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Glossary
ACL Access Control List. ACLs can limit network traffic and restrict access to certain users or
devices by checking each packet for certain IP or MAC (i.e., Layer 2) information.
ARP Address Resolution Protocol converts between IP addresses and MAC (hardware) addresses.
ARP is used to locate the MAC address corresponding to a given IP address. This allows the
switch to use IP addresses for routing decisions and the corresponding MAC addresses to
forward packets from one hop to the next.
CoS Class of Service is supported by prioritizing packets based on the required level of service,
and then placing them in the appropriate output queue. Data is transmitted from the
queues using weighted round-robin service to enforce priority service and prevent
blockage of lower-level queues. Priority may be set according to the port default, the
packet’s priority bit (in the VLAN tag), TCP/UDP port number, IP Precedence bit, or DSCP
priority bit.
DHCP Dynamic Host Control Protocol. Provides a framework for passing configuration information
to hosts on a TCP/IP network. DHCP is based on the Bootstrap Protocol (BOOTP), adding the
capability of automatic allocation of reusable network addresses and additional
configuration options.
DHCP Option 82 A relay option for sending information about the requesting client (or an intermediate relay
agent) in the DHCP request packets forwarded by the switch and in reply packets sent back
from the DHCP server. This information can be used by DHCP servers to assign fixed IP
addresses, or set other services or policies for clients.
DHCP Snooping A technique used to enhance network security by snooping on DHCP server messages to
track the physical location of hosts, ensure that hosts only use the IP addresses assigned to
them, and ensure that only authorized DHCP servers are accessible.
DiffServ Differentiated Services provides quality of service on large networks by employing a well-
defined set of building blocks from which a variety of aggregate forwarding behaviors may
be built. Each packet carries information (DS byte) used by each hop to give it a particular
forwarding treatment, or per-hop behavior, at each network node.
DiffServ allocates
different levels of service to users on the network with mechanisms such as traffic meters,
shapers/droppers, packet markers at the boundaries of the network.
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General