0 NAT support, 501-506 AVF (Active Virtual Forwarder), 190 object groups and, 475-477 AVG (Active Virtual Gateway), 190 remote access, 506 avoiding frustration routed mode, 493 change control and, 725-727 Index computer jerks and, 727-730 bipolar violation (BPV), 358, 359, 362 selling ideas to management, 718-722 Bit Error Rate Test (BERT), 344, 369 when and why to upgrade, 722-725 blades, defined, 16 why everything is messed up, 715-718 blind transfers, 541 blocking state, 90 blue alarm, 366 BNC connectors, 5 B-channels, 347 boot-order command, 286 B8ZS (Binary Eight Zero Substitution), 358 Border Gateway Protocol (see BGP) BA (bridge assurance), 103 BPDU Guard feature (spanning tree), 96 Baby Bells, 351 BPDUs (bridge protocol data units) backbone routers, 138 BPDU Guard feature and, 96 BackboneFast feature (spanning tree), 93, 99- bridge assurance and, 103 defined, 88 backplane duplex mismatch and, 100 Cisco 6509 example, 236 unidirectional links and, 102 defined, 267 BPV (bipolar violation), 358, 359, 362 module support, 240 BRI (Basic Rate Interface), 347 Nexus design features, 280 bridge assurance (BA), 103 backup designated router (BDR), 138 bridge ID, 88 Backward-Explicit Congestion Notification bridge irb command, 516 (BECN), 395 bridge protocol data units (see BPDUs) bandwidth Bridge Virtual Interface (BVI), 519 defined, 343 bridges, 88 determining requirements, 592-593 (see also root bridges) QoS misconceptions, 587 defined, 81 bandwidth command, 596, 608 designated, 89 basic authentication in ecommerce website designs, 644 configuring local users, 439-442 transparent mode and, 493 defined, 437 British Thermal Unit (BTU), 635 line passwords, 437-439 broadcast domains, 8 PPP, 442-449 broadcast networks, 141 Basic Rate Interface (BRI), 347 broadcast storms, 9, 82-86 bay face layouts, 634 BTU (British Thermal Unit), 635 BDR (backup designated router), 138 buffer-delete command, 304 bearer channels, 347, 357, 524 buffer-move command, 304 bearer traffic, 524 burst rate, 390 BECN (Backward-Explicit Congestion