Dell PowerConnect 5548 User Guide - Page 27

SNTP The Simple Network Time Protocol (SNTP) assures accurate network Ethernet Switch clock time synchronization up to the millisecond. Time synchronization is performed by a network SNTP server. Time sources are prioritized by strata. Strata define the distance from the reference clock. The higher the stratum (where zero is the highest), the more accurate the clock. For more information, see "Time Synchronization" on page 162. Domain Name System Domain Name System (DNS) converts user-defined domain names into IP addresses. Each time a domain name is assigned, the DNS service translates the name into a numeric IP address. For example, www.ipexample.com is translated into 192.87.56.2. DNS servers maintain domain name databases containing their corresponding IP addresses. For more information, see "Domain Name System" on page 235. 802.1ab (LLDP-MED) The Link Layer Discovery Protocol (LLDP) enables network managers to troubleshoot, and enhances network management by discovering and maintaining network topologies over multi-vendor environments. LLDP discovers network neighbors by standardizing methods for network devices to advertise themselves to other systems, and to store discovered information. The multiple advertisement sets are sent in the packet Type Length Value (TLV) field. LLDP devices must support chassis and port ID advertisement, as well as system name, system ID, system description, and system capability advertisements. LLDP Media Endpoint Discovery (LLDP-MED) increases network flexibility by enabling various IP systems to co-exist on a single network LLDP. It provides detailed network topology information, emergency call service via IP phone location information, and troubleshooting information. For more information, see "LLDP" on page 531. Dell PowerConnect 55xx Systems User Guide 27