Cisco CloudCenter: Get the Hybrid IT Advantage

Hold Down Timer

Definition - What does Hold Down Timer mean?

A hold down timer is a technique used by routers. When a router receives a notification about an offline route or node, the router will initiate a hold down timer allowing the offline router to recover and not update its routing table until the time expires.

The router starts a hold down timer as soon as it receives an update that a specific network, node, path or router is unreachable. During this time it will not accept any update from the neighbors falling on that route.

Techopedia explains Hold Down Timer

An internetwork, Internet or autonomous system may consist of many different nodes, networks and intermediary devices like routers and switches. Routers maintain paths to all the nodes and networks in its routing table, continuously updating the optimal path whenever it receives a new or better path from its neighboring routers.

If a router receives a notification that a specific path or network has gone offline, the router starts a timer and discards all the updates it gets from the neighboring routers. The primary objective for this technique is to allow the node to regain its online status and discard updates still advertising the old and inferior route. By initiating the hold down timer, a router can prevent itself and the network from a possible routing loop. Normally the hold down time is 180 seconds in routing information protocols.

Share this:

Connect with us

Email Newsletter

Join thousands of others with our weekly newsletter

The 4th Era of IT Infrastructure: Superconverged Systems
The 4th Era of IT Infrastructure: Superconverged Systems:
Learn the benefits and limitations of the 3 generations of IT infrastructure – siloed, converged and hyperconverged – and discover how the 4th...
Approaches and Benefits of Network Virtualization
Approaches and Benefits of Network Virtualization:
Businesses today aspire to achieve a software-defined datacenter (SDDC) to enhance business agility and reduce operational complexity. However, the...
Free E-Book: Public Cloud Guide
Free E-Book: Public Cloud Guide:
This white paper is for leaders of Operations, Engineering, or Infrastructure teams who are creating or executing an IT roadmap.
Free Tool: Virtual Health Monitor
Free Tool: Virtual Health Monitor:
Virtual Health Monitor is a free virtualization monitoring and reporting tool for VMware, Hyper-V, RHEV, and XenServer environments.
Free 30 Day Trial – Turbonomic
Free 30 Day Trial – Turbonomic:
Turbonomic delivers an autonomic platform where virtual and cloud environments self-manage in real-time to assure application performance.