The point-to-point series link is a lilliputian unlike than the Frame Relay series link. As y'all recall, Frame Relay is used inward many cases inward a point-to-multipoint environment. To do a point-to-point connexion betwixt 2 routers, y'all tin exercise other types of WAN encapsulations, such every bit HDLC, PPP, in addition to SLIP. For a consummate review of these encapsulations, refer to Chapter xi of the ICDN book. We volition exercise the default series encapsulation, which is HDLC.
For 2 series interfaces to communicate, y'all must provide the clock rate. The clock charge per unit of measurement provides chip synchronization in addition to has other uses that are beyond the reach of this chapter's purposes. The device that provides this clock charge per unit of measurement is the information circuit-terminating equipment (DCE). The other device is denoted every bit the information terminal equipment (DTE). In the existent world, the router is the DTE. The telecom equipment, such every bit the Frame Relay switch, is the DCE. Because the lab scenario bypasses the telecom equipment, y'all demand to specify which router is the DTE in addition to which 1 is the DCE; y'all also demand to provide the clock rate. To bypass the telecom equipment, y'all demand to take connect the routers amongst a DTE–DCE crossover cable. Each cease of this cable is labeled every bit DTE or DCE. Whichever router is plugged into the DCE cease of the cable volition demand to provide the clock rate. In the Frame Relay network, the Frame Relay switch is the DCE, so none of the Frame Relay routers needs to provide clock rate. For to a greater extent than information on WAN series cabling in addition to signaling, refer to Chapter 2 of Interconnecting Cisco Network Devices from Cisco Press.
First, review the routers that y'all are going to exercise to configure a point-to-point series connection. Figure 7-4 shows routers R3 in addition to R5. This is the exclusively point-to-point connexion inward the lab.
In the figure, y'all tin encounter the R5 has been cabled every bit the DCE, so it volition demand to provide the clock rate.
Begin yesteryear configuring the series link in addition to assign IP addresses to the interfaces. Start amongst R5.
You concluding configured R2, so y'all demand to become dorsum to the terminal server in addition to resume the connexion to R5. When there, y'all demand to become into global configuration manner in addition to so into the appropriate interface configuration. For R5, that would hold upwards Serial 0. Example 7-26 walks y'all through these initial configuration steps.
Example 7-26. R5 Serial Configuration
R2# R2#<crtl-shft-6-x> Termserver#5 [Resuming connexion five to r5 ... ] R5#config t Enter configuration commands, 1 per line. End amongst CNTL/Z. R5(config)#interface series 0 R5(config-if)#Now that y'all are inward interface configuration manner for R5's Serial 0, y'all tin execute the necessary configuration commands. The start affair to do is brand the encapsulation type HDLC for the interface. Because HDLC is the default encapsulation method, y'all actually don't demand to execute the command. However, merely for the sake of practice, in addition to so that y'all sympathise that at that topographic point is a information link layer configuration ascendancy for the series link, specify HDLC every bit the encapsulation yesteryear entering it every bit a ascendancy option. This is the same ascendancy issued previously when specifying the encapsulation type for routers R2, R3, in addition to R4; the exclusively divergence is that y'all specify the hdlc choice instead of frame-relay.
This is the ascendancy for R2's S0, R3's S0, in addition to R4's S0:
Router(config-if)#encapsulation frame-relay [cisco | ietf]This is the ascendancy for R3's S1 in addition to R5's S0:
Router(config-if)#encapsulation hdlcUnlike Frame Relay, at that topographic point aren't whatever unlike types of HDLC encapsulation. After y'all specify the encapsulation type every bit HDLC, y'all tin assign the appropriate IP address to the interface.
Example 7-27 shows the commands executed on R5.
Example 7-27. R5 Configuration Commands
R5(config-if)#encapsulation hdlc R5(config-if)#ip address 192.168.35.5 255.255.255.0 R5(config-if)#Before removing the interface from shutdown mode, y'all demand to provide the clock charge per unit of measurement to R3 using the next command:
Router(config-if)#clock rate {300-8000000 bps} The exclusively choice inward this ascendancy is to give the speed of the link inward bits per second. Because this is a T1 or E1 interface, y'all tin specify an easy-to-remember value of 2,000,000. This is the equivalent of an E1 link, which volition piece of work for this lab environment. As mentioned earlier, inward the existent world, y'all volition non accept to configure this parameter. The telecom service provider volition laid this value on its equipment. After y'all laid this value, give the interface a description in addition to withdraw the interface from shutdown mode, every bit demonstrated inward Example 7-28.Example 7-28. clock rate Command
R5(config-if)#clock charge per unit of measurement 2000000 R5(config-if)#description This interface connects to R3's S1 (DTE) R5(config-if)#no shutdown R5(config-if)# %LINK-3-UPDOWN: Interface Serial0, changed acre to down R5(config-if)#At start glance, y'all mightiness instruct a lilliputian nervous that the interface did non come upwards up, but that is normal. R3's series interface has non been configured yet, so the R5 interface is non receiving whatever signaling from R3; thus, the interface volition rest inward the downwards acre until R3 is configured in addition to removed from shutdown mode. Before y'all instruct besides far into this configuration, y'all should know close a really helpful show command:
Router#show interfaces [bri | null | serial | tokenring | accounting | crb | irb] {number} This ascendancy is really useful inward troubleshooting in addition to verifying interface configuration. The start choice is to select which type of interface y'all would similar to see; the minute choice is to select the number of the interface. If y'all do non select whatever type of interface, the ascendancy shows y'all all the interfaces that the router has. Example 7-29 demonstrates sample output of the ascendancy on R5.Example 7-29. show interfaces series 0 Command Output
R5#show interfaces series 0 Serial0 is down, employment protocol is down Hardware is HD64570 Description: This interface connects to R3's S1 (DTE) Internet address is 192.168.35.5/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, charge 1/255 Encapsulation HDLC, loopback non set, keepalive laid (10 sec) Last input never, output 2w5d, output hang never Last clearing of "show interface" counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops five infinitesimal input charge per unit of measurement 0 bits/sec, 0 packets/sec five infinitesimal output charge per unit of measurement 0 bits/sec, 0 packets/sec 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 212 packets output, 18206 bytes, 0 underruns 0 output errors, 0 collisions, 37557 interface resets 0 output buffer failures, 0 output buffers swapped out 111 carrier transitions DCD=up DSR=up DTR=down RTS=down CTS=upThe highlighted text reveals merely about of import information regarding the interface Serial 0. The start affair that y'all encounter is the acre inward which the interface resides: "Serial0 is down, employment protocol is down." The start "down" (this is referred to every bit interface or the physical layer state) tells y'all that at that topographic point is a physical problem. Influenza A virus subtype H5N1 physical employment mightiness effect from a cable non existence plugged in, or the connected device mightiness non hold upwards receiving whatever electrical signaling, which is the instance here. The "line protocol down" way that Layer 2 is non functional, important that HDLC is non operating correctly for merely about reason. It is of import to banker's complaint that the employment protocol volition never hold upwards up if the interface is inward the downwards state. Next, the output shows the description placed on the Serial 0 interface. You encounter the IP address that y'all assigned earlier. This is a proficient house to review your configuration in addition to brand certain that what y'all typed inward the interface configuration manner was correct. You also encounter the encapsulation type here. For a consummate review of the output, refer to Chapter three of Interconnecting Cisco Network Devices. You volition encounter this ascendancy 1 time to a greater extent than afterwards configuring R3's series interface to encounter what changes.
To configure R3, y'all demand to become dorsum to the terminal server in addition to resume the session amongst R3, but don't forget to salve the configuration before leaving. When at R3, y'all demand to move into global configuration manner in addition to so become into interface configuration manner for Serial 1. Remember, y'all volition configure Serial 0 for Frame Relay. Serial 1 connects to R5's S0 interface. (Refer to your lab diagram.) See Example 7-30.
Example 7-30. R3 Interface Configuration Mode
R5#copy running-config startup-config Building configuration... [OK] R5#<ctrl-shft-6><x> Termserver#3 [Resuming connexion three to r3 ... ] R3# R3#config t Enter configuration commands, 1 per line. End amongst CNTL/Z. R3(config)#interface series 1 R3(config-if)#Now y'all are inward interface configuration manner for Serial 1 on R3, in addition to y'all tin assign the appropriate IP address in addition to mask. After that, don't forget to withdraw the interface from shutdown mode. Example 7-31 illustrates the commands.
Example 7-31. R3 Serial 1 Configuration Commands
R3(config-if)#encapsulation hdlc R3(config-if)#ip address 192.168.35.3 255.255.255.0 R3(config-if)#description This interface connects to R5's S0 (DCE) R3(config-if)#no shutdown R3(config-if)# %LINK-3-UPDOWN: Interface Serial1, changed acre to up R3(config-if)# %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed acre to up R3(config-if)#As y'all tin see, the interface came up, in addition to so did the employment protocol. Return to R5 in addition to encounter how the show interface ascendancy output has changed. Example 7-32 shows the changes inward the output.
Example 7-32. R5 show interface series 0 Command Output
R3(config-if)#end %SYS-5-CONFIG_I: Configured from console yesteryear console R3#copy running-config startup-config Building configuration... [OK] R3#<ctrl-shft-6-x> Termserver#5 [Resuming connexion five to r5 ... ] R5# R5#show interface series 0 Serial0 is up, employment protocol is up Hardware is HD64570 Description: This interface connects to R3's S1 (DTE) Internet address is 192.168.35.5/24 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, rely 255/255, charge 1/255 Encapsulation HDLC, loopback non set, keepalive laid (10 sec) Last input 00:00:01, output 00:00:01, output hang never Last clearing of "show interface" counters never Queueing strategy: fifo Output queue 0/40, 0 drops; input queue 0/75, 0 drops five infinitesimal input charge per unit of measurement 0 bits/sec, 0 packets/sec five infinitesimal output charge per unit of measurement 0 bits/sec, 0 packets/sec 25 packets input, 1865 bytes, 0 no buffer Received 25 broadcasts, 0 runts, 0 giants, 0 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort 236 packets output, 20009 bytes, 0 underruns 0 output errors, 0 collisions, 37629 interface resets 0 output buffer failures, 0 output buffers swapped out 112 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up R5#Great! You right away should hold upwards capable of pinging R3 from R5, every bit demonstrated inward Example 7-33.
Example 7-33. R5 ping Result
R5#ping 192.168.35.3 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.35.3, timeout is 2 seconds: !!!!! Success charge per unit of measurement is 100 pct (5/5), round-trip min/avg/max = 4/4/8 ms R5#You got 100 pct success! R3 in addition to R5 accept total IP connectivity. Question: Should R5 hold upwards capable of pinging R3's Serial 0 IP address? Why not? Even though R5 tin accomplish R3 through interface Serial 1, R5 cannot ping R3's Serial 0 interface. This is because y'all do non accept whatever routing protocols configured to permit R5 know close the 192.168.100.0 network, to which R3's Serial 0 interface belongs. When y'all accept configured all the interfaces on all the routers, y'all volition start configuring the routing protocols. Then y'all should hold upwards capable of pinging whatever interface on whatever router.
