CCIE Pursuit Blog

December 1, 2007

Internetwork Expert Volume II: Lab 2 – Section 2

Section 2 – Frame Relay – 9 Points

The first task sank me.  It asks you to configure a fully meshed Frame Relay network between routers 1 – 4 without using any static Frame Relay mappings.  Easy right?  Just let Frame Relay Inverse-ARP work its magic.

Well…not so easy.  I would have lost points on this because I did exactly that. 

IE’s method:

interface Serial0/0
 ip address 132.1.0.1 255.255.255.0
 encapsulation frame-relay
 no frame-relay inverse-arp IP 105
 no frame-relay inverse-arp IP 113

r1#sh frame map
Serial0/0 (up): ip 132.1.0.2 dlci 102(0x66,0x1860), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 132.1.0.3 dlci 103(0x67,0x1870), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 132.1.0.4 dlci 104(0x68,0x1880), dynamic,
              broadcast,, status defined, active

My method:

interface Serial0/0
 ip address 132.1.0.1 255.255.255.0
 encapsulation frame-relay

r1#sh frame map
Serial0/0 (up): ip 132.1.0.2 dlci 102(0x66,0x1860), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 132.1.0.3 dlci 103(0x67,0x1870), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 132.1.0.4 dlci 104(0x68,0x1880), dynamic,
              broadcast,, status defined, active

The end results are the same.  There is a full mesh dynamically assigned.  Kinda.  🙂

IE’s solution is the better solution.  There are some DLCIs being advertised to the router that do not get mapped via Frame Relay Inverse-ARP (because they are not associated with an IP address), BUT they would be mapped if they were to be assigned to an interface with an IP address:

r1#sh frame pvc | i DLCI
DLCI = 102, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0
DLCI = 103, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0
DLCI = 104, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0
DLCI = 105, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0
DLCI = 113, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial0/0

Frame inverse-arp is on by default, so it’s trying to map for those DLCIs:

r1#sh frame map
Serial0/0 (up): ip 0.0.0.0 dlci 113(0x71,0x1C10)
              broadcast,
              CISCO, status defined, active
Serial0/0 (up): ip 0.0.0.0 dlci 105(0x69,0x1890)
              broadcast,
              CISCO, status defined, active

Serial0/0 (up): ip 0.0.0.0 dlci 104(0x68,0x1880)
              broadcast,
              CISCO, status defined, active
Serial0/0 (up): ip 0.0.0.0 dlci 103(0x67,0x1870)
              broadcast,
              CISCO, status defined, active
Serial0/0 (up): ip 0.0.0.0 dlci 102(0x66,0x1860)
              broadcast,
              CISCO, status defined, active
Serial0/0 (up): ip 132.1.0.3 dlci 103(0x67,0x1870), dynamic,
              broadcast,
              CISCO, status defined, active

I need to make sure that DLCIs 102, 103, and 104 use Inverse-ARP to map, but not DLCIs 105 and 113.  That means using “no frame-relay inverse-arp ip [DLCI]” for the DLCIs that I do not want to be mapped.

IE’s initial configurations have the interfaces no shut with Frame Relay encapsulation.  This means that Frame Relay Inverse-ARP is already chugging away.  I’ve learned to simply shut the interface and reload the router in order to clear the 0.0.0.0 mappings.  All other methods seem pretty hit or miss.

I also stumbled across a configuration error:

r3(config)#do sh ip int br | i 132.1.0.3
Serial0/0:0                132.1.0.3       YES NVRAM  up                    up
Serial0/1:0                132.1.0.3       YES NVRAM  up                    up

The rest of the tasks were easy with the exception of 2.4 which involved Frame Relay Traffic Shaping.  In a mock lab I would have skipped this section and come back to it later.  I did pretty good on it except that I would have lost the points anyways because of a stupid mistake.  I typed 1800 instead of 2800 for the Bc of the remaining bandwidth statements.  All of that work for naught. 😦

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1 Comment »

  1. […] Expert Volume II Lab 2 Posts: Internetwork Expert Volume II: Lab 2 – Section 1 Internetwork Expert Volume II: Lab 2 – Section 2 Internetwork Expert Volume II: Lab 2 – Section 3 Internetwork Expert Volume II: Lab 2 – Section 4 […]

    Pingback by Internetwork Expert Volume II: Lab 2 - Wrap Up « CCIE Pursuit — December 11, 2007 @ 1:59 pm | Reply


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