HP ProCurve 7000dl Series Basic Management And Configuration Manual page 853

PDP Policy Decision Point. In QoS-managed systems, a PDP is a server that makes
policy decisions. This server has global knowledge of network policies and is
consulted by the network devices (like routers) that enforce the policies.
PEM Format Privacy-Enhanced Mail Format. Base64-encoded data surrounded by header
lines. Some digital certificates use this format.
PEP Policy Enforcement Point. In QoS-managed systems, a PEP is a device on
which policy decisions are carried out—usually a network node like a router
or a switch.
PFC Protocol Field Compression. A PPP configuration option that allows routers
to agree that they will compress the PPP protocol field into a single octet. See
also LCP and PPP.
PFS Perfect Forward Secrecy. A key-establishment protocol used for establishing
secure VPN communications—for example, through an IPSec SA. PFS
ensures that each new encryption key generated to secure the VPN tunnel
does not rely on any previous key. If one encryption key is compromised, only
data encrypted by that specific key is compromised.
PHB Per Hop Behavior. A quality of service designation. PHBs define what type of
service labeled with a particular DiffServ value should receive. PHB can define
such parameters as how much absolute or relative bandwidth is allocated to
a certain type of traffic and which traffic is dropped first if a network becomes
congested. For information on PHB identification codes, see RFC 3140 (at
http://www.ietf.org/rfc/rfc3140.txt). See also DiffServ.
Physical Layer Layer 1 of the OSI model. This layer conveys the bit stream through the
network at the electrical and mechanical level. It includes a line's physical
media and defines standards such as those for signaling and frame formatting.
Ethernet and ATM are protocols with physical layer components.
PKI Public Key Infrastructure. A system of digital certificates, CAs, and other
registration authorities that verify and authenticate the validity of each party
involved in an Internet transaction. PKI enables users to privately exchange
data using a public infrastructure, like the Internet, by managing keys and
certificates. A user obtains a public and private key pair from a trusted CA.
The user authenticates itself with a certificate, which includes its identifica-
tion information, public key, and a CA signature. The user can authenticate
messages with its private key. See also CA, digital certificates, and DSS.
Appendix B: Glossary
B-39