoIP device which vLAN is which.
and v2win: it helps also when people move ports thinking they can without calling the Helpdesk first ;D , that way when the port dies, and i can point out that they moved ports without telling IT they get very bashful. I have sites in Utah, Idaho, etc, I can't just walk over and move the port back.
-Ian
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Thanks for all the responses.
I have a couple of follow up questions which will hopefully solidify all this for me.
VinceWhirlwind what you posted makes since to me but I also was reading something about how Cisco phones boot up and the bold text is what I read. If this isn't the same for Mitel and it's how you described it with the phone waiting around for an LLDP message from the switch to tell it that it's voice is there any documentation out there on this? Not that I'm questioning your knowledge I just like to learn and understand things to the best of my ability. I have not come across any really good articles explaining LLDP and VOICE.
Thanks,
Do Mitel phones have a small switch in them andunderstand 802.1Q, when the phone sends the first packet to the switch the port knows if it's configured with a voice vlan since the packet was tagged it can then send a LLDP message saying here is your voice vlan? If not, I know the phones have LLDP enabled on them does the phone advertise to the switch here's all my info and btw I'm a phone so put me in the voice vlan? If that's the case what exactly in the LLDP advertisement says I'm a phone?
To iboyd....if you don't use LLDP or CDP I assume you program everything in DHCP then? I use 802.1X with MAB so it doesn't matter to me where end users move devices to just so that my wall jack numbers match my patch panel life is good...:)
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I did do a packet capture with WS and saw that my BIA of my switchport was the source for the LLDP packet so the phone waits for an LLDP packet with the correct vlan info before proceeding like you mention below.
Thanks,
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.... does the phone advertise to the switch here's all my info and btw I'm a phone so put me in the voice vlan? If that's the case what exactly in the LLDP advertisement says I'm a phone?
Well, it might depend on the phone, but I see no reason why the phone needs to send any LLDP, it just needs to listen.
The phone needs to be running LLDP, as well as the network switch.
When you connect the phone to the switch, the phone will see LLDP advertisements from the switch.
Those advertisements contain info about the Voice VLAN.
The phone now knows how to tag its voice traffic.
But I already explained all this, so not sure what you are asking really.
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Since I did the packet capture and verified for myself that the phone receives the LLDP info from the switch no further questions on this.
I do however have another question since were talking about phone boot up process. I ran across this just this morning so its good timing. I found a particular switchport that didn't have 802.1X settings nor was it setup on the voice vlan. When I looked at the mac table It showed a phone and pc registered. I confirmed the PBX had this phone in the all IP phone inventory and had an IP address from our data side.
I'm wondering how this phone is working since only PBX's hand out DHCP info to our phones and we have a separate DHCP server on our domain controllers for data. I was under the impressing that phones had to have option 125 in order to work properly? I don't have any phone options on the DC related to phones.
Thanks,
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I was under the impressing that phones had to have option 125 in order to work properly? I don't have any phone options on the DC related to phones.
If you put a handset in teleworker mode it will work without any DHCP options [it doesn't care the if IP you gave it is an MBG or an MCD if there's no NAT]. I have used this as quick fix a number of times.
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Do Mitel phones have a small switch in them andunderstand 802.1Q, ... If that's the case what exactly in the LLDP advertisement says I'm a phone?
Yes, basically a 3-port switch.
The LLDP capabilities field indicates that it's a phone.
If you didn't already know, look at the neighbours table on your switch - you will see the DN of each device. Very handy.
To iboyd....if you don't use LLDP or CDP I assume you program everything in DHCP then?
Yes, or do it manually, but nobody wants to do that!
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If you put a handset in teleworker mode it will work without any DHCP options [it doesn't care the if IP you gave it is an MBG or an MCD if there's no NAT]. I have used this as quick fix a number of times.
Wouldn't call it a fix, maybe a work around for a misconfigured network. I too have had to do this and find it is often because the L2 device isn't setup properly or they only have L1
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Thanks for the responses regarding DHCP but those answers I don't think apply in my case. That phone is on site and I definitely don't go around putting phones in teleworker mode and I'm sure the end user didn't do this. So that begs the question how did this phone boot up and work off our DHCP server without option 125?
Let's say this phone did have teleworker turned on somehow, with me putting it in the voice vlan now and it booting up off the controller using option 125 would teleworker mode prevent this? I could have the end user verify for me that it's on or off but thought I would ask.
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In the ideal setup, phones should run on their own vlan so that priority can be establihed. With that said, certain ports for devices must be setup correct, i.e. the data dchp server is only on the data vlan, depending upon model of controller it may need to be only on the voice vlan.
There are several methods to get phones to reside on the desired vlan, i.e. cdp, lldp, dhcp. Not all Mitel phone will support these methods, but most will.
Upon boot the newer phones will seek info from cdp, lldp and then dhcp. Within dhcp, there are several ways to provide phones the needed info. options 43 and 125 versus the older 128,129 etc.
This is in the tech handbook. may not be explained well though.
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There is some good documentation in the Appendix of the Engineering Guidelines.
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I found a particular switchport that didn't have 802.1X settings nor was it setup on the voice vlan. When I looked at the mac table It showed a phone and pc registered. I confirmed the PBX had this phone in the all IP phone inventory and had an IP address from our data side.
I'm wondering how this phone is working since only PBX's hand out DHCP info to our phones and we have a separate DHCP server on our domain controllers for data. I was under the impressing that phones had to have option 125 in order to work properly? I don't have any phone options on the DC related to phones.
If the phone is registered to the controller then something has told it the controller's IP address - what options are present in your DHCP scope for the subnet the phone is in?
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Hello VinceWhirlwind,
Inside the DHCP scope for our phone subnets there is option 125 among others. My point is that this phone registered to a different DHCP server one that does not hand out anything related to phones yet the phone managed to find it's way to the controller and somehow register. I found another phone like the one I found and will investigate a little further.
Thanks,
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My point is that this phone registered to a different DHCP server one that does not hand out anything related to phones yet the phone managed to find it's way to the controller and somehow register.
What is this device? It may need to be set to only reside on it's primary vlan.
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My point is that this phone registered to a different DHCP server one that does not hand out anything related to phones yet the phone managed to find it's way to the controller and somehow register.
My point was to ask do you really know that? Usually the explanation for a mysterious occurrence is that an assumption has occurred.
If I was in that situation, I would make sure I knew because I had seen with own eyes exactly which DHCP server(s) was seeing the DHCP broadcast and which one(s) was(were) answering and what the offer contained and where the lease was recorded, etc..
If I didn't find something there, I would try factory-resetting the phone to see if things stay the same, or trying a new phone.
I recall with Ericsson phones, if the phone was unable to contact a DHCP server, it would magically remember the VLAN and IP address it had last used and use them. Maybe Mitel phones remember stuff?