The short description about Border Gateway Protocol. This presentation given in Green University of Bangladesh

1. Border Gateway
Protocol
Presented By
Fozle Rabbi
173002018
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2. Contents
• Introduction
• What is BGP
• Inter-AS Routing and ASNs
• Why Use BGP?
• Who needs BGP?
• Examples of Multihomed network
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3. What is BGP?
• Border Gateway Protocol Version 4
• Standard based
 RFC 4271
• Exterior Gateway Protocol (EGP)
 Used for inter-domain routing between Autonomous Systems
• Path Vector routing
• Classless
 Supports VLSM and summarization
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4. Inter-AS Routing and ASNs
• Autonomous System (AS)
• “An AS is a group of IP networks operated by one or more network operator(s) that
has a single and clearly defined external routing policy.
• Exterior routing protocols are used to exchange routing information between
Autonomous Systems.”
• Like IP address space, Autonomous System Numbers (ASNs) allocated by internet
Assigned Numbers Authority (IANA)
• https://www.iana.org/numbers
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5. Why Use BGP?
• Scalability
 IGPS can scale to thousands of routes
 BGP can scale to hundreds of thousands of routes
 The other interesting point is that at the start of 2017 the reporting systems have some 50,000 route
entries, yet by the end of 2019 this is increasing to some 100,000 routing entries.
• Enforce routing policy
 IGP uses link cost for routing decision
 BGP uses attributes of the route itself
 Traffic engineering feasible and simple to implement
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6. Who needs BGP?
• Transit networks
 Service Providers that sell access or transit bandwidth to customers
• Multihomed networks
 Enterprise networks with two or more connections to ISPs
 Allows control of inbound and outbound routing policy
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7. Examples of Multihomed network
8/28/2020 7https://www.noction.com/blog/bgp-multi-homing-enough-for-network-performance

8. Example of BGP Transit Network
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9. When not to used BGP?
• Single ISP connectivity
 Default routing sufficient
• Limited Memory or Limited Processes.
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10. BGP Table size
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11. Thank You
For Your Attention
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12. References
• BGP protocol version 4 RFC https://tools.ietf.org/html/rfc4271#section-1.1
• Brian McGahan the master of BGP trainer https://my.ine.com/course/ine-ccie-spv41-core-bgp/98611328-cbaa-43a7-8cd6-f1b40e3f805c
• Single Home and Dual or Multihomed network https://networklessons.com/cisco/ccna-routing-switching-icnd2-200-105/singledual-homed-and-multi-
homed-designs [7]
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