Cisco Discovery 3 Module 7 Course Curriculum Picture Description Module 7.0 ? Chapter Introduction 7.0.1 ? Introduction One Diagram Diagram 1, Slideshow Introduction Connecting remote sites together by an enterprise WAN allows users to access network resources and information. As information traverses the WAN, the Layer 2 encapsulation adapts to match the technology. A popular WAN technology that uses packet-switching is Frame Relay After completion of this chapter, you should be able to: Describe the features and benefits of common WAN connectivity options. Compare common WAN encapsulations and configure PPP. Describe Frame Relay. 7.1 - Connecting the Enterprise WAN 7.1.1 - WAN Devices and Technology Five Diagrams Diagram 1, Animation This animation shows the cities of New York, Osaka, Boston and Orlando connected together in a WAN. Diagram 2, Image Diagram depicts a network cloud containing a WAN network, switches and trunk. On the edge of the cloud a CO switch is connected to a corporate network via a CSU/DSU (owned by the customer). Diagram 3, Image A Data Terminal Equipment (DTE) interface to WAN link is connected to a Data Communication Equipment (DCE) End of service providers communication facility. The DCE is the connected to the ISP. The connection between the DTE and DCE can have the following types: EIA/TIA - 232 Allows signal speeds of up to 64 Kbps on a 25 pin D connector over short distances Formerly known as RS-232 Same as ITU-T V.24 specification EIA/TIA - 449/530 Faster (up to 2 Mbps) version of EIA/TIA-232 Uses a 36 pin D connector and is capable of longer cable runs Also known as RS-422 and RS-423 EIA/TIA - 612/613 Provides access to services of up to 52 Mbps on a 60 pin D connector V.35 An ITU-T standard for synchronous communications between a network access device and a packet network at speeds up to 48 Kbps Uses a 34 pin rectangular connector X.21 An ITU-T standard for synchronous digital communications Uses a 15 pin D connector Diagram 4, Tabular Line Type: 56 Signal Standard: DSO Bit rate Capacity: 54 Kbps Line Type: 64 Signal Standard: DSO Bit rate Capacity: 64 Kbps Line Type: T1 Speed Standard: DS1 Bit rate Capacity: 1.544 Mbps Line Type: E1 Signal Standard: ZM Bit rate Capacity: 2.048 Mbps Line Type: E3 Signal Standard: M3 Bit rate Capacity: 34.064 Mbps Line Type: J1 Signal Standard: Y1 Bit rate Capacity: 2.048 Mbps Line Type: T3 Signal Standard: DS3 Bit rate Capacity: 44.736 Mbps Line Type: OC-1 Signal Standard: SONET Bit rate Capacity: 51.84 Mbps Line Type: OC-3 Signal Standard: SONET Bit rate Capacity: 155.54 Line Type: OC-9 Signal Standard: SONET Bit rate Capacity: 466.56 Mbps Line Type: OC-12 Signal Standard: SONET Bit rate Capacity: 622.08 Mbps Line Type: OC-18 Signal Standard: SONET Bit rate Capacity: 933.12 Mbps Line Type: OC-24 Signal Standard: SONET Bit rate Capacity: 1244.16 Mbps Line Type: OC-36 Signal Standard: SONET Bit rate Capacity: 1866.24 Mbps Line Type: OC-48 Signal Standard: SONET Bit rate Capacity: 2488.32 Mbps Diagram 5, Activity Match the WAN term to the definition. WAN Term A: demarc B: CPE C: DTE D: DCE E: CO F: local loop G: CSU/DSU H: modem Definition 1. The location where the service provider takes over control of the WAN link. 2. Equipment located at the site of the customer. 3. The local router is this type of equipment. 4. The CSU/DSU is this type of equipment. 5. The location where the service provider houses equipment and accepts connections from customer networks. 6. The portion of media that connects the end user with the CO. 7. The device that formats the WAN traffic into a format acceptable to the ISPs network. 8. The device required to use an analog connection into the WAN. 7.1.2 - WAN Standards Two Diagrams Diagram 1, Image OSI Model Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical addressing Flow control Encapsulation type LAPF for Frame Relay HDLC PPP Physical Layer Diagram 2, Activity Determine whether the standards are part of Layer 1 or Layer 2. VTP Transport Mode Service Provider Check PPP X.21 EIA/TIA-232 V.35 LAPF HDLC 7.1.3 - Accessing the WAN Four Diagrams Diagram 1, Image This image shows that digital signals are sent between the computer and the modem. Analog signals are sent between the modem and the telephone network Diagram 2, Image Site A connects to the service provider via a T1-1.544 Mbps link. Site B connects to the service provider Fractional T1 via a 128 Kbps and Site C connects to the service provider via a Fractional T1 via a 64 Kbps. Diagram 3, Animation Animation shows the difference between the output from a multiplexor using TDM and STDM. TDM The animation shows four host sending input into a multiplexor. Each host inputs three time slices. There are three unused time slices between the four hosts. TDM - 12 time slices used 9 delivered STDM The animation shows four host sending input into a multiplexor. Each host inputs three time slices. There are three unused time slices between the four hosts. STDM - 9 time slices used 9 delivered Diagram 4, Activity Drag the data blocks into the correct order to show how TDM and STDM uses bandwidth. This exersise is not accessible but text is included for reference. Input Host A: unused, A, unused Host B: B, B, unused Host C: C, C, C Host D: unused, unused, D Output TDM: Insert the output in order to fill all 12 time slices. STDM: Insert the output in order to fill all 7 time slices. 7.1.4. - Packet and Circuit Switching Four Diagrams Diagram 1, Animation Animation shows two modems both connected to a PSTN cloud containing a network of switches. The first modem says ?I am initiating a call.? For the duration of the call the line is dedicated to the sender and receiver. A circuit is established between the modems in the PSTN cloud. The other modem says ?I am accepting a call.? At the end of the call the second router says ?I am terminating the call.? Once the call has ended the dedicated connection disappears. Diagram 2, Animation Site A, Site B, Site C and Site D are all connected to a cloud of switches. Site A and Site D are both sending packets into the cloud. Traffic from two virtual circuits share the same links. The packets traverse the cloud and reach their destinations at Site B and Site C. Diagram 3, Image An enterprise network connects via a CSU/DSU to another enterprise network also using a CSU/DSU. Between the two networks is an network cloud. The connection through the network is an SVC. SVC is built-up and torn-down as required. An enterprise network connects via a CSU/DSU to another enterprise network also using a CSU/DSU. Between the two networks is a network cloud. The connection through the network is a PVC. PVC is configured by network administrator and loaded at switch startup. Diagram 4, Activity Identify the best WAN convention to support the scenario. Options are Leased Line, Circuit Switched, Packet Switched or Cell Switched. 1. Remote offices connect once a day to upload sales orders. 2. A company WAN supports voice, video and data connections. 3. An organization connects to multiple remote sites but only has one serial interface on their router. 4. A company connects to their branch offices and securely transfers classified technical drawings. 5. A small real estate company provides support to their sales staff to pick up email from their home offices. 7.1.5 - Last Mile and Long Range WAN Technologies Three Diagrams Diagram 1, Image Image shows a number of devices connecting to the ISP. Its shows: Dialup using the telephone line to connect DSL using the telephone line to connect Cable modem using coaxial cable to connect Wireless Enterprise using T1 Leased Line Satellite modem connecting to a satellite which connects to the ISP Diagram 2, Image Map of the world with enterprise networks superimposed over Asia, North America and South Africa. These are all connecting to a DWDM network cloud. Diagram 3, Activity High speed internet service over existing copper phone cables (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) Always on, last mile connectivity using same cable for TV and data (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) Internet access for remote locations (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) 80 channels on existing strand of fiber for extremely long range network (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) Transfer of fixed length cells at 155Mbps (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) Connectivity to office in old hotel that has no high speed service (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) Dedicated connectivity for new company selling on-line shopping service (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) Long range technology to move voice video and data over fiber cable (DSL, Cable, Satellite, DWDM, ATM, Dial Up, Leased Line or SONET?) 7.2 ? Comparing Common WAN Encapsulation 7.2.1 ? Ethernet and WAN Encapsulation 3 Diagrams Diagram 1, Image The diagram depicts a man sitting at one end of a network and he has been labeled the source and there is another person sitting at the other end of the network and he has been labeled the destination. In between these two are a myriad of network devices and connection types that make up the network between the source and destination. Connected to this network is a server farm, a DMZ and the ISP. The protocols that may be in use during the transmission of a message from the source to the destination include HDLC, PPP and ATM. These protocols may be implemented in different networks within the larger to accommodate the transmission of the message. As the message traverses the network the frame format changes to accommodate the different protocols implemented within the different networks that the message travels through. Diagram 2, Image The diagram depicts a computer named H1 connected to a switch named S1 which is in turn connected to the Router R1. There is a serial link between R1 and R2, R2 has the switch S2 and the computer named H2 connected. H1 sends a message out and the header is marked as an Ethernet header. As the protocol changes at the router to PPP, the header within this message changes to the PPP header so the message can travel through the network. As the message reaches the far side of Router R2, the header is changed back to the Ethernet header so the message can traverse the Ethernet network and finally reach H2. Diagram 3, Activity Match the layer 2 encapsulation terms to its definition. Term A: Address B: Control C: Protocol D: Flag E: Header F: Data G: FCS H: Flag Definition 1. Provides a mechanism to verify that the frame was not damaged in transit. 2. Used to specify the type of encapsulation network layer protocol, not present in all WAN encapsulation 3. Used to indicate the type of frame 4. Used as Layer 3 data and IP datagram 5. Marks the beginning and end of each frame 6. Depends on the encapsulation type, not required if the WAN link is point to point. 7.2.2 ? HDLC and PPP 5 Diagrams Diagram 1, Image The diagram depicts the Open Standard HDLC Frame and the Cisco HDLC Frame. The composition of these frames is listed below. Open Standard HDLC Frame Flag 8 bits Address 8 bits Control 8/16 bits Information Variable length 0 or more bits, multiples of 8 FCS 16/32 Flag 8 bits Cisco HDLC Frame Flag 8bits Address 8 bits Control 8 bits 16 bits Information Variable length 0 or more bits, multiples of 8 FCS 16 bits Flag 8 bits Diagram 2, Image The diagram depicts the three lower layers of the OSI model. At the bottom is the physical layer which deals with the synchronous or asynchronous media. At the Data Link layer there is the Authentication, other options and Link Control Protocol. Also inside the Data Link layer is the Network Control Protocol which is encompassed by the PPP protocol. The layer three network layer and the boundary of the data link layer act as the merge point for the different layer 3 protocols these being, IP, IPX, IPCP IPXCP and many others. Diagram 3, Image The diagram depicts the LCP negotiation process. The process and a description of the devices during the process are listed below. Authentication A CSU/DSU linked to a switch that is link by a serial connection to the network cloud, which is then linked by serial link to a switch and then a computer. The flow of information is from the CSU?DSU to the computer. Authentication options require that the calling side of the link enter information to ensure the caller has the permission to make the call. Peer routers exchange authentication messages. Two authentication choices are Password Athentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP). Callback A CSU/DSU linked to a switch that is link by a serial connection to the network cloud which is then linked by serial link to a switch and then a computer. With this LCP, a Cisco router can act as a callback client or as a callback server. The client makes the initial call. The callback router answers the initial call and makes the return call to the client based on information configured in its memory. Compression The diagram depicts two CSU/DSU modules at the ends of a network. In between the two modules is a two compression devices that compress information on the fly between the two CSU/DSU module. The flow of information in this diagram is in both directions through the network. Compression options increase the effective throughput on PPP connections by reducing the amount of data in the frame that travels across the link. The protocol decompresses the frame at its destination. Two compression protocols available in Cisco routers are Stacker and Predictor. MultiLink The diagram depicts 3 computers directly connected to a CSU/DSU and then to a multilink device that provides load balancing over the PPP router interfaces. Diagram 4, Image The diagram depicts Router R1 connected by serial link to Router R2. R1 says, ?I want to form a PPP connection with you. Can we agree to communicate using PPP with PAP authentication and compression?? Router R2 receives the message and replies, ? I can form the PPP connection and can use PAP authentication but I cannot support compression.? Router R2 sends a message back to R1 with this information included in the message. R1 responds, ? Can we agree to communicate using PPP with PAP authentication and no compression?? Router R2 replies, ? We can communicate using PPP with PAP authentication and no compression.? Router R1 receives this message and replies, ? My name is R1 and my password is cisco.? Router R2 looks in its table of users and references the username and password to the one given to it by R1. Router R2 replies, ? The password matches so I am now ready to form the connection.? Router R1 replies, ? I only have IP traffic so we only need to bring up IPCP. I am starting it now.? R2 replies, ? I have also started IPCP. We can now move IP traffic.? Diagram 5, Activity Identify the correct layer and phase with the correct PPP components. Layer and Phase A: Data Link Layer B: Physical Layer C: Phase 3 D: Phase 2 E: Phase 1 PPP Component 1. Link encapsulation 2. Authentication other options, Link Control Protocol 3. Synchronous or Asynchronous Physical Media 4. NCP Negotiation 5. Network Control Protocol 7.2.3 ? Configuring PPP 3 Diagrams Diagram 1, Image The diagram depicts two routers named R1 and R2 connected to each other by serial link. The commands entered at the console terminal window are as follows: R1 R1(config)# encapsulation ppp with R1(config)# encapsulation ppp R2 R2(config)# encapsulation ppp with R2(config)# encapsulation ppp Diagram 2, Image The diagram depicts two routers connected to each other by serial link. The network address is 192.168.2.0 and both routers have LANs connected to them. Router R1 has network 192.168.1.0 connected to Fa0/0 and R2 has network 192.168.3/0 connected to Fa0/0. The image has radio buttons that can be pushed to highlight the commands, show interfaces serial, show controllers, debug serial interfaces and debug PPP. The outputs for these commands can be viewed in greater detail in the labs at the end of the module. Diagram 3, Hands on Lab 7.2.4 ? PPP Authentication 3 Diagrams Diagram 1, Image The diagram depicts two routers named R1 and R2 in the process of a PAP two way handshake. R1?s username is Santa Cruz and its password is boardwalk which it sends to router R2 to authenticate. Router R3 looks at its table for the username and password and accepts or rejects based on this authentication procedure. Diagram 2, Image The diagram depicts two routers named R1 and R2 linked by a serial connection. R1 sends a message to R2 indicating that it wants to run PPP. R2 says, Run CHAP?, and sends a message, ? Here is my Challenge information. Send me your username and password.? Router R1 calculates a special value using the secret password and the challenge value. The one way hash is 6G4#9P4. Router R1 sends a message back to R2 with the username R1 and the password 6G4#9P4. Router R2 calculates 6G4#9P4 using the same secret password. Router R1 randomly challenges the remote router to verify authentication. R2 sends a message back to R1, ? Here is a different Challenge value. Send me your username and password again to make sure its still you.? Diagram 3, Activity Sort the characteristic as either belonging to PAP or CHAP. CHAP or PAP Characteristic - password never sent across link - uses two way handshake - uses three-way handshake - single authentication when link formed - authentication occurs at configuration intervals - password sent in clear text - uses shared secret - immune to replay attack - username/password easily sniffed from wire 7.2.5 ? Configuring PAP and CHAP 3 Diagrams Diagram 1, Image The diagram depicts two routers connected to a service provider by serial links. The commands used to configure PAP and CHAP on both routers can be viewed in greater detail in the labs attached to this module. Diagram 2, Image The diagram depicts two routers connected to each other by serial link. The output of the debug ppp command is listed. The different phases of the authentication process can be viewed by using this command. The different states can be defined as Challenge, Response, Successful Authentication and Unsuccessful Authentication. The phases can be viewed more clearly when the command is entered by the student after PAP and CHAP are configured. Diagram 3, Hands on Lab Module 7.3 ? Using Frame Relay 7.3.1 ? Overview of Frame Relay One Diagram Diagram 1, Image Overview of Frame Relay The picture depicts a network, there is a cloud with 10 interconnected switches inside. Around the outside of the cloud are four building sites (SiteA, SiteB, SiteC, SiteD), connected to the switches inside the cloud via Router. Information is being sent from SiteA to SiteD, there is a Virtual circuit (path) from SiteA to SiteD which the packets travel along. 7.3.2 ? Frame Relay Functionality Five Diagrams Diagram 1, Movie Frame Relay Functionality The picture depicts the use of DLCI to obtain the IP address of a remote Router. R1 sends a DLCI request to R2, R2 sends a response to R1 with its IP address information. Network There is a frame relay cloud with two switches (S1, S2) inside. Two Routers (R1, R2) R1 is connected to S1 via Serial link on interface S0/0/0 IP:209.165.200.225 DLCI 16 R2 is connected to S2 via Serial link on interface S0/0/0 IP: 209.165.200.226 DLCI 20 S1 is connected to S2 (Frame Relay) R1 ?DLCI 16 is active. I will send an Inverse ARP request to learn the IP address of the remote router.?. There are speech bubbles as follows: S1 ?DLCI 16 is active?. R1 ?CLCI 16 is active. I will send an Inverse ARP request to learn the IP address of the remote router?. R2 ?I have received an Inverse ARP request on DLCI 20 from 209.165.200.225?. R2 ?Inverse ARP response from 209.165.200.226?. Table DLCI ? 16 Status ? Active Remote IP Address ? 209.165.200.226 Diagram 2, Frame Relay Functionality The picture depicts the use of LMI. Three Routers (R1, R2, R3) Three Switches (S1, S2, S3) R1 is connected to the CSUDSU All switches are inside a cloud S1 is connected to the CSUDSU S2 is connected to S1 S3 is connected to S1 S2 is connected to S3 R2 is connected to S2 R3 is connected to S3 There is a double-sided arrow with a cross through it from R1 to R2 symbolizing the connection from R1 to R2 (DLCI = 400) There is a double-sided arrow from R1 to R3 symbolizing the connection from R1 to R3 (DLCI = 500) There is a keepalive getting sent to R3, which says (LMI, 500 = Active, 400 = Inactive) Diagram 3, Image Frame Relay Functionality The picture depicts the use of CIR, There is a Cloud (service Provider), which is connected to the SiteA (Building) Router via link (Local Access Loop = T1), and the siteB (Building) Router via link (Local Access Loop = 1544Kbps link. SiteA sends SiteB information, there is a caption on SiteA, which says ?My provider guarantees bandwidth of 768Kbps, 768Kbps is my CIR?. After SiteA sends some information a caption appears on the Cloud, which says ?The network is not congested so we are going to burst your speed to 1.544Mbps?. ?All packets above your CIR are Discard Eligible?. Frames continue to transmit until SiteA is finished. Diagram 4, Frame Relay Functionality The picture depicts a bottleneck, there is a cloud(Frame Relay Cloud), which is connected to the Branch office Router via 56Kbps link, and the Central Site (Building) Router via T1 link. There is a speech bubble on the Central Site, which says ?I have received a lot of BECNs. The network must be congested. I need to reduce the pace at which I send packets.?, Diagram 5, Activity Frame Relay Functionality Match the terms to their corresponding definition. Terms BECN, DLCI, FECN, CIR, DE, SVC, PVC Definitions 1. The type of VC most service providers will not permit 2. Used to inform a receiving device that congestion was experienced 3. The type of virtual circuit most often used by Frame Relay 4. The layer 2 address used by Frame Relay 5. The contracted data rate that the service provider agrees to transfer 6. Used to inform a sending device that congestion has occurred 7. Marks a frame as being less important on a network 7.4 - Chapter Summary 7.4.1 - Summary Single Diagram Diagram 1, Slideshow There are three sides with the following: Slide 1 Image shows enterprises connecting to an cloud. A WAN uses many different technologies, each offering distinct advantages. Depending on the technology in use, converting the data format into an acceptable one requires a modem or a CSU/DSU. WAN technologies divide into circuit switching, packet switching and cell switching. Circuit switching technologies create a physical circuit between end devices before sending information. Packet and cell switching technologies use either a PVC or SVC to send information across the network. WAN technologies are either last mile, which connects the ISP to the customer, or long range which interconnects ISPs. Slide 2 Shows two users communicating across a complex network topology. HDLC is the default Layer 2 serial line encapsulation on Cisco routers. Cisco HDLC incorporates an extra field to allow it to carry multiple Layer 3 protocols. The Layer 2 encapsulation changes as frames are moved across the WAN. PPP allows the negotiation of many advanced features including authentication, load balancing, call back and compression. PPP supports both PAP and CHAP authentication. PAP authentication sends the username/password in clear text and is subject to sniffing and replay attacks. CHAP issues challenges at configurable intervals and forces the connected device to re-authenticate. Slide 3 Shows the bottleneck when a branch office connects using a 56 kbps connection to connect via the frame relay cloud to the central site which is used a T1 connection. The central sites router says ?I have received a lot of BECNs. The network must be congested. I need to reduce the pace at which I send packets.? Frame Relay is a packet switched technology. Frame Relay uses virtual circuits to connect a specific source to a destination. Virtual circuits can be switched or permanent. Use FECNs and BECNs to inform the receiving and sending devices that the network is congested so that routers can take appropriate actions. Frame Relay uses parameters such as CIR to establish the bandwidth used on each VC.