BGP v/s OSPF

References:
https://serverfault.com/questions/185635/what-is-the-difference-between-bgp-and-ospf

https://community.fs.com/blog/ospf-vs-bgp-routing-protocol-choice.html

https://techdifferences.com/difference-between-ospf-and-bgp.html
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It will be worthwhile comparing two popular routing protocols widely used for making routing decisions across the internet.

BGP stands for Border Gateway Protocol
OSPF stands for Open shttps://techdifferences.com/difference-between-ospf-and-bgp.htmlhortest distance First.





 BGP is exterior, OSPF is interior

OSPF is an intranetwork protocol which is used with in an AS(Autonomous System) while BGP is an inter network protocol and hence used between two different AS

If you are doing internal routing, i.e. routing within a site, company, or campus, you will want to use OSPF. Typically BGP is needed at a site edge, where you route out to the public internet. In small and medium size networks, static routes to the outside will usually be preferable to setting up BGP. If you have a complicated multi-homed site, regardless of size, you might consider BGP. 

Here is a chart summarizing the differences of OSPF vs BGP:

	OSPF	BGP
Gateway Protocol	Internal gateway protocol	External gateway protocol
Implementation	Easy	Complex
Convergence	Fast	Slow
Design	Hierarchical network possible	Meshed
Need for device resources	Memory and CPU Intensive	Scaling is better in BGP although it relies on the size of the routing table
Size of the networks	Used on primarily smaller scale network which could be administered centrally	Mostly used on large scale networks such as the internet
Function	The fastest route is preferred over shortest	Best path is determined for the datagram
Algorithm Used	Dijkstra algorithm	Best path algorithm
Protocol	IP	TCP

 Implementation    Easy                                      Tough

 Works on Protocol 89                                          179

Although BGP is used between multiple autonomous systems as an external routing protocol, many network giants like Microsoft and Facebook would use it internally – in this case, BGP is typically fit for very large networks which OSPF fails to handle. One of the many reasons that BGP does not function well as an internal gateway protocol is that it is very slow to converge.