The following technologies are Cisco proprietary:

  • CDP

CDP is a protocol that runs on all Cisco-manufactured equipment including routers, bridges and switches. Using CDP, you can view information about all the Cisco devices directly attached to the switch. In addition, CDP detects native VLAN and port duplex mismatches. Network management applications can retrieve the device type and SNMP-agent address of neighboring Cisco devices using CDP. This enables applications to send SNMP queries to neighboring devices. CDP allows network management applications to discover Cisco devices that are neighbors of already known devices, in particular, neighbors running lower-layer, transparent protocols.

CDP runs on all media that support Subnetwork Access Protocol (SNAP), including LAN and Frame Relay. CDP runs over the Data Link layer only. Cisco devices never forward CDP packets. When new CDP information is received, Cisco devices discard old information.

  • GLBP

Gateway Load Balancing Protocol (GLBP) is a Cisco proprietary protocol that attempts to overcome the limitations of existing redundant router protocols by adding basic load balancing functionality.

In addition to being able to set priorities on different gateway routers, GLBP allows a weighting parameter to be set. Based on this weighting (compared to others in the same virtual router group), ARP requests will be answered with MAC addresses pointing to different routers. Thus, load balancing is not based on traffic load, but rather on the number of hosts that will use each gateway router. By default GLBP load balances in round-robin fashion.

  • HNAP

HNAP can be implemented in network devices to allow configuration and management by remote entities, such as Network Magic or any other software application that discovers and manages network devices. By implementing HNAP in a device, manufacturers can ensure their devices are correctly identified and provide detailed information about the device. HNAP can be implemented in any network device, including PCs, routers, cameras, NAS, and media players.


EIGRP is a Cisco proprietary routing protocol loosely based on their original IGRP. EIGRP is an advanced distance-vector routing protocol, with optimizations to minimize both the routing instability incurred after topology changes, as well as the use of bandwidth and processing power in the router. Routers that support EIGRP will automatically redistribute route information to IGRP neighbours by converting the 32 bit EIGRP metric to the 24 bit IGRP metric. Most of the routing optimizations are based on the Diffusing Update Algorithm (DUAL) work from SRI, which guarantees loop-free operation and provides a mechanism for fast convergence.

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