Trying to bond 2 T1's between local and remote site. I have the multilink interface configured on both ends and I have one of the two Serial interfaces configured in the multilink interface. The remaining T1 is configured as a ptp. The multilink interface is up and I can ping back and forth. In order to complete the configuration I need to configure the remaining Serial interface to be part of the multilink interface. My question is: If I telnet to the remote router via the multilink interface will I lose connectivity when I attempt to configure the remaining Serial interface? Do I need to reconfigure the default route to insure that traffic will use the multilink interface before configuring the remaining Serial interface? Thank you.
You will not loose connectivity.
As long as the multilink as an active member link as part of the bundle, it will stay up.
It seems you already have a route to the Multilink ip address, or you wouldn't be telnetting into it, but to be on the safe side, schedule a reload for some number of minutes ahead and make your chages.
If you loose connectivty, the router will reload in the amount of time you scheduled, and come up back in the startup config, which does not have any changes in it.