I've read somewhat about LLDP and LLDP-MED. It seems that as far as end devices go, they're mostly used by VoIP phones.

I'm interested in the idea of an end device implementing LLDP or LLDP-MED, so that network equipment could possibly configure it specially. Eg:

  • IP Cameras that identify themselves as such are put on a separate VLAN, with different QoS configuration.
  • Home automation or home security devices are put on a separate VLAN.

Are there any categories of devices other than VoIP phones that use LLDP to identify themselves?

Would network equipment have the capability to configure devices into separate VLAN, QoS, etc on the basis of information they provide via LLDP?

  • Network engineers routinely use LLDP and CDP for network troubleshooting. On the CLI they can use “show LLDP ....” commands to see what network devices are connected to what ports. Most “enterprise” network gear advertises LLDP, allowing network engineers to map out a network at L2. It sounds like your question is more directed at using LLDP info to dynamically assign vlans for access gear. Jan 22 '20 at 5:35

LLDP-MED is an LLDP extension that is specifically aimed at IP phones. LLDP itself is extensively used to identify various network equipment, especially switches and routers.

In theory, LLDP extensions could be used to e.g. select the end node VLAN, but usually DHCP vendor extensions are used as DHCP is better suited: it uses a request-response model, so the DHCP server can tailor the response to the client attributes.

In contrast, LLDP is a one-way discovery or announcement protocol. Additionally, LLDP is a link-layer protocol and cannot be routed, so it can only be used to identify directly connected devices and their attributes.

  • VLAN allocation happens at the link-layer, so I thought LLDP reporting makes sense to facilitate automation of VLAN allocation. Whereas, DHCP is network layer, so that makes sense for configuring network layer things like DSCP. Jan 22 '20 at 23:41
  • @CraigMcQueen From the layer perspective you're correct, but practically DHCP simply does a better job. ;-)
    – Zac67
    Jan 23 '20 at 7:32

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