rks, 473 designated port, 75 divide by half IP subnet allocation, 496 failure of link on, 81 DLCIs (data link control identifiers), 301 designated root MAC address, 78 assigned to subinterface and mapped to IP designated router (DR), OSPF, 122 address, 315 designing networks, 461-483 mapping IP addresses to, 312 documentation, 461-471 mapping IP addresses to, using Inverse bay face layouts, 468 ARP, 302 IP and VLAN layouts, 466 status information from LMI, 310 network diagrams, 471 DMZ (demilitarized zone), 363-367 port layout, 463-466 connectivity to a third party, 365 power and cooling firewall configuration, 364 requirements, 469-471 allowing services only as needed, 365 driving forces of network multiple DMZ example, 366 design, 521-523 NAT example, 387 Index DNS load balancing, 396 documentation, 461-471 bay face layouts, 468 E-carrier hierarchy, 259 IP and VLAN spreadsheets, 466 echo reply messages, 333 e-commerce web sites, 477-482 network diagrams, tips for, 471 benefits of 6509 chassis-based port layout spreadsheets, 463-466 solution, 205 power and cooling firewalls, 368 requirements, 469-471 IP scheme, 482 requirements document, 462 domain names, fully qualified, 472 systems considerations, 482 domains, VTP, 44 three-tier architecture, 478 configuring, 49 bridged, 479 DR (designated router), OSPF, 122, 123 management network, 480 routed, 480 drop rate, 451 converged network, too small priority EES (extreme errored seconds), 276 queue, 454 EGPs (external gateway protocols), 110 DS (digital signal) hierarchy, 258 EHLO command, preventing execution of, 376 DS2 (Digital Signal 2), speed, 290 DS3 (Digital Signal 3), 288-298 EIGRP (Enhanced Internal Gateway Routing Protocol), 117 configuring, 292-298 channelized DS3, 295-298 administrative distances, 120 clear-channel DS3, 293-294 ASN identifying EIGRP instance, 117 framing, 288-292 autonomous systems, 104 C-bits, 290 combining features of distance-vector and clear-channel DS3 framing, 292 link-state protocols, 117 databases used to store information, 120 M13