11. Explain BGP Weight attribute?
The weight attribute is a Cisco proprietary attribute that is used in the path selection process when there is more than one route to the same destination. A path with the Higher weight value is preferred. The default value for weight is 0. The weight attribute is local to the router and is not propagated to any BGP peers. Weight attribute is set by a router when receiving Updates influencing that one router’s route for a prefix.
12. Explain BGP Local preference?
Local preference is an indication to the AS about which path has preference to exit the AS in order to reach a certain network. A path with a higher local preference is preferred more. By default value for local preference is 100 and can be changed manually. Unlike the weight attribute, which is only relevant to the local router, local preference attribute is communicated throughout a single AS for the purpose of influencing the choice of best path to exit the AS.
13. Explain BGP MED?
The purpose of MED is to influence how other autonomous systems enters into your AS to reach a certain prefix. BGP MED is an attribute which is not propagated throughout the whole network but just to adjacent AS. The lower the MED the more the path will be preferred.
14. What is Recursive Lookup?
The router looks up the BGP route and the next hop to reach a destination in the remote AS. Then the router looks up the route to reach the next hop. In this way router has to perform lookup twice to reach to a destination, this process is called recursive lookup.
15. What is route reflector and why it is required?
In BGP, route learned from an iBGP neighbor will not be advertised to another iBGP neighbor. To overcome this situation route reflector is used. It acts as a route reflector server and makes IBGP neighbors as route reflector clients enabling route advertisements between them.
Read More Questions:
BGP Interview Questions Part1
BGP Interview Questions Part2
BGP Interview Questions Part3
BGP Interview Questions Part4
The weight attribute is a Cisco proprietary attribute that is used in the path selection process when there is more than one route to the same destination. A path with the Higher weight value is preferred. The default value for weight is 0. The weight attribute is local to the router and is not propagated to any BGP peers. Weight attribute is set by a router when receiving Updates influencing that one router’s route for a prefix.
12. Explain BGP Local preference?
Local preference is an indication to the AS about which path has preference to exit the AS in order to reach a certain network. A path with a higher local preference is preferred more. By default value for local preference is 100 and can be changed manually. Unlike the weight attribute, which is only relevant to the local router, local preference attribute is communicated throughout a single AS for the purpose of influencing the choice of best path to exit the AS.
13. Explain BGP MED?
The purpose of MED is to influence how other autonomous systems enters into your AS to reach a certain prefix. BGP MED is an attribute which is not propagated throughout the whole network but just to adjacent AS. The lower the MED the more the path will be preferred.
14. What is Recursive Lookup?
The router looks up the BGP route and the next hop to reach a destination in the remote AS. Then the router looks up the route to reach the next hop. In this way router has to perform lookup twice to reach to a destination, this process is called recursive lookup.
15. What is route reflector and why it is required?
In BGP, route learned from an iBGP neighbor will not be advertised to another iBGP neighbor. To overcome this situation route reflector is used. It acts as a route reflector server and makes IBGP neighbors as route reflector clients enabling route advertisements between them.
Read More Questions:
BGP Interview Questions Part1
BGP Interview Questions Part2
BGP Interview Questions Part3
BGP Interview Questions Part4
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