Configure Cisco IOS routers to aggregate 2 B channels for a
total link speed of 128kbps.
Scenario:
Configure the branch office router and central site router to
dial two B channels for a total link speed of 128kbps. Use two
dialer maps to dial the two phone numbers and enable PPP multilink.
Notes:
Lab Tasks:
Cable the lab as show in the diagram. Use the Adtran Atlas 550
to simulate the ISDN network.
Configure the branch office router and the central site router
for PPP encapsulation and CHAP authentication. Set the ISDN switch
type, assign the ISDN SPIDs to the interface, and create the
dialer-map entries. Configure DDR to dial the connection when any
IP traffic is present.
What would be the commands to enable DDR on the branch router
to trigger a dial on any IP traffic?
Test your DDR configuration. Ensure that you are able to dial
the central site.
When DDR triggers a connection, only one B channel is activated.
To trigger the other B channel to come up, we need to add another
dialer-map command to dial the other phone number at the central
site. In some situations, the central site would have a phone
company hunt group set up so the same phone number could be dialed
twice. In this case, we need to dial the second phone number.
What is the command to add the second dialer-map on the branch
router?
Try to ping the central site router (192.168.3.2). Do both B
channels come up?
We also have to define a threshold at which we dial the second B
channel. In our case we will set the threshold to 1 in either
direction so it immediately brings up the second B channel.
One the BranchRouter:
BranchRouter(config)#int bri0/0
BranchRouter(config-if)#dialer load-threshold 1 either
Now try to ping the central site router (192.168.3.2). Do both B
channels come up?
Look at the B channel on the BRI interface while the link is up
with the
show interface bri0/0:1
and
show ppp multilink
commands.
Does it look like multilink is working?
Why?
Add the
ppp multilink
command to the central site router.
What are the commands to do this?
Try again - Look a B channel on the BRI interface while the link
is up with the
show interface bri0/0:1
and
show ppp multilink
commands.