Backup in case of errors on link

[sdhamankar]

We have a star network with 1751s at edges and 3662 at center.

the edge routers connect to central router with 64kbps link. ISDN is provided for backup.

some of the links show heavy CRC errors, due to which the application times out.

But as the link is up, no switchover to ISDN takes place?

Is there any way by which we can shift to ISDN backup in case of heavy linke errors?

[o.hassairi]

normally, we can make backup if serial interface is down or if load is important.

so we should make the interface down if there 'r many errors.

use the command:

ROUTER2(config-if)#ppp ?

authentication Set PPP link authentication method

bridge Enable PPP bridge translation

chap Set CHAP authentication parameters

compression Enable PPP Compression control negotiation

lcp PPP LCP configuration

max-bad-auth Allow multiple authentication failures

multilink Make interface multilink capable

pap Set PAP authentication parameters

quality Set minimum Link Quality before link is down

reliable-link Use LAPB with PPP to provide a reliable link

timeout Set PPP timeout parameters

use-tacacs Use TACACS to verify PPP authentications

ROUTER2(config-if)#ppp qua

ROUTER2(config-if)#ppp quality ?

<0-100> Percent of traffic successful

ROUTER2(config-if)#ppp quality