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Chair of Network Architectures and Services Department of Informatics Technical University of Munich Network Emulation using Linux Network Namespaces Daniel Schubert Friday 5 th July, 2019 IITM SS19 Garching b. Mnchen, Germany Chair of

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Chair of Network Architectures and Services Department of Informatics Technical University of Munich

Network Emulation using Linux Network Namespaces

Daniel Schubert

Friday 5th July, 2019 IITM SS19 Garching b. München, Germany Chair of Network Architectures and Services Department of Informatics Technical University of Munich

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Agenda

Options for Network Testing
Linux lightweight emulation features
Mininet
Conclusion
D. Schubert — Network Emulation using Linux Network Namespaces

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Introduction

Options for Network Testing

Hardware Testbed accurate expensive hard to reconfigure Simulator inexpensive might be unrealisc flexible Emulator inexpensive real code flexible

D. Schubert — Network Emulation using Linux Network Namespaces

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Introduction

Hardware Testbed

Switch Host Hardware Host

eth0 tap0 tap1

Host Hardware Host

eth0

Hardware Switch

D. Schubert — Network Emulation using Linux Network Namespaces

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Introduction

Network Emulation

v Switch Hardware Host Host Virtual machine

eth0

Host Virtual machine

eth0 tap0 tap1

D. Schubert — Network Emulation using Linux Network Namespaces

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Introduction

Network Emulation

Switch Hardware Host Host Network Namespace

eth0

Host Network Namespace

eth0 veth0 veth1 Virtual Ethernet pairs

D. Schubert — Network Emulation using Linux Network Namespaces

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Linux Emulation Features

Namespaces

Isolate one or serveral processes
Own view of system resource
Examples:
Mount Namespace
PID Namespace
Network Namespace
D. Schubert — Network Emulation using Linux Network Namespaces

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Linux Emulation Features

Network Namespaces

Individual copy of network stack per namespace
Network devices
Routing tables
Ports
...
Creation
ip netns add <name>
ip netns exec <name> <command>
D. Schubert — Network Emulation using Linux Network Namespaces

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Linux Emulation Features

Virtual Ethernet Devices

Always created as interconnected pairs
Acts as tunnel connecting two namespaces
Creation:
ip link add <d1> type veth peer name <d2>
ip link set <d2> netns <d2-namespace>
D. Schubert — Network Emulation using Linux Network Namespaces

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Linux Emulation Features

Control Groups

Limit resources for group of processes
Used to emulate CPU limited Hosts
D. Schubert — Network Emulation using Linux Network Namespaces

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Linux Emulation Features

Control Groups

Limit resources for group of processes
Used to emulate CPU limited Hosts

Linux Traffic Control (tc)

Configure Traffic Control of Linux kernel
Influence how packets are handled at specific interfaces
Used to emulate links with lower bandwidth or delay
D. Schubert — Network Emulation using Linux Network Namespaces

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Linux Emulation Features

Creating Emulation Manually

1 1From [1]

D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Overview

CLI and API to create and interact with network
Open source project written in Python
Emulation is performed by C-code
Developped as a tool for rapid prototyping of SDNs
D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Create Emulation with Mininet API

2 2From [1]

D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Create Emulation with Mininet API

3 3From [1]

D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Create Emulation with Mininet API

4 4From [1]

D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Performance

v Switch Host1 Host2 HostN

Hosts (N) 1 100 500 1000 Setup (s) 0.103 ± 0.005 0.652 ± 0.033 3.32 ± 0.166 7.06 ± 0.353 RAM (MB) 396 ± 9.17 438 ± 30.52 941 ± 19.49 1570 ± 155.77 NRFR (%) 0.0 0.0 0.0 30.91

v Switch Host1 Host2 v Switch v Switch

Switches (N) 1 100 500 1000 Setup (s) 0.104 ± 0.005 5.47 ± 0.273 185.5 ± 9.276 230.95 ± 15.70 RAM (MB) 308 ± 12.17 433 ± 54.41 961 ± 51.43 1737 ± 158.41 NRFR (%) 0.0 0.0 65.08 85.48

[2]

D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Pros

Fast Setup of Networks
Use real programs on Network Nodes
Runs on a single laptop
Easy to install (included with Ubuntu 12.10)
Easy to use with CLI and Python scripts
Open source
Under active development
D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Pros

Fast Setup of Networks
Use real programs on Network Nodes
Runs on a single laptop
Easy to install (included with Ubuntu 12.10)
Easy to use with CLI and Python scripts
Open source
Under active development

Cons

Resource limits
Only with Linux kernel
By default all hosts share file system and PID space
No timing guarantees
No virtual time
D. Schubert — Network Emulation using Linux Network Namespaces

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Mininet

Related Work

ns-3: open source discret-event simulator
Mahimahi: record-and-replay network emulator
Mininet clustering: Split network topology between multiple machines
D. Schubert — Network Emulation using Linux Network Namespaces

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Conclusion

Linux Network Namespaces + Virtual Ethernet Pairs + Open Flow Switches = Lightweight

Network Emulation

Mininet offers API to build network conveniently
Networks with several hundred nodes possible
For larger networks distributed Mininet exists/is being developed
D. Schubert — Network Emulation using Linux Network Namespaces

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Bibliography

[1] T.-Y. Huang, V. Jeyakumar, B. Lantz, N. Feamster, K. Winstein, and A. Sivaraman. Teaching computer networking with mininet. In ACM SIGCOMM, 2014. [2] P . Isaia and L. Guan. Performance benchmarking of sdn experimental platforms. In 2016 IEEE NetSoft Conference and Workshops (NetSoft), pages 116–120, June 2016.

D. Schubert — Network Emulation using Linux Network Namespaces