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.


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.


Powered device. In PoE, the PD is the powered device that plugs into the PoE switch.


Protocol data unit. A PDU is a message of a given protocol comprising payload and protocol-specific control information, typically contained in a header.


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.)


Power Entry Circuit.


Power Entry Module.


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.


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.


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.


Public Key Infrastructure.


PIM multicast border router. A PIMBR integrates PIM-DM and PIM-SM traffic.


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.


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.


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.


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+.