Last Updated on August 1, 2021 by Admin
You are using an aggregate static route to null 0 to redistribute static routes into BGP.
Which problem can result if the router loses access to one of these routes?
- Black hole
- Routing loop
- Split horizon
- Unstable BGP table
If one of the aggregated routes is lost, the router will discard packets destined for that route. This condition is known as a black hole.
For example, suppose you have a number of subnets of range 11.1.0.0/16, all of which have 24 bit masks, such as 11.1.2.0/24. You aggregate them all to 11.1.0.0/16 and advertise that aggregate. If this router were to lose connectivity to one of the subnets, for example 11.1.3.0/24, then any traffic routed through this router to that subnet would never reach it, even if there were another valid path.
Split horizon is a loop avoidance mechanism that is by default always in effect, and is not affected by the loss of a subnet route that is part of an aggregate route.
BGP tables are not made unstable by the loss of the loss of a subnet route that is part of an aggregate route.
Routing loops would not occur simply from the loss of a subnet route that is part of an aggregate route.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify manual and autosummarization with any routing protocol