Network Utility Force LLC, 15 Wieuca Trace Northeast, Atlanta, Georgia, 30342 -- +1-404-635-6667 -- sales@netuf.net © 2012, Network Utility Force LLC Companyconfidential information, transmittal to third parties by prior permission only

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InteropNet LV 2013Intro to Wide Area Routing

Network Utility Force LLC, 15 Wieuca Trace Northeast, Atlanta, Georgia, 30342 -- +1-404-635-6667 -- sales@netuf.net © 2012, Network Utility Force LLC Companyconfidential information, transmittal to third parties by prior permission only

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Agenda

• Introduction• Review concepts• Goals of BGP• BGP in Practice• Conclusion

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Introduction

• The Internet is made up of a bunch of different organizations– Big ISPs– Little ISPs– Enterprises

• Everyone needs to exchange traffic with everyone else…mostly

• Need to be able to create policy for how traffic is sent and received, over what paths and deal with redundancy

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Concept Review• What is routing?

– Forwarding• Every packet has a destination IP address• Address is looked up in the local router’s routing table (FIB – Forwarding

Information Base)• Packet is routed (forwarded) out the proper interface

– Routing Protocol• Proscribes a method for how routes get into the FIB• Many are available that fulfill different needs and situations

– Static– IGP

» RIP» EIGRP» OSPF & ISIS

– EGP» BGP

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Goals of BGP

• Tell your organization’s neighbors about the destinations you are able to reach

• Provide controls to influence the path traffic takes to get to you as well as how it leaves your network

• Distribute global routing information throughout your network

• Easily filter what you send and what you receive

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BGP Concepts

• AS– An autonomous system is a network typically

controlled by a single entity, usually one per company

– Assigned a 4 byte (was 2 byte) number to identify it, an ASN

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BGP Concepts

• iBGP (internal BGP)– Distributes information throughout your AS– All iBGP routers must talk directly to all other

routers or use scalability features such as route reflectors or confederations

– iBGP is NOT an IGP, it is not intended to tell every router about the paths in your AS, instead it tells routers about global connectivity

– You must still run an IGP such as OSPF, as BGP depends on it for local connectivity

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BGP Concepts

• eBGP (external BGP)– eBGP is used to speak to your network neighbors,

usually your upstream transit provider– Your network neighbors use eBGP to send you

routing information about reachability in the rest of the world

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BGP in practice

• Globally all ISPs “peer” with each other• An entire ecosystem has developed around

BGP peering, mostly based on the amount of traffic exchanged

• Exchanges where multiple service providers come together are located in many major cities across the world, known as IX (Internet eXchange)

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Routing Table Growth

• Size of the global routing table is currently around 455,000 routes for v4 and 12,600 v6 routes

• Depletion of IPv4 address space may cause “deaggregation” of the IPv6 global routing table, which could result in explosive growth

• Growth of IPv6 also could result in rapid growth of the global routing table

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Brandon Ross – Chief Network Architect – Network Utility Force – bross@netuf.net