Computer Networking Problems and Solutions: An innovative approach to building resilient, modern networks

833 Pages·2018·9.435 MB·English

by  Russ White

Computer Networking
Problems and Solutions
This page intentionally left blank
Computer Networking
Problems and Solutions
An innovative approach to building
resilient, modern networks
Russ White and Ethan Banks
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or omissions. No liability is assumed for incidental or consequential damages in
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ISBN-13: 978-1-58714-504-9
ISBN-10: 1-58714-504-9
Compositor
1 17 codeMantra
To Lori, my beautiful wife of 20 years.
To Bruce Little and Doug Bookman; for challenging
me to think.
To Brett Bartow, Eyvonne Sharp, Phil Gervasi, and
Jordan Martin; for inspiring me.
May God bless each of you for the blessings you have
brought into my life.
—Russ White
To Summerset; for enabling me to pursue the things
I must chase.
To Drew Conry-Murray; for commiseration, advice,
and encouragement.
To Robin Young and Greg Ferro; for freedom to write
and moral support.
To Jordan Martin; for not saying no.
To the Packet Pushers community; for their
multiplied voices, both frustrated and victorious.
—Ethan Banks
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xxii
Part I: The Data Plane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Chapter 1: Fundamental Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Art or Engineering? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Circuit Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Packet Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Packet Switched Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Flow Control in Packet Switched Networks . . . . . . . . . . . . . . . . . 15
Fixed Versus Variable Length Frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Calculating Loop-Free Paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Quality of Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
The Revenge of Centralized Control Planes . . . . . . . . . . . . . . . . . . . . . . . 25
Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Why So Complex? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Defining Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Managing Complexity through the Wasp Waist . . . . . . . . . . . . . . 32
Final Thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
Chapter 2: Data Transport Problems and Solutions . . . . . . . . . . . . . . . . . . . 37
Digital Grammars and Marshaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Digital Grammars and Dictionaries . . . . . . . . . . . . . . . . . . . . . . . 40
Fixed Length Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Type Length Value . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Shared Object Dictionaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
vi
Contents vii
Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Error Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
Error Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
Addressing Devices and Applications . . . . . . . . . . . . . . . . . . . . . . 56
Multicast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
Anycast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
Windowing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
Negotiated Bit Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
Final Thoughts on Transport . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
Chapter 3: Modeling Network Transport . . . . . . . . . . . . . . . . . . . . . . . . . . .75
United States Department of Defense (DoD) Model . . . . . . . . . . . . . . . . 76
Open Systems Interconnect (OSI) Model . . . . . . . . . . . . . . . . . . . . . . . . . 80
Recursive Internet Architecture (RINA) Model . . . . . . . . . . . . . . . . . . . . 84
Connection Oriented and Connectionless . . . . . . . . . . . . . . . . . . . . . . . . 86
Final Thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
Chapter 4: Lower Layer Transports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
Error Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
Data Marshaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
Wireless 802.11 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
Data Marshaling, Error Control, and Flow Control . . . . . . . . . . 109
Final Thoughts on Lower Layer Transmission Protocols . . . . . . . . . . . . 110
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
viii Contents
Chapter 5: Higher Layer Data Transports . . . . . . . . . . . . . . . . . . . . . . . . . .115
The Internet Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
Transport and Marshaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
Multiplexing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
Transmission Control Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
Flow Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129
Error Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
TCP Port Numbers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
TCP Session Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
QUIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136
ICMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142
Final Thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
Chapter 6: Interlayer Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149
Interlayer Discovery Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150
Well-Known and/or Manually Configured Identifiers . . . . . . . . . 151
Mapping Database and Protocol . . . . . . . . . . . . . . . . . . . . . . . . . 152
Advertising Identifier Mappings in a Protocol . . . . . . . . . . . . . . 153
Calculating One Identifier from the Other . . . . . . . . . . . . . . . . . 154
Interlayer Discovery Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
The Domain Name System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
IPv4 Address Resolution Protocol . . . . . . . . . . . . . . . . . . . . . . . . 159
IPv6 Neighbor Discovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
The Default Gateway Problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 164
Final Thoughts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169
Chapter 7: Packet Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171
Physical Media to Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173
Processing the Packet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174
Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175
Why Route? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 176
Contents ix
Equal Cost Multipath . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 178
Packet Processing Engines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 183
Across the Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186
Crossbars and Contention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188
Memory to Physical Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
Final Thoughts on Packet Switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193
Chapter 8: Quality of Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195
Defining the Problem Space . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
Why Not Just Size Links Large Enough? . . . . . . . . . . . . . . . . . . . 197
Classification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199
Preserving Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203
The Unmarked Internet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206
Congestion Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
Timeliness: Low-Latency Queueing . . . . . . . . . . . . . . . . . . . . . . 208
Fairness: Class-Based Weighted Fair Queueing . . . . . . . . . . . . . . 212
Overcongestion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214
Other QoS Congestion Management Tools . . . . . . . . . . . . . . . . 214
Queue Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Managing a Full Buffer: Weighted Random
Early Detection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 215
Managing Buffer Delay, Bufferbloat, and CoDel . . . . . . . . . . . . . 216
Final Thoughts on Quality of Service . . . . . . . . . . . . . . . . . . . . . . . . . . . 218
Further Reading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219
Review Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 220
Chapter 9: Network Virtualization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
Understanding Virtual Networks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 222
Providing Ethernet Services over an IP Network . . . . . . . . . . . . . 226
Virtual Private Access to a Corporate Network . . . . . . . . . . . . . 227
A Summary of Virtualization Problems and Solutions . . . . . . . . 229
Segment Routing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
Segment Routing with Multiprotocol Label Switching . . . . . . . . 232
Segment Routing with IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Signaling Segment Routing Labels . . . . . . . . . . . . . . . . . . . . . . . . 237
Software-Defined Wide Area Networks . . . . . . . . . . . . . . . . . . . . . . . . . 239