Which three routing protocols utilize TLVs?

IS-IS, originally designed for Open System Interconnection (OSI) routing, uses TLV parameters to
carry information in Link State Packets (LSPs). The TLVs make IS-IS extendable. IS-IS can
therefore carry different kinds of information in the LSPs.
Several routing protocols use TLVs to carry a variety of attributes. Cisco Discovery Protocol
(CDP), Label Discovery Protocol (LDP), and Border Gateway Protocol (BGP) are examples of
protocols that use TLVs. BGP uses TLVs to carry attributes such as Network Layer Reachability
Information (NLRI), Multiple Exit Discriminator (MED), and local preference.
The IP header of the EIGRP packet specifies IP protocol number 88 within it, and the maximum
length of the packet will be the IP MTU of the interface on which it is transmitted, most of the time
1500 octets. Following the IP header is the various Type/Length/Value (TLV) triplets. These TLVs
will not only carry the route entries but also provide fields for the management of the DUAL
process, multicast sequencing, and IOS software versions from the router.
References: http://www.cisco.com/c/en/us/support/docs/ip/integrated-intermediate-system-tointermediate-
system-is-is/5739-tlvs-5739.html
http://ericleahy.com/index.php/eigrp-packets-neighborships/