Implement a standby ISDN DDR system
for your Frame Relay network between Orlando and Atlanta for
on-demand bandwidth when the Frame Relay interface is overloaded.
Scenario:
You have just installed an ISDN line
to be used as standby reserve bandwidth your Frame Relay connection
between the Atlanta and Orlando office. Configure DDR on the BRI
interface of the Orlando router. Configure Frame Relay on the serial
interfaces connecting to the Frame Relay network. Configure parallel
static routes so that when both links are up traffic will load
balance between the two links.
Lab Tasks:
Cable the lab as shown in the
diagram. Use the Adtran Atlas 550 as your ISDN and Frame Relay networks.
First configure your ISDN BRI lines.
Assign the appropriate SPIDs and dialer maps to implement DDR. Be
sure to configure the following items:
PPP encapsulation
CHAP authentication
ISDN Spid numbers
Idle timeouts
Map statements
Test your DDR configuration to make
sure it is functional.
Next, setup your Frame Relay network. Configure
Frame Relay encapsulation on your serial links. Use the DLCIs specified in the
above diagram.
Use ANSI as your LMI type.
Use sub-interfaces. Configure the
appropriate IP addresses.
Test your Frame Relay configuration
to make sure it is functional.
When you are satisfied that both
components are functional, turn on the standby dial feature on the
Orlando Frame Relay interface. This will enable the BRI line to use
DDR when the Frame Relay link is overloaded.
Note: If you have a WIC 2T card, add
the command bandwidth 128 to the serial interface. This will make
the interface easier to load.
For the Orlando router, you need
default routes that will point to both the Frame Relay and ISDN
interfaces.
What commands would you use to
install these routes?
For the Atlanta router, you need a
route to Orlando's Ethernet (192.168.1.0) that will point to
both the Frame Relay and ISDN interfaces.
What commands would you use to
install these routes?
At this point, your Frame Relay network should be up. From the
Orlando router, look at your routing table. What is the next hop
address of your default route?
In what state is your BRI interface?
Check the serial interface to
verfiy the backup interface load levels with the show interface s0/0
command.
What load level is the back setup to
kick in at?
Create a large amount of traffic
destined for the Atlanta router. Create a telnet session into the
Orlando router from the Atlanta router. This will allow you to keep
the Orlando console free to see console messages.
From the telnet session to Orlando do
an extended ping using very large packet sizes. This will saturate
the link and cause the backup to kick in. Make sure you create
enough of them to keep the traffic going for a while. This will give
you more time to observe what is happening.
Orlando#ping
Protocol [ip]:
Target IP address: 192.168.2.1
Repeat count [5]: 500
Datagram size [100]: 1460
Timeout in seconds [2]:
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 500, 1460-byte ICMP Echos to 192.168.2.1, timeout is 2
seconds:
!!!!!!!!!!!!!!!!
Watch your console session on the
Orlando router to see what happens to the BRI interface.
What happened?
Look at the routing table on the
Orlando router. What do you notice?
Look at the status of the dial backup
link with the show backup command.
What do you see?
Stop your ping.
What happens?
When everything is back to
normal, check the status of the dial backup link using the show backup
command.