Podcast
Questions and Answers
What is the primary dynamic routing protocol used by service providers to share routes with each other?
What is the primary dynamic routing protocol used by service providers to share routes with each other?
In the TCP/IP protocol suite, what layer is Border Gateway Protocol classified as?
In the TCP/IP protocol suite, what layer is Border Gateway Protocol classified as?
What is the destination well-known port used by Border Gateway Protocol?
What is the destination well-known port used by Border Gateway Protocol?
How do BGP peers communicate with each other at layer 3?
How do BGP peers communicate with each other at layer 3?
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What is required for two routers to become BGP peers?
What is required for two routers to become BGP peers?
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What is assigned to a service provider in BGP?
What is assigned to a service provider in BGP?
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What is the function of BGP in the context of service providers?
What is the function of BGP in the context of service providers?
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What is the term used to refer to the other router that we're talking to when using BGP?
What is the term used to refer to the other router that we're talking to when using BGP?
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What is the main reason R2's static route for 10.1.0.0 is not advertised to R3?
What is the main reason R2's static route for 10.1.0.0 is not advertised to R3?
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Why is the 10.1.0.0 network learned via EIGRP after the static route is removed?
Why is the 10.1.0.0 network learned via EIGRP after the static route is removed?
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What happens to the EIGRP-learned route for 10.1.0.0 when BGP is configured and the network is advertised?
What happens to the EIGRP-learned route for 10.1.0.0 when BGP is configured and the network is advertised?
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What is the purpose of the neighbor command in the BGP configuration on R1?
What is the purpose of the neighbor command in the BGP configuration on R1?
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What is the significance of the remote-as command in the BGP configuration on R1?
What is the significance of the remote-as command in the BGP configuration on R1?
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Why is the BGP route for 10.1.0.0 not immediately learned on R3 after the BGP configuration is applied?
Why is the BGP route for 10.1.0.0 not immediately learned on R3 after the BGP configuration is applied?
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What is the show ip bgp summary command used for in this scenario?
What is the show ip bgp summary command used for in this scenario?
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What is the main reason the BGP-learned route for 10.1.0.0 replaces the EIGRP-learned route in the routing table of R3?
What is the main reason the BGP-learned route for 10.1.0.0 replaces the EIGRP-learned route in the routing table of R3?
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Which of these methods is NOT mentioned as a way a router can learn a network route?
Which of these methods is NOT mentioned as a way a router can learn a network route?
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What does the statement "The router or the device with the network interface card that's configured with an IP address effectively lives on that network" refer to?
What does the statement "The router or the device with the network interface card that's configured with an IP address effectively lives on that network" refer to?
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What is the main difference between eBGP and iBGP?
What is the main difference between eBGP and iBGP?
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What is the administrative distance for routes learned via external BGP?
What is the administrative distance for routes learned via external BGP?
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Which routing protocol has the highest administrative distance, thus is considered the least trustworthy?
Which routing protocol has the highest administrative distance, thus is considered the least trustworthy?
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When R3 learns about the 10.1.0.0 network from multiple sources, which source will it prioritize?
When R3 learns about the 10.1.0.0 network from multiple sources, which source will it prioritize?
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What represents a peering relationship where two routers belong to different autonomous systems?
What represents a peering relationship where two routers belong to different autonomous systems?
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In the context of BGP routing, what does 'neighborship' refer to?
In the context of BGP routing, what does 'neighborship' refer to?
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If Router 3 learns the same network route from multiple sources, which route from the sources it learns would it trust the least?
If Router 3 learns the same network route from multiple sources, which route from the sources it learns would it trust the least?
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Which statement best describes the relationship between Router 4, Router 5, and Router 6 in the context of internal BGP?
Which statement best describes the relationship between Router 4, Router 5, and Router 6 in the context of internal BGP?
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Which routing protocol has the lowest administrative distance and therefore is the most preferred among the ones discussed?
Which routing protocol has the lowest administrative distance and therefore is the most preferred among the ones discussed?
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Which routing protocol is most commonly used internally by organizations that have specific needs or are Cisco shops?
Which routing protocol is most commonly used internally by organizations that have specific needs or are Cisco shops?
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What determines which route successfully enters the routing table when a router learns the same exact network from multiple sources?
What determines which route successfully enters the routing table when a router learns the same exact network from multiple sources?
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Which of the following is not an example of an interior gateway routing protocol mentioned?
Which of the following is not an example of an interior gateway routing protocol mentioned?
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What is the primary type of routing protocol used by service providers for sharing routes?
What is the primary type of routing protocol used by service providers for sharing routes?
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Which of the following statements about link-state routing protocols is true?
Which of the following statements about link-state routing protocols is true?
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Why are static routes considered a challenge in dynamic networks?
Why are static routes considered a challenge in dynamic networks?
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Study Notes
Border Gateway Protocol (BGP)
- BGP is a dynamic routing protocol used to share routes between service providers on the internet.
- It can handle tens and hundreds of thousands of routes.
- BGP is an application layer service that uses TCP (Transmission Control Protocol) and has a destination well-known port of 179.
Characteristics of BGP
- BGP does not use a multicast address; instead, it uses a unicast address of the peer (other router).
- BGP routers are assigned an autonomous system number (ASN).
- BGP peers can be in different autonomous systems, and they can still share routes with each other.
BGP Peering Relationships
- External BGP (eBGP) peering relationships occur between two BGP routers in different autonomous systems.
- Internal BGP (iBGP) peering relationships occur between two BGP routers in the same autonomous system.
- eBGP has a better administrative distance than iBGP, making it more believable and reliable.
Administrative Distance
- The administrative distance (AD) of a routing protocol determines how believable it is to a router.
- The lower the AD, the more believable the route is.
- The AD of BGP-learned routes is 20, which is better than most interior gateway routing protocols.
BGP and Route Selection
- If a router learns the same network from multiple sources (e.g., RIP, OSPF, EIGRP, BGP), it will choose the route with the lowest administrative distance.
- The route with the lowest AD will be placed in the routing table.
Comparison of Routing Protocols
- Directly connected networks: directly connected to the network interface card (NIC) of a router.
- Static routes: manually configured routes that require manual changes when networks change.
- Interior gateway routing protocols (IGRP): used internally in organizations, e.g., RIP, EIGRP, OSPF, IS-IS.
- Exterior gateway routing protocols (EGRP): used between service providers on the internet, e.g., BGP.
Summary
- BGP is a dynamic routing protocol used to share routes between service providers on the internet.
- BGP has a better administrative distance than most interior gateway routing protocols.
- A router will choose the route with the lowest administrative distance from multiple sources.
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Description
Learn about the Border Gateway Protocol, a dynamic routing protocol used to share routes between service providers on the internet, including its characteristics and functions.
