BGP Techniques for Network Operators

208 Pages·2016·9.42 MB·English

by  Philip Smith

BGP Techniques for
Network Operators
Philip Smith
<[email protected]>
APRICOT 2016
22nd – 26th February 2016
Auckland, New Zealand
Last updated 21st February 2016
Presentation Slides
Will be available on
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http://bgp4all.com/ftp/seminars/
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APRICOT2016-BGP-Techniques.pdf
And on the APRICOT2016 website
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Feel free to ask questions any time
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BGP Techniques for Network Operators
BGP Basics
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Scaling BGP
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Using Communities
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Deploying BGP in an ISP network
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BGP Basics
What is BGP?
Border Gateway Protocol
A Routing Protocol used to exchange routing
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information between different networks
Exterior gateway protocol
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Described in RFC4271
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RFC4276 gives an implementation report on BGP
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RFC4277 describes operational experiences using BGP
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The Autonomous System is the cornerstone of
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BGP
It is used to uniquely identify networks with a common
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routing policy
Autonomous System (AS)
AS 100
Collection of networks with same routing policy
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Single routing protocol
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Usually under single ownership, trust and
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administrative control
Identified by a unique 32-bit integer (ASN)
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Autonomous System Number
(ASN)
Two ranges
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0-65535 (original 16-bit range)
65536-4294967295 (32-bit range – RFC6793)
Usage:
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0 and 65535 (reserved)
1-64495 (public Internet)
64496-64511 (documentation – RFC5398)
64512-65534 (private use only)
23456 (represent 32-bit range in 16-bit world)
65536-65551 (documentation – RFC5398)
65552-4199999999 (public Internet)
4200000000-4294967295 (private use only – RFC6996)
32-bit range representation specified in RFC5396
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Defines “asplain” (traditional format) as standard notation
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Autonomous System Number
(ASN)
ASNs are distributed by the Regional Internet
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Registries
They are also available from upstream ISPs who are
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members of one of the RIRs
Current 16-bit ASN assignments up to 64297
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have been made to the RIRs
Around 43000 16-bit ASNs are visible on the Internet
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Around 200 left unassigned
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Each RIR has also received a block of 32-bit ASNs
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Out of 12400 assignments, around 9500 are visible on
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the Internet
See www.iana.org/assignments/as-numbers
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BGP Basics
Peering
A C
AS 100 AS 101
B D
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Runs over TCP – port 179
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p  Path vector protocol AS 102
Incremental updates
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“Internal” & “External” BGP
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Demarcation Zone (DMZ)
A C
DMZ
AS 100 AS 101
Network
B D
E
AS 102
DMZ is the link or network shared between ASes
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