The Illustrated Network- P82

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The Illustrated Network- P82:In this chapter, you will learn about the protocol stack used on the global public Internet and how these protocols have been evolving in today’s world. We’ll review some key basic defi nitions and see the network used to illustrate all of the examples in this book, as well as the packet content, the role that hosts and routers play on the network, and how graphic user and command line interfaces (GUI and CLI, respectively) both are used to interact with devices.

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Nội dung Text: The Illustrated Network- P82

Index 779 routing, 218–19 Interior Gateway Routing Protocol (IGRP), routing tables, 322–23 355 SNMP, 610–11 Enhanced (EIGRP), 355, 364–65 sockets, 302–3 RIP improvement, 365 SONET link display, 76–78 Intermediate device control, 638 SSH, 634–35 Intermediate System–Intermediate System SSL, 586–87 (IS–IS), 345, 354 TCP, 280–81 areas, 374 UDP, 260–61 attraction, 373 VLANs, 660–61 backbone area, 373 VoIP, 736–37 DIS, 375 VPLS, 673 IPv6, 376 Web servers, 560–61 as link-state protocol, 354 Web sites, 586–87 LSP handling, 375 wireless link display, 81–83 metrics, 375 In-band management, 248 M-ISIS, 413 Independent basic service set (IBSS), 98 network addresses, 375 Indirect delivery, 229 network types, 375 packet destination address, 232–33 OSPF and, 373–74 router and, 231–34 OSPF differences, 374–75 Informational RFCs, 20 OSPF similarities, 374 Ingress routers, 446, 450 route leaking, 374 Institute of Electrical and Electronics routers, 373 Engineers (IEEE). See IEEE 802.11; Intermediate systems, 6 IEEE 802.3 as TCP/IP device category, 26 Integrated Information Services (IIS), Internal representation conversion, 562 41–42 Integrated Services Digital Network (ISDN), International Standards Organization (ISO), 85, 90 17–18 DSL as extension, 94 International Telecommunications Union - Integrity, 593–94 Telecommunications sector (ITU-T), Integrity check value (ICV), 723 18 Inter-Domain Routing Protocol (IDRP), 379 Internet Interface addresses, 212–13 administration, 21–22 Interfaces, 27–28 autonomous system and, 332–34 application layer, 52 backbone routers, 246 GRE, 241 connectivity check, 195 for packets, 84 drafts, 18, 19, 21 routers, 233–34 standards, 18, 20 TCP/IP application, 11 today, 334–36 Interior BGP (IBGP), 382, 389–90 zones, 489 full mesh, 392 Internet Architecture Board (IAB), 22 need for, 390 Internet Assigned Numbers Authority (IANA), peers, 391 421 sessions, 389 Internet Control Message Protocol (ICMP), uses, 389 189–215 See also Border Gateway Protocol (BGP) Destination Unreachable codes, 200 Interior gateway protocols (IGPs), Destination Unreachable errors, 199, 201 342, 345 Illustrated Network, 190–91 bootstrapping themselves, 354 IP packets, 165 next hops, 390 packets, 193 shortcuts, 447 ping and, 192–96 types of, 354 round-trip time, 192
780 Index Internet Control Message Protocol dynamic assignment, 121 (cont’d) host, 121 sequence numbers, 192 Illustrated Network, 110–11 time-exceeded errors, 199 packet headers and, 168–70 See also ICMP messages private, 121 Internet Corporation for Assigned public, 120 Names and Numbers (ICANN), 22, static assignment, 121 36 unicast, 116 Internet Engineering Task Force (IETF), IP layer, 57–58, 165 18 IP mapping, 44 working groups, 22 IPoFW IP over Firewire, 85 Internet exchange points (IXPs), 334 IPSec, 665, 713–31 linking, 336 in action, 716–19 running of, 334 AH, 713 Internet Group Management Protocol BITS, 720 (IGMP), 416–17 BITW, 720 backward compatibility, 416 endpoints, 719 messages, 204 ESP, 713 multicast group, 408 IKE, 713, 719 versions, 416–17 Illustrated Network, 714–15 Internet key exchange (IKE), 713, 719, implementation, 719–21 728–29 introduction to, 719–21 ISAKMP, 728, 729 RFCs, 719 OAKLEY, 729 routers and, 721 protocols, 728–29 SPI, 203 SKEME, 729 support components, 719 Internet Message Access Protocol (IMAP), topology, 717 542 transport mode, 721 Internet Network Information Center tunnel mode, 721 (InterNIC), 22 tunnels, 717, 718 Internet Research Task Force (IRTF), 22 IP source routing, 638 Internet Security Association and Key IP spooﬁng, 638 Management Protocol (ISAKMP), IPv4 728, 729 browsers, 251 Internet service providers (ISPs) dual protocol stacks, 252 chained, 334 ESP packet formats, 727 grid-net, 334, 338 fragmentation and, 172–77 peering arrangements, 334–35, 339 fragmentation example, 177–82 peer selection, 340–42 limitations, 179 router/routing protocol use, 319 multicast, 406–8 Internet Society (ISOC), 21 Options, 179 Internetworking, 47 ping and, 193–95 Illustrated Network, 48–49 routing tables, 221 Interoperability, 16 transition to IPv6, 256 Intra-site Automatic Tunnel Addressing tunnels, 255 Protocol (ISATAP) tunnels, 255 UDP pseudo-header, 268 Inverse ARP (InARP), 146, 159 IPv4 addresses, 50, 118–23 IP addressing, 36, 112–17 ARP, 58 anycast, 116–17 classful, 114, 118, 120 assignment, 138–40 classless, 119, 120 automatic, 112 dotted decimal notation, 119 broadcast/multicast, 116 formats, 122, 141 duplicate, 213 illustrated, 118
Index 781 Linux assignment, 113 tunnels, 254 multicast, 420, 421–23 UDP pseudo-header, 268, 269 overview, 109 IPv6 addresses, 123 private, 121, 122 address allocation, 139 protocol ﬁeld, 51 address discovery options, 124 public, 120, 121 address resolution, 152, 162 special forms, 123 address type, 126 subnetting and, 127–31 address types and notation, 125–26 understanding, 122–23 assignment, 138–40 IPv4-compatible IPv6 address, 256 chained headers, 124 IPv4-mapped IPv6 address, 256 details, 135–40 IPv4 packet headers, 170–79 Ethereal capture and display, 152 Ethereal interpretation of ﬁelds, features, 123–25 169 ﬂow caching, 124 ﬁelds, 168, 169 formats, 136–37, 141 Flags ﬁeld, 171 future of, 109 Fragment Offset ﬁeld, 171 header compression and extension, Header Checksum ﬁeld, 172 124 Header Length ﬁeld, 171 hexadecimal notation for, 119, 125 Identiﬁcation ﬁeld, 171 interface, 212–13 illustrated, 170 LAN interface, 114 Illustrated Network, 166–67 link-local, 7, 127, 136 IPv6 header comparison, 182–84 local use, 136 multicast, converting, 421 multicast, 213, 423–24 Options ﬁeld, 172 multicast, format, 424 Padding ﬁeld, 172 neighbor discovery and address Protocol ﬁeld, 172 resolution, 162 Source and Destination Address ﬁeld, preﬁxes, 126–27 172 preﬁx masks, 137 Total Packet Length ﬁeld, 171 private, 127 ToS ﬁeld, 171 provider based, 136 TTL ﬁeld, 172 provider independent, 126, 136 Version ﬁeld, 171 routable, 349 IPv6 router-assigned preﬁxes, 113 AH packet formats, 723 routing, 135 ARP and, 159–62 site-local, 126–27 core routers, 139 size increase, 124 dual protocol stacks, 252 support, 114–15 ESP packet formats, 726 transition to, 125 fragmentation and, 184–86 ULA-L, 137 Fragmentation Header ﬁelds, 186 unique local-unicast, 127 FTP passive command and, 515 use of, 123 IS–IS for, 376 IPv6-only address, 256 multicast, 427–28 IPv6 packet headers, 179–82 multicast groups, 160 64-bit units, 183 NAT and, 684 changes, 183–84 OSPFv3 for, 372 Extension Headers, 184 ping and, 195–96 Flow Label ﬁeld, 181, 183 router announcements, 406 Hop Limit ﬁeld, 182 routers, 212 illustrated, 181 routing tables, 221, 332 Illustrated Network, 166–67 transition to, 251, 256 IPv4 header comparison, 182–84 tunnel-addressing format, 254 Next Header ﬁeld, 182
782 Index IPv6 packet headers (cont’d) customer edge, 669–70 Payload Length ﬁeld, 181, 183 provider edge, 670 Trafﬁc Class ﬁeld, 181 See also Virtual private networks (VPNs) Version ﬁeld, 181 Layers, 22–25 ISDN DSL (IDSL), 95 applications and, 301–4 ISPs. See Internet service providers ARP and, 146 combining, 24 J encapsulation, 28–29 Java Applets, 570 IP, 57–58, 165 Java sandbox, 706 protocol, 24–25 Jitter, 742, 743 simple networking and, 23–24 Juniper Network routers, 237, 241, 246 TCP/IP, 14, 25, 26–27, 30–41 DHCP relay agent, 464–65 See also speciﬁc layers enabling SNMP on, 612 Link Control Protocol (LCP), 92, 662 stateful inspection, 702 Link-local IPv6 addresses, 7, 113 Links K backdoor, 368 Keepalive message, BGP, 397 broken, 356–57 Keepalive packets, 78 DSL, 78–81 Kerberos, 514 external, 348 Key exchange, 643, 644, 652 internal, 348 SONET, 76–78 L wireless, 81–83 Label Distribution Protocol (LDP), 447 Link-state advertisements (LSAs), 366, Label stacking, 444, 448–49 373 Label switched paths (LSPs), 446 Link states, 365–66 constrained, 447 Linux nested, 448 ARP cache display, 151 path details, 452 BSD style, 152 signaled, 446 ﬂags, 224 static, 446, 450–53 FTP and, 514 traceroute and, 452–53 FTP passive using, 515 trafﬁc engineering, 447 hosts, 224 VPNs and, 449 IP forwarding, 243 Label tables, 449 IPv4 address assignment, 113 LACNIC (Latin American and Caribbean Kerberos, 514 Network Information Center), 138 routing tables and, 330–31 Latency, 742 sockets on, 311–16 Layer 2 forwarding (L2F), 666 Listeners, 409 Layer 2 tunneling protocol (L2TP), 666, 667 Load balancing, 352 Access Concentrator (LAC), 662 Local area networks (LANs), 7 encryption, 667 100BaseT Ethernet, 62 PPTP comparison, 668 ARP and, 146–53 Layer 2 VPNs (L2VPNs), 659, 671–72 IEEE 802.11 and, 98–104 architecture, 671 individual address, 420 creation, 659 linking, 47 MPLS-based, 672–76 multicasting on, 420–21 service delivery, 671 segmentation, 47, 61–62, 87 variations, 671 subnetting, 130 See also Virtual private networks (VPNs) switches, 64–65 Layer 3 VPNs (L3VPNs), 442, 668–70 virtual, 47, 58, 65–68, 671 complexity, 669 wireless, 82 connectivity, 669 Longest match, 250
Index 783 M Media access control (MAC), 33 MAC addresses, 58, 75, 89–90 IEEE 802.11 layer protocol, 100 all-zero, 149 See also MAC addresses destination host, 231 Media gateways, 752 direct delivery and, 227 Megaco/H.248, 748, 749, 752–53 frame IP and, 229 Memory interplay, 104 DRAM, 245 NICs, 231 nonvolatile, 243 wireless LAN frame, 89, 103–4 packet, 245 Mailboxes, 538 RAM and ROM, 243, 245 Mail user agents (MUAs), 535 routers, 243, 244 Major components, 7 volatile, 243 Management information bases (MIBs), 609, Message access agent (MAA), 538 620–22 Message delimiters, 15 access ﬁeld, 621 Message digest, 594 coding/implementing, 621 Message formats, 15 compiler, 621 Message transfer agent (MTA), 538, 543 as database description, 618 Methods, HTTP, 575–76 defval ﬁeld, 621 Metrics description ﬁeld, 621 IS–IS, 375 Ethernet, 621, 622 netstat command and, 223 extensible, 622 OSPF, 366 ﬁelds, 620–21 RIP, 355 index ﬁeld, 621 RIPv1, 359 information structure, 618 routing tables, 221 MIB-II, 618 Windows output, 226 naming tree, 618 Mobile IP, 203 object-code module, 621 Mobility, in protocol evolution, 3–6 objects, 620 MPLS. See Multiprotocol label private, 622–23 switching reference ﬁeld, 621 MPLS-Enabled Applications (Minei and sample object deﬁnitions, 621 Lucek), 659 SONET/SDH, 622 Multicast, 266, 403–29 status ﬁeld, 621 administratively scoped addresses, syntax ﬁeld, 620 407 trees, 620 applications, 406, 407 variables, 618 concepts, 411–14 Management tasks, 10 dense-mode, 410 Managers, 616 in DHCP, 266 console database, 617 downstream interface, 409 “Man-in-the-middle” threat, 595 frames and, 420–21 Manually conﬁgured tunnels, 255 groups, 160, 410 Maximum segment size (MSS), 286 hosts, 415 Maximum Transmission Units (MTUs), 112 IGMP group, 408 default sizes, 172 Illustrated Network, 404–5 fragmentation and, 175–76 IPv4, 406–8 frame size, 234 IPv6, 427–28 minimum size, 176 on LANs, 420–21 path, 206–8 notation, 411 path determination, 176–77 one-to-many operation, 403 small size, 174, 176 packet capture, 407 typical sizes, 175 PGM, 416
784 Index Multicast (cont’d) Multiprotocol BGP (MBGP), 392, 413, 447–48 rendezvous point (RP) model, 414 backward compatibility, 448 rendezvous-point tree (RPT), 414 extensions, 447 reverse-path forwarding, 411–12 Multiprotocol label switching (MPLS), 388, RIP use, 350 442–53 RIPv2, 362 32-bit label ﬁelds, 444 routers, 409, 415–16 architecture, 444 routing loops and, 409 as BGP shortcut, 443 RPF table, 412–13 domains, 446, 448 shortest-path tree (SPT), 413–14 egress router, 446, 451–52 sparse-mode, 410–11 Illustrated Network, 432–33 TCP/IP, 408 ingress router, 446, 450 terminology, 408–10 label stacking, 444, 448–99 upstream interface, 409 label values, 445 Multicast addresses, 421–24 LSP, 664 IPv4, 421–23 management, 445 IPv6, 423–24 rationale, 443 for protocols, 422 reconﬁguration, 445 ranges, 422, 423 signaling and, 447–48 source addresses and, 421–22 static LSPs and, 450–53 Multicast Listener Discovery (MLD), tables, 449–50 415, 417 terminology, 446–47 Multicast Open Shortest Path First (MOSPF), trafﬁc engineering, 442 413, 417 transit router, 446, 450–51 Multicast protocols, 415–28 tunnels and, 442 ASM, 418–19 VPNs and, 449 CBT, 418 Multipurpose Internet Mail Extensions characteristics, 418 (MIME), 543, 547–50 DVMRP, 417 composite types, 548 group membership, 416–17 discrete types, 548 IGMP, 416–17 encoding, 548–49 MLD, 415, 417 entity headers and, 579 MOSPF, 417 media types, 548 MSDP, 419–20 message, 548 PGM, 426 message example, 549–50 PIM DM, 417 security (S/MIME), 544 PIM SM, 417–18 Multitasking, Windows, 310 routing, 409, 417–18, 426–27 SSM, 418–19 N suite, 407 Name servers, 491 support, 403 application interaction, 489 Multicast Source Discovery Protocol referral queries to, 495 (MSDP), 406, 419–20 Negotiation of parameters, 15 Multihomed, 389 Neighbor discovery Multihop BGP, 392 ICMPv6 functions, 211–12 Multimedia, in protocol evolution, 3–6 routers and, 212 Multimedia Gateway Control Protocol Neighbor Discovery Protocol, 160–61 (MGCP), 748, 749, 752–53 address resolution, 161–62 Multiplexing, 39, 301–16 Neighbor Advertisement message, 161, 162 need for, 301 Neighbor Solicitation message, 160 ports, 270 Router Advertisement message, 161 SSH-CONN, 645 Router Solicitation message, 161 Multipoint conﬁguration, 31 Neighbor routers, 353
Index 785 Nested MPLS domains, 448 host boundary, 117 NetBIOS, 310 illustrated, 4–5 Netstat command link technologies, 71–105 lp option, 264 private, 71 metrics and, 223 public, 71 nr option, 223, 225, 329 remote device access, 8–10 r option, 222 router access, 248–49 Network address translation (NAT), 525, Network Service Attachment Point (NSAP) 681–95 addresses, 126 in action, 691–94 Network Virtual Terminal (NVT), 42 address types, 686 Next hop, 233 advantages, 684–85 BGP, 390 bidirectional, 687–89 determination, 249 device, 115 identiﬁcation, RIPv2, 361–62 disadvantages, 658 IGP, 390 FTP passive command and, 515 RIPng, 364 Illustrated Network, 682–83 self, 391 IPv6, 137, 684 Nodal processing delay, 742 overlapping, 690–91 Nonauthoritative servers, 487 port-based, 689–90 Non-broadcast multiaccess (NBMA), private address translation, 122 159 translation, 693 Nonrepudiation, 594, 603–4 translational mappings, 686 Nonvolatile RAM (NVRAM), 243, 245 types of, 685–86 startup-conﬁg, 245 unidirectional, 686–87 Notiﬁcation message, BGP, 396, 399–400 using, 684–91 Not-so-stubby areas (NSSAs), 374 Network File System (NFS), 60, 530–31 Nslookup utility, 497, 501 XDR standard, 531 NULL Cipher Suite, 599 Networking ﬁrst explorations in, 14 O layers and, 23–24 OAKLEY, 729 visions, 91 On-demand connections, 279 Network interface cards (NICs), 231 One-way hash, 594 Network intrusion detection (NID), 289 Online Certiﬁcate Status Protocol (OCSP), Network layer, 30, 35–38 603 fragmentation, 36 Open message, BGP, 396, 397, 398 illustrated, 35 Open Shortest Path First (OSPF), 237, 354, MTUs and, 175–76 365–72 routing, 324–25 area types, 369 routing tables, 37 backbone area, 367 source-to-destination delivery, 37 BDR, 370–71 switching, 324–25 classless addressing, 367 See also TCP/IP layers DR, 370–71 Network layer reachability information equal-cost multipaths, 366 (NLRI), 382 functions, 366–68 Network Management Protocol, 617 internal/external routes, 367 Network operations centers (NOCs), 341, IS–IS and, 373–74 609 IS–IS differences, 374–75 Network processor engines (NPEs), 244 IS–IS similarities, 374 Networks as link-state routing protocol, 354, 365 addresses, 36 metrics, 366 connectionless, 325–28 MOSPF, 413, 417 connection-oriented, 325–28 non-backbone, non-stub area, 369
786 Index Open Shortest Path First (cont’d) RAS, 740 not-so-stubby area, 370 reassembly, 176, 178 OSPFv1, 365 RIPv1, 358 OSPFv3, 345, 372 RIPv2, 359–61 packets, 371–72 RTP, 740 reliable ﬂooding, 366 signaling, 740, 741 router hierarchies, 367 on SVCs, 324 router types, 368–70 tunneling, 237 security, 367 X.25, 436 stub area, 369–70 Passive open, 56 ToS routing, 367–68 Path MTU total stub area, 370 discovery, 206–8 OpenSSH, 637 plateaus, 208 OpenSSL, 588, 602 seed or probe size, 208 testing certiﬁcate, 589, 604 size, tuning, 207 See also Secure socket layer (SSL) Path Vector Protocol, 388–89 Open Standard Interconnection (OSI) Payload, 24 reference model, 25 Peering, 334–35, 339 Outgoing interface list (OIL), 411 candidates, 341 Overﬂows, 274–75 public points, 340 Overlapping NAT, 690–91 Peer-to-peer models, 55 cases, 690 Peer-to-Peer Protocol process, 27 illustrated, 691 Penultimate hop popping (PHP), See also Network address translation 446–47 Permanent connections, 279 P Permanent virtual circuits (PVCs), 90, 324, Packet ﬁlters, 700–701, 706 446 implementation, 706 packets on, 324 See also Firewalls Physical connections, 15 Packet headers, 165–87 Physical layer, 30–32 addresses and, 168–70 bit synchronization, 31 Extension Headers, 184 conﬁguration, 31 ﬁelds, 168, 169 contents, 30 IPv4, 170–79 data rate, 31 IPv6, 179–82 illustrated, 31 Packetization delay, 742 mode, 31–32 Packetized voice, 744 RFCs and, 84 Packet memory, 245 speciﬁcation, 30 Packet over SONET/SDH (POS), 97–98 topology, 31 Packets See also TCP/IP layers ARP, 153–55 Ping, 192, 204–5 arriving, 178 in checking connectivity, 195 CLNP, 372 ICMP and, 192–96 CS, 740 ICMP requests and replies, 194 forwarding, 237–57 implementations, 194, 205 fragmentation, 168, 178 IPv4 and, 193–95 ICMP, 193 IPv6 and, 195–96 interfaces for, 84 PID identiﬁer, 205 IS–IS, 372 quirks, 205 keepalive, 78 Pocket calculator encryption, 595–98 OSPF, 371–72 at client, 595–96 processing, 242–43 Difﬁe-Hellman, 643–44 on PVCs, 324 at server, 597–98
Index 787 Point coordination function (PCF), 100 IPv6, 127 Points of presence (POP), 334 translation, 122 Point-to-point links, 31 See also IP addressing Point-to-Point Protocol (PPP), 78, 84 Private keys, 591 compressed data, 666 clear, 602–3 DSL and, 91–92 decryption with, 593 frames, 93 primes, 596 framing for packets, 92–93 Private MIB, 622–23 Link Control Protocol (LCP), 92, 662 Private networks, 71 Network Control Protocol (NCP), Private ports, 264, 271, 272 92 Process addressing, 39 Point-to-Point Tunneling Protocol (PPTP), Process-to-process delivery, 38, 40 659, 666–67 Protocol data units (PDUs), 27, 165 access concatenator (PAC), 666 Protocol Independent Multicast dense mode architecture, 667 (PIM DM), 417, 426 compressed data, 666 Protocol Independent Multicast sparse mode L2TP comparison, 668 (PIM SM), 417–18, 425 network server (PNS), 666 Protocols, 14–21, 27 over DSL session, 663 bandwidth and mobility, 3–6 Policy routing, 333 email, 542–44 Polling, SNMP, 625, 627 end-to-end, 570 Pop, 446 interfaces and, 27–28 POP3, 550–52 layers, 24–25 capture, 550, 557 multicast, 403, 407, 415–28 connection, 551 multimedia use, 3 TCP port, 551 new, 6 See also Email security, 6 Port addresses, 39 speciﬁcations, 15 Port address translation (PAT), 689 standards versus, 15 Port-based NAT, 689–90 trends, 3–6 Port mapper, 531 tunneling, 91 Ports for VoIP, 744–53 auxiliary, 248 VPNs and, 665–66 console, 248 See also speciﬁc protocols dynamic, 264, 271, 272 Protocol stacks dynamically mapping, 531 DSL, 94 echo, 265 dual, 252 FTP, 518 Illustrated Network, 50–51 input, 243 RTP, 746 LAN switch, 64 SSL, 599–601 multiplexing and distribution, 270 TCP/IP, 624 numbers, 52, 269–74 Provider-edge (PE) routers, 9, 670 output, 243 PE1, 675–76 persistent, 270 PE5, 673–74 registered, 271 Provider (P) routers, 9, 670, 674–76 UDP, 260–61, 262–66 Proxy agents, 617 well-known, 269–73 Proxy ARP, 157–58 Pragmatic General Multicast (PGM), Proxy servers, 752 416, 426 Pseudo-header, 266, 267 goals, 426 illustrated, 268, 269 Privacy, 593 IPv4, 268 Private IP addresses, 121 IPv6, 268, 269 IPV4, 122 presence, 268
788 Index Pseudo-header (cont’d) R TCP, 297 RAM UDP, 268–69 nonvolatile, 243, 245 Pseudorandom number generators (PRNGs), as working storage, 245 603 Random seeds, 640 Public IP addresses, 120 Raw sockets, 306 obtaining, 121 threat, 308–9 voice trafﬁc types, 741–42 Unix-based access, 309 See also IP addressing Windows and, 308 Public key encryption, 595–98 See also Sockets example, 596 Real-Time Protocol (RTP), 59, 739 pocket calculator, at client, 595–96 application layer framing, 745 pocket calculator, at server, 597–98 architecture, 745 security, 595 header, 746 SSL use, 598 header ﬁelds, 747 See also Encryption packets, 740 Public key infrastructure (PKI), 585, 598 payload formats, 747 Public keys, 591 protocol stack, 746 association, 595 reports, 747–48 digital signatures, 598 as transport mechanism, 747 message encryption, 593 for VoIP transport, 745–78 primes, 596 Reassembly, 176, 178 with symmetrical encryption, 598 Recursive queries, 490–91 toolkits, 601–22 Regional Internet Registries (RIRs), Public networks, 71 138 Public switched telephone network (PSTN), Registered ports, 271 18, 36 Relay agents, 464–65 trafﬁc percentage, 738 BOOTP, 464, 471, 472 VoIP and, 735 DHCP, 464–65 Push, 446 Reliable ﬂooding, 366 PuTTY, 654 Remote access, 8–10 for FTP, 10 Q securing, 10 Quadruple play, 431 Remote procedure calls (RPCs), 531 Quality of service (QoS), 170, 321, 327 Rendezvous point (RP) bandwidth, 327 embedded, 415 connectionless networks, 326–28 model, 414 connection-oriented networks, Rendezvous-point tree (RPT), 414 326–27 Repeater operation, 60 consistency, 328 Requests for comments (RFCs), 18–19 jitter, 327–28 CIDR, 132 methodology, 326 Elective, 20 parameter list, 327 experimental, 20 parameters, 57, 326–28 FTP, 518 security, 328 informational, 20 Queries IPSec, 719 iterative, 491 Limited Use, 20 recursive, 490–91 maturity levels, 19 Query messages, 201–2 Not Recommended, 21 DNS, 495 physical layers and, 84 list of, 201, 202 Recommended, 20 See also Internet Control Message Required, 20 Protocol (ICMP)