GL-21
Cisco Router and Security Device Manager Version 2.2 User’s Guide
OL-4015-08
Glossary
NHRP Next Hop Resolution protocol. A client and server protocol used in DMVPN
networks, in which the hub router is the server and the spokes are t he clients. The
hub maintains an NHRP database of the public interface addresses of the each
spoke. Each spoke registers its real address when it boots and queries the NHRP
database for real addresses of the destination spokes in order to build direct
tunnels to them.
non-repudiation
service
A third-party security service that stores evidence for later, possible retrieval,
regarding the origin and destination of all data included i n a communication —
without storing the actual data. This evidence can be used to safeguard all
participants in that communication against false denials by any participant of
having sent information, as well as false denials by any participan t of having
received information.
NTP Network Time Protocol. A protocol to synchronize the system clocks on network
devices. NTP is a UDP protocol.
O
Oakley A protocol for establishing secret keys for use by authenticated parties, based on
Diffie-Hellman and designed to be a compatible component of ISAKMP.
OFB output feedback. An IPSec function that feeds encrypted output (generally, but
not necessarily, DES-encrypted) back into the original input. Plaintext is
encrypted directly with the symmetric key. This produces a pseudo- random
number stream.
outside global The IP address assigned to a host on the outside network by the host's owner. The
address was allocated from globally routable address or network space.
outside local The IP address of an outside host as it appears to the inside network. Not
necessarily a legitimate address, it was allocated from an addr ess space routable
on the inside.
OSPF Open Shortest Path First. Link-state, hierarchical IGP routing algo rithm
proposed as a successor to RIP in the Internet community. OSPF features include
least-cost routing, multipath routing, and load balancing.