PISCES: A Programmable, Protocol-Independent Software Switch - - PowerPoint PPT Presentation

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PISCES: A Programmable, Protocol-Independent Software Switch - - PowerPoint PPT Presentation

Dec 23, 2023 1.03k likes •1.35k views

PISCES: A Programmable, Protocol-Independent Software Switch Muhammad Shahbaz, Sean Choi , Ben Pfaff, Changhoon Kim, Nick Feamster, Nick McKeown, and Jennifer Rexford Fixed Set of Protocols Fixed-Function Switch Chip Ethernet TCP HTTP UDP

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PISCES: A Programmable, Protocol-Independent Software Switch

Muhammad Shahbaz, Sean Choi, Ben Pfaff, Changhoon Kim, Nick Feamster, Nick McKeown, and Jennifer Rexford

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TCP IPv4 Ethernet UDP IPv6 BGP HTTP TLS

Fixed-Function Switch Chip Fixed Set of Protocols

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  • Ease of Adding new protocols
  • Ease of Removing unused protocols
  • Gain greater Visibility into the network
  • Perform network functions at the switch

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TCP IPv4 Ethernet

CUSTOM_P

IPv6 BGP HTTP TLS

Programmable Switching Chip Custom Protocols

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Software Switch

VM VM

Virtual Port Physical Port

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20 40 60 2010 2011 2012 2013 2014 2015 Millions

  • Approx. Number of Physical Ports vs. Virtual Ports in

Global Data Centers [1]

Phyical Ports Virtual Ports

[1] Martin Casado, VMWorld 2013

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Not really…

It should be EASY to program software switches!

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Fast Packet Forwarding

Software Switch

Kernel DPDK

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Packet Processing Logic

Software Switch

Kernel DPDK

Parser Match-Action Pipeline

Requires domain expertise in:

  • Network protocol design
  • Kernel development

Slow to release changes

Specialized APIs

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Software Switch

Kernel DPDK

Parser Match-Action Pipeline

To add TCP Flag in Open vSwitch… changed 20 files and 370 lines of code[1] Weeks of development and Test

[1] https://github.com/openvswitch/ovs/commit/dc235f7fbcff

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We can do this in 4 lines and within minutes with PISCES!

header_type tcp_t { fields { srcPort : 16; dstPort : 16; seqNo : 32; ackNo : 32; dataOffset : 4; res : 4; tcp_flags : 12; window : 16; checksum : 16; urgentPtr : 16; } } parser tcp { extract(tcp); set_metadata(flow.tcp_flags, tcp.tcp_flags); return ingress; } header_type flow_t { fields { ... tcp_flags_pad : 4; tcp_flags : 12; ... } } 11

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Kernel DPDK

Software Switch

Parser Match-Action Pipeline

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Kernel DPDK

Software Switch

Domain-Specific Language (DSL) Parser Match-Action Pipeline

Compile

Parser Match-Action Pipeline

TCP Header

header_type tcp_t { fields { srcPort : 16; dstPort : 16; seqNo : 32; ackNo : 32; dataOffset : 4; res : 4; window : 16; checksum : 16; urgentPtr : 16; } } parser tcp { extract(tcp); return ingress; } ... 13

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Kernel DPDK

Software Switch

Domain-Specific Language Parser Match-Action Pipeline

Compile

Parser Match-Action Pipeline Domain-Specific Language 2 Parser Match-Action Pipeline

Kernel DPDK

Switch 2

Parser Match-Action Pipeline

PISCES is a software switch that takes

  • a Domain-Specific Language input

and outputs a customized

  • a Software Switch Target

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Kernel DPDK

OVS Parser Match-Action Pipeline

Compile

Parser Match-Action Pipeline

[1] http://p4.org

P4 is an open-source language.[1] Easily defines

  • Packet headers and fields
  • Parser
  • Actions
  • Match-Action Tables

P4[1]

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Kernel DPDK

P4 Parser Match-Action Pipeline

Compile

Parser Match-Action Pipeline

Native OVS Packet Processing Logic 341 lines of P4 code 14,535 lines of C code

OVS

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Compiler P4 Program P.I. OVS

parse match action

OVS Executable

header_type tcp_t { fields { srcPort : 16; dstPort : 16; seqNo : 32; ackNo : 32; dataOffset : 4; res : 4; window : 16; checksum : 16; urgentPtr : 16; } } parser tcp { extract(tcp); return ingress; } ... header_type tcpv2_t { fields { srcPort : 16; dstPort : 16; seqNo : 32; ackNo : 32; dataOffset : 4; res : 4; tcp_flags : 8; window : 16; checksum : 16; urgentPtr : 16; } } parser tcpv2 { extract(tcpv2); set_metadata(flow.tcp_flags, tcpv2.tcp_flags); return ingress; } ... 17

PISCES

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Kernel DPDK

OVS P4 Parser Match-Action Pipeline Parser Match-Action Pipeline

Performance Overhead?

Compile

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8.29 13.62 19.00 25.71 13.43 23.35 33.17 43.00

5 10 15 20 25 30 35 40 45 50

64 128 192 256 Throughput (Gbps) Packet Size (Bytes) PISCES v0.1 OVS

Throughput on Eth + IPv4 + ACL benchmark application

Performance overhead of

~40%

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Packet Parser Ingress Match-Action Tables Packet Deparser Egress Checksum Verify Checksum Update

CPU Cycles per Packet

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Cause for the Overhead

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Extra CPU cycles are consumed by

  • Checksum computation
  • Packet header editing mode

and more…

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Packet Parser Ingress Match-Action Pipeline Egress Checksum Verify Checksum Update

Checksum Verify ( version, ihl, diffserv, totalLen, identification, flags, fragOffset, ttl, protocol, hdrChecksum, srcAddr, dstAddr) Checksum Update ( version, ihl, diffserv, totalLen, identification, flags, fragOffset, ttl, protocol, hdrChecksum, srcAddr, dstAddr)

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Checksum Inefficiencies

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Packet Parser Ingress

Decrement(ttl)

Egress Checksum Verify Checksum Update

Checksum Verify ( version, ihl, diffserv, totalLen, identification, flags, fragOffset, ttl, protocol, hdrChecksum, srcAddr, dstAddr) Incremental Checksum Update (ttl)

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Checksum Inefficiencies

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Packet Parser Match-Action Tables Packet Deparser Ingress Egress Header Fields Ingress Packet Egress Packet Checksum Update Checksum Verify

Post-Pipeline Editing

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Packet Parser Ingress Egress Packet Ingress Packet Egress Match-Action Tables

Inline Editing

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Editing Mode Advantage Disadvantage

Post-Pipeline Packet header size is adjusted only once Extra copy of headers Inline No extra copy of headers Packet header size is adjusted multiple times

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Editing Mode Advantage Disadvantage

Post-Pipeline Extra copy of headers Inline No extra copy of headers

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Packet Parser Ingress Match-Action Tables Packet Deparser Egress

PISCES automatically chooses between

  • Inline Editing
  • Post-pipeline Editing

Checksum Verify Checksum Update

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7.59 12.28 12.56 13.32 13.43

2 4 6 8 10 12 14 16

64 Throughput (Gbps) Packet Size (Bytes)

PISCES v0.1 Incremental Checksum Editing Mode Selection PISCES v1.0 Native OVS

Performance overhead of

< 2%

Throughput on Eth + IPv4 + ACL benchmark application

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28 18 20 1 1 1

5 10 15 20 25 30 Connection Label Tunnel OAM Flag TCP Flag

Number of Files Changed

Native OVS PISCES

411 170 370 5 6 4

50 100 150 200 250 300 350 400 450 Connection Label Tunnel OAM Flag TCP Flag

Lines of Code Changed

Native OVS PISCES

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  • A method to quickly develop and deploy packet

processing logic on a software switch

  • With hardly any performance cost!

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Learn more and Try PISCES here: http://pisces.cs.princeton.edu