Waiting for LLDP

7 steps to help you troubleshoot lldp issues

By the end of this post’Waiting for LLDP’, you will be able to correct in most cases the “Waiting for LLDP” issue.  Based on the Avaya Admin Guide “Link Layer Discovery Protocol (LLDP) is an open standard layer 2 protocol utilized by IP Telephones. It is use to advertise their identity, capabilities, and finally to receive administration from an LLDP server. IP/SIP Phones can use LLDP for the following: manage power, and administer VLANs”.

As service technicians and installer we find ourself experiencing the “Waiting for LLDP” issue normally when 70% of the time, specially when the network administrator fail to set the LLDP settings accordingly by the Avaya standards, this is the reason why I decided to write this post, to help you solve this issue in most cases.

When deploying IP Phones there are many moving parts that we need to take care before installing them. From Switch configurations, DHCP Options, and Gatekeeper settings, which makes it crucial for a successful install.

Months ago I found myself in this predicament where most of the IP Phones were coming up with the “waiting for LLDP’ message”, and as you might also experience this type of issues only happen whenever implementing a new solution.

Here I am sharing the 6 steps that helped me successfully fix this problem.

• 1.- Understanding LLDP
• 2.- Connectivity
• 3.- Switch Tagging
• 4.- Routing
• 5.- Firewalls
• 6.- Call Server Configuration
• 7.- LLDP best practices

1.- Understanding LLDP

Link Layer Discovery Protocol was introduced in May 2005. It is responsible for gathering network data or devices available in the customer’s network into a database, providing an inventory of devices attached to the network, information such as: device IP Address, MAC, and Auto Negotiation.

Other discovery protocols and vendors

• Cisco uses CDP
• Nortel uses NDP
• Extreme uses EDP

LLDP-MED (Media Endpoint Discovery) is another great enhancement to allow push information to the device. It can push TFTP, HTTP, TLS, Framing, and PoE information.

LLDP and IP Phone relationship – LLDP needs to be implement in the L2 switch before the IP Phone can send LLDP information back to the switch.

2.- Connectivity 

I have created these subcategories to help you test connectivity.

Check your router/gatekeeper connections

Before troubleshooting this “Waiting for LLDP” error message first you need to understand the OSI Model. Connectivity falls in the Layer 1 – Physical Layer which covers electrical signals and wiring. Check the activity lights in your switch. If there is a broken link or wire connecting back to the gatekeeper or router, this will cause the phone to go into lldp error mode.

Check for MAC Address Tables

Look for MAC Address flooding, and Loops. these two conditions will not allow the switch to learn new MAC Addresses, filling up the MAC buffer.

when a device is plugged into a switch port, it will send an ARP/Broadcast request, the switch then will try to match the destination header with its MAC table; and finally establish communication. If the MAC Address doesn’t exist in the MAC table, it will flood the switch and create a new MAC table entry.

Is the phone getting all of his information?

If you have verified that all of the above is working okay, then try checking the Avaya phones by going through the Menu Options/IP Interfaces – IP Address assigned to the Phone as well as the Subnet Mask.The Voice Subnet and Voice VLAN are assigned here by the DHCP Server, CLAN, PE or IP Office. Any of these gatekeepers will be displayed as the Call Server IP Address, then check the Call Server Port 1719, File Server is shown as the HTTP Server IP Address, and Router IP Address is the same as the Default Gateway.

3.-Switch Tagging

The Network Switch needs to be tagging the voice packets with 801.2Q/P (2Q= voice tag and /p= Priority of 6 in most cases). Run your maintenance command in the switch = show vlan voice. Make sure that your VLAN interface is created and the DHCP Relay is pointing to the right DHCP Server.  DHCP is responsible in assigning not only IP Addresses but also the 802.1Q tags in the frames’ headers.

 

4.- Routing

Now that you have verified that VLANs and port connectivity are okay, phones should be getting the correct IP Addresses from the DHCP Server. and booting up in the right VLAN ID.

Routing is your next step – Ping your edge router then the far-end. Once you confirmed that this can be accomplished move on to troubleshoot layer four – Firewalls.

5.- Firewalls

Verify that all policies are checked, and ALG is turned off or disabled; at least disable your VoIP. Check RTP traffic and Zones are configured correctly.

Pull your traffic log and go through them looking for any blocked traffic with RTP or IP Addresses relating to your voice infrastructure. This will help you identify ports and allow traffic to those interfaces. If any RTP Media is been dropped, then create a rule to allow the range of RTP ports to pass-through.

6.- Call Server Configuration

This is one of the most important steps.

Gatekeeper’s health

Check if your CLANs, MedPros, VCMs, Combo cards, anything that is responsible to convert your RTP media and signaling is working right. Run tests on all of your hardware. Check connectivity from your Call Server. You can run a simple ping test out to an IP Phone.

Gatekeeper Configuration

Avaya Aura – check the IP Network Region Forms. Look for the RTP range, make sure those get added to the firewall exception list. If using VLAN tagging in your network, then set the DiffServ/TOS Parameters to a high value, the higher the number the higher the priority on your voice traffic.

Avaya IP Office– Go to the IP Office / LAN / VoIP tab. Here check that Gatekeeper is enabled. Also have the IT-Person add the range of RTP ports to the firewall exception list. If VLAN tag is configured in your network, then have the DiffServ Settings Value= 46. In some cases I had to also change the SIG DSCP from 34 to match 46.

Routing

In order to reach any other network outside, you will need a router/gateway to handle this for you. It is very important to create static routes under your=

ECG – IP Node Names Tables – add  your default route. Also if using the H.248 Media Gateways then you most add the default route here as well.

SME- IP Routes – add a new default route to your IP Office.

 

lldp-timer – It is a good practice to configured the network switch-LLDP-repeat-timer to be less than 30 seconds.

lldp-holdtimer – The time it will hold before discarding the packet

LLDP Reinit Delay – Sets the reinitialization delay, which is the number of seconds that must elapse after LLDP is disabled on a port before it can be reinitialized. The range is 1 – 10 seconds.

Follow these steps=

lldp timer 15
lldp holdtime 30
lldp reinit 2
lldp run

Verify that you have the following services available=

1. Gatekeeper or Call Server
2. HTTP / FTP Server
3. Routing available between VLANs
4. VLAN Tags

 

Question – When Troubleshooting LLDP. What’s the first step that you normally take?

 

Resources

Avaya 9600 Administration Chapter 7

LLDP  and LLDP-MED  – ANSI / TIA – 1057

Cisco – enabling LLDP Doc

Avaya LLDP Troubleshooting steps