Alexander ChernikovNetwork Engineer

Using netmap

What is netmap?

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What is Netmap?

• All-in-one solution? No.– Part of framework to build solutions? Yes.

• Efficient Instrument for I/O

• Other instruments needed– Memory allocator (like UMA in userspace)– Packet chaining libraries (handling fragments)– Lockless queues– Flow inspection primitives

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Similar tools

• Intel DPDK– WindRiver INP

• PacketShader I/O engine

• PF_RING

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Key Features

• User-space

• Zero-copy

• Batching

• Simplicity

• Hardware independent

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Programming simplicity

• Get NIC info– ioctl(fd, NIOCGINFO, &nmr)

• Open HW queue (or entire NIC)– ioctl(fd, NIOCREGIF, &tifreq)

• Mmap ring memory– mmap(0, mmap_size, .., fd, 0);

• Go!– select() / poll() on fd

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Using NIC rings for balancing

• Thread-per-ring model

• Process-per-ring model

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Framework simplicity

• Targets to different NICs

• ~400 lines per driver– Not many places for bugs to hide– Complicated drivers code (not related to nemap)

• Currently supported– if_em(4)– igb(4)– ixgbe(4)– re(4)

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Existing open-source users

• Pkt-gen

• libpcap consumers

• Ipfw

• Click router

• Sandstorm web server

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Users: pkt-gen

• /usr/src/tools/tools/netmap/

• Linerate sending/receiving data

• Src/Dst address wildcards

• Features– MAC rewriting

– IP src/dst wildcards

– PCAP replay

• Note– Check flow control ( dev.ix.*.fc )

– Check older NICs ( Intel 82598 )

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Users: libpcap consumers

• /usr/src/tools/tools/netmap/

• Transparent

• s/lpcap/lnetmap/

• Improvements in 'easy' packet processing

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Users: ipfw

• 20120813 version

• On-going work to ease kernel/userland sync

• Pros– Batching

• Cons– Not all features work (iface matching, fwd, etc..)

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Users: Sandstorm

• All-in-one app– ethernet library

– libtcpip as light-weight TCP stack

– libmnio as netmap i/o abstraction

• Arch– optimizied for specific task

– small number of components

– ability to do easy cross-layering

– (mostly) lockless scheme

• Features– Very high throughput for small files

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Future: routing

• /usr/ports/net/netmap_router

• Near to zero configuration

• Existing utilities to control interfaces/routing

• Kernel for control plane

• Netmap appliance for data plane

• Modified routing daemon for route export

Alexander ChernikovNetwork Engineer

melifaro@yandex-team.ru

Thank you