reply to krock83
Re: CDP I disable it because a) it's pretty much useless, and b) it's a Cisco proprietary thing noone else is allowed to implement.
(If you're building a cisco voice+data network, CDP is what tells the ip phone which vlans are which.)
CDP/LLDP is also used for auto smart port configuration. To say its useless is nuts. As a networking consultant, CDP can save a lot of time when it comes to troubleshooting and mapping a client's network.
reply to cramer
i do disagree from considering it useless. However, By default all non-cisco ports ought to be in "no cdp enable" mode.
reply to Paulg
CDP will only tell you about CISCO equipment. Non-cisco devices will not show up in your map if all you look at is CDP neighbors. I've never working with a 100% Pure Cisco(tm) network; there's always pieces of other vendor gear in the mix.
LLDP is a different zoo of monkeys. Yet, it will not paint a complete picture of your network either -- you're at the mercy of the devices participating. (most of the gear I've used doesn't have LLDP enabled by default)
[BTW, cdp can also create an administrative headache when setting up or changing vlan configurations.]
CDP is highly useful if you have a datacenter loaded with VMware boxes. vsphere does understand CDP and can be used for basic network troubleshooting by the systems guys. It is also important for offices loaded with Cisco phones. There is plenty value leaving it enabled, and no harm. It is not the open LLDP standard, but until everything supports that there is no point in changing.
Do I have to copy my post? "MOSTLY USELESS" It's only value is in Cisco Proprietary setups... telling a CISCO ip phone what it's voice vlan is, CISCO smartport configuration, etc. Despite VMware's support of CDP, none (Z-E-R-O) of the dozens of ESX/ESXi hosts in my network are visible -- the nexus 1000V's do, as does an ancient 2950.
*I* turn it off -- and have for 20 years. It's one less source of broadcast noise in the network. It's one less resource drain on the switch / router (both CPU and memory) -- those little vampires add up. It has never had a meaningful use in any network I have managed; it can only tell you about cisco devices attached to cisco devices.