P4のはなし

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%BO%BMZ (MFO(JCC .BSUJO*[[BSE /JDL.D,FPXO +FOOJGFS 3FYGPSE $PMF4DIMFTJOHFS %BO5BMBZDP "NJO7BIEBU (FPSHF7BSHIFTF %BWJE8BMLFS l1SPHSBNNJOH1SPUPDPMJOEFQFOEFOU1BDLFU1SPDFTTPST z IUUQTBSYJWPSHQEGQEG͔ΒҾ༻ Software-Defined Networking (SDN) gives operators pro- grammatic control over their networks. In SDN, the control plane is physically separate from the forwarding plane, and one control plane controls multiple forwarding devices. While forwarding devices could be programmed in many ways, having a common, open, vendor-agnostic interface (like OpenFlow) enables a control plane to control forwarding devices from di↵erent hardware and software vendors. Version 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 Table 1: Fields recognized by the OpenFlow standard The OpenFlow interface started simple, with the abstrac- tion of a single table of rules that could match packets on a dozen header fields (e.g., MAC addresses, IP addresses, protocol, TCP/UDP port numbers, etc.). Over the past five years, the specification has grown increasingly more com- Figur Recen be achie grammi easy. E microco sign of indepen relation it how p as Open tables i stractio arXiv:1312

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5 ར༻ऀ ϓϩάϥϚ Πϥετ $ ͍Β͢ͱ΍ λʔήοτ ΞʔΩςΫνϟ ػثϝʔΧʔ 1ίϛϡχςΟ
DPSFQ QSPHSBNQ BSDIQ Πϯετʔϧ ίϯύΠϧ ొ৔ਓ෺ 1ϓϩάϥϜ

6 λʔήοτ ΞʔΩςΫνϟ ػثϝʔΧʔ QSPHSBNQ BSDIQ Πϯετʔϧ ίϯύΠϧ 1ϓϩάϥϜ ొ৔ਓ෺
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7 QSPHSBNQ Πϯετʔϧ ίϯύΠϧ DPSFQ 1ίϛϡχςΟ 1ϓϩάϥϜ ػثϝʔΧʔ BSDIQ ར༻ऀ
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8 λʔήοτ ΞʔΩςΫνϟ ػثϝʔΧʔ BSDIQ Πϯετʔϧ ίϯύΠϧ DPSFQ 1ίϛϡχςΟ QSPHSBNQ
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9 ར༻ऀ ϓϩάϥϚ λʔήοτ ΞʔΩςΫνϟ ػثϝʔΧʔ 1ίϛϡχςΟ DPSFQ QSPHSBNQ BSDIQ
Πϯετʔϧ ίϯύΠϧ ొ৔ਓ෺ Πϥετ $ ͍Β͢ͱ΍ 1ϓϩάϥϜ

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1PSUBCMF4XJUDI"SDIJUFDUVSF 14" w 1ίϛϡχςΟʹΑͬͯඪ४Խ͕ਐΊΒΕ͍ͯΔඪ४తͳωοτ ϫʔΫεΠονΛදݱ͢ΔΞʔΩςΫνϟ w 14"Λλʔήοτʹ͓͚ͯ͠͹14"ରԠͷػث͕ग़ͨ࣌ʹ༰қʹϙʔ ςΟϯάͰ͖Δʁ w 1ϓϩάϥϜͰ͸্هͷਫ৭ͷ࢛֯ͷ෦෼Λ࣮૷͢Δ 10 *OHSFTT 1BSTFS &HSFTT %FQBSTFS *OHSFTT *OHSFTT %FQBSTFS 1LU#VG 3FQMJDB &HSFTT 1BSTFS &HSFTT #VG2VFVF &OHJOF 5SB⒏D .BOBHFS 1BSTFS %FQBSTFS 7FSJGZ $IFDLTVN *OHSFTT &HSFTT $PNQVUF $IFDLTVN

1PSUBCMF4XJUDI"SDIJUFDUVSF 14" w 1ίϛϡχςΟʹΑͬͯඪ४Խ͕ਐΊΒΕ͍ͯΔඪ४తͳωοτ ϫʔΫεΠονΛදݱ͢ΔΞʔΩςΫνϟ w 14"Λλʔήοτʹ͓͚ͯ͠͹14"ରԠͷػث͕ग़ͨ࣌ʹ༰қʹϙʔ ςΟϯάͰ͖Δʁ w 1ϓϩάϥϜͰ͸্هͷਫ৭ͷ࢛֯ͷ෦෼Λ࣮૷͢Δ 11 *OHSFTT 1BSTFS &HSFTT %FQBSTFS *OHSFTT *OHSFTT %FQBSTFS 1LU#VG 3FQMJDB &HSFTT 1BSTFS &HSFTT #VG2VFVF &OHJOF 5SB⒏D .BOBHFS 1BSTFS %FQBSTFS 7FSJGZ $IFDLTVN *OHSFTT &HSFTT $PNQVUF $IFDLTVN w ύʔα w ύέοτͷϔομΛղੳ͢Δ෦෼

1PSUBCMF4XJUDI"SDIJUFDUVSF 14" w 1ίϛϡχςΟʹΑͬͯඪ४Խ͕ਐΊΒΕ͍ͯΔඪ४తͳωοτ ϫʔΫεΠονΛදݱ͢ΔΞʔΩςΫνϟ w 14"Λλʔήοτʹ͓͚ͯ͠͹14"ରԠͷػث͕ग़ͨ࣌ʹ༰қʹϙʔ ςΟϯάͰ͖Δʁ w 1ϓϩάϥϜͰ͸্هͷਫ৭ͷ࢛֯ͷ෦෼Λ࣮૷͢Δ 12 *OHSFTT 1BSTFS &HSFTT %FQBSTFS *OHSFTT *OHSFTT %FQBSTFS 1LU#VG 3FQMJDB &HSFTT 1BSTFS &HSFTT #VG2VFVF &OHJOF 5SB⒏D .BOBHFS 1BSTFS %FQBSTFS 7FSJGZ $IFDLTVN *OHSFTT &HSFTT $PNQVUF $IFDLTVN w ϚονΞΫγϣϯύΠϓϥΠϯ w ϔομͷ஋ʹԠͯ͡Կ͔ॲཧ ΞΫγϣϯ Λߦ͏෦෼

1PSUBCMF4XJUDI"SDIJUFDUVSF 14" w 1ίϛϡχςΟʹΑͬͯඪ४Խ͕ਐΊΒΕ͍ͯΔඪ४తͳωοτ ϫʔΫεΠονΛදݱ͢ΔΞʔΩςΫνϟ w 14"Λλʔήοτʹ͓͚ͯ͠͹14"ରԠͷػث͕ग़ͨ࣌ʹ༰қʹϙʔ ςΟϯάͰ͖Δʁ w 1ϓϩάϥϜͰ͸্هͷਫ৭ͷ࢛֯ͷ෦෼Λ࣮૷͢Δ 13 *OHSFTT 1BSTFS &HSFTT %FQBSTFS *OHSFTT *OHSFTT %FQBSTFS 1LU#VG 3FQMJDB &HSFTT 1BSTFS &HSFTT #VG2VFVF &OHJOF 5SB⒏D .BOBHFS 1BSTFS %FQBSTFS 7FSJGZ $IFDLTVN *OHSFTT &HSFTT $PNQVUF $IFDLTVN w σύʔα w ϔομΛॻ͖׵͑Δ෦෼

ίΞϥΠϒϥϦ 14 IUUQTHJUIVCDPNQMBOHQDCMPCNBTUFSQJODMVEFDPSFQ 22 /// Standard error codes. New error
codes can be declared by users. 23 error { 24 NoError, /// No error. 25 PacketTooShort, /// Not enough bits in packet for 'extract'. 26 NoMatch, /// 'select' expression has no matches. 27 StackOutOfBounds, /// Reference to invalid element of a header stack. 28 HeaderTooShort, /// Extracting too many bits into a varbit field. 29 ParserTimeout /// Parser execution time limit exceeded. 30 } 66 /// Built-in action that does nothing. 67 action NoAction() {} 69 /// Standard match kinds for table key fields. 70 /// Some architectures may not support all these match kinds. 71 /// Architectures can declare additional match kinds. 72 match_kind { 73 /// Match bits exactly. 74 exact, 75 /// Ternary match, using a mask. 76 ternary, 77 /// Longest-prefix match. 78 lpm 79 }

ίΞϥΠϒϥϦ 15 IUUQTHJUIVCDPNQMBOHQDCMPCNBTUFSQJODMVEFDPSFQ 32 extern packet_in { 33 /// Read
a header from the packet into a fixed-sized header @hdr and advance the cursor. 34 /// May trigger error PacketTooShort or StackOutOfBounds. 35 /// @T must be a fixed-size header type 36 void extract<T>(out T hdr); 37 /// Read bits from the packet into a variable-sized header @variableSizeHeader 38 /// and advance the cursor. 39 /// @T must be a header containing exactly 1 varbit field. 40 /// May trigger errors PacketTooShort, StackOutOfBounds, or HeaderTooShort. 41 void extract<T>(out T variableSizeHeader, 42 in bit<32> variableFieldSizeInBits); 43 /// Read bits from the packet without advancing the cursor. 44 /// @returns: the bits read from the packet. 45 /// T may be an arbitrary fixed-size type. 46 T lookahead<T>(); 47 /// Advance the packet cursor by the specified number of bits. 48 void advance(in bit<32> sizeInBits); 49 /// @return packet length in bytes. This method may be unavailable on 50 /// some target architectures. 51 bit<32> length(); 52 }

ίΞϥΠϒϥϦ 16 IUUQTHJUIVCDPNQMBOHQDCMPCNBTUFSQJODMVEFDPSFQ 54 extern packet_out { 55 /// Write
@hdr into the output packet, advancing cursor. 56 /// @T can be a header type, a header stack, a header_union, or a struct 57 /// containing fields with such types. 58 void emit<T>(in T hdr); 59 } 61 // TODO: remove from this file, convert to built-in 62 /// Check a predicate @check in the parser; if the predicate is true do nothing, 63 /// otherwise set the parser error to @toSignal, and transition to the `reject` state. 64 extern void verify(in bool check, in error toSignal);

ΞʔΩςΫνϟએݴ 7.PEFMͷྫ 17 IUUQTHJUIVCDPNQMBOHQDCMPCNBTUFSQJODMVEFWNPEFMQ 218 parser Parser<H, M>(packet_in b, 219
out H parsedHdr, 220 inout M meta, 221 inout standard_metadata_t standard_metadata); ... লུ ... 229 @pipeline 230 control Ingress<H, M>(inout H hdr, 231 inout M meta, 232 inout standard_metadata_t standard_metadata); 233 @pipeline 234 control Egress<H, M>(inout H hdr, 235 inout M meta, 236 inout standard_metadata_t standard_metadata); ... লུ ... 244 @deparser 245 control Deparser<H>(packet_out b, in H hdr); 247 package V1Switch<H, M>(Parser<H, M> p, 248 VerifyChecksum<H, M> vr, 249 Ingress<H, M> ig, 250 Egress<H, M> eg, 251 ComputeChecksum<H, M> ck, 252 Deparser<H> dep 253 ); 5SB⒏D .BOBHFS 1BSTFS %FQBSTFS 7FSJGZ $IFDLTVN *OHSFTT &HSFTT $PNQVUF $IFDLTVN

1ϓϩάϥϜͷྫ 18 IUUQTHJUIVCDPNQMBOHUVUPSJBMTCMPCNBTUFS1%@@'BMMFYFSDJTFTCBTJDTPMVUJPOCBTJDQ 2 #include <core.p4> 3 #include <v1model.p4> 11
typedef bit<9> egressSpec_t; 12 typedef bit<48> macAddr_t; 13 typedef bit<32> ip4Addr_t; 15 header ethernet_t { 16 macAddr_t dstAddr; 17 macAddr_t srcAddr; 18 bit<16> etherType; 19 } 21 header ipv4_t { 22 bit<4> version; 23 bit<4> ihl; ... লུ ... 29 bit<8> ttl; 30 bit<8> protocol; 31 bit<16> hdrChecksum; 32 ip4Addr_t srcAddr; 33 ip4Addr_t dstAddr; 34 } 40 struct headers { 41 ethernet_t ethernet; 42 ipv4_t ipv4; 43 }

1ϓϩάϥϜͷྫ 19 IUUQTHJUIVCDPNQMBOHUVUPSJBMTCMPCNBTUFS1%@@'BMMFYFSDJTFTCBTJDTPMVUJPOCBTJDQ 49 parser MyParser(packet_in packet, 50 out headers
hdr, 51 inout metadata meta, 52 inout standard_metadata_t standard_metadata) { 53 54 state start { 55 transition parse_ethernet; 56 } 57 58 state parse_ethernet { 59 packet.extract(hdr.ethernet); 60 transition select(hdr.ethernet.etherType) { 61 TYPE_IPV4: parse_ipv4; 62 default: accept; 63 } 64 } 65 66 state parse_ipv4 { 67 packet.extract(hdr.ipv4); 68 transition accept; 69 } 70 71 } ࢀߟ) v1model.p4 218 parser Parser<H, M>(packet_in b, 219 out H parsedHdr, 220 inout M meta, 221 inout standard_metadata_t standard_metadata);

1ϓϩάϥϜͷྫ 20 IUUQTHJUIVCDPNQMBOHUVUPSJBMTCMPCNBTUFS1%@@'BMMFYFSDJTFTCBTJDTPMVUJPOCBTJDQ 86 control MyIngress(inout headers hdr, 87 inout
metadata meta, 88 inout standard_metadata_t standard_metadata) { ... লུ ... 93 action ipv4_forward(macAddr_t dstAddr, egressSpec_t port) { 94 standard_metadata.egress_spec = port; 95 hdr.ethernet.srcAddr = hdr.ethernet.dstAddr; 96 hdr.ethernet.dstAddr = dstAddr; 97 hdr.ipv4.ttl = hdr.ipv4.ttl - 1; 98 } 100 table ipv4_lpm { 101 key = { 102 hdr.ipv4.dstAddr: lpm; 103 } 104 actions = { 105 ipv4_forward; 106 drop; 107 NoAction; 108 } 109 size = 1024; 110 default_action = NoAction(); 111 } 113 apply { 114 if (hdr.ipv4.isValid()) { 115 ipv4_lpm.apply(); 116 } 117 } 118 } ࢀߟ) v1model.p4 229 @pipeline 230 control Ingress<H, M>(inout H hdr, 231 inout M meta, 232 inout standard_metadata_t standard_metadata);

1ϓϩάϥϜͷྫ 21 IUUQTHJUIVCDPNQMBOHUVUPSJBMTCMPCNBTUFS1%@@'BMMFYFSDJTFTCBTJDTPMVUJPOCBTJDQ 158 control MyDeparser(packet_out packet, in headers hdr)
{ 159 apply { 160 packet.emit(hdr.ethernet); 161 packet.emit(hdr.ipv4); 162 } 163 } ࢀߟ) v1model.p4 247 package V1Switch<H, M>(Parser<H, M> p, 248 VerifyChecksum<H, M> vr, 249 Ingress<H, M> ig, 250 Egress<H, M> eg, 251 ComputeChecksum<H, M> ck, 252 Deparser<H> dep 253 ); ࢀߟ) v1model.p4 244 @deparser 245 control Deparser<H>(packet_out b, in H hdr); 169 V1Switch( 170 MyParser(), 171 MyVerifyChecksum(), 172 MyIngress(), 173 MyEgress(), 174 MyComputeChecksum(), 175 MyDeparser() 176 ) main;

ύʔα w ύέοτͷϔομΛղੳ͢Δ෦෼ w ύʔε͢Δύέοτ͸QBDLFU@JOͱͯ͠౉͞ΕΔ w QBDLFU@JOͷFYUSBDUϝιου΍MPPLBIFBEϝιου΍BEWBODFϝιο υΛ༻͍ͯϔομΛղੳ͠ϔομߏ଄ମʹͦͷ৘ใΛ֨ೲ͍ͯ͘͠ w QBDLFU@JOͷFYUSBDUϝιουΛ࣮ 
ߦ͢ΔͱҾ਺ͷϑΟʔϧυ෼ύέ  οτ͕ॖΈҾ਺ʹ஋͕֨ೲ͞ΕΔ  ৄࡉޙड़ w ঢ়ଶػցΛ࣋ͪॳظঢ়ଶTUBSU͔Β  ࠷ऴతʹ͸BDDFQU͔SFKFDUʹࢸΔ w USBOTJUJPOͰ࣍ͷঢ়ଶʹҠߦ͢Δ w TFMFDUΛ࣮ߦ͢ΔͱҾ਺ͷ஋ʹԠ  ͨ͡ঢ়ଶΛฦ͢͜ͱ͕Ͱ͖Δ w ঢ়ଶ͸࠶ؼՄೳ 22 49 parser MyParser(packet_in packet, 50 out headers hdr, 51 inout metadata meta, 52 inout standard_metadata_t sta 53 54 state start { 55 transition parse_ethernet; 56 } 57 58 state parse_ethernet { 59 packet.extract(hdr.ethernet); 60 transition select(hdr.ethernet.etherT 61 TYPE_IPV4: parse_ipv4; 62 default: accept; 63 } 64 } 65 66 state parse_ipv4 { 67 packet.extract(hdr.ipv4); 68 transition accept; 69 } 70 71 }

σύʔα w ύέοτͷϔομΛॻ͖׵͑Δ෦෼ w σύʔε͢Δύέοτ͸QBDLFU@PVUͱͯ͠౉͞ΕΔ w FNJUϝιουΛ༻͍ͯϔομߏ଄ମ͔ΒϔομΛ૊Έཱ͍ͯͯ͘ w ֎ଆͷϔομ͔ΒFNJUϝιουΛݺͼग़͍ͯ͘͠ w
ϔομʹ͸WBMJEϑϥά͕͋Γ  WBMJEͳ΋ͷͷΈ͕ॻ͖ग़͞ΕΔ w WBMJEϑϥά͸ύʔα΍ޙड़͢Δ  ϚονΞΫγϣϯύΠϓϥΠϯ  Ͱߋ৽͞ΕΔ 23 158 control MyDeparser(packet_out packet, in headers hdr) { 159 apply { 160 packet.emit(hdr.ethernet); 161 packet.emit(hdr.ipv4); 162 } 163 }

FYUSBDUͱFNJU 24 packet.extract(hdr.ethernet); packet.extract(hdr.ipv4); IFBEFST FUIFSOFU@U JQW@U QBDLFU@JO 0010101101010111010101110101111010 ˣΧʔιϧ
QBDLFU@JO 0010101101010111010101110101111010 ˣΧʔι IFBEFST FUIFSOFU@U JQW@U 00101011... 11010101... ✔WBMJE ✔WBMJE QBDLFU@JO 0010101101010111010101110101111010 ˣΧʔιϧ IFBEFST FUIFSOFU@U JQW@U 00101011... ✔WBMJE

FYUSBDUͱFNJU 25 QBDLFU@PVU 0010101101010111010101110101111010 ˣΧʔιϧ packet.emit(hdr.ethernet); packet.emit(hdr.ipv4); QBDLFU 111010 ˣΧʔι
IFBEFST FUIFSOFU@U JQW@U 00101011... 11010101... ✔WBMJE ✔WBMJE QBDLFU@PVU 11010101110101111010 ˣΧʔιϧ IFBEFST FUIFSOFU@U JQW@U 00101011... 11010101... ✔WBMJE ✔WBMJE IFBEFST FUIFSOFU@U JQW@U 00101011... 11010101... ✔WBMJE ✔WBMJE ˞FNJUͱ͸ٯॱͰWBMJEͳ΋ͷΛੵΜͰ͍͘

MPPLBIFBEͱBEWBODF 26 hdr.ethernet = packet.lookahead<ethernet_t>(); packet.advance(14); IFBEFST FUIFSOFU@U JQW@U QBDLFU@JO
0010101101010111010101110101111010 ˣΧʔιϧ QBDLFU@JO 0010101101010111010101110101111010 ˣΧʔιϧ IFBEFST FUIFSOFU@U JQW@U 00101011... ✔WBMJE QBDLFU@JO 0010101101010111010101110101111010 ˣΧʔιϧ IFBEFST FUIFSOFU@U JQW@U 00101011... ✔WBMJE

ϚονΞΫγϣϯύΠϓϥΠϯ w ύʔαͰղੳͨ͠ϔομ৘ใ͔ΒςʔϒϧΛ୳ࡧ͠Ϛονͨ͠ΞΫγϣ ϯΛ࣮ߦ͢Δͱ͍͏Ұ࿈ͷॲཧͷྲྀΕΛهड़ͨ͠΋ͷ w BQQMZ w NBJOؔ਺ͷΑ͏ͳ΋ͷ w ςʔϒϧͷBQQMZ
ϝιουΛ  ݺͼग़͢͜ͱͰϔομ৘ใ͔Β  ΞΫγϣϯΛݺͼग़͢ w UBCMF w LFZͰͲͷϔομ৘ใ͔Β୳ࡧ  ͢Δ͔Λఆٛ w LFZʹ͸-1.΍&YBDUͳͲͷ  NBUDI@LJOE ΞʔΩςΫνϟ  ଆͰఆٛՄೳ Λࢦఆ͢Δ w BDUJPOTʹ͸ςʔϒϧʹొ࿥͞  ΕಘΔΞΫγϣϯΛྻڍ 27 86 control MyIngress(inout headers hdr, 87 inout metadata meta, 88 inout standard_metadata_t s ... লུ ... 93 action ipv4_forward(macAddr_t dstAddr, eg 94 standard_metadata.egress_spec = port; 95 hdr.ethernet.srcAddr = hdr.ethernet.d 96 hdr.ethernet.dstAddr = dstAddr; 97 hdr.ipv4.ttl = hdr.ipv4.ttl - 1; 98 } 100 table ipv4_lpm { 101 key = { 102 hdr.ipv4.dstAddr: lpm; 103 } 104 actions = { 105 ipv4_forward; 106 drop; 107 NoAction; 108 } 109 size = 1024; 110 default_action = NoAction(); 111 } 113 apply { 114 if (hdr.ipv4.isValid()) { 115 ipv4_lpm.apply(); 116 } 117 } 118 }

ϚονΞΫγϣϯύΠϓϥΠϯ w ύʔαͰղੳͨ͠ϔομ৘ใ͔ΒςʔϒϧΛ୳ࡧ͠Ϛονͨ͠ΞΫγϣ ϯΛ࣮ߦ͢Δͱ͍͏Ұ࿈ͷॲཧͷྲྀΕΛهड़ͨ͠΋ͷ w UBCMF DPOU w LFZͱBDUJPOT͸ඪ४ςʔϒϧ 
ϓϩύςΟ w FOUSJFTͰఆ਺هड़΋Մೳ w EFGBVMU@BDUJPO͸Φϓγϣφϧ  ςʔϒϧϓϩύςΟ w ͦΕҎ֎͸ΞʔΩςΫνϟґଘ w BDUJPO w ςʔϒϧʹϚονͨ࣌͠ʹݺͼ  ग़͞ΕΔؔ਺ͷΑ͏ͳ΋ͷ w Ҿ਺ʹ͸ςʔϒϧʹ֨ೲ͞Εͨ  ஋͕༻͍ΒΕΔ 28 86 control MyIngress(inout headers hdr, 87 inout metadata meta, 88 inout standard_metadata_t s ... লུ ... 93 action ipv4_forward(macAddr_t dstAddr, eg 94 standard_metadata.egress_spec = port; 95 hdr.ethernet.srcAddr = hdr.ethernet.d 96 hdr.ethernet.dstAddr = dstAddr; 97 hdr.ipv4.ttl = hdr.ipv4.ttl - 1; 98 } 100 table ipv4_lpm { 101 key = { 102 hdr.ipv4.dstAddr: lpm; 103 } 104 actions = { 105 ipv4_forward; 106 drop; 107 NoAction; 108 } 109 size = 1024; 110 default_action = NoAction(); 111 } 113 apply { 114 if (hdr.ipv4.isValid()) { 115 ipv4_lpm.apply(); 116 } 117 } 118 }

ϚονΞΫγϣϯύΠϓϥΠϯ w .Z*OHSFTTͷྫͰ͸ҎԼͷॲཧ͕ߦΘΕΔ w ϔομͷIESJQW͕WBMJEͩͬͨΒETU"EESΛΩʔʹJQW@MQNςʔ ϒϧΛ୳ࡧ w ΋͠Ϛον͢ΔΤϯτϦʔ͕ଘࡏͨ͠ͳΒͦͷΞΫγϣϯΛొ࿥ ͞ΕͨҾ਺Ͱݺͼग़͢ w
ͳ͚Ε͹EFGBVMU@BDUJPOͰ͋Δ/P"DUJPOΛݺͼग़͢ w Ͱɺ͜ͷςʔϒϧ͸Ͳ͏΍ͬͯ؅ཧ͢Δͷʁʁʁ 29 table ipv4_lpm IESJQWETU"EES ΞΫγϣϯ Ҿ਺ JQW@GPSXBSE ETU"EESEEC QPSU JQW@GPSXBSE ETU"EESEEC QPSU

ࢀߟ 13VOUJNF"1* 30 Copyright © 2017 – P4.org Control plane
What is P4Runtime? • Framework for runtime control of P4 targets ◦ Open-source API + server implementation ▪ 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 46 p4runtime.proto (API) Program-independent server (e.g. gRPC) Target driver P4 target l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

ࢀߟ 13VOUJNF"1* 31 Copyright © 2017 – P4.org More details
on the P4Runtime API 47 Full protobuf definition: https://github.com/p4lang/PI/blob/master/proto/p4/p4runtime.proto message TableEntry { uint32 table_id; repeated FieldMatch match; Action action; int32 priority; ... } message FieldMatch { uint32 field_id; message Exact { bytes value; } message Ternary { bytes value; bytes mask; } ... oneof field_match_type { Exact exact; Ternary ternary; ... } } message Action { uint32 action_id; message Param { uint32 param_id; bytes value; } repeated Param params; } p4runtime.proto simplified excerpts: To add a table entry, the control plane needs to know: • IDs of P4 entities ◦ Tables, field matches, actions, params, etc. • Field matches for the particular table ◦ Match type, bitwidth, etc. • Parameters for the particular action • Other P4 program attributes l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

ࢀߟ 13VOUJNF"1* 32 Copyright © 2017 – P4.org P4Runtime workflow
48 test.p4 test.json Control plane p4runtime.proto P4Runtime server BMv2 driver BMv2 simple_switch p4c-bm2-ss (compiler) P4Info • 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. test.p4info Full P4Info protobuf specification: https://github.com/p4lang/PI/blob/master/proto/p4/config/p4info.proto l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

ࢀߟ 13VOUJNF"1* 33 Copyright © 2017 – P4.org P4Info example
49 ... action ipv4_forward(bit<48> dstAddr, bit<9> port) { /* Action implementation */ } ... table ipv4_lpm { key = { hdr.ipv4.dstAddr: lpm; } actions = { ipv4_forward; ... } ... } basic_router.p4 actions { id: 16786453 name: "ipv4_forward" params { id: 1 name: "dstAddr" bitwidth: 48 ... id: 2 name: "port" bitwidth: 9 } } ... tables { id: 33581985 name: "ipv4_lpm" match_fields { id: 1 name: "hdr.ipv4.dstAddr" bitwidth: 32 match_type: LPM } action_ref_id: 16786453 } basic_router.p4info P4 compiler l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

ࢀߟ 13VOUJNF"1* 34 Copyright © 2017 – P4.org P4Runtime example
50 table_entry { table_id: 33581985 match { field_id: 1 lpm { value: "\n\000\002\002" prefix_len: 32 } } action { action_id: 16786453 params { param_id: 1 value: "\000\000\000\000\000\n" } params { param_id: 2 value: "\000\007" } } } action ipv4_forward(bit<48> dstAddr, bit<9> port) { /* Action implementation */ } table ipv4_lpm { key = { hdr.ipv4.dstAddr: lpm; } actions = { ipv4_forward; ... } ... } hdr.ipv4.dstAddr=10.0.1.1/32 -> ipv4_forward(00:00:00:00:00:10, 7) basic_router.p4 Logical view of table entry Protobuf message Control plane generates l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

ࢀߟ 13VOUJNF"1* 35 Copyright © 2017 – P4.org Remote control
51 P4Runtime control server Target driver Vendor A P4Runtime control server Target driver Vendor B P4Runtime control server Target driver Vendor C Remote control plane OSPF BGP P4-defined custom protocol etc. table_entry { table_id: 33581985 match { field_id: 1 lpm { value: "\f\000\... prefix_len: 8 } } action { action_id: 16786453 params { param_id: 1 value: "\000\0... } params { param_id: 2 value: 7 } } } Target-independent protobuf format p4info p4info p4info p4info l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

ࢀߟ 13VOUJNF"1* 36 Copyright © 2017 – P4.org Local control
52 P4Runtime control server Target driver P4 target Local control plane OSPF BGP P4-defined protocol etc. table_entry { table_id: 33581985 match { field_id: 1 lpm { value: "\f\000\... prefix_len: 8 } } action { action_id: 16786453 params { param_id: 1 value: "\000\0... } params { param_id: 2 value: 7 } } } Same target-independent protobuf format p4info p4info The P4 Runtime API can be used equally well by a remote or local control plane l1-BOHVBHF5VUPSJBMzIUUQTHJUIVCDPNQMBOHUVUPSJBMTSBXNBTUFS 1%@@'BMM1@UVUPSJBM@MBCTQEG͔ΒҾ༻

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P4のはなし

P4のはなし

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