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Figure 4.20. 4/16 Token Ring data link (MAC), and physical (PHY) layer interfaces. Token Ring PHY Implementations The PHY-to-MAC service interface performs the encoding/decoding of the MAC frame into Manchester encoded symbols. The encoded/decoded serial bitstream operates at a rate of 4MHz or 16MHz depending on the ring operating rate. Signal timing for all stations is derived from the active monitor. The ring functions as a timing loop, which is set by the AM. Stations defer to their upstream neighbor when
they first join the ring or in the event that they lose phase lock with the ring. The active monitor is also responsible for setting the minimum latency for the ring, which is based on the size of the active token. The minimum latency is 24 bits.The IBM and IEEE electromechanical interface specifications for the PHY differ somewhat. IBM defines the use of three different cable and connector specifications with an active hub or MAU. The IEEE specification provides a description for a two-wire shielded 150-ohm cable, known as a Medium Interface Cable (MIC). This provides the interconnection between the end-station network adapter and the Trunk Coupling Unit (TCU). This model is in essence the IBM Type 1 cabling specification. According to IBM, a Token Ring network consists of three elements: • Token Ring Network Adapter Card (TR-NAC)—The TR-NAC provides the logic and signaling functions to implement the MAC and PHY layers of the network. It provides the physical interface between the connected end-station and the other adjacent end-stations attached to the physical network media. • Token Ring Network Multistation Access Unit (MAU)—The IBM MAU (IEEE TCU) using Type 1 cabling is a ten-port active hub that can connect up to eight end-stations. The remaining two ports are used for interconnecting with additional MAUs, which enables multiple MAUs to be connected together to form a logical ring. One port is the "ring in," the other is the "ring out" (see Figure 4.21). Connections between MAUs are made with patch cables, and connections between MAU and end-stations are made with lobe cables (IEEE MIC). Today, Token Ring MAUs are almost identical to Ethernet repeaters, with port densities ranging between 12 and 24 ports, using RJ-45 connectors instead of the type 1 MIC connector (see Figure 4.22).
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Understanding the Network A Practic
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IOS Authentication and Accounting S
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About the Reviewers These reviewers
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Tell Us What You Think As the reade
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mostly dealt with interconnecting m
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• A short introduction to SNMP Ap
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In theory, a computer network can o
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Coaxial cable has a single solid co
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• Radio transmission—It is achi
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• Baseband transmission applies t
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Ring Topology Figure 1.3. The bus t
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Packets and frames are often used a
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Asynchronous transmission involves
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Figure 1.6. Collision handling unde
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In a ring topology, a token is pass
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Repeaters The repeater was introduc
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the network. If your 50-node networ
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Figure 1.12. A collection of nodes
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their destination, type, and conten
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shop, you are using Novell's Direct
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Figure 1.14. The OSI and Internet r
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Layer 7: Application This layer pro
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end-to-end, sequenced data delivery
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outer, the delivery path might be d
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and network transport is a very imp
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Figure 1.16. The "bottom up" commun
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Chapter 2. The Networker's Guide to
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Internet Society, a nonprofit organ
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• First, it performs translations
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Figure 2.2. The IP header. • Vers
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To assist in the reassembly process
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Figure 2.3. IP address classes comp
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taking the natural mask of the addr
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Classful Subnetting Examples The im
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21 2,000 8,000 255.255.248.0 22 1,0
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classful-based address space model.
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Table 2.6. Classless Network Addres
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NOTE Because CIDR is used for addre
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will connect in the future, it is b
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Routers are also called intermediat
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IP datagrams for which the local ho
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1. The Layer 3 to Layer 2 address m
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3. Router B—Router B receives the
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connected networks. Figure 2.11 ill
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Figure 2.12. A simple regional (ISP
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gw1, gw2, gw4 3 gw1, gw3, gw4 3 gw1
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Dynamic routing might not be requir
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The transport layer as a whole repr
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window to reflect changes in the pa
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The TCP Header The TCP header provi
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53 DNS (Domain Name Service) 67 BOO
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SNMP Simple Network Management Prot
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uses both TCP and UDP for service d
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RFC 974 Mail routing and the domain
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Figure 3.1. Physical versus logical
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Figure 3.2. The AppleTalk protocol
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AppleTalk Address Resolution Protoc
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of 400 microseconds, in addition to
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Along with the SAP, there is a 5-by
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delivery is a best-effort delivery
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• DDP checksum (long header only)
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eachable within the internetwork. T
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information from the router's other
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AppleTalk Update Based Routing Prot
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• type is the service classificat
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application layers. AppleTalk has n
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Figure 3.10. ZIP message formats. E
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Printer Access Protocol Printer Acc
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Figure 3.11. Novell (IPX) protocol
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The other nodes on the network that
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Figure 3.13. IPX datagram format.
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the cumulative information gleaned
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• Hop Count is the number of rout
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Upper Layer Protocols IPX is used t
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Msg.Add.Name Adds a unique name to
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Related RFCs RFC 1001 RFC 1002 RFC
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service enhancement or replacement
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Figure 4.1. The LLC interfaces in r
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it does not provide for error recov
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and smooth pattern flow enables MTL
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cabling, backbone length 800m Categ
Page 165 and 166: combination of light refraction and
Page 167 and 168: NOTE Cladding is the glass "shell"
Page 169 and 170: Ethernet The original Ethernet prot
Page 171 and 172: UTP telephone cabling infrastructur
Page 173 and 174: Since the introduction of the IEEE
Page 175 and 176: In the event that two Ethernet end-
Page 177 and 178: The 802.3 frame type used in Figure
Page 179 and 180: • Frame check sequence (4 bytes)
Page 181 and 182: • Physical layer signaling (PLS)
Page 183 and 184: cable segment length (for coaxial s
Page 185 and 186: transmission medium using BNC (Brit
Page 187 and 188: Figure 4.12. A basic 3-cable 10Base
Page 189 and 190: Figure 4.14. 10Base-T hub-to-hub in
Page 191 and 192: Figure 4.16. 10Base-T in a consulta
Page 193 and 194: • Support for full-duplex operati
Page 195 and 196: mechanisms, in terms of encoding an
Page 197 and 198: etween different PHY encoding imple
Page 199 and 200: 100Base Ethernet) is based on the p
Page 201 and 202: The Gigabit PHY The Gigabit PHY con
Page 203 and 204: CSMA/CD is sensitive to operating r
Page 205 and 206: The main advantage of using FDR ove
Page 207 and 208: have to transmit against the priori
Page 209 and 210: • Ring timing maintenance—The A
Page 211 and 212: check the lobe cable. If the lobe t
Page 213 and 214: Token Ring addresses are expressed
Page 215: • Report Active Monitor Error (RA
Page 219 and 220: Figure 4.22. The IBM type 1 MIC con
Page 221 and 222: FDDI Work on the Fiber Distributed
Page 223 and 224: However, all this comes at a cost,
Page 225 and 226: Figure 4.25. FDDI MAC data frame an
Page 227 and 228: topologies needed for the transmiss
Page 229 and 230: Chapter 5. WAN Internetworking Tech
Page 231 and 232: Placing a Call The functional model
Page 233 and 234: LATAs to provide local exchange ser
Page 235 and 236: The PSTN was originally designed fo
Page 237 and 238: sampling rate is 8,000 times per se
Page 239 and 240: Figure 5.1. A multiplexer from a lo
Page 241 and 242: Table 5.1. The American (DS) and In
Page 243 and 244: The M24/D4 frame standard is the ba
Page 245 and 246: contains consecutive ones and zeros
Page 247 and 248: • Line loopback/line build-out (L
Page 249 and 250: process. The T3 multiplexer adds st
Page 251 and 252: committee. The committee provided t
Page 253 and 254: The photonic layer defines the elec
Page 255 and 256: such as T1/E1, FDDI, and others. Th
Page 257 and 258: SS7 signaling components are connec
Page 259 and 260: SCCP operates as an OSI-RM Layer 3.
Page 261 and 262: WAN point-to-point links. It can be
Page 263 and 264: Figure 5.11. The ISDN protocol refe
Page 265 and 266: • The R interface acts as a point
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• Flag—This is an 8-bit (011111
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terminals attached to the ISDN swit
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X.25 networks are comprised of four
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Frame Relay, like the ISDN effort i
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• Flag—This functions as a fram
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Figure 5.17. the B-ISDN reference m
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environments is implemented using A
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endpoints. A Virtual Path Link (VPL
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ATM endpoints. The user adaptation
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1. The ATM end-device issues a setu
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Data-Link Framing Point-to-point de
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PPP PPP can provide multiprotocol d
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PPP Framing There are three HDLC fr
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• The HDLC and PPP data-link prot
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Chapter 6. Network Switches In this
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Figure 6.1. Partial and full mesh m
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protocol. Figure 6.3 illustrates th
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All hosts can see the traffic that
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To get a better understanding of th
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Figure 6.5. A bridged LAN with span
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support a path discovery method. So
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or performance limitations, network
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network data encryption, WAN reacha
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The Impact of Switching on Traditio
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• Switch backplane—Also referre
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Switch Port Flow Control In full-du
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In the event that the primary trunk
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Figure 6.9. Layer 2 collision domai
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Figure 6.10. Multiport repeaters an
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Figure 6.11. Distributed and collap
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utilization performance. To calcula
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Ideally, the goal of all switch and
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Cut-through uses the same technolog
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VLANs A switch that supports VLAN p
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MAC Address-Based VLANs Another com
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Figure 6.13. Switches running indep
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The configuration layer uses the Ge
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Layer 2 infrastructures to operate
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need. This method not only allocate
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transmitting and receiving. Without
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ATM-specific applications would be
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ATM private-class switches are comp
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Because both the VPI and VCI are us
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environment. The goal is to have La
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Broadcast and Unknown Server The Br
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Figure 6.15. An LEC and its VCC rel
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ATM hosts are accomplished by estab
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• VLANs • Full-duplex switch po
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Chapter 7. Introduction to Cisco Ro
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The 4000 series routers come in a t
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series routers, this partition can
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need to crimp the CAT 5 strands fol
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Use the cable set to build the cabl
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Step 2. This command specifies whic
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AppleTalk FDDI IPX Token Ring VINES
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The IOS Command Line and Configurat
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disconnect Disconnect an existing n
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changes (user to privileged, for ex
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• Router(config)#hostname test-ro
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or • On 7x00 only, use: • •
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Null Null interface Tunnel Tunnel i
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Router(config)#ip rou? route routin
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Ctrl+P, up arrow Previous command i
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mop Copy from a MOP server (not ava
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Now let's see what is on the PCMCIA
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When copying any file, unless no pr
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Ethernet LANs with a dedicated T1 c
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Compiled Fri 03-Apr-98 07:00 by rna
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172.16.2.0 /25 172.16.2.128 /26 or
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Ridge-GW(config)# ip route 0.0.0.0
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In addition to their native protoco
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D - EIGRP, EX - EIGRP external, O -
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Configuring Dumb Terminal Service T
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Ctrl+Shift+6+X suspends a session).
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cornpops|Printer on Cisco termserve
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Concord-GW(config-if)#flowcontrol h
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The AUX port configuration for Ridg
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outer and enter the break sequence
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Setting the conf-reg Value in ROM M
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• Register setting 0x2010—Confi
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8. 9. Router#configure terminal 10.
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!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
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Router#config t Enter configuration
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-#- ED --type----crc--- -seek--nlen
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to xmodem or TFTP (2600 only) an IO
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Mountain Standard Time (MST) -7 Pac
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eference time is BB0FC7AA.95E93186
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in production for a little while. T
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use debug mode often. When using th
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uucp UNIX-to-UNIX copy system IOS a
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Log Management Logs are useless unl
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IOS Authentication and Accounting I
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hostnames (which can be corrected w
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$telnet 192.160.56.5 Trying 192.160
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In this example, the authentication
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makes it easier to configure, becau
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define what authentication type sho
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Caution should be taken when using
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pairs (similar to those used to cre
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• Using rommon and disaster recov
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In the following section, we review
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Deciding to Use a Routing Protocol
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Now, here is the qualifier: Not eve
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If RIP was the routing protocol for
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Distance Vector Protocols All routi
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space) based on a power of 2. Class
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address space), but you would run i
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destination address that falls with
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the different IP address spaces int
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Weaknesses of Static Routing Static
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Today, RIP is considered by some to
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RIP 192.124.32.0 /24 192.124.35.1 3
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All routers on the network keep tra
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RIP's Value Today RIP is old, it's
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• Better reliability—OSPF route
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Figure 8.10. Single- and multi-area
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• Internal routers—These router
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to the backbone. In Figure 8.13, al
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Figure 8.14. OSPF router designatio
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oundary routers. They describe netw
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outer's point of view. The path con
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Autonomous Systems and Exterior Rou
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Figure 8.16. The IGP to ERP handoff
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Figure 8.17. The BGP finite state m
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EGPs have been increasing in popula
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Chapter 9. Advanced Cisco Router Co
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specified ACL number range. Table 9
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default, all traffic is denied. Onl
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asbr-a2#config t Enter configuratio
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trying to build ACLs with the comma
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trace Multicast trace IGMP log Log
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Tftp Trivial File Transfer Protocol
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access-list 100 permit tcp any 172.
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Table 9.5. AppleTalk ACL Filtering
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Figure 9.1. The AnyCo corporate App
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One word of caution: If you plan to
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You can also log hits on ports by a
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Table 9.8. Route-Map Operators for
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exists, a group identifier (which c
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hegel# With this configuration, bec
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NAT is commonly used in a fashion s
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The [prefix-length] or [netmask] se
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NAT's Shortcomings Although NAT is
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NOTE Administrators beware: Tunneli
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connects, the active key informatio
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encapsulation, framing, and line si
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asbr-a2(config-if)#ip address 172.1
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problem if you are provisioning ISD
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22:41:34: %LINK-3-UPDOWN: Interface
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POP mail request is made. Now let's
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leibniz(config-if)#backup interface
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When the primary link fails, the BR
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1.544Mbps. The actual transport lin
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the cost-effective and bandwidth-ef
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interface configuration subcommand
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it is possible to exchange packets
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interface serial0.2 point-to-point
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Figure 9.6. A multipoint FR example
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2. ATM encapsulation must be enable
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are commonly used in large-scale cl
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persephone(config)#interface atm 3/
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• The creation and application of
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Chapter 10. Configuring IP Routing
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After you have a list of requiremen
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Control commands: Displaying
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not active, it is quite common for
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Incoming update filter list for all
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When changing any IP routing behavi
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asbr-a1(config-if)#^Z asbr-a1# When
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For asbr-a2 to reach all the testne
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192.168.160.0/30 is subnetted, 1 su
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order to maintain computability wit
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Configuring Dynamic IGP and EGP IP
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passive-interface s1 By enabling th
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asbr-a1(config-router)#network 12.0
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To verify that the adjusted route m
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The command is a general routing p
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EIGRP, as I'm sure you have guessed
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No matter how the announcement entr
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Incoming update filter list for all
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is adjustable using the router con
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• IOS also supports various debu
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outers: • Backbone Routers—Thes
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process. The router would construct
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e1/1 192.168.9.0 fe0/0 192.168.0.0
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An alternative to this is to use th
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C 192.168.191.0/24 is directly conn
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Link State Age Interval is 00:20:00
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C 192.168.191.0/24 is directly conn
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to asbr-a1 was a remote office that
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interface Serial1 ip address 192.16
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which to exchange OSPF messages. Th
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OSPF Monitoring Commands Throughout
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• • • NOTE • will display
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Figure 10.4. AURP tunnel interfaces
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appletalk glean-packets hostname as
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For many users, the usefulness of B
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internal/Internet access router whe
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externally destined traffic arrives
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Routers asbr-a1/a2 and asbr-b1/b2 a
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BGP Reflectors An alternative to ha
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network 192.168.0.0 mask 255.255.25
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dynamic routing protocols are used
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Figure 10.8. An example network run
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Controlling Redistribution In some
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hostname ABR-a57 ! access-list 1 pe
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access-list 2 deny 10.0.1.0 access-
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Keep in mind that route-maps, li
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Chapter 11. Network Troubleshooting
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However, the most valuable tool of
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• Description of primary function
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of cable fault, different CSFSs are
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For Windows Systems, check out the
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command. On a Windows NT system, us
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#Do not change these variables logf
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# If any of the hosts fail to respo
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upgrade. So, when the time comes to
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throughput over time, instead of si
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protocol is the most prone to perfo
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NOTE When looking at network broadc
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NOTE Another common network error n
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and the physical ring segment that
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tolerances the frames, timing shift
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practical terms, this means that at
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etransmissions, however, usually ha
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4. Don't get lost in the big pictur
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• Link and services monitoring, n
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eports on network utilization, avai
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o Bandwidth utilization rates o Rat
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and improved management capabilitie
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After the supported SNMP version is
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Table 11.3. ASN.1 Keywords Used wit
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application-wide tags, which are us
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TestSequence ::= SEQUENCE { example
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The MIB-2 and RMON-MIB modules are
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iso.identfied-orgnaization.dod.inte
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accepted values are getRequest, get
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Spectrum is available in both UNIX
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Figure 11.8. Windows NT 4.0 SNMP Ag
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To access any of the NT SNMP agent
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The installation of the SNMP agent
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Figure 11.13. The Windows 95/98 Sel
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Figure 11.15. Locating the Windows
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Figure 11.17. The SNMP configuratio
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2. Scroll to Network Connectivity o
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sysLocation information, go to the
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example that just implements the ba
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protocol, service, and application
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RFC 1089 RFC 1147 RFC 1155 RFC 1157
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Appendix A. Binary Conversion Table
show all

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