3Com 3CBLSG48 User Manual page 200

Table 11 Features of the Baseline Switch 2948-SFP Plus
Feature
Automatic MAC Addresses Aging
Back Pressure
Address Resolution
Protocol (ARP)
Class Of Service (CoS)
Command line Interface
Configuration File
Management
DHCP Clients
Fast link
Full 802.1Q VlAn
Description
MAC addresses from which no traffic is received for a given period
are aged out. This prevents the Bridging Table from overflowing.
On half duplex links, the receiver may employ back pressure
(i.e. occupy the link so it is unavailable for additional traffic), to
temporarily prevent the sender from transmitting additional traffic.
This is used to prevent buffer overflows.
ARP converts between IP addresses and MAC (i.e., 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.
Provide traffic belonging to a group preferential service (in terms of
allocation of system resources), possibly at the expense of other traffic.
The Command line Interface (ClI) is an interface using a serial connection
that allows basic features to be configured, including IP address
management and firmware upgrading. The ClI is not intended as the main
interface for the switch.
The device configuration is stored in a configuration file. The Configuration
file includes both system wide and port specific device configuration. The
system can display configuration files in the form of a collection of ClI
commands, which are stored and manipulated as text files.
Dynamic Host Client Protocol. DHCP enables additional setup parameters to
be received from a network server upon system startup. DHCP service is an
on-going process.
STP can take up to 30-60 seconds to converge. During this time, STP detects
possible loops, allowing time for status changes to propagate and for
relevant devices to respond. 30-60 seconds is considered too long of a
response time for many applications. The Fast link option bypasses this
delay, and can be used in network topologies where forwarding loops do not
occur.
IEEE 802.1Q defines an architecture for virtual bridged lAns, the Tagging
Compliance services provided in VlAns, and the protocols and algorithms
involved in the provision of these services. An important requirement
included in this standard is the ability to mark frames with a desired Class of
Service (CoS) tag value.
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