Arista Warrior, 2nd Edition

Chapter 11. Link Layer Discovery Protocol

Link Layer Discovery Protocol (LLDP) is the open standard (IEEE 802.1AB) means of discovering neighbors over the link layer (Layer 2 [L2]). Let’s take a look at LLDP in action and see what you might need to do to make it work with other vendors’ devices.

To show a bit of intervendor compatibility, I’ve connected my Arista 7010T switch to an old Cisco 3750. The connection is between G1/0/52 on the 3750 and e24 on the Arista. When I turn up the port, I get the following message on the Arista console:

Apr 10 23:21:35 Arista Lldp: %LLDP-5-NEIGHBOR_NEW: LLDP neighbor with
chassisId 001c.b084.cfb4 and portId "[ Arista e24 ]" added on
interface Ethernet24

Without configuring anything, the Arista switch has discovered the Cisco switch, even though the Arista switch is not running Cisco Discovery Protocol (CDP). Let’s dig in and see what Arista sees:

Arista-7010T#sho lldp LLDP transmit interval : 30 seconds LLDP transmit holdtime : 120 seconds LLDP reinitialization delay : 2 seconds LLDP Management Address VRF : default Enabled optional TLVs: Port Description System Name System Description System Capabilities Management Address (best) IEEE802.1 Port VLAN ID IEEE802.3 Link Aggregation IEEE802.3 Maximum Frame Size Port Tx Enabled Rx Enabled Et1 Yes Yes Et2 Yes Yes Et3 Yes Yes Et4 Yes Yes Et5 Yes Yes Et6 Yes Yes Et7 Yes Yes Et8 Yes Yes Et9 Yes Yes Et10 Yes Yes [--snippage--] Et45 Yes Yes Et46 Yes Yes Et47 Yes Yes Et48 Yes Yes Et49 Yes Yes Et50 Yes ...