Piggybacking PC's on Ericsson IP Phones 1

[dard]

Hi All

Sorry for the long post but wanted to give as full a picture as I can.

We are currently trying to reduce cabling and as a result want to be able to use the LAN port on the Ericsson IP Phones to connect up our desktops.

We have an Ericsson MD110 PABX
We are using Cisco 3750 Switches, there is a separate vlan for voice and data. Data 480, Voice 481

The IP phones work fine but we cannot get the phones and PC's working together. An example of a port config which the IP Phones work fine on is below

!
interface FastEthernet1/0/24
switchport access vlan 481
switchport mode access
no logging event link-status
no snmp trap link-status
spanning-tree portfast
!

An exampe of the config we are trying to use on a port which PC and phone would be on is below.
!
interface FastEthernet1/0/4
description Test IP Phones and PC
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 480,481
switchport mode trunk
no logging event link-status
no snmp trap link-status
spanning-tree portfast
!

We have included "Option 43" on the Data DHCP Scope to include the IP address of the server and the VLAN ID for the VOice VLAN but it aint playing ball!!

Any help is apreciated.

 

[whosrdaddy]

did you add the correct VLAN's in the config file?
(look at the L2Qos Section)

/Daddy

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[dard]

Thanks a lot for replying whosrdaddy.

I havent added anything at all to the config files on the server. This was all installed by the contracted telecomms company and now I am trying to do this pretty much on my own.

See below for a copy and paste of the l2qos section from one of the config files.

[L2QOS]
MIIPort=6,1 ;prio (0-7) ,VID(1-4095)
PCPort=0,2 ;prio (0-7) ,VID(1-4095)
LANPort=0,0 ;MAC based VLAN/802.1Q based VLAN , untagged/unmodified PC originating traffic

I'm presuming from your post that there are entries which need to be added here?

Bear in mind that the voice vlan and data vlans 480 and 481 apply only to this switch. Each switch has its own voice and data vlans so I presume there will need to be some sort of an entry for all of them going forward?

Thanks

 

[ADB100]

Depending on the firmware of the IP Phones then the Voice VLAN can be provided via the configuration file or via DHCP Option 43. IMO it is much cleaner to do it via DHCP as this means you don't have to have multiple copies of the configuration file if you have lots of different Voice VLANs.

Th coding of Option 43 can catch you out if you don't do it correctly - its a TLV thing using HEX.... I would recommend putting the Software Server address, the Telephony Domain Name (TDN) and the Voice VLAN ID in DHCP Option 43. This goes in the DHCP scope for the Access VLAN, you then need to replicate this for the Voice VLAN DHCP scope but you can omit the Voice VLAN ID from the Option 43 here as it is ignored.

Your switchport configuration is also wrong, it shouldn't be configured as a trunk. It just needs to be an access port with a Voice VLAN:

interface FastEthernet1/0/4
 switchport access vlan 480
 switchport mode access
 switchport voice vlan 481
 no logging event link-status
 no snmp trap link-status
 spanning-tree portfast

If you post the IP address of your software server I can tell you what the Option 43 should look like.

With later firmware the IP Phones will also perform DNS lookups for the software server IP address to allow you set up some redundancy. I currently just send the Voice VLAN and the TDN via Option 43, the phones use DNS to locate the Software Server (and the IP Phone Administrator server).

HTH

Andy

 

[whosrdaddy]

complete description:

7.18 Virtual LAN (VLAN)
The built in Ethernet switch can handle virtual LAN identities and priorities for the LAN port, for the telephone port and for the PC port.

The following possibilities to assign VLAN identities exist:

From DHCP in option 43 (only the phone port, but not the PC port). A list of maximum three VLAN identities can be handled, see Figure 7-38 .
From the configuration file (both the LAN- and the PC port).
From a menu where it can be manually set (both the LAN- and the PC port).
It is possible to change the different VLAN options from the menu in the boot sequence. The following menu is shown:




Enter the administrator mode, go down in the Network list until the line VLAN for Phone occurs. Change the value to one of the options below :

No VLAN . VLAN shall not be used, but if a VLAN identity is read from the configuration file, VLAN will be used.
Auto. This is the default value when the telephone is delivered from the factory. If the telephone receives a VLAN identity list from DHCP (in option 43) or if there is a VLAN identity defined in the configuration file it will be used. The VLAN identity received from DHCP has priority over the configuration file. For more information, see 7.18.1 Automatic VLAN detection with DHCP and see 7.18.2 Assigning the VLAN identity via the configuration file .
Manually . The manually entered VLAN identity will be used, see 7.18.3 Manual setting of the VLAN identity .If the manually entered VLAN identity shall be used, the [L2QOS] header in the configuration file has to be omitted.
Even when VLAN is not used this parameter can have the default value Auto .

Concerning the priority of the frames: For outgoing frames the following priorities will be set at level 2 for each frame by default, when VLAN is used:

For frames originating in the telephone the default value will be 6, meaning voice traffic with less than 10 ms latency.
For frames originating in the PC the default value is 0, meaning best effort.
The priorities can be changed via the configuration file, see description for CONFIGURATION FILE FOR DBC 42X .

7.18.1 Automatic VLAN detection with DHCP
Prerequisites on the LAN

When the telephone is connected to a layer 2 switch, the switch will add the IEEE 802.1Q header, to untagged frames with the default VLAN identity and forward the frames. The first layer 3 switch must be initiated for DHCP relay and having an ingress port with an IP address on each of the offered VLANs. The address to the DHCP server must be set in the layer 3 switch.

When the layer 3 switch has received a DHCP discover message, it will forward this packet to the DHCP server adding the IP address of its ingress port corresponding to the VLAN. It is this address information that informs the DHCP server to which IP subnet that this telephone will be assigned to.

Description of when a VLAN identity list is received from the native LAN

At installation (and hardware reboot) the telephone asks for a temporary IP address from DHCP by initiating the DHCP negotiation with untagged messages (native LAN). The relay agent adds the address of its ingress port corresponding to the native LAN. DHCP provides the temporary IP address together with the VLAN identity list. The telephone releases the temporary IP address.

Then the telephone uses the first VLAN identity in the list and sends a new tagged request to the DHCP server. The relay agent adds the address of the ingress port corresponding to the selected VLAN. If there is any available IP address, the DHCP server provides this address to the telephone. If there is no available IP address for this VLAN, the telephone takes the next VLAN id in the list and asks for an IP address.

If there is no IP address available in any VLAN in the list, the telephone will ask for an IP address in the native LAN.

Reboot

At warm reboot (the power is not disconnected), the telephone will continue to use the previously used VLAN identity.

At cold reboot (disconnect / connect the power), the complete automatic VLAN discovery procedure will start from the beginning. For DBC 42x 01 telephones (ARM platform), the power must be disconnected for at least one minute to get this cold reboot.

7.18.2 Assigning the VLAN identity via the configuration file
The description of how to set the parameters, see description for CONFIGURATION FILE FOR DBC 42X .

The configuration file is read from the native LAN

At installation (and hardware reboot) the telephone asks for an IP address from DHCP by initiating the DHCP negotiation with untagged messages (native LAN). DHCP provides the IP address but no VLAN identity list. The telephone reads the configuration file, but in this case when no VLAN identity list is received from DHCP, a software reboot is done automatically in the telephone to get the IP address valid for the tagged VLAN defined in the configuration file.

The configuration file is read from the VLAN

At installation (and hardware reboot) and the configuration file is available in the VLAN but not in the native LAN, the VLAN identity must be set manually in the boot menu.

7.18.3 Manual setting of the VLAN identity
Set the VLAN identity from the menu in the boot sequence. To use the manual entered VLAN identity all the time, disable the VLAN settings in the configuration file.

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[dard]

Thanks for all the help everyone, I have gotten this working eventually on the test switch.

The problem was, as ADB100 suggestd above, the switch port configuration. Once I changed the port config back to an access port and added the line

switchport voice vlan 481

everything came together perfectly as I had already put the Option 43 information into the DHCP scopes.

One last question is, I was given the code to put in for option 43 and I know that all that will change for the rest of the scopes is the VLAN ID of the voice vlan.

In this instance Vlan 481 was represented as 343831.

Is there a website or tool I can use to convert the other Vlans to the correct format?

 

[whosrdaddy]

any ascii to hex value conversiontool will do...

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What You See Is What You Get
Never underestimate tha powah of tha google!

 

[VinceWhirlwind]

As you are connecting your Cisco switches to non-cisco devices, the Cisco-specific "voice vlan xxx" isn't particularly appropriate.

Contrary to what Andy is saying, the phone is connecting as an 802.1q trunk (which is how the phone LAN port is configured see the manual quoted above at 7.18.1: "When the telephone is connected to a layer 2 switch, the switch will add the IEEE 802.1Q header..."), so that's what I always explicitly configure on the switch, although "voice vlan xxx" should normally work but it's pointless as the Ericsson phones don't support CDP.

The actual reason your original configuration didn't work was because you had the switch tagging the Data VLAN. You should have had
"switchport trunk native vlan 481" and
"spanning-tree portfast trunk