Cisco CCNA Certification Exam Tutorial: Frame Relay DLCIs And Mappings
4800
Computers > Computer Certification
Mar 1, 2007
Chris Bryant
Cisco CCNA Certification Exam Tutorial: Frame Relay DLCIs And Mappings
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach ?Router A? by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router?s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Frame Relay VCs use Data-Link Connection Identifiers (DLCI - pronounced "del-see") as their addresses. Unlike other Cisco technologies, VCs have only a single DLCI in their header. They do not have a source and destination.
DLCIs have local significance only. DLCI numbers are not advertised to other routers, and other routers can use the same DLCI numbers without causing connectivity issues.
Cisco uses the term global addressing to describe a technique by which a router in a frame relay network is reached via the same DLCI number from each router in the network. For example, in a 25-router network, the same DLCI number would be used to reach ?Router A? by each router.
Global Addressing is an organizational tool that does not affect the fact that DLCIs have local significance only.
The locally significant DLCI must be mapped to the destination router?s IP address. There are two options for this, Inverse ARP and static mapping.
In both of the following examples, the single physical Serial interface on Router 1 is configured with two logical connections through the frame relay cloud, one to Router 2 and one to Router 3.
Inverse ARP runs by default once Frame Relay is enabled, and starts working as soon as you open the interface. By running show frame-relay map after enabling Frame Relay, two dynamic mappings are shown on this router. If a dynamic mapping is shown, Inverse ARP performed it.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), dynamic,
broadcast,, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), dynamic,
broadcast,, status defined, active
Static mappings require the use of a frame map statement. To use static mappings, turn Inverse ARP off with the no frame-relay inverse-arp statement, and configure a frame map statement for each remote destination that maps the local DLCI to the remote IP address. Frame Relay requires the broadcast keyword to send broadcasts to the remote device.
R1#conf t
R1(config)#interface serial0
R1(config-if)#no frame-relay inverse-arp
R1(config-if)#frame map ip 200.1.1.2 122 broadcast
R1(config-if)#frame map ip 200.1.1.3 123 broadcast
The syntax of the frame map statement maps the remote IP address to the local DLCI.
Broadcasts will not be transmitted by default; the broadcast option must be configured.
R1#show frame map
Serial0 (up): ip 200.1.1.2 dlci 122(0x7A,0x1CA0), static,
broadcast,
CISCO, status defined, active
Serial0 (up): ip 200.1.1.3 dlci 123(0x7B,0x1CB0), static,
broadcast,
CISCO, status defined, active
Hands-on practice is the best way to prepare for CCNA exam success. Working with Frame Relay in a lab environment practically guarantees that you'll truly master the concepts shown here - and then you're on your way to the CCNA and becoming a master network engineer.
Article Source: http://www.articlerich.com
Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage , home of free CCNA and CCNP tutorials! Pass the CCNA exam with Chris Bryant!
Write a Review
Add to My Favorite
Refer it to Friend
Report Article
Other links owned by this user
CCNA exam success deends artially on knowing the details of ISDN, and there are lenty of them! To hel you review for your CCNA exam, here are a few ISDN details that you must know on exam day. (They hel in the real world, too ? and there are still
Category:
QoS - Quality o Service - is a huge topic on both the BCMSN exam and real-world networks. QoS is so big today that Cisco's created separate specialist certiications that cover nothing but QoS! It can be an overwhelming topic at irst, but master the
Category:
Passing the CCNA is tough, and one of the toughest parts is keeping all the acronyms straight! Frame Relay has plenty of those, and today we're going to examine what DLCIs do and how they're mapped on a Cisco router. Frame Relay VCs use
Category:
Multicasting is a vital topic on your BCMSN, CCNP, and CCIE exams, and it can also be very confusing when you first start studying it. Multicasting uses concepts that are unlike anything you've run into in your routing protocol studies, and that can
Category:
To be truly prepared for your CCNA and CCNP exams, you need real hands-on experience with real Cisco routers and switches. However, a production network is a really bad place to practice your configurations, but an excellent way to get fired and/or
Category:
While routers accept and generate broadcasts, they do not forward them. This can be quite a problem when a broadcast needs to get to a device such as a DHCP or TFTP server that's on one side of a router with other subnets on the other side.
Category:
In this CCNA case study, we'll take some basic switching and trunking theory and put it into action. We have two routers (R2 and R3) along with two switches (SW1 and SW2). R2 is connected to SW1 at fast 0/2, and R3 is connected to SW2 at fast 0/3. Both
Category:
RIP isn't exactly the most complex routing protocol on the CCNA exam, but that makes it easy to overlook some of the important you must keep in mind in order to pass the exam! To help you review for the exam, here are just a few of those
Category:
Ever since you picked up your first CCNA book, you've heard about multicasting, ten a fair idea of what it is, and you've memorized a couple of reserved multicasting addresses. Now as you prepare to pass the BCMSN exam and become a CCNP, you've
Category:
OSPF route ibution is an important topic on the BSCI exam, and it's a topic full of details and defaults that you need to know for the exam room and the job. To help you pass the BSCI exam, here's a quick review of some of the OSPF route
Category:
EIGRP is a major subject of the CCNA exam, and Cisco goes into even more detail with EIGRP on your CCNP exams. Part of that detail is the purpose and configuration of EIGRP stub routers. A problem with EIGRP comes in when a successor is
Category:
Your BSCI exam and CCNP certification success depend on mastering BGP, and a ig part of that is knowing how and when to use the many BGP attriutes. And for those of you with an eye on the CCIE, elieve me - you've got to know BGP attriutes like the
Category:
QoS is a big topic on your BCMSN and CCNP exams, and for good reason. As more and more traffic flows through today's networks, accurately plying QoS to both your routers and switches becomes more important. Note the phrase "accurately
Category:
To pass the BSCI exam, you need to know the difference between IRDP and HSRP. While they have the same basic function, the operation and configuration of each are totally different. The aim of both is to allow hosts to quickly discover a
Category:
I know from experience that part of the excitement and anxiety of putting together your own CCNA / CCNP home lab is deciding what to buy! While you can make a workable home lab out of almost any combination of Cisco routers and switches, some routers
Category:
To pass e CCNA exam, you've got to know how to work wi IGRP and EIGRP unequal-cost load balancing. You may not see much IGRP in production networks anymore, but you'll see a lot of EIGRP, and part of fine-tuning your EIGRP network is making sure
Category:
If a Layer Two switch doesn't have the capabilities to run IGMP Snooping, it will be able to run CGMP - Cisco Group Membership Protocol. CGMP allows the multicast router to work with the Layer Two switch to eliminate unnecessary multicast forwarding.
Category:
The most common method of configuring ISDN is with dialer maps, but dial information can also be configured on a logical interface. To pass the CCNA exam, you must know how to configure and troubleshoot both dialer maps and dialer
Category:
Other links at Computers > Computer Certification
Not only is your CCNA exam going to have questions on VLAN trunking protocol, almost any network that has more than one VLAN is going to have VTP running. Whether you're planning on passing the CCNA exam or just brushing up on your networking skills,
Category:
Like TCP, BGP is connection-oriented. An underlying connection between two BGP speakers is established before any routing information is exchanged. This connection takes place on TCP port 179. As with EIGRP and OSPF, keepalive messages are sent out by
Category:
While routers accept and generate broadcasts, they do not forward them. This can be quite a problem when a broadcast needs to get to a device such as a DHCP or TFTP server that's on one side of a router with other subnets on the other side.
Category:
ISDN is a huge topic on both your Cisco CCNA and BCRAN CCNP exams. While many ISDN topics seem straightforward, it?s the details that make the difference in the exam room and working with ISDN in production networks. Configuring and troubleshooting
Category:
To earn your Cisco CCNA certification and pass the BSCI CCNP exam, you have to know your protocol basics like the back of your hand! To help you review these important concepts, here's a quick look at the basics of RIPv1, RIPv2, IGRP, and
Category:
Site Sponsor
Directory Statistics
Articles: 68222
Categories: 501
Yahoo Entertainment
