P
packet
This is the unit of data sent across a network. Packet is a generic term used to
describe units of data at all levels of the protocol stack, but it is most correctly used to
describe application data units. The packet is a group of bits, including data and control
signals, arranged in a specific format. It usually includes a header, with source and
destination data, and user data. The specific structure of the packet depends on the protocol
used.
PAP
Password Authentication
Protocol. This is the most basic form of authentication, in which a user's name and password
are transmitted over a network and compared to a table of name-password pairs. Typically, the
passwords stored in the table are encrypted. (See
CHAP.)
partner node
In
EAPS, the partner node is that end of the common link that is not
a controller node; the partner node does not participate in any form of blocking.
PD
Powered device. In PoE, the PD is the powered device that plugs into the PoE
switch.
PDU
Protocol data unit. A PDU is a message of a given protocol comprising payload and
protocol-specific control information, typically contained in a header.
PEAP
Protected Extensible
Authentication Protocol. PEAP is an IETF draft standard to authenticate wireless LAN clients
without requiring them to have certificates. In PEAP authentication, first the user
authenticates the authentication server, then the authentication server authenticates the
user. If the first phase is successful, the user is then authenticated over the SSL tunnel
created in phase one using EAP-Generic Token Card (EAP-GTC) or Microsoft Challenged Handshake
Protocol Version 2 (MSCHAP V2). (See also
EAP-TLS.)
PIM-DM
Protocol-Independent Multicast - Dense mode. PIM-DM is a multicast protocol that uses
Reverse Path Forwarding but does not require any particular unicast protocol. It is used when
recipients are in a concentrated area.
PIM-SM
Protocol-Independent Multicast - Sparse mode. PIM-SM is a multicast protocol that
defines a rendezvous point common to both sender and receiver. Sender and receiver initiate
communication at the rendezvous point, and the flow begins over an optimized path. It is used
when recipients are in a sparse area.
ping
Packet Internet Groper.
Ping is the
ICMP echo message and its reply that tests network
reachability of a device. Ping sends an echo packet to the specified host, waits for a
response, and reports success or failure and statistics about its operation.
PKCS #8 (Public-Key
Cryptography Standard #8)
One of several standard
formats which can be used to store a private key in a file. It can optionally be encrypted
with a password.
PKI
Public Key Infrastructure.
PMBR
PIM multicast border router. A PIMBR integrates PIM-DM and PIM-SM traffic.
PoE
Power over Ethernet. The PoE standard (IEEE 802.3af) defines how power can be provided
to network devices over existing Ethernet connections, eliminating the need for additional
external power supplies.
policy files
You use policy files in
ExtremeXOS to specify
ACLs and policies. A policy file is a
text file (with a .pol extension) that specifies a number of conditions to test and actions to
take. For ACLs, this information is applied to incoming traffic at the hardware level.
Policies are more general and can be applied to incoming routing information; they can be used
to rewrite and modify routing advertisements.
port mirroring
Port mirroring configures the switch to copy all traffic associated with one or more
ports to a designated monitor port. A packet bound for or heading away from the mirrored port
is forwarded onto the monitor port as well. The monitor port can be connected to a network
analyzer or RMON probe for packet analysis. Port mirroring is a method of monitoring network
traffic that a network administrator uses as a diagnostic tool or debugging feature; it can be
managed locally or remotely.
POST
Power On Self Test. On Extreme Networks switches, the POST runs upon powering-up the
device. Once the hardware elements are determined to be present and powered on, the boot
sequence begins. If the MGMT LED is yellow after the POST completes, contact your supplier for
advice.
primary port
In
EAPS, a primary port is a port on the master node that is
designated the primary port to the ring.
protected VLAN
In STP, protected VLANs are the other
(other than the carrier VLAN) VLANs that are members of the STPD but do not define the scope
of the STPD. Protected VLANs do not transmit or receive STP BPDUs, but they are affected by
STP state changes and inherit the state of the carrier VLAN. Also known as non-carrier
VLANs, they carry the data traffic.
In EAPS, a protected VLAN is a VLAN that
carries data traffic through an EAPS domain. You must configure one or more protected VLANs
for each EAPS domain. This is also known as a data VLAN.
proxy ARP
This is the technique in which one machine, usually a router, answers ARP requests
intended for another machine. By masquerading its identity (as an endstation), the router
accepts responsibility for routing packets to the real destination. Proxy ARP allows a site to
use a single IP address with two physical networks. Subnetting is normally a better
solution.
pseudowire
Sometimes spelled as
"pseudo-wire" or abbreviated as PW. As described in RFC 3985, there are multiple methods for
carrying networking services over a packet-switched network. In short, a pseudowire emulates
networking or telecommunication services across packet-switched networks that use Ethernet,
IP, or MPLS. Emulated services include T1 leased line, frame relay, Ethernet, ATM, TDM, or
SONET/SDH.
push-to-talk
(PTT)
The push-to-talk is
feature on wireless telephones that allows them to operate like a walkie-talkie in a group,
instead of standard telephone operation. The PTT feature requires that the network be
configured to allow multicast traffic.
A PTT call is initiated by selecting a channel and
pressing the 'talk' key on the wireless telephone. All wireless telephones on the same network
that are monitoring the channel will hear the transmission. On a PTT call you hold the button
to talk and release it to listen.
PVST+
Per VLAN Spanning Tree +. This implementation of STP has a 1:1 relationship with
VLANs. The Extreme Networks implementation of PVST+ allows you to interoperate with
third-party devices running this version of STP. PVST is a earlier version of this protocol
and is compatible with PVST+.