CCNA 4 Chapter 3

Based on the information given in the exhibit, the DLCI 110 will be used to send the ping.

In a Frame Relay network, a virtual circuit is created between two DTEs (Data Terminal Equipment). A virtual circuit is a logical connection that allows data to be transmitted between the two devices. It provides a communication path that appears to be a dedicated physical circuit, even though it is actually sharing the physical network infrastructure with other virtual circuits. This allows for efficient and cost-effective data transmission in a Frame Relay network.

Point-to-point subinterfaces act like leased lines and eliminate split-horizon routing issues. This means that each subinterface is treated as a separate connection, allowing for direct communication between the two endpoints without any routing restrictions. This eliminates the need for split-horizon routing, which prevents routing loops in networks with redundant connections. By using point-to-point subinterfaces, the Frame Relay network can efficiently transmit data without the risk of routing issues.

To complete the Frame Relay topology and allow traffic between R1 and R2 to travel through HQ first, the serial interface on HQ should be configured with two point-to-point subinterfaces. This configuration will enable separate virtual circuits to be established between HQ and each of the remote sites. Each subinterface will have its own IP address, allowing for proper routing and communication between the sites.

The benefit of using Frame Relay as opposed to a leased line or ISDN service is that customers only pay for the local loop and the bandwidth they purchase from the network provider. Unlike leased lines or ISDN services where customers pay for an end-to-end connection that includes the local loop and the network link, with Frame Relay, customers have the flexibility to choose and pay for only the local loop and the specific bandwidth they require from the network provider. This allows for more cost-effective and customizable network solutions for customers.

The correct answer is the configuration option that includes the correct IP addresses and DLCIs for each router. In this case, R2 should have a frame-relay map command for IP address 10.1.1.1 with DLCI 201, and IP address 10.1.1.3 with DLCI 201. R3 should have a frame-relay map command for IP address 10.1.1.1 with DLCI 301, and IP address 10.1.1.2 with DLCI 301. This configuration allows for successful pinging between all routers.

The point-to-point configuration on subinterface S0/0.110 eliminates split horizon issues without increasing the likelihood of routing loops. Split horizon is a technique used in routing protocols to prevent routing loops by not advertising a route back out of the interface it was learned from. In a point-to-point configuration, there is only one possible path between two devices, so split horizon is not necessary. By eliminating split horizon, the router can advertise routes more efficiently and prevent unnecessary routing loops. The other options are incorrect because they do not relate to the effect of the point-to-point configuration on the router's operation.

The correct answer is the last set of configuration options. In this configuration, R2 is configured with a point-to-point interface on serial0/0/1.201 and R3 is configured with a point-to-point interface on serial0/0/1.301. The frame-relay interface-dlci command is used to specify the Data Link Connection Identifier (DLCI) for each interface, with R2 using DLCI 201 and R3 using DLCI 301. This configuration allows each router to establish a direct point-to-point connection with R1, providing connectivity between all three routers.

A partial mesh topology is a compromise of costs, reliability, and complexity when the WAN contains one headquarters site, 40 regional sites, and several sites within each regional site. In a partial mesh topology, not all sites are directly connected to each other, but there are still multiple connections between different sites. This allows for efficient communication between the headquarters and regional sites, as well as between the sites within each region. It strikes a balance between the high cost and complexity of a full mesh topology and the limited connectivity of a star or point-to-point topology.

Inverse ARP and LMI status messages are the two items that allow the router to map data link layer addresses to network layer addresses in a Frame Relay network. Inverse ARP is used to dynamically map the network layer (IP) addresses to the data link layer (MAC) addresses in Frame Relay. LMI (Local Management Interface) status messages are used to exchange information between the router and the Frame Relay switch, including mapping tables that associate data link layer addresses with network layer addresses.

When a Frame Relay switch detects an excessive build-up of frames in its queue, it performs three actions. Firstly, it drops frames from the queue that have the DE (Discard Eligible) bit set. Secondly, it sets the FECN (Forward Explicit Congestion Notification) bit on all frames it receives on the congested link, indicating to the receiving device that congestion is occurring. Lastly, it sets the BECN (Backward Explicit Congestion Notification) bit on all frames it places on the congested link, informing the sending device about the congestion. These actions help manage and alleviate congestion in the Frame Relay network.

The output shows that the Frame Relay switch has a high number of frames in BECN (Backward Explicit Congestion Notification) and FECN (Forward Explicit Congestion Notification) states. This indicates that the switch is experiencing congestion and is unable to process frames at the desired rate.

Adding the broadcast keyword in the Frame Relay map command on both routers will allow the routers to forward broadcast traffic over the Frame Relay network. By default, Frame Relay does not forward broadcast traffic, so adding the broadcast keyword will enable the routers to send and receive broadcast packets. This will allow router R1 to successfully ping network 192.168.3.0/24.

The output indicates that the command "encapsulation frame-relay ietf" has been used on the Serial 0/0/0 interface of router R1.

In order to forward routing updates on Frame Relay multiaccess networks, the address-to-DLCI mapping must be established using the frame-relay map command along with the broadcast keyword. This allows the routing updates to be sent as broadcast traffic to all connected nodes on the network. By using this mapping, the updates can be properly propagated and reach their intended destinations.

The Frame Relay connection between R1 and R2 is failing because the frame-relay map commands are using incorrect DLCIs. This means that the Data Link Connection Identifiers (DLCIs) specified in the frame-relay map commands do not match the DLCIs assigned by the service provider. As a result, the routers are unable to establish a successful connection over the Frame Relay network.

A data-link connection identifier (DLCI) is a locally significant address that is used to identify a virtual circuit. This means that the DLCI serves as a label or identifier for a specific connection within a Frame Relay network. It helps to differentiate and establish a connection between different virtual circuits within the network. The DLCI is used to route data packets to the correct destination across the network.

Frame Relay technology uses two methods to process frames that contain errors. Firstly, it depends on the upper layer protocols to handle error recovery. This means that the higher layer protocols, such as TCP/IP, are responsible for detecting and recovering from errors. Secondly, the receiving device drops any frames that contain errors without notifying the sender. This means that if a frame is found to have errors, it is simply discarded by the receiving device without any notification sent back to the sender. These two methods help to ensure efficient and reliable transmission of data over Frame Relay networks.

The output shows that Serial 0/0/0 has the feature frame-relay inverse-arp enabled. This means that the router is using Inverse ARP (Address Resolution Protocol) to dynamically map IP addresses to DLCIs (Data Link Connection Identifiers) in a frame-relay network. Inverse ARP allows the router to automatically discover the DLCI associated with a particular IP address, simplifying the configuration process.

The correct answer is that the local DLCI number is 401 and Inverse ARP is being used on this connection. This can be determined from the output shown in the exhibit. The line "Local DLCI 401" indicates that the local DLCI number is indeed 401. Additionally, the line "Type: dynamic, Status: active" suggests that Inverse ARP is being used, as Inverse ARP dynamically maps IP addresses to DLCI numbers.

The correct answer suggests that the LMI type for the Serial 0/0/0 interface has not been modified and is still in its default configuration. This means that the router is using the default LMI type for that interface, which could indicate that LMI updates are being received properly. However, the other options do not provide any information about the LMI updates or the configuration of the interface.

The configuration shown indicates that DLCI 22 is being used for forwarding data to the IP address 10.1.1.1. This means that the router will use DLCI 22 to send data packets to the destination IP address. Additionally, frames sent by 10.1.1.1 and arriving on interface serial 0/0/0 of RT_1 will have a data link layer address of 22. This suggests that the frames will be encapsulated with DLCI 22 as the data link layer address during transmission.