P4 Introduction

1. P4 Introduction Define your network packet forwarding on switch using P4 2018/04/18, Hsinchu, PyHUG Presenter: Shan-Jung Fu (Samina)
2. • Shan-Jung Fu (Samina) ◦ National Chiao Tung University, Taiwan ◦ Wireless Internet Laboratory • Department of Computer Science • ITRI Intern • Was a Information Technology Service Center Network & System Engineer @ NCTU before • GitHub: @sufuf3 • Twitter: @sufuf3149 About Me 2
3. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 3
4. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 4
5. What is P4 • Programming Protocol-Independent Packet Processors ◦ processors: eg. switches, smart NIC, etc • Web site: https://p4.org • GitHub: https://github.com/p4lang • White Paper(July 2014) 5
6. • A high-level language • Can program the network data plane What is P4 (Cont’d) Ref: https://www.slideshare.net/Docker/docker-networking-control-plane-and-data-plane 6
7. • What is P4 • Why P4 ◦ Motivation ◦ Benefits • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 7
8. • Network changes Motivation • Why P4 ◦ Motivation ◦ Benefits 2014 P4: Programming Protocol-Independent Packet Processors 2008 Software Defined Networking (SDN) with OpenFlow Before 2008 Traditional Network 8
9. • Using SDN to solve the problems of traditional network • The problems of traditional network are ◦ Closed equipment ▪ Software bundled with hardware ▪ Vendor-specific CLI interfaces ◦ Networks are hard to evolve ▪ Networks are stuck in the past • Routing algorithms change very slowly • Network management extremely primitive ◦ Networks design not based on formal principles ▪ Networks used to be simple • Basic Ethernet/IP straightforward ▪ New control requirements have led to complexity • ACLs, VLANs, TE, Middleboxes, DPI,… ◦ … etc. Traditional network problem • Why P4 ◦ Motivation ◦ Benefits 9
10. • What is Software-Defined Networking(SDN) ◦ Physical separation of the network control plane from the forwarding plane (data plane) ◦ Control plane controls several devices ◦ The network control to become directly programmable SDN • Why P4 ◦ Motivation ◦ Benefits Ref: https://www.sdxcentral.com/sdn/definitions/inside-sdn-architecture/ 10
11. SDN with OpenFlow • Why P4 ◦ Motivation ◦ Benefits Ref: http://flowgrammable.org/sdn/openflow/ https://www.opennetworking.org/images/stories/downloads/sdn-resources/onf-specifications/ope nflow/openflow-spec-v1.4.0.pdf#page=9 11
12. • OpenFlow explicitly specifies protocol headers on which it operates. This set has grown from 12 to 41 fields in a few years, increasing the complexity of the specification while still not providing the flexibility to add new headers. Using P4 to solve Openflow problems • Why P4 ◦ Motivation ◦ Benefits Versio n Date Header Fields OF 1.0 Dec 2009 12 fields (Ethernet, TCP/IPv4) OF 1.1 Feb 2011 15 fields (MPLS, inter-table metadata) OF 1.2 Dec 2011 36 fields (ARP, ICMP, IPv6, etc.) OF 1.3 Jun 2012 40 fields OF 1.4 Oct 2013 41 fields Ref: https://www.sigcomm.org/sites/default/files/ccr/papers/2014/July/0000000-0000004.pdf 12
13. • Reconfigurability in the field ◦ Controller can redefine the packet parsing & processing in the field • Protocol independence ◦ Switches should not be tied to any specific network protocols. ◦ Controller should be able to specify ▪ A packet parser for extracting header fields with particular names and types ▪ A collection of typed match + action tables that process these headers • Target independence ◦ Programmers should be able to describe packet-processing functionality independently of the specifics of the underlying hardware. The goals of P4 • Why P4 ◦ Motivation ◦ Benefits Ref: https://www.sigcomm.org/sites/default/files/ccr/papers/2014/July/0000000-0000004.pdf 13
14. Compared to state-of-the-art packet-processing systems • Flexibility • Expressiveness • Resource mapping and management • Software engineering • Component libraries • Decoupling hardware and software evolution • Debugging Benefits of P4 • Why P4 ◦ Motivation ◦ Benefits Ref: https://p4.org/p4-spec/docs/P4-16-v1.0.0-spec.html#sec-benefits-of-p4 14
15. Benefits of Data Plane Programmability • New Features - Add new protocols • Reduce complexity - Remove unused protocols • Efficient use of resources - flexible use of tables • Greater visibility - New diagnostic techniques, telemetry, etc. • Software style development - rapid design cycle, fast innovation, fix data plane bugs in the field • You keep your own ideas Think programming rather than protocols... Benefits of P4 (Cont’d) • Why P4 ◦ Motivation ◦ Benefits Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf 15
16. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 16
17. P4.org Membership Ref: https://github.com/p4lang/tutorials/blob/master/P4D2_2017_Fall/P4_tutorial_labs.pdf 17
18. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 18
19. • Headers ◦ Describes the sequence & structure of a series of fields • Parsers ◦ Specifies how to identify headers & valid header sequences within packets • Tables (match + action tables) ◦ The mechanism for performing packet processing • Actions ◦ P4 supports construction of complex actions from simpler protocol-independent primitives. These complex actions are available within match + action tables. • Control Program ◦ Determines the order of tables that are applied to a packet. A simple imperative program describe the flow of control between match + action tables Key Components of P4 19
20. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language ◦ Program Template ◦ Approach ▪ Target ▪ Architecture • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 20
21. P4 16 Program Template • P4 16 Language ◦ Program Template ◦ Approach ▪ Target ▪ Architecture Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf 21
22. P4 16 Approach • • P4 16 Language ◦ Program Template ◦ Approach ▪ Target ▪ Architecture Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf Term Explanation P4 Target An embodiment of a specific hardware implementation P4 Architecture Provides an interface to program a target via some set of P4-programmable components, externs, fixed components 22
23. Programming a P4 Target • • P4 16 Language ◦ Program Template ◦ Approach ▪ Target ▪ Architecture Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf 23
24. P4 16 Architecature • P4 16 Language ◦ Program Template ◦ Approach ▪ Target ▪ Architecture • Ingress Pipeline • Egress Pipeline • Traffic Manager ◦ N:1 Relationships: Package Queueing, Congestion Control ◦ 1:N Relationships: Replication ◦ Scheduling Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf https://github.com/NetFPGA/P4-NetFPGA-public/blob/master/slides/FPGA-2018/FPGA%202018%20P4%20tut orial.pdf 24
25. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code ◦ Topology ◦ Source code ◦ Explain • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 25
26. Basic Forwarding: Topology • For every packet, the L3 switch must perform: ◦ Update the source and destination MAC addresses ◦ Decrement the time-to-live (TTL) in the IP header ◦ Forward the packet out the appropriate port • Topology • Source code • Explain 26 • Have a single table: the control plane will populate with static rules • Each rule will map an IP address to the MAC address and output port for the next hop • Already defined the control plane rules
27. Basic Forwarding: Source code • Code: https://github.com/p4lang/tutorials/blob/master/P4D2_2018 _East/exercises/basic/solution/basic.p4 • Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf • Topology • Source code • Explain 27
28. Explain • Some Elements • Headers • Parser • Controls ◦ Checksum Verification ◦ Ingress Processing ◦ Egress Processing ◦ Checksum Computation ◦ Deparser • Switch • Topology • Source code • Explain 28
29. • Some Elements • Headers • Parser • Controls ◦ Checksum Verification ◦ Ingress Processing ◦ Egress Processing ◦ Checksum Computation ◦ Deparser • Switch Explain • Topology • Source code • Explain 29
30. • Include P4 core library ◦ Defines some standard data-types and error codes ◦ https://p4.org/p4-spec/docs/P4-16-v1.0.0-spec.html#sec-p4-core-lib • https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/ basic/solution/basic.p4#L2-L5 Ref: https://en.wikipedia.org/wiki/EtherType Some Elements #include <core.p4> #include <v1model.p4> const bit<16> TYPE_IPV4 = 0x800; 30
31. • Some Elements • Headers • Parser • Controls ◦ Checksum Verification ◦ Ingress Processing ◦ Egress Processing ◦ Checksum Computation ◦ Deparser • Switch Explain • Topology • Source code • Explain 31
32. Headers typedef bit<9> egressSpec_t; typedef bit<48> macAddr_t; typedef bit<32> ip4Addr_t; header ethernet_t { macAddr_t dstAddr; macAddr_t srcAddr; bit<16> etherType; } • Typedef ◦ Alternative name for a type • Basic Types ◦ bit<n> ◦ bit == bit<1> ◦ int<n> ◦ varbit<n> • Header Types ◦ Ordered collection of members https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/s olution/basic.p4#L11-L19 32
33. Headers (Cont’d) header ipv4_t { bit<4> version; bit<4> ihl; bit<8> diffserv; bit<16> totalLen; bit<16> identification; bit<3> flags; bit<13> fragOffset; bit<8> ttl; bit<8> protocol; bit<16> hdrChecksum; ip4Addr_t srcAddr; ip4Addr_t dstAddr; } https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/s olution/basic.p4#L21-L34 33
34. • Other useful types • Struct ◦ Unordered collection of members (with no alignment restrictions) • Header Stack ◦ array of headers • Header Union ◦ one of several headers Headers (Cont’d) struct metadata { /* empty */ } struct headers { ethernet_t ethernet; ipv4_t ipv4; } https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/s olution/basic.p4#L36-L43 34
35. • Some Elements • Headers • Parser • Controls ◦ Checksum Verification ◦ Ingress Processing ◦ Egress Processing ◦ Checksum Computation ◦ Deparser • Switch Explain • Topology • Source code • Explain 35
36. Parser parser MyParser(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { state start { transition parse_ethernet; } state parse_ethernet { packet.extract(hdr.ethernet); transition select(hdr.ethernet.etherType) { TYPE_IPV4: parse_ipv4; default: accept; } } state parse_ipv4 { packet.extract(hdr.ipv4); transition accept; } } https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/s olution/basic.p4#L49-L71 36
37. parser MyParser(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { state start { transition parse_ethernet; } state parse_ethernet { packet.extract(hdr.ethernet); transition select(hdr.ethernet.etherType) { TYPE_IPV4: parse_ipv4; default: accept; } } state parse_ipv4 { packet.extract(hdr.ipv4); transition accept; } } Parser (Cont’d) Parsers are functions that map packets into headers and metadata, written in a state machine style • packet_in: reads its input from a packet_in • in: read-only • out: are treated as a storage • inout: both in & out 37
38. parser MyParser(packet_in packet, out headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { state start { transition parse_ethernet; } state parse_ethernet { packet.extract(hdr.ethernet); transition select(hdr.ethernet.etherType) { TYPE_IPV4: parse_ipv4; default: accept; } } state parse_ipv4 { packet.extract(hdr.ipv4); transition accept; } } Every parser has three predefined states • start • accept • reject Parser (Cont’d) select statement that can be used to branch in a parser 38
39. • Some Elements • Headers • Parser • Controls ◦ Checksum Verification (CV) ◦ Ingress Processing ◦ Egress Processing ◦ Checksum Computation (CC) ◦ Deparser • Switch Explain • Topology • Source code • Explain 39
40. • Similar to C functions (without loops) • Can declare variables, create tables, instantiate externs, etc. • Functionality specified by code in apply statement • Represent all kinds of processing that are expressible as DAG(Directed Acyclic Graph): ◦ Additional forms of packet processing (updating checksums) ◦ Match-Action Pipelines ◦ Deparsers Controls control MyVerifyChecksum(inout headers hdr, inout metadata meta) { apply { } } Evaluating a program that has several instantiations of the same component. parameters of control • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 40
41. Controls (Cont’d) • The control instances enclose controllable entities: ◦ actions ◦ tables ◦ keys ◦ extern instances • Control flow control MyIngress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { action drop() { ... } action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) { standard_metadata.egress_spec = port; hdr.ethernet.srcAddr = hdr.ethernet.dstAddr; hdr.ethernet.dstAddr = dstAddr; hdr.ipv4.ttl = hdr.ipv4.ttl - 1; } table ipv4_lpm { ... } apply { //bosy of the pipeline if (hdr.ipv4.isValid()) { ipv4_lpm.apply(); } } } • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 41
42. • After the switch parse headers’ value, the switch needs to do something to update some of the headers’ value. • How does the switch update the headers’ value? 1. Write some logical program to deal with them ▪ Action function 2. Does the actions according to the rules which are sent from the SDN controller ▪ Table function Controls (Cont’d) • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 42
43. Controls (Cont’d) • Actions ◦ Very similar to C functions ◦ Reside in tables; invoked automatically on table match. ◦ Can be declared inside a control or globally ◦ Parameters have type and direction ◦ Variables can be instantiated inside ◦ Many standard arithmetic and logical operations are supported • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 43
44. • Tables ◦ The fundamental unit of a Match-Action Pipeline ◦ Specifies what data to match on and match kind ◦ Specifies a list of possible actions ◦ Optionally specifies a number of table properties ▪ Size ▪ Default action ▪ Static entries ▪ etc. ◦ Each table contains one or more entries (rules) ◦ An entry contains: ▪ A specific key to match on ▪ A single action that is executed when a packet matches the entry ▪ Action data (possibly empty) Controls (Cont’d) • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 44
45. table ipv4_lpm { key = { hdr.ipv4.dstAddr: lpm; } action = { ipv4_forward; drop; NoAction; } size = 1024; default_action = NoAction(); } Controls (Cont’d) Data Plane (P4) Program • Defines the format of table ◦ Key Fields ◦ Actions ◦ Action Data • Performs the lookup • Executes the chosen action Control Plane (IP stack, Routing protocols) • Populates table entries with specific information ◦ Based on the configuration, automatic discovery, protocol calculations Tables(Cont’d) • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 45 table_add ipv4_lpm ipv4_forward 10.0.1.1/32 => 00:00:00:00:01:01 1 Longest prefix match
46. Controls (Cont’d) Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf Tables(Cont’d) • Match-Action Processing • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 46
47. Checksum Verification • No built-in constructs in P4 16 for manipulating packet checksums • You can write your checksum verification • Ref: https://p4.org/p4-spec/docs/P4-16-v1.0.0-spec.html#sec-checksums control MyVerifyChecksum(inout headers hdr, inout metadata meta) { apply { } } https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/s olution/basic.p4#L77-L79 • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 47
48. Ingress Processing control MyIngress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { action drop() { mark_to_drop(); } action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) { standard_metadata.egress_spec = port; hdr.ethernet.srcAddr = hdr.ethernet.dstAddr; hdr.ethernet.dstAddr = dstAddr; hdr.ipv4.ttl = hdr.ipv4.ttl - 1; } table ipv4_lpm { key = { hdr.ipv4.dstAddr: lpm; } action = { ipv4_forward; drop; NoAction; } size = 1024; default_action = NoAction(); } apply { if (hdr.ipv4.isValid()) { ipv4_lpm.apply(); } } } https://github.com/p4lang/tutorials/blob/master/P4D2_2 018_East/exercises/basic/solution/basic.p4#L86-L118 • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 48
49. control MyEgress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { apply { } } Egress Processing • Egress processing https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/solution/basic.p4# L124-L128 • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 49
50. Checksum Computation control MyComputeChecksum(inout headers hdr, inout metadata meta) { apply { update_checksum( hdr.ipv4.isValid(), { hdr.ipv4.version, hdr.ipv4.ihl, hdr.ipv4.diffserv, hdr.ipv4.totalLen, hdr.ipv4.identification, hdr.ipv4.flags, hdr.ipv4.fragOffset, hdr.ipv4.ttl, hdr.ipv4.protocol, hdr.ipv4.srcAddr, hdr.ipv4.dstAddr }, hdr.ipv4.hdrChecksum, HashAlgorithm.csum16); } } Computes the checksum of the supplied data https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/solutio n/basic.p4#L134-L152 • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 50
51. Deparser • Assembles the headers back into a well-formed packet • P4 16 does not provide a separate language for packet deparsing • Deparsing is done in a control block that has at least one parameter of type packet_out • packet_out extern is defined in core.p4: emit(hdr): serializes header if it is valid • Advantages: ◦ Makes deparsing explicit...but decouples from parsing control MyDeparser(packet_out packet, in headers hdr){ apply { packet.emit(hdr.ethernet); packet.emit(hdr.ipv4); } } https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/solution/basic.p4#L1 58-L163 • Controls ◦ CV ◦ Ingress ◦ Egress ◦ CC ◦ Deparser 51
52. Explain • Topology • Source code • Explain • Some Elements • Headers • Parser • Controls ◦ Checksum Verification ◦ Ingress Processing ◦ Egress Processing ◦ Checksum Computation ◦ Deparser • Switch 52
53. • Instantiate the top-level V1Switch package • All the arguments of the V1Switch package constructor have been evaluated (instances of MyParser, MyVerifyChecksum ...). • Their signatures are matched w/ the V1Switch declaration • The result of the program evaluation is the value of the main variable Switch V1Switch( MyParser(), MyVerifyChecksum(), MyIngress(), MyEgress(), MyComputeChecksum(), MyDeparser() ) main; https://github.com/p4lang/tutorials/blob/master/P4D2_2018_East/exercises/basic/solution/basic.p4#L1 69-L176 53
54. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 54
55. P4 Tools & Environments • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ Packet Test Framework (PTF) ◦ P4 Container • Environments ◦ Behavioral Model (BMv2) ◦ Programmable Network Devices Ref: https://p4.org/code/ 55
56. P4 Compiler • p4c • A new, alpha-quality reference compiler • Supports both P4 14 and P4 16 • Provides a standard frontend and midend which can be combined with a target-specific backend to create a complete P4 compiler • The compiler supports several backends: ◦ p4c-bmv2 – targets the behavioral model ◦ p4c-ebpf, p4c-graphs, p4test … etc. • Repository: https://github.com/p4lang/p4c Eg. $ p4c -b bmv2-ss-p4org program.p4 -o program.bmv2.json • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 56
57. • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices P4 Runtime • Runtime control of P4 data planes Ref: https://p4.org/api/announcing-p4runtime-a-contribution-by-the-p4-api-working-group.html 57
58. P4 Runtime (Cont’d) Ref: https://p4.org/p4-runtime/ https://p4.org/api/p4-runtime-putting-the-control-plane-in-charge-of-the-forwarding-plane.html • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices • Framework for control plane software to control forwarding plane ◦ https://github.com/p4lang/PI ◦ Initial contribution by Google and Barefoot • Work-in-progress by the p4.org API WG • Protobuf-based API definition ◦ p4runtime.proto ◦ gRPC as a possible RPC transport • P4 program-independent ◦ API doesn’t change with the P4 program • Enables field-reconfigurability ◦ Ability to push new P4 program without recompiling deployed switches • A runtime API & protocol for controlling data-plane programs • Can be used for local or remote control plane 58
59. Ref: https://github.com/p4lang/tutorials/blob/master/P4D2_2017_Fall/P4_tutorial_labs.pdf P4 Runtime (Cont’d) • P4Runtime workflow • Captures P4 program attributes needed at runtime ◦ IDs for tables, actions, params, etc. ◦ Table structure, action parameters, etc. • Protobuf-based format • Target-independent compiler output ◦ Same P4Info for BMv2, ASIC, etc. • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 59
60. Ref: https://github.com/p4lang/tutorials/blob/master/P4D2_2017_Fall/P4_tutorial_labs.pdf P4 Runtime (Cont’d) • Can be used for ◦ Local control plane ◦ Remote control plane ◦ Local control plane • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 60
61. Ref: https://github.com/p4lang/tutorials/blob/master/P4D2_2017_Fall/P4_tutorial_labs.pdf P4 Runtime (Cont’d) • Can be used for ◦ Local control plane ◦ Remote control plane ◦ • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 61
62. Packet Test Framework • PTF • A Python based dataplane test framework • Based on unittest • Enables configuring a switch and creating tests that send, receive, and verify packets of different formats. • PTF interfaces with P4 Runtime. • Repository: https://github.com/p4lang/ptf • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 62
63. P4 Container • A Docker container • pre-packaged with a development environment • Can compile & deploy P4 programs using simple configuration rules • Repository: https://github.com/p4lang/p4app • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 63
64. Behavioral Model • aka behavioral model • nicknamed BMv2 • The second version of the P4 software switch • A simulation environment to run the P4 software switch, standalone or in Mininet • Allows you to easily simulate new architectures by implementing new externs • Enabling you to organize the forwarding elements as needed • Repository: https://github.com/p4lang/behavioral-model • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices 64
65. Programmable Network Devices • Tools ◦ P4 Compiler ◦ P4 Runtime ◦ PTF ◦ P4 Container • Environments ◦ BMv2 ◦ Network Devices • Protocol-Independent Switch Architecture (PISA): Flexible Match+Action ASICs ◦ Intel Flexpipe, Cisco Doppler, Cavium (Xpliant), Barefoot Tofino, ... • Network Processor Unit (NPU) ◦ EZchip, Netronome, ... • CPU ◦ Open Vswitch, eBPF, DPDK, VPP... • Field-Programmable Gate Array (FPGA) ◦ Xilinx, Altera, ... Ref: https://p4.org/assets/P4_tutorial_01_basics.gslide.pdf 65
66. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On ◦ Implementing ECN • What can you do with P4? • Conclusion • Additional Outline 66
67. Hands-On • Let’s implement Explicit Congestion Notification (ECN) • You could refer to all P4 tutorials: https://github.com/p4lang/tutorials • This hands-on is ref to https://github.com/p4lang/tutorials/tree/master/P4D2_2018_ East/exercises/ecn 67
68. Implementing ECN • What is ECN • Before Hands-on ◦ Obtaining required software ◦ Get exercises code • Steps ◦ Run the (incomplete) starter code ◦ Implement ECN ◦ Run the solution 68
69. What is ECN • Explicit Congestion Notification • Extend basic L3 forwarding • Allows end-to-end notification of network congestion without dropping packets • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution Ref: https://github.com/p4lang/tutorials/tree/master/P4D2_2017_Fall 69
70. What is ECN (Cont’d) • Puts 1 or 2 value in the ipv4.ecn field • Each switch may change the value to 3 if the queue size is larger than a threshold • The receiver copies the value to sender, and the sender can lower the rate • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution • Type of Service field • DSCP(DiffServ Code Points RFC 2474) + ECN (RFC 3168) Ref: https://en.wikipedia.org/wiki/Type_of_service 70
71. What is ECN (Cont’d) • Explicit Congestion Notification ◦ 00: Non ECN-Capable Transport, Non-ECT ◦ 10: ECN Capable Transport, ECT(0) ◦ 01: ECN Capable Transport, ECT(1) ◦ 11: Congestion Encountered, CE • For packets originating from ECT, ECN-capable switches set the CE bit upon congestion ◦ E.g., observed queue depth > threshold • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution Ref: https://github.com/p4lang/tutorials/tree/master/P4D2_2017_Fall 71
72. • These are two ways to setup P4 Env ◦ OS & HW requirement ▪ OS: Ubuntu 16.04 64-bits ▪ CPU: at least 2 cores ▪ RAM: at least 2G ▪ Disk: at least 25G ◦ Build your env by yourself (not root), after finish OS installation ◦ Download VM (ovf file) https://goo.gl/VQRFPt $ wget -O setup.sh https://goo.gl/EHgk4v && sudo bash setup.sh && wget -O - https://goo.gl/NKaau7 | bash Before Hands-on • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution Ref: https://github.com/sufuf3/p4-install-environment https://github.com/p4lang/tutorials/tree/master/P4D2_2018_East 72
73. Run the (incomplete) starter code • Please just follow this README: https://github.com/p4lang/tutorials/tree/master/P4D2_2018_East/ exercises/ecn • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution 73
74. Implement ECN • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution header ipv4_t { bit<4>version; bit<4>ihl; bit<8>tos; bit<16> totalLen; bit<16> identification; bit<3>flags; bit<13> fragOffset; bit<8>ttl; bit<8>protocol; bit<16> hdrChecksum; ip4Addr_t srcAddr; ip4Addr_t dstAddr; } • Before bit<6> diffserv; bit<2> ecn; • After 74
75. Implement ECN (Cont’d) • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution control MyEgress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { apply { /* * TODO: * - if ecn is 1 or 2 * - compare standard_metadata.enq_qdepth * with threshold and set hdr.ipv4.ecn to 3 if larger */ } } • Before https://github.com/p4lang/p4c/blob/master/p4include/v1model.p4#L 51 75
76. Implement ECN (Cont’d) • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution control MyEgress(inout headers hdr, inout metadata meta, inout standard_metadata_t standard_metadata) { action mark_ecn() { hdr.ipv4.ecn = 3; } apply { if (hdr.ipv4.ecn == 1 || hdr.ipv4.ecn == 2){ if (standard_metadata.enq_qdepth >= ECN_THRESHOLD){ mark_ecn(); } } } } • After 76
77. Implement ECN (Cont’d) • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution control MyComputeChecksum(inout headers hdr, inout metadata meta) { apply { /* TODO: replace tos with diffserve and ecn */ update_checksum( hdr.ipv4.isValid(), { hdr.ipv4.version, hdr.ipv4.ihl, hdr.ipv4.tos, hdr.ipv4.totalLen, hdr.ipv4.identification, hdr.ipv4.flags, hdr.ipv4.fragOffset, hdr.ipv4.ttl, hdr.ipv4.protocol, hdr.ipv4.srcAddr, hdr.ipv4.dstAddr }, hdr.ipv4.hdrChecksum, HashAlgorithm.csum16); } } • Before hdr.ipv4.diffserv, hdr.ipv4.ecn, • After 77
78. Run the solution • Follow the instructions from Step 1. • On h2 run $ ./receive.py > h2.log • $ grep tos h2.log • What is ECN • Before Hands-on ◦ Obtaining software ◦ Get code • Steps ◦ Run starter code ◦ Implement ◦ Run solution tos = 0x1 tos = 0x1 tos = 0x1 tos = 0x1 tos = 0x3 tos = 0x3 tos = 0x3 tos = 0x3 tos = 0x3 tos = 0x3 tos = 0x1 tos = 0x1 tos = 0x1 tos = 0x1 78
79. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 79
80. • Applications of P4 ◦ Layer 4 Load Balancer – SilkRoad[1] ◦ Low Latency Congestion Control – NDP[2] ◦ Fast In-Network cache for key-value stores – NetCache[3] ◦ In-band Network Telemetry – INT[4] ◦ Consensus at network speed – NetPaxos[5] ◦ ... and much more [1] Miao, Rui, et al. "SilkRoad: Making Stateful Layer-4 Load Balancing Fast and Cheap Using Switching ASICs." SIGCOMM, 2017. [2] Handley, Mark, et al. "Re-architecting datacenter networks and stacks for low latency and high performance.” SIGCOMM, 2017. [3] Xin Jin et al. “NetCache: Balancing Key-Value Stores with Fast In-Network Caching.” To appear at SOSP 2017 [4] Kim, Changhoon, et al. "In-band network telemetry via programmable dataplanes.” SIGCOMM. 2015. [5] Dang, Huynh Tu, et al. "NetPaxos: Consensus at network speed.” SIGCOMM, 2015 What can you do with P4? 80
81. What can you do with P4? (Cont’d) • In-band Network Telemetry (INT) ◦ A framework ◦ Designed to allow the collection and reporting of network state, by the data plane ◦ Without requiring intervention or work by the control plane ◦ Spec: https://p4.org/assets/INT-current-spec.pdf 81
82. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 82
83. Conclusion • Introduce P4, its concepts, languages & some applications • With P4, SDN programmers can design these goals ◦ Can keep the new ideas secret ▪ Don’t have to let switch chip vendor know ◦ Unique features in every network 83
84. • What is P4 • Why P4 • P4.org Membership • Key Components of P4 • P4 16 Language • Explain Basic Forwarding P4 code • P4 Tools & Environments • Hands-On • What can you do with P4? • Conclusion • Additional Outline 84
85. Additional • Clarifying the differences between P4 and OpenFlow: https://p4.org/p4/clarifying-the-differences-between-p4-and-openflow.ht ml • P416 Portable Switch Architecture (PSA) Draft: https://p4.org/p4-spec/docs/PSA.html • Protocol Independent Switch Architecture (PISA): https://p4.org/assets/p4-ws-2017-p4-architectures.pdf && http://conferences.sigcomm.org/sigcomm/2013/papers/sigcomm/p99.pd f && https://www.barefootnetworks.com/resources/worlds-fastest-most-progr ammable-networks/ • Programming the Forwarding Plane: https://platformlab.stanford.edu/Presentations/Platform%20Lab%20Rev iew%202016.pdf 85
86. Thanks for your attention! Q & A If it any unreasonable point, please let me know and accept my sincere apology. Thank you. • GitHub: @sufuf3 • Twitter: @sufuf3149 Facebook: SDNDS.TW