PISCES: A Programmable, Protocol-Independent Software Switch

Transcription

1 PISCES: A Programmable, Protocol-Independent Software Switch Muhammad Shahbaz, Sean Choi, Ben Pfaff, Changhoon Kim, Nick Feamster, Nick McKeown, and Jennifer Rexford

2 Fixed Set of Protocols Fixed-Function Switch Chip TCP IPv4 IPv6 Ethernet UDP HTTP BGP TLS

3 Ease of Adding new protocols Ease of Removing unused protocols Gain greater Visibility into the network Fold network functions into the switch

4 Custom Protocols Programmable Switching Chip TCP IPv4 IPv6 Ethernet CUSTOM_P HTTP BGP TLS

5 VM VM Hypervisor Switch 3 Virtual Ports 1 Physical Port

6 60 Approx. Number of Physical Ports vs. Virtual Ports [1] Phyical Ports Virtual Ports [1] Martin Casado, VMWorld 2013

7 It should be EASY to program software switches! Not really

8 Software Switch Kernel DPDK Fast Packet Forwarding

9 Software Switch Requires domain expertise in: - Network protocol design - Kernel development Packet Match-Action Processing Logic Pipeline Kernel DPDK Slow to release changes Specialized APIs

10 Software Switch Adding TCP Flag in Open vswitch required changes in Match-Action Pipeline Kernel DPDK 20 Files and 370 Lines of Code! [1] Weeks of Development and Test [1]

11 We can do this in 4 lines and within minutes with PISCES! header_type tcpv2_t { fields { srcport : 16; dstport : 16; seqno : 32; ackno : 32; dataoffset : 4; res : 4; tcp_flags : 12; window : 16; checksum : 16; urgentptr : 16; } } parser tcpv2 { extract(tcpv2); set_metadata(flow.tcp_flags, tcpv2.tcp_flags); return ingress; } header_type flow_t { fields {... tcp_flags_pad : 4; tcp_flags : 12;... } }

12 Software Switch Match-Action Pipeline Kernel DPDK

13 Domain-Specific Language (DSL) Software Switch Match-Action Pipeline Compile Match-Action Pipeline Kernel DPDK 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; }...

14 Domain-Specific Language Domain-Specific Language 2 Match-Action Pipeline Match-Action Pipeline Compile PISCES is an implementation with a Specific Domain-Specific Language Software Switch Switch 2 Match-Action Pipeline Match-Action Pipeline Kernel Kernel DPDK DPDK Specific Software Switch Target

15 P4 [1] Match-Action Pipeline P4 is an open-source language. [1] OVS Compile Match-Action Pipeline Kernel DPDK Easy to express different aspects of a packet processor: - Packet headers and fields - - Actions - Match-Action Tables [1]

16 P4 Match-Action Pipeline 341 lines of code OVS Compile Match-Action Pipeline Kernel DPDK Native OVS Packet Processing Logic 14,535 lines of code

17 P4 Compiler parse match action OVS OVS Executable header_type tcp_t { fields header_type { tcpv2_t { srcport fields {: 16; dstport srcport : 16; : 16; seqno dstport : 32; : 16; ackno seqno : 32; : 32; dataoffset ackno : 32; : 4; res dataoffset : 4; : 4; window res :: 4; 16; checksum tcp_flags : 16; : 8; urgentptr window :: 16; 16; } checksum : 16; } urgentptr : 16; parser } tcp { extract(tcp); } return parser ingress; tcpv2 { }... }... extract(tcpv2); set_metadata(flow.tcp_flags, tcpv2.tcp_flags); return ingress;

18 P4 Match-Action Pipeline Compile Performance Overhead? OVS Match-Action Pipeline Kernel DPDK

19 Throughput (Gbps) Throughput on L2L3-ACL benchmark application Packet Size (Bytes) PISCES v0.1 OVS Performance overhead of ~40%

20 Causes for the Cost on Performance Match-Action Tables Cache Misses Ingress Packet Checksum Verify Match-Action Cache Checksum Update Packet Deparser Egress CPU Cycles per Packet

21 Factors affecting CPU Cycles per Packet a. Fully-specified Checksum b. Parsing unused header fields and more

22 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) Ingress Packet Checksum Verify Match-Action Pipeline Checksum Update Egress

23 Checksum Verify ( version, ihl, diffserv, totallen, identification, flags, fragoffset, ttl, protocol, hdrchecksum, srcaddr, dstaddr) Incremental Checksum Update (ttl) Ingress Packet Checksum Verify Decrement(ttl) Checksum Update Egress

24 Selective Parsing L3 L2 L4 L2 Ingress Packet Match-Action Pipeline Packet Deparser Egress

25 Throughput (Gbps) Throughput on L2L3-ACL benchmark application PISCES v0.1 incremental Checksum Header Memory Locality Selective Parsing PISCES v1.0 Native OVS Packet Size (Bytes) Performance overhead of < 2%

26 Summary P4 PISCES vswitch - Quickly develop and deploy new packet header format. - With hardly any performance cost! OVS

27 Questions? Learn more and Try PISCES here: