3Com 3CBLSG48 User Guide - Page 200

appendix b: DEVICE SPECIFICATION AND FEATURES 189 Table 11 Features of the Baseline Switch 2948-SFP Plus Feature Automatic MAC Addresses Aging Back Pressure 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. Address Resolution Protocol (ARP Class Of Service (CoS) 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. Command Line Interface 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. Configuration File Management 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. DHCP Clients 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. Fast Link 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. Full 802.1Q VLAN 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.