Cisco CCNA Certification Exam Tutorial Frame Relay DLCIs And Mappings
Below is a MRR and PLR article in category Computers Technology -> subcategory Computer Certification.
Cisco CCNA Certification Exam Tutorial: Frame Relay DLCIs and Mappings
Summary:
Gain insights into Frame Relay DLCIs and mapping techniques with guidance from Chris Bryant, CCIE
12933.
Keywords:
Cisco, CCNA, certification, exam, Frame Relay, DLCI, mapping, Inverse ARP, static, pass, free
---
Preparing for the CCNA exam can be challenging, especially when navigating the plethora of acronyms involved! Frame Relay is packed with these terms, and today we'll explore the role of Data-Link Connection Identifiers (DLCIs) and how they're mapped on Cisco routers.
DLCIs, pronounced "del-see," act as the addresses for Frame Relay virtual circuits (VCs). Unlike some Cisco technologies, VCs feature only one DLCI in their header, lacking distinct source and destination addresses. DLCIs are known for having local significance only?"meaning that they aren’t shared across routers, allowing different routers to use identical DLCI numbers without connectivity conflicts.
Cisco offers a global addressing technique where a router in a Frame Relay network can be accessed using the same DLCI number from any router within that network. For instance, if there are 25 routers in a network, the same DLCI could be used to reach a particular router.
While global addressing is useful for organizational purposes, it doesn’t change the local significance of DLCIs. To connect the locally significant DLCI to a destination IP address, you have two options: Inverse ARP and static mapping.
Let's look at how these mappings work using an example where Router 1's serial interface connects to Router 2 and Router 3 through the Frame Relay cloud.
Inverse ARP
By default, Inverse ARP runs as soon as Frame Relay is enabled, automatically creating mappings when the interface opens. You can verify this with the `show frame-relay map` command, which displays dynamic mappings if Inverse ARP is active.
Example:
```
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
Static mappings require more manual configuration. First, disable Inverse ARP with the `no frame-relay inverse-arp` command, then set up a `frame map` statement for each remote IP address to map it to the local DLCI. Don’t forget the `broadcast` keyword to enable broadcasts to the remote device.
Example:
```
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
```Here's how it appears:
```
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
```
Practice Makes Perfect
Hands-on practice is essential for mastering these concepts. Working in a lab environment with Frame Relay will solidify your knowledge, paving the way to success in the CCNA exam and your journey toward becoming a master network engineer.
You can find the original non-AI version of this article here: Cisco CCNA Certification Exam Tutorial Frame Relay DLCIs And Mappings.
You can browse and read all the articles for free. If you want to use them and get PLR and MRR rights, you need to buy the pack. Learn more about this pack of over 100 000 MRR and PLR articles.