Problem Description

 Q： 
As required by the customer, the AR router needs to track and detect the BGP primary 

link so that traffic is automatically switched from the faulty BGP primary link to the 

ADSL or ADSL2+ backup PPPoE link. When the BGP link recovers, the router 

switches the traffic back to the BGP link and cuts the ADSL link automatically. 
For details about the customer’s requirements and networking diagram, see the 

attachment "Description of the NQA Application Scenario."  

Solution

 A： 
The major configurations of NQA are listed below. For the complete configurations of NQA,

 see the appendix NQA config.txt. Through these configurations, the AR router can track 

and detect the BGP primary route so that traffic is automatically switched from the faulty

 BGP primary link to the ADSL or ADSL2+ backup PPPoE link. When the BGP link recovers, the router switches the traffic back to the BGP link and cuts the ADSL link automatically. 
1. Configure NQA. 
nqa server enable 
nqa entry admintest 
type icmp-echo 
destination ip 20.20.20.1 
frequency 1000 
reaction 1 checked-element probe-fail threshold-type consecutive 5 action-type 

trigger-only 
nqa schedule admintest start-time now lifetime forever 
track 1 nqa entry admintest reaction 1 
2. Configure ADSL-related interfaces. 
interface Atm2/0 
adsl standard t1413 
interface Atm2/0.1 
pvc 8/81 
map bridge Virtual-Ethernet 1 
interface Virtual-Ethernet1 
pppoe-client dial-bundle-number 1 
interface Dialer1 
link-protocol ppp 
ppp pap local-user sucursal3@respinet.com password simple sucursal3 
mtu 1492 
ip address 192.168.11.1 255.255.255.0 
dialer user CENTRAL 
dialer-group 1 
dialer bundle 1 
standby track 1 
3. Configure static route tracking and set different priorities for the routes. 
ip route-static 5.10.1.0 255.255.255.0 192.168.100.9 track 1 preference 5 
ip route-static 5.10.1.0 255.255.255.0 192.168.11.254 preference 8  

thanks for sharing ...............

pls explain the below line

dialer-group 1 

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pls add more