CCIE Pursuit Blog

January 30, 2008

Internetwork Expert Volume II: Lab 6 – Section 2

WAN Technologies – 7 Points

2.1 Hub-and-Spoke

This was a simple Frame Relay Hub-and-Spoke configuration using physical interfaces and frame maps.  The only “twist” is the last subtask:

“Do not send any redundant broadcast traffic from the spokes to the hub.”

You only need to add the ‘broadcast’ keyword to the frame map to the hub router on the spokes:

r5(spoke):
interface Serial0/0
 ip address 191.17.125.5 255.255.255.0
 encapsulation frame-relay
 frame-relay map ip 191.17.125.1 501 broadcast <- to the hub
 frame-relay map ip 191.17.125.2 501
<-to other spoke
 no frame-relay inverse-arp

Also, IE has the interface up so Frame Relay Inverse ARP is already running:

r1(config-if)#do sh frame map
Serial0/0 (up): ip 191.17.125.2 dlci 102(0x66,0x1860), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 191.17.125.5 dlci 105(0x69,0x1890), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 191.17.34.3 dlci 103(0x67,0x1870), dynamic,
              broadcast,, status defined, active
Serial0/0 (up): ip 191.17.34.4 dlci 104(0x68,0x1880), dynamic,
              broadcast,, status defined, active

Use your favorite method to clear the dynamic Frame Relay mappings.  I ususally reload the routers.

2.2 Point-To-Point

“When r3 pings its own IP address, these packets should be sent to r4 and redirected back.”

This task was pretty easy for me because of all of the times that I have accidentally created a frame map with my local IP address instead of the far end IP address,  :-)

Before:
r3(config-if)#do sh run int s1/0
interface Serial1/0
 ip address 191.17.34.3 255.255.255.0
 encapsulation frame-relay
 frame-relay map ip 191.17.34.4 304 broadcast
 no frame-relay inverse-arp

r3(config-if)#do ping 191.17.34.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 191.17.34.3, timeout is 2 seconds:
…..
Success rate is 0 percent (0/5)

r3(config-if)#do sh ip route 191.17.34.3
Routing entry for 191.17.34.0/24
  Known via “connected”, distance 0, metric 0 (connected, via interface)
  Routing Descriptor Blocks:
  * directly connected, via Serial1/0
      Route metric is 0, traffic share count is 1

r3(config-if)#do sh frame map
Serial1/0 (up): ip 191.17.34.4 dlci 304(0x130,0x4C00), static,
              broadcast,
              CISCO, status defined, active

After:
r3(config-if)#int s1/0
r3(config-if)#frame map ip 191.17.34.3 304
r3(config-if)#do sh frame map
Serial1/0 (up): ip 191.17.34.3 dlci 304(0x130,0x4C00), static,
              CISCO, status defined, active
Serial1/0 (up): ip 191.17.34.4 dlci 304(0x130,0x4C00), static,
              broadcast,
              CISCO, status defined, active

r3(config-if)#do p 191.17.34.3

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 191.17.34.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5),
round-trip min/avg/max = 116/117/124 ms

2.3 Point-to-Point

“Configure the Frame Relay connection between r6 and bb1 using PVC 51 on r6’s main Serial interface.”
“Do not allow r6 to send Frame Relay Inverse-ARP requests on any other circuits assigned to this interface.”

While this task does not explicly tell you which method to use to map the IP address to the DLCI, the second subtask makes it sound like we are supposed to allow Frame Relay Inverse-ARP create our mapping on DLCI 51, but not the rest of the PVCs.

r6(config-if)#do sh frame pvc | i DLCI|Serial0/0
PVC Statistics for interface Serial0/0 (Frame Relay DTE)
DLCI = 51, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial0/0
DLCI = 100, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial0/0
DLCI = 101, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial0/0
DLCI = 201, DLCI USAGE = UNUSED, PVC STATUS = DELETED, INTERFACE = Serial0/0
DLCI = 301, DLCI USAGE = UNUSED, PVC STATUS = DELETED, INTERFACE = Serial0/0
DLCI = 401, DLCI USAGE = UNUSED, PVC STATUS = DELETED, INTERFACE = Serial0/0

r6(config-if)#no frame inverse-arp ip ?
  <16-1007>  Set DLCI for inverse ARP

  vc-bundle  vc-bundle

r6(config-if)#no frame inverse-arp ip 100
r6(config-if)#no frame inverse-arp ip 101
r6(config-if)#no frame inverse-arp ip 201
r6(config-if)#no frame inverse-arp ip 301
r6(config-if)#no frame inverse-arp ip 401

r6#sh frame map
Serial0/0 (up): ip 54.17.3.254 dlci 51(0x33,0xC30), dynamic
              broadcast,, status defined, active

2.4 PPP

An easy task asking you to configure header compression.  One twist:

“Allow for the maximum number of TCP sessions to be compressed over this link.”

ip tcp header-compression

ip tcp compression-connections

r1(config-if)#ip tcp ?
  adjust-mss               Adjust the mss of transit packets
  compression-connections  Maximum number of compressed connections
  header-compression       Enable TCP header compression

r1(config-if)#ip tcp compression-connections ?
  <1-256>  Number of connections

r1(config-if)#ip tcp compression-connections 256

r3#sh ip tcp header-compression
TCP/IP header compression statistics:
  Interface Serial1/2 (compression on, VJ)
    Rcvd:    0 total, 0 compressed, 0 errors, 0 status msgs
             0 dropped, 0 buffer copies, 0 buffer failures
    Sent:    0 total, 0 compressed, 0 status msgs, 0 not predicted
             0 bytes saved, 0 bytes sent
    Connect: 256 rx slots, 256 tx slots,
             0 misses, 0 collisions, 0 negative cache hits, 256 free contexts

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