BGP configuring authentication on an established BGP session
When configuring or changing the BGP Authentication configuration on an already established peering, you must note the following:
If you configure or change the password used for MD5 authentication between two BGP peers, the local router will not tear down the existing session after you configure the password. The local router will attempt to maintain the peering session using the new password until the BGP hold-down timer expires. The default time period is 180 seconds. If the password is not entered or changed on the remote router before the hold-down timer expires, the session will time out.