Section IV: WAN Technologies – Test Online

Hint

Star is the most popular topology for Ethernet topology but hub and spoke is the most appropriate WAN topology. In a Hub-and-spoke network topology, one physical site act as Hub (Example, Main Office or Head Quarter), while other physical sites act as spokes. Spoke sites are connected to each other via Hub site. In Hub-and-spoke topology, the network communication between two spokes always travel through the hub (except when using DMVPN Phase II or Phase III where spokes can communicate with each other directly). The networking device at Hub site is often much more powerful than the ones at spoke sites. Hub and spoke is an ideal topology when most of the resources lie at the Hub site and the branch sites only need to access to the Hub. Note: Although some books may say Hub-and-spoke and Star topologies are the same but in fact they have difference. When talking about Hub-and-spoke we often think about the communication between Hub site and Spoke sites. When talking about Star we think about the communication between end devices.

Hint

The Resource Reservation Protocol (RSVP) protocol allows applications to reserve bandwidth for their data flows. It is used by a host, on the behalf of an application data flow, to request a specific amount of bandwidth from the network. RSVP is also used by the routers to forward bandwidth reservation requests.

Hint

PPP supports both synchronous (like analog phone lines) and asynchronous circuits (such as ISDN or digital links). With synchronous circuits we need to use clock rate. Note: Serial links can be synchronous or asynchronous. Asynchronous connections used to be only available on low-speed (<2MB) serial interfaces, but now, there are the new HWICs (High-Speed WAN Interface Cards) which also support asynchronous mode. To learn more about them please visit http://www.cisco.com/en/US/prod/collateral/modules/ps5949/ps6182/prod_qas0900aecd80274424.html

Hint

PPPoE provides a standard method of employing the authentication methods of the Point-to-Point Protocol (PPP) over an Ethernet network. When used by ISPs, PPPoE allows authenticated assignment of IP addresses. In this type of implementation, the PPPoE client and server are interconnected by Layer 2 bridging protocols running over a DSL or other broadband connection. PPPoE is composed of two main phases: + Active Discovery Phase: In this phase, the PPPoE client locates a PPPoE server, called an access concentrator. During this phase, a Session ID is assigned and the PPPoE layer is established. + PPP Session Phase: In this phase, PPP options are negotiated and authentication is performed. Once the link setup is completed, PPPoE functions as a Layer 2 encapsulation method, allowing data to be transferred over the PPP link within PPPoE headers. Reference: http://www.cisco.com/c/en/us/td/docs/security/asa/asa92/configuration/vpn/asa-vpn-cli/vpn-pppoe.html

Hint

The advantages of leased lines include: + Simplicity: Point-to-point communication links require minimal expertise to install and maintain. + Quality: Point-to-point communication links usually offer high service quality, if they have adequate bandwidth. The dedicated capacity removes latency or jitter between the endpoints. + Availability: Constant availability is essential for some applications, such as e-commerce. Point-to-point communication links provide permanent, dedicated capacity, which is required for VoIP or Video over IP. The disadvantages of leased lines include: + Cost: Point-to-point links are generally the most expensive type of WAN access. The cost of leased line solutions can become significant when they are used to connect many sites over increasing distances. In addition, each endpoint requires an interface on the router, which increases equipment costs. + Limited flexibility: WAN traffic is often variable, and leased lines have a fixed capacity, so that the bandwidth of the line seldom matches the need exactly (therefore answer D is not correct). Any change to the leased line generally requires a site visit by ISP personnel to adjust capacity. (Reference: Connecting Networks Companion Guide Book published by Cisco Networking Academy – Page 54)

Hint

Point-to-point leased line is the most expensive interconnection between two ends as the line is dedicated to a single user, the user should still pay for all available bandwidth, including those unused. -> A is not correct. With the cost of point-to-point leased line, the full-mesh capability is only achieved when your company has very very strong budget to pay all the bills. To create a full-mesh topology for n sites, we need n*(n-1)/2 leased line connections. For example if we have 6 sites then we need 6*5/2 = 15 leased line connections -> It is nearly impossible for a normal company to achieve full-mesh topology -> B is not correct. Flexibility is not an advantage of leased line connection -> C is not correct. Point-to-point leased line simplifies the configuration as the circuit is available on a permanent basis and does not require a connection to be set up before traffic is passed. It does not require to define a permanent virtual circuit (PVC) in the configuration either -> D is correct.

Hint

The command “ppp authentication chap pap” command indicates the CHAP authentication is used first. If it fails or is rejected by other side then uses PAP instead. If you want to use PAP first (then CHAP) you can use the “ppp authentication pap chap” command.

Hint

The Multilink PPP feature provides load balancing functionality over multiple WAN links while providing multivendor interoperability and support for packet fragmentation, proper sequencing, and load calculation on both inbound and outbound traffic. Multilink PPP combines multiple physical links into a logical bundle called a Multilink PPP bundle. A Multilink PPP bundle is a single, virtual interface that connects to the peer system. Having a single interface (Multilink PPP bundle interface) provides a single point to apply hierarchical queueing, shaping, and policing to traffic flows. Individual links in a bundle do not perform any hierarchical queueing. None of the links have any knowledge about the traffic on parallel links. Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/wan_mlp/configuration/xe-3s/wan-mlp-xe-3s-book/wan_cfg_mlppp_conn_xe.html MLPPP supports two authentication protocols: Password Authentication protocol (PAP) and Challenge-Handshake Authentication Protocol (CHAP)

Hint

Full-mesh is a network topology in which there is a direct link between all pairs of nodes. Below is an example of full-mesh topology.

Hint

Both routers must use the same password for CHAP to authentication.

Hint

The idea behind a WAN is to be able to connect two DTE networks together through a DCE network. The network’s DCE device (includes CSU/DSU) provides clocking to the DTE-connected interface (the router’s serial interface). A modem modulates outgoing digital signals from a computer or other digital device to analog signals for a conventional copper twisted pair telephone line and demodulates the incoming analog signal and converts it to a digital signal for the digital device. A CSU/DSU is used between two digital lines -> A & D are correct but B & C are not correct. For more explanation of answer D, in telephony the local loop (also referred to as a subscriber line) is the physical link or circuit that connects from the demarcation point of the customer premises to the edge of the carrier or telecommunications service provider’s network. Therefore a modem terminates an analog local loop is correct.

Hint

The picture below shows all configuration needed for PPPoE: There is no Dialer interface on the PPPoE Server so answer “Dialer interface” is not correct. The most suitable answer is “Virtual Template” interface as it contains the pool which is used to assign IP address to the PPPoE Client. But this question is weird because according to the CCNAv3 syllabus, candidates only need to grasp the PPPoE on client-side, not sure why this question asked about PPPoE on Server side. For more information about PPPoE, please read our PPPoE tutorial.

Hint

MPLS supports IPv4, IPv6, IPX, AppleTalk at the network layer. MPLS supports Ethernet, Token Ring, FDDI, ATM, FR, PPP at the link layer. MPLS uses label switching to forward packets over Ethernet. Labels are assigned to packets based on groupings or forwarding equivalence classes (FECs). The label is added between the Layer 2 and the Layer 3 header.

Hint

The following diagram illustrates the key difference between traffic policing and traffic shaping. Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate (or committed information rate), excess traffic is dropped (or remarked). The result is an output rate that appears as a saw-tooth with crests and troughs. In contrast to policing, traffic shaping retains excess packets in a queue and then schedules the excess for later transmission over increments of time. The result of traffic shaping is a smoothed packet output rate.

Hint

Suppose R1 has two Serial interfaces which are directly connected to R2. This is how to configure multilink on R1:

R1(config-if)# interface Serial 0/0 
R1(config-if)# encapsulation ppp 
R1(config-if)# ppp multilink 
R1(config-if)# ppp multilink group 1 
R1(config-if)# no shutdown

R1(config-if)# interface Serial 0/1 
R1(config-if)# encapsulation ppp 
R1(config-if)# ppp multilink 
R1(config-if)# ppp multilink group 1 
R1(config-if)# no shutdown

R1(config)# interface multilink 1 
R1(config-if)# ip address 192.168.42.1 255.255.255.252 
R1(config-if)# ppp multilink 
R1(config-if)# ppp multilink group 1

Therefore we must configure IP address under multilink interface, not physical member interfaces.

Hint

The following diagram illustrates the key difference between traffic policing and traffic shaping. Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate (or committed information rate), excess traffic is dropped (or remarked). The result is an output rate that appears as a saw-tooth with crests and troughs. In contrast to policing, traffic shaping retains excess packets in a queue and then schedules the excess for later transmission over increments of time. The result of traffic shaping is a smoothed packet output rate. Note: Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the routing device.

Hint

The Branch2 network is communicating to the Server farm, which is connected to R2, via GRE Tunnel so we should check the GRE tunnel first to see if it is in “up/up” state with the “show ip interface brief” command on the two routers. On Branch2: We see interfaces Tunnel0 at two ends are “up/up” which are good so we should check for the routing part on two routers with the “show running-config” command and pay attention to the static routing of each router. On Branch2 we see: The destination IP address for this static route is not correct. It should be 192.168.24.1 (Tunnel0’s IP address of R2), not 192.168.24.10 -> Answer C is correct. Note: You can use the “show ip route” command to check the routing configuration on each router but if the destination is not reachable (for example: we configure “ip route 10.10.10.0 255.255.255.0 192.168.24.10” on Branch2, but if 192.168.24.10 is unknown then Branch2 router will not display this routing entry in its routing table. Note: The IP address or configuration may be different in the exam.

Hint

First we should check Branch3 (and R1) with the “show ip interface brief” command to find any Layer1/Layer2 issue. We see interfaces connecting between them are in “up/down” states which indicates a Layer 2 issue so we should check the configuration of these interfaces carefully witch the “show running-config” command and pay attention to these interfaces. and on Branch3: We learn from above config is R1 is using CHAP to authenticate Branch3 router (via the “ppp authentication chap” command on R1). Branch3 router is sending CHAP hostname “Branch_3” and CHAP password “Branch3_Secret!” to R1 to be authenticated. Therefore, we should check if R1 has already been configured with such username and password or not with the “show running-config” command on R1: On R1 we see the configured username is “Branch3”, not “Branch_3” so the usernames here are mismatchedand this is the problem -> Answer A is correct.

Hint

In this question we have to check each option to see if it is correct. When we check Branch3 router we notice that “network 192.168.10.0” command is missing under “router eigrp 100” – > Answer D is correct.

Hint

This question clearly stated there is a WAN connectivity issue between R1 and Branch1 so we should check both of them with the “show ip interface brief” command. On R1: On Branch1: We can see that although the Multilink1 interfaces are in “up/up” state but they are not in the same subnet. According to the IP address scheme shown on the topology we can deduce the Multilink interface on Branch1 has been misconfigured, it should be 192.168.14.2 instead.

Hint

Output from real deviceRouter2901#sh int g0/0 GigabitEthernet0/0 is up, line protocol is up Hardware is CN Gigabit Ethernet, address is c471.fe99.9999 (bia c471.fe99.9999) Description: Lan Internet address is 10.1.1.1/25 MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Full Duplex, 1Gbps, media type is RJ45 output flow-control is unsupported, input flow-control is unsupported ARP type: ARPA, ARP Timeout 04:00:00 Last input 00:00:00, output 00:00:00, output hang never Last clearing of “show interface” counters never Input queue: 0/75/61/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue: 0/40 (size/max) 5 minute input rate 39000 bits/sec, 30 packets/sec 5 minute output rate 73000 bits/sec, 37 packets/sec 41068530 packets input, 3905407112 bytes, 0 no buffer Received 8678853 broadcasts (0 IP multicasts) 0 runts, 0 giants, 45 throttles 0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 79853 multicast, 0 pause input 39267208 packets output, 2262399504 bytes, 0 underruns 0 output errors, 0 collisions, 0 interface resets 79926 unknown protocol drops 0 babbles, 0 late collision, 0 deferred 0 lost carrier, 0 no carrier, 0 pause output 0 output buffer failures, 0 output buffers swapped out Router2901# Router2901 ip int g0/0 GigabitEthernet0/0 is up, line protocol is up Internet address is 10.1.1.1/25 Broadcast address is 255.255.255.255 Address determined by non-volatile memory MTU is 1500 bytes Helper address is not set Directed broadcast forwarding is disabled Secondary address 192.168.1.7/24 Multicast reserved groups joined: 224.0.0.10 Outgoing access list is not set Inbound access list is not set Proxy ARP is enabled Local Proxy ARP is disabled Security level is default Split horizon is enabled ICMP redirects are always sent ICMP unreachables are always sent ICMP mask replies are never sent IP fast switching is enabled IP fast switching on the same interface is disabled IP Flow switching is disabled IP CEF switching is enabled IP CEF switching turbo vector IP multicast fast switching is enabled IP multicast distributed fast switching is disabled IP route-cache flags are Fast, CEF Router Discovery is disabled IP output packet accounting is disabled IP access violation accounting is disabled TCP/IP header compression is disabled RTP/IP header compression is disabled Policy routing is disabled Network address translation is enabled, interface in domain inside BGP Policy Mapping is disabled Input features: Common Flow Table, Stateful Inspection, Virtual Fragment Reassembly, Virtual Fragment Reassembly After IPSec Decryption, CAR, MCI Check Output features: NAT Inside, Common Flow Table, Stateful Inspection, NAT ALG proxy, CAR Post encapsulation features: CAR IPv4 WCCP Redirect outbound is disabled IPv4 WCCP Redirect inbound is disabled IPv4 WCCP Redirect exclude is disabled Router2901#

Hint

With point to point PVC, each connection needs to be in a separate subnet. The R2-R1 connection (DLCI 16to 99) would have each router within the same subnet. Similarly, the R3-R1 connection would also be in the same subnet, but it must be in a different one than the R2-R1 connection.

Hint

Interface can be enabled or disabled with shutdown/no shutdown command. If you interface is down, it will display administratively down status. You can bring up an interface having administratively down interface using no shutdown command.

Hint

The PVC STATUS displays the status of the PVC. The DCE device creates and sends the report to the DTE devices. There are 4 statuses: + ACTIVE: the PVC is operational and can transmit data + INACTIVE: the connection from the local router to the switch is working, but the connection to the remote router is not available + DELETED: the PVC is not present and no LMI information is being received from the Frame Relay switch + STATIC: the Local Management Interface (LMI) mechanism on the interface is disabled (by using the “no keepalive” command). This status is rarely seen so it is ignored in some books.

Hint

This command tells the router to first use CHAP and then go to PAP if CHAP isn’t available.

Hint

IPSec is a framework of open standards that provides data confidentiality, data integrity, and data authentication between participating peers at the IP layer. IPSec can be used to protect one or more data flows between IPSec peers.

Hint

Broadcast is added to the configurations of the frame relay, so the PVC supports broadcast, allowing therouting protocol updates that use the broadcast update mechanism to be forwarded across itself.

Hint

The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol datagrams over point-to-point links. PPP was originally emerged as an encapsulation protocol for transporting IP traffic between two peers. It is a data link layer protocol used for WAN connections. DSL is also considered a WAN connection, as it can be used to connect networks, typically when used with VPN technology

Hint

Cisco supports two Frame Relay encapsulation types: the Cisco encapsulation and the IETF Frame Relay encapsulation, which is in conformance with RFC 1490 and RFC 2427. The former is often used to connect two Cisco routers while the latter is used to connect a Cisco router to a non-Cisco router. You can test with your Cisco router when typing the command Router(config- if)# encapsulation frame-relay ? on a WAN link. Below is the output of this command (notice Cisco is the default encapsulation so it is not listed here, just press Enter to use it). Note: Three LMI options are supported by Cisco routers are ansi, Cisco, and Q933a. They represent the ANSI Annex D, Cisco, and ITU Q933-A (Annex A) LMI types, respectively. HDLC is a WAN protocol same as Frame-Relay and PPP so it is not a Frame Relay encapsulation type.

Hint

First we have to say this is an unclear question and it is wrong. The “frame-relay map ip” statement is correct thus none of the four answers above is correct. But we guess there is a typo in the output. Maybe the “ip address 172.16.100.2 255.255.0.0 command should be “ip address 172.16.100.1 255.255.0.0.

Hint

Inverse Address Resolution Protocol (Inverse ARP) was developed to provide a mechanism for dynamic DLCI to Layer 3 address maps. Inverse ARP works much the same way Address Resolution Protocol (ARP) works on a LAN. However, with ARP, the device knows the Layer 3 IP address and needs to know the remote data link MAC address. With Inverse ARP, the router knows the Layer 2 address which is the DLCI, but needs to know the remote Layer 3 IP address. When using dynamic address mapping, Inverse ARP requests a nexthop protocol address for each active PVC. Once the requesting router receives an Inverse ARP response, itupdates its DLCI-to-Layer 3 address mapping table. Dynamic address mapping is enabled by default for all protocols enabled on a physical interface. If the Frame Relay environment supports LMI autosensing and Inverse ARP, dynamic address mapping takes place automatically. Therefore, no static address mapping is required.

Hint

Sample “show frame-relay map” output: R1#sh frame mapSerial0/0 (up): ip 10.4.4.1 dlci 401(0x191,0x6410), dynamic,broadcast, status defined, activeSerial0/0 (up): ip 10.4.4.3 dlci 403(0x193,0x6430), dynamic,broadcast,, status defined, activeSerial0/0 (up): ip 10.4.4.4 dlci 401(0x191,0x6410), static,CISCO, status defined, active

Hint

If device A is sending data to device B across a Frame Relay infrastructure and one of the intermediate Frame Relay switches encounters congestion, congestion being full buffers, over- subscribed port, overloaded resources, etc, it will set the BECN bit on packets being returned to the sending device and the FECN bit on the packets being sent to the receiving device.

Hint

When connecting Cisco devices with non-Cisco devices, you must use IETF4 encapsulation on both devices. Check the encapsulation type on the Cisco device with the show frame-relay map exec command.

Hint

For multiple PVC’s on a single interface, you must use subinterfaces, with each subinterface configured for each PVC. Each subinterface will then have its own IP address, and no IP address will be assigned to the main interface.

Hint

Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the Frame Relay switch. Frames that are sent in excess of the CIR are marked as discard eligible (DE) which means they can be dropped if the congestion occurs within the Frame Relay network. Note: In the Frame Relay frame format, there is a bit called Discard eligible (DE) bit that is used to identify frames that are first to be dropped when the CIR is exceeded.

Hint

DLCI-Data Link Connection Identifier Bits: The DLCI serves to identify the virtual connection so that the receiving end knows which information connection a frame belongs to. Note that this DLCI has only local significance. Frame Relay is strictly a Layer 2 protocol suite.

Hint

This command identifies the DLCI that should be used for all packets destined to the 192.168.1.2 address. In this case, DLCI 202 should be used.

Hint

Subinterfaces are used for point to point frame relay connections, emulating virtual point to point leased lines. Each subinterface requires a unique IP address/subnet. Remember, you can not assign multiple interfaces in a router that belong to the same IP subnet.

Hint

Sample “show frame-relay map” output: R1#sh frame mapSerial0/0 (up): ip 10.4.4.1 dlci 401(0x191,0x6410), dynamic,broadcast,, status defined, activeSerial0/0 (up): ip 10.4.4.3 dlci 403(0x193,0x6430), dynamic,broadcast,, status defined, activeSerial0/0 (up): ip 10.4.4.4 dlci 401(0x191,0x6410), static,CISCO, status defined,

Hint

Dynamic address mapping relies on the Frame Relay Inverse Address Resolution Protocol (Inverse ARP), defined by RFC 1293, to resolve a next hop network protocol (IP) address to a local DLCI value. The Frame Relay router sends out Inverse ARP requests on its Frame Relay PVC to discover the protocol address of the remote device connected to the Frame Relay network. The responses to the Inverse ARP requests are used to populate an address-to-DLCI mapping table on the Frame Relay router or access server. The router builds and maintains this address-to- DLCI mapping table, which contains all resolved Inverse ARP requests, including both dynamic and static mapping entries.

Hint

Many rural areas do not have cable Internet access and their only choice to connect to the Internet is via satellite. Satellite internet leverages the hundreds of satellites in orbit around the Earth to send and receive data over the Internet. Of course the speed of this type of connection is much slower than DSL and cable connections. But with new technologies, satellite connections may achieve data speed up to 50 Mbps -> B is correct, D is not correct.In general, the speeds of popular types of Internet connections are like this: DSL/cable > satellite Internet > dial-up (analog modem).Satellite Internet uses satellite for Internet connection -> E is not correct Satellites use radio waves to communicate with the customer’s gateway, also known as a ground station (like a customer’s satellite dish), but not with cellular phone towers -> F is not correct. For your information, satellite Internet uses high frequency signals, which range from 18.3 gigahertz to 31 gigahertz (Ka band). Answer A C are two options left and they are acceptable answers. Although in practical they may vary a lot.

Hint

Below is an example of the output of this command: https://itexamanswers.net/wp-content/uploads/2018/09/show_controllers.jpg The “show controllers serial …” command tells us about the type of the cable (in the case V.35 DTE cable) and the status of the physical layer of the interface. In above output we learn that there is an cable attached on S0/0 interface. If no cable is found we will see the line “No DTE cable” instead.

Hint

The topology of DMVPN is always hub-and-spoke as all Spokes are required to connect to the Hub router directly.

Hint

MPLS belongs to the family of packet-switched networks. MPLS operates at a layer that is generally considered to lie between traditional definitions of OSI Layer 2 (data link layer) and Layer 3 (network layer), and thus is often referred to as a layer 2.5 protocol.

Hint

The output of the above show command displays that the local DLCI number corresponding to the subinterface of s1/0 whose IP address is 172.30.0.4 is 702.

Hint

Based on the output of the command “show frame-relay map”, we know that DLCI mapped to the router SAMER is 196. (.3 In the above network topology, the complete Layer 3 IP address is 172.30.0.3)

Hint

On the basis of the configuration on Dubai provided in the exhibit, we know that the encapsulation types of different interfaces are as follows: Serial 1/0 : encapsulation frame-relay Serial 1/2 and Serial 1/3 : both interfaces are encapsulated PPP Serial 1/1: There is no related encapsulation information displayed, so its default encapsulation type is HDLC . Based on the network topology provided in the exhibit, the interface Serial 1/1 is connected to the router MidEast of the branch office, so the encapsulation type of the router MidEast is by default. The default encapsulation on a serial interface is HDLC. The original HDLC encapsulation was defined by the International Organization for Standards (ISO), those same folks who developed the OSI model. The ISO version of HDLC had one shortcoming, however; it had no options to support multiple Layer 3 routed protocols. As a result, most vendors have created their own form of HDLC. Cisco is no exception because it has its own proprietary form of HDLC to support various Layer 3 protocols such as IPX, IP, and AppleTalk. The Serial connection to the Dub branch office using the default encapsulation type. You can change using: * encapsulation command on interface

Hint

In the diagram, DeepSouth is connected to Dubai’s S1/2 interface and is configured as follows: Interface Serial1/2 IP address 192.168.0.5 255.255.255.252 Encapsulalation PPP ; Encapsulation for this interface is PPP Check out the following Cisco Link: http://www.cisco.com/en/US/tech/tk713/tk507/ technologies_configuration_example09186a0080094333.shtml#configuringausernamedifferentfromtherouters name Here is a snipit of an example: If Router 1 initiates a call to Router 2, Router 2 would challenge Router 1, but Router 1 would not challenge Router 2. This occurs because the ppp authentication chap callin command is configured on Router 1. This is an example of a unidirectional authentication. In this setup, the ppp chap hostname alias-r1 command is configured on Router 1. Router 1 uses “alias-r1” as its hostname for CHAP authentication instead of “r1.” The Router 2 dialer map name should match Router 1’s ppp chap hostname; otherwise, two B channels are established, one for each direction.

Hint

http://www.cisco.com/c/en/us/support/docs/wan point-to-point-protocol-ppp/10241-ppp-callin-hostname.html

Hint

In the Dialer interface, we can use the “ip address negotiated” command to ask for an IP address from the PPPoE Server.

Hint

The following diagram illustrates the key difference between traffic policing and traffic shaping. Traffic policing propagates bursts. When the traffic rate reaches the configured maximum rate (or committed information rate), excess traffic is dropped (or remarked). The result is an output rate that appears as a saw-tooth with crests and troughs. In contrast to policing, traffic shaping retains excess packets in a queue and then schedules the excess for later transmission over increments of time. The result of traffic shaping is a smoothed packet output rate. Note: Committed information rate (CIR): The minimum guaranteed data transfer rate agreed to by the routing device.

Hint

This question is to examine the show int command. According to the information provided in the exhibit, we can know that the data link protocol used in this network is the Frame Relay protocol. “LMI enq sent…”