Reference Guide

Simple Network Time Protocol is used to synchronize the system clocks throughout the network. An
extension of NTP, SNTP can usually operate with a single server and allows for IPv6 addressing.
SSL
Secure Socket Layer is a protocol for transmitting private documents using the Internet. SSL works by
using a public key to encrypt data that is transferred over the SSL connection. SSL uses the public-and-
private key encryption system, which includes the use of a digital certificate. SSL is used for other
applications than SSH, for example, OpenFlow.
STP
Spanning Tree Protocol, defined in IEEE 802.1d, used to eliminate redundant data paths and to increase
network eciency. STP allows a network to have a topology that contains physical loops; it operates in
bridges and switches. STP opens certain paths to create a tree topology, thereby preventing packets
from looping endlessly on the network. To establish path redundancy, STP creates a tree that spans all
of the switches in an extended network, forcing redundant paths into a standby, or blocked, state.
STP allows only one active path at a time between any two network devices (this prevents the loops)
but establishes the redundant links as a backup if the initial link should fail. If STP costs change, or if one
network segment in the STP becomes unreachable, the spanning tree algorithm reconfigures the STP
topology and re-establishes the link by activating the standby path.
syslog
A protocol used for the transmission of event notification messages across networks, originally
developed on the University of California Berkeley Software Distribution (BSD) TCP/IP system
implementations, and now embedded in many other operating systems and networked devices. A
device generates a messages, a relay receives and forwards the messages, and a collector (a syslog
server) receives the messages without relaying them.
syslog uses the UDP as its underlying transport layer mechanism. The UDP port that has been assigned
to syslog is 514. (RFC 3164)
virtual router
In the Extreme Networks implementations, virtual routers allow a single physical switch to be split into
multiple virtual routers. Each virtual router has its own IP address and maintains a separate logical
forwarding table. Each virtual router also serves as a configuration domain. The identity of the virtual
router you are working in currently displays in the prompt line of the CLI. The virtual routers discussed in
relation to Extreme Networks switches themselves are not the same as the virtual router in VRRP.
In VRRP, the virtual router is identified by a virtual router (VRID) and an IP address. A router running
VRRP can participate in one or more virtual routers. The VRRP virtual router spans more than one
physical router, which allows multiple routers to provide redundant services to users.
Glossary
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