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FRAME RELAY EXMCRAM
FRAME RELAY EXAM CRAM CH 15
Question | Answer |
---|---|
What's DLCI stand for? | Data-Link Connection Identifier. Locally significant only. |
What's LMI stand for? | Local Management Interface works as a status inquiry, reporting message & keep alive. LMI messages are sent between your router and the Frame Relay provider’s equipment to verify and report on the status of your PVC |
What are The three possible states that your PVC can be in? | Active=all is up/working Inactive=problem with the far-end connection. The problem is most likely between the far-end router and its connection to the Frame Relay provider Deleted=problem between your router and the Frame Relay provider’s equipment. |
What's the advantage of FRAME RELAY | You can connect to multiple remote sites using only one single interface on a router and virtual circuits |
What are the three types of LMI | CISCO, Ansi, Q933A. Auto-sensed after IOS 11.2 and higher. |
BECN | Backward Explicit Congestion Notification is sent back to the sender |
FECN | is sent forward to the destination to notify them of congestion. |
Inverse-Arp | Frame Relay needs a mechanism called inverse ARP to map Layer 3 addresses withLayer 2 Frame Relay DLCIs. |
NBMA | Frame Relay is a nonbroadcast multi-access (NBMA) medium, which means that broadcast traffic is not allowed to traverse Frame Relay traffic |
FRAME RELAY'S Split-Horizon Problem | route learned on an interface should not be advertised back out that same interface. This poses a problem in NBMA networks where multiple circuits can connect to a single interface in a hub-and-spoke topology. |
List four options to get around the split-horizon problem | "no ip split-horizon" command, this could create a loop. Have a fully meshed topology where every router has a PVC to every other router. This can get expensive. Use static routes solution. Use subinterfaces. This is your best option. |
The best option to get arouind the split-horizon problem | Use subinterfaces. This is your best option. |
two types of subinterfaces | Point-to-point—This maps a single IP subnet to a single subinterface and DLCI Multipoint—This maps a single IP subnet to multiple DLCIs on a subinterface |
Which type of subinterface addresses the split-horizon problem | only point-to-point subinterfaces address the issue of split horizon |
Configuring Frame Relay step one: | Changing the encapsulation for Frame Relay |
Configuring Frame Relay step two: | Configuring the LMI type (optional for IOS 11.2 or higher) |
Configuring Frame Relay step three: | Configuring the Frame Relay map (optional unless you are using subinterfaces) |
Configuring Frame Relay step four: | Configuring subinterfaces (optional) |
Configuring Frame Relay step five: | If using a point-to-point subinterface, configuring your DLCI |
Configuring Frame Relay involves the following steps | set encapsulation for Frame Relay set the LMI type (optional for IOS 11.2 or higher) Config the Frame Relay map (optional unless you are using subinterfaces) Config subinterfaces (optional) If using a ptp subinterface, configuring your DLCI |
What command is used to set Frame Relay encapsulations: | Cisco and IETF. Cisco is the default. The syntax to set your encapsulation is "encapsulation frame-relay [ietf]" |
For IOS earlier than 11.2 What command is used to set LMI type | frame-relay lmi-type [cisco|ansi|q933a] |
configuring a static Frame Relay map, is ___________ if subinterfaces are used | required |
The Frame Relay Map will map a ______ to a ______ | The Frame Relay map will map a Layer 3 address to a local DLCI. This step is optional because inverse-arp will automatically perform this map for you. |
What's the syntax for a Frame Relay Map | frame-relay map protocol address dlci [broadcast] [cisco | ietf] |
For example, if you were connected to another router using DLCI 100 and the router had the IP address of 10.0.0.2, your frame-relay map statement would be ________ | Router(config-if)#frame-relay map ip 10.0.0.2 100 |
Define each piece of syntax in the following command: frame-relay map protocol address dlci [broadcast] [cisco | ietf] | PROTOCOL Layer 3 protocol. ADDRESS The Layer 3 address of remote router address). DLCI Your local DLCI defining your PVC to the remote router. BROADCAST Optional, this allows for broadcasts and multicasts to traverse your NBMA Frame Relay network. |
Define [Cisco| ietf] from syntax in the following command: frame-relay map protocol address dlci [broadcast] [cisco | ietf] | [Cisco | ietf] Optional, this allows you to change your Frame Relay encapsulation per DLCI |
If you want to use a routing protocol across your Frame Relay network, you will need to add the keyword ______to the end of this command | "broadcast" |
If you are using ___ to create your maps for you, you DON'T need to add "broadcast" to the end of the frame-relay map command | inverse-arp assumes that you want to use routing protocols and adds the broadcast feature for you. |
When using Frame-Relay, in which topology would you want to use subinterfaces and why? | If you are using a routing protocol in a hub-and-spoke topology, you will probably want to use subinterfaces to avoid the split-horizon problem. |
The following command creates point-to-point subinterface serial0/0.1 | Router(config)#interface serial0/0.1 point-to-point |
The following command creates a multipoint subinterface: | Router(config)#interface serial0/0.1 multipoint |
If you are using a _____ subinterface, you will need to configure framerelay maps and you cannot rely on inverse-arp | If you are using a MULTIPOINT subinterface, you will need to configure framerelay maps and you cannot rely on inverse-arp. |
If you are using a _____ subinterface, you will need to assign a DLCI to the subinterface | If you are using a POINT-TO-POINT subinterface, you will need to assign a DLCI to the subinterface. This is only for point-to-point subinterfaces; this is not needed on the main interface or on multipoint subinterfaces |
To assign a DLCI to a point-to-point subinterface, enter the following command under the subinterface: | "frame-relay interface-dlci ##" |
configure Frame Relay for the xyz router using a point-to-point subinterface | interface serial 0/0 encapsulation frame-relay interface serial 0/0.1 point-to-point ip address 10.0.0.1 255.0.0.0 frame-relay interface-dlci 100 |
asuming the "encapsualtion frame-relay" command was already issued on the "main" interface make another subinterface & configure Frame Relay multipoint subinterface to connect to the abc router | interface serial 0/0.2 multipoint ip address 14.0.0.1 255.0.0.0 frame-relay map ip 14.0.0.3 200 broadcast |
What are three commands to verify & troubleshoot frame-relay? | show frame-relay lmi....... show frame-relay pvc....... show frame-relay map....... |
"show frame-relay lmi" | Invalid Unnumbered info 0 Invalid Prot Disc 0 Invalid dummy Call Ref 0 Invalid Msg Type 0 ........ ............. Num Status Enq. Sent140 Num Status msgs Rcvd139 |
What info does the "show frame-relay lmi" give you? | LMI statistics, including the number of status inquiries sent and received. Because the status inquiries and responses are used as continuous keepalives, these should be incrementing |
What info does the "show frame-relay pvc" give | status of your PVC. The status should read ACTIVE. This is also where you will see if your router is receiving BECN and FECN messages |
The "show frame-relay map" command | The "show frame-relay map" shows you any static maps configured and maps created by inverse-arp. This command will also show you the status of your PVC. Serial0/0 (up): ip 10.0.0.1 dlci 100(0x64,0x1840), dynamic, broadcast,, status defined, active |
Remember, the three show frame-relay commands and what they do. | Show framerelay lmi shows your LMI statistics, whereas show frame-relay pvc and show frame-relay map will show your PVC status |