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You are setting up BGP using loopback interfaces, what do you need to consider?-
- - Router ID
- - ebgp-multihop
- - next-hop-self/routing to that potential next hop
- - Idle - Nothing
- - Connect - Try to establish TCP
- - Active - TCP established
- - OpenSent - BGP Open Sent
- - OpenConfirm - BGP Open received, keepalive next
- - Established - Parameters good
NLRI (Network Layer Reachability Information)
eBGP and iBGP administrative distance?
What is BGP Synchronization?
- BGP will not advertise something that it
- learns from an IBGP neighbor to an EBGP neighbor if the prefix can't be
- validated in its IGP. Default = Off
How is a BGP router-id chosen?
- 1. Configured (bgp router-id)
- 2. Highest loopback
- 3. Highest other interface
Explain ebgp multihop
By default an advertisement is set with IP TTL of 1. When a loopback interface is used this consumes one hop so TTL must be set to 2
In what situation is next-hop-self required?
If a iBGP neighbor of a border router does not know how to reach the next hop (external router id)
Why is a Full Mesh now required in most modern networks?
Traffic routed through the network may get dropped as an internal router does not learn the route
What commands are used to create a peer group?
- router> neighbor NAME peer-group
- router> neighbor x.x.x.x peer-group NAME
What are the well known mandatory attributes?
What are the well known non-mandatory attributes?
- Local Pref
- Atomic Aggregate
What are the optional transitive attributes?
What are the optional non-transitive attributes?
- Originator ID
- Cluster list
How is aggregation applied (3 ways)?
- - Through IGP if redistributed into BGP
- - Through a null static route
- - Through the aggregate-address command
What are the 4 types of BGP message
What does each attribute mean, how would you influence it?