BGP hold timer

When forming neighbor adjacencies, BGP routers use a hold timer to maintain those peerings. When a BGP router receives updates or keepalives, the hold timer is reset. If the hold timer is exhausted, the peering goes down.

By default, the hold timer is set to 180 seconds, but it can be modified. It is initially negotiated between peers during the OpenSent state, where the lowest hold timer value between the two routers is selected.

This timer is not to be confused with the hold timer or hold down timer often used in IGPs to maintain routing table routes.