Extensions To OpenFlow Protocol In Support Circuit Switching

The port number is a value that the datapath associates with a physical port. The port numbers usagehas been changed to account for additional port types:/* Port numbering. Physical ports are numbered starting from 0. */enum ofp port {/* Max number of real Ethernet and TDM ports – 0xfa00 (0x0000 to 0xf9ff)*//* Switch internal ports - 0xfa00 to 0xfaff *//* Switch virtual circuit ports - 0xfb00 to 0xfeff*//* Other virtual ports – 0xff00 to 0xffff*/OFPP MAX/* Fake output "ports". */OFPP IN PORTOFPP TABLEOFPP NORMALOFPP FLOODOFPP ALLOFPP CONTROLLEROFPP LOCALOFPP NONE}; 0xfa00, 0xfff8, /* Send the packet out the input port. Thisvirtual port must be explicitly usedin order to send back out of the input port. */ 0xfff9, /* Perform actions in flow table.NB: This can only be the destinationport for packet-out messages. */ 0xfffa, /* Process with normal L2/L3 switching. */ 0xfffb, /* All physical ports except input port andThose disabled by STP. */ 0xfffc, /* All physical ports except input port. */ 0xfffd, /* Send to controller. */ 0xfffe, /* Local openflow "port". */ 0xffff /* Not associated with a physical port. */The only change made from the OpenFlow packet switch specification is that we have limited thenumber of physical ports to 0xfa00 instead of 0xff00 and used the numbers in between to specifyinternal and virtual ports used in circuit switches. These internal port numbers can be used to specify“mapper” ports that map Ethernet packets to TDM time‐slots, while the virtual ports can be used todefine Virtual Concatenation Group (VCG) numbers used for VCAT technology in TDM switches.The hardware address is the Ethernet address of the port for Ethernet ports, and is zeroed out for othertypes of ports (SONET/Wavelength) in circuit switches. The name field is a null terminated stringcontaining a human readable name for the interface. In packet switches, examples are eth0, eth1 etc. Incircuit switches, it can correspond to the standard Rack‐Shelf‐Slot‐Port designation for telecomequipment. The config and state fields are currently the same as described in the OpenFlowspecification for packet switches. The features bitmap has been modified to include line‐rates intransport networks./* Features of physical ports available in a datapath. */enum ofp port features {OFPPF 10MB HD 1 0, /* 10 Mb half-duplex rate support. */OFPPF 10MB FD 1 1, /* 10 Mb full-duplex rate support. */OFPPF 100MB HD 1 2, /* 100 Mb half-duplex rate support. */OFPPF 100MB FD 1 3, /* 100 Mb full-duplex rate support. */OFPPF 1GB HD 1 4, /* 1 Gb half-duplex rate support. */OFPPF 1GB FD 1 5, /* 1 Gb full-duplex rate support. */

OFPPF 10GB FDOFPPF COPPEROFPPF FIBEROFPPF AUTONEGOFPPF PAUSEOFPPF PAUSE ASYM 1 6, /* 10 Gb full-duplex rate support (10.3125 Gbps LAN PHY). */ 1 7, /* Copper medium */ 1 8, /* Fiber medium */ 1 9, /* Auto-negotiation */ 1 10, /* Pause */ 1 11, /* Asymmetric pause *//* The following have been added for WAN interfaces*/OFPPF X 1 20, /* Don’t care – applicable to fiber switch ports */OFPPF OC1 1 21, /* 51.84 Mbps OC-1/STM-0 */OFPPF OC3 1 22, /* 155.52 Mbps OC-3/STM-1 */OFPPF OC12 1 23, /* 622.08 Mbps OC-12/STM-4 */OFPPF OC48 1 24, /* 2.48832 Gbps OC-48/STM-16 */OFPPF OC192 1 25, /* 9.95328 Gbps OC-192/STM-64 */OFPPF OC768 1 26, /* 39.81312 Gbps OC-768/STM-256 */OFPPF 100GB 1 27, /* 100 Gbps */OFPPF 10GB WAN 1 28, /* 10 Gbps Ethernet WAN PHY (9.95328 Gbps) */OFPPF OTU1 1 29, /* OTN OTU-1 2.666 Gbps */OFPPF OTU2 1 30, /* OTN OTU-2 10.709 Gbps */OFPPF OTU3 1 31 /* OTN OUT-3 42.836 Gbps */};The above line rates are OCs (SONET standard) and their corresponding STMs (SDH standard). OpticalTransport Network (OTN, G.709, digital wrapper) data rates have been added above as placeholders –this specification does not currently support OTN. The swtype fields are defined as:/*Switching type of physical ports available in a datapath. */enum ofp port swtype {OFPST L4 1 0, /* Capable of switching packets based on TCP or UDP headers*/OFPST IP 1 1, /* Capable of switching packets based on IP headers */OFPST MPLS 1 2, /* Capable of switching packets based on MPLS labels*/OFPST VLAN 1 3, /* Capable of switching packets based on VLAN tags */OFPST ETH 1 4, /* Capable of switching packets based on Ethernet headers */OFPST T SONET 1 11, /* Capable of switching circuits (timeslots) based on SONET standard */OFPST T SDH 1 12, /* Capable of switching circuits (timeslots) based on SDH standard */OFPST T OTN 1 13, /* Capable of switching circuits (timeslots) based on OTN standard */OFPST WAVE 1 14, /* Capable of switching circuits (wavelengths) based on ITU-T grid wavelengths */OFPST FIBER 1 15 /* Capable of switching circuits (fibers) */};An OpenFlow packet switch can switch flows on the basis of Ethernet, IP, VLAN and transport layerheaders. Such a switch will set multiple bits above. This specification does not currently support MPLSlabel switching or TDM switching based on OTN frame formats. The sw tdm gran fields are defined as:/* Minimum switching granularity of TDM physical ports available in a datapath. */enum ofp port tdm gran{OFPTSG STS 1,/* STS-1/STM-0 */OFPTSG STS 3,/* STS-3/STM-1 */OFPTSG STS 3c,/* STS-3c/STM-1*/OFPTSG STS 12,/* STS-12/STM-4 */OFPTSG STS 12c,/* STS-12c/STM-4c */OFPTSG STS 48,/* STS-48/STM-16 */OFPTSG STS 48c,/* STS-48c/STM-16c */OFPTSG STS 192,/* STS-192/STM-64 */OFPTSG STS 192c,/* STS-192c/STM-64c */

OFPTSG STS 768,OFPTSG STS 768c/* STS-768/STM-256 *//* STS-768c/STM-256c */}The STS‐*c signal bits should only be set if the switch supports contiguous concatenation in the switchcapabilities. Note that the OpenFlow protocol does not support TDM signals smaller than STS‐1 –i.e. noSONET VT’s or SDH LOVC’s are supported.The bandwidth1 and bandwidth2 fields of the ofp phy cport struct need to be explained in moredetail. Their purpose is to flexibly indicate the bandwidth supported and currently used/available by thecircuit port. Their interpretation depends on the switching type of the switch port. If the switching type of the port (defined in the supp swtype field) is OFPST WAVE, thenbandwidth1 and bandwidth2 are bitmaps corresponding to the OFPCBL * flags. Additionally,bandwidth1 identifies the wavelengths supported by the switch and bandwidth2 identifies thewavelengths currently under use (ie. cross‐connected) If the switching type of the port is OFPST T SONET or OFPST T SDH, then bandwidth1 andbandwidth2 identify available time slots for various TDM signals. Depending on the line‐rate, wedefine different interpretations of the bits in the 64‐bit field below. Note that we do not need one ofthe fields to identify supported time‐slots as that can be inferred from the line‐rate and TDMswitching granularity.For a switching type of OFPST WAVE, bandwidth 1 has the following meaning: The lower 10 bits of the64 bit uint64 t will be used for flags with special meaning. The upper 54 bits will be used to designateITU‐T grid frequencies supported by the switch port./*Switching granularity of TDM physical ports available in a datapath. */enum ofp port lam bw{OFPCBL X 1 0, /* 1 if fiber switch – don’t care what wavelength is used, 0 if lambda switch */OFPCBL 100 50 1 1, /* 1 if 100GHz channel spacing, 0 if 50 GHz */OFPCBL C L 1 2, /* 1 if C –band, 0 if L-band */OFPCBL OSC 1 3, /* 1 if supporting the OSC at 1510nm, 0 if not */OFPCBL TLS 1 4 /* 1 if using TLS, 0 if not */};Bits 5 through 9 are reserved for future use. In a 100 GHz channel spaced system, the bits 10‐63 are asfollows: bit 10 corresponds to 196.7 THz (1524.11 nm), bit 11 to 196.6 THz, bit 12 to 196.5 THz and soon, with bit 63 corresponding to 191.4 THz (1566.33 nm). In an L‐Band system, bit 10 would correspondto 190.7 THz (1572.06 nm) and bit 63 to 185.4 THz (1617.08 nm).bandwidth1 and bandwidth2 fields:

Although bit 1 is used to identify a 100GHz systtem or a 50GGHz system, this specification currentlyy doesnot suppoort a 50GHz spaced systeem. Bit 2 ideentifies a C or L band system. A waveelength switch hasmux/demmux filters that are designeed to operatee in either thee C or L bandss but not both. Accordinglly thisbit indicates whether the flags in bit 10‐63 coorrespond to C or L band wavelengthss. Bit 0 is used toidentify a fiber switchh as opposed to a waveleength switch which can distinguish beetween and switchswavelengths individuaally. A fiber switch is typpically agnostic to whateever signals area carried in theincoming fiber and thhus a ‘don’t care’ applies in this casee. However iff a fiber swittch is used withw atranspondder on the poort, then the switch port shouldsbe treated as a wavelength swittch port (bit 0 0,one of bitts 10‐63 should be set, andd the line‐ratee flag OFPPF * should be set).sAnother relevantrsituaation is with regards to a wavelengthh switch used in a systemm where diffferentwavelengths support different linee‐rates. For example,ein a 40 channel C‐band systtem, it is possibleuthat some waveleengths have transceiverstoat 10 Gbps.(though unlikely)running at 2.5 Gbps and othersWhile it maym seem thaat a wavelength switch shhould be agnnostic to the line‐rate akinn to fiber swiitches, this is not always truee. This is beccause waveleength switches have filteers towithout transponderstmux/demmux wavelenggths and thesse filters have passband widthswdesignned for a cerrtain line‐ratee andchannel spacing. Whilee a filter desiigned for 10 Gbps signal canc pass a 2.55 Gbps signall (albeit with morecpass a 40 Gbps signnal. Thus for a wavelengthh switch, we neednto speciify for the port thenoise) it cannothighest linne‐rate it can support withh the OFPPF * flags.Bit 3 is used to identifyy the Optical Supervisory ChannelC(OSCC‐typically at 15101nm) which is convertted tothe electrical domain, processed and then ree‐converted tot the opticaal domain foor transmission (aprocess known as OEOO). Bit 4 is useed to identify a Path Terminating Equipmment (PTE) whichwhas a tunablelaser sourrce (TLS) on thhe output port. In this case, the bandwwidth1 field identifies the tuning range ofo theTLS and thet bandwidtth2 field idenntifies the currrent laser wavelength.wNote that the TLS must supportITU grid wavelengths.wAlso our use of ‘PTE’ heree signifies equipment thatt adapts packkets to circuitts andvice versaa – for eg. a laarge backbone packet swittch with circuit ports.For a swittching type off OFPST T SOONET or OFPSST T SDH, baandwidth1 annd bandwidthh2 fields shouuld beused togeether to identify the availlable startingg time slots ono the opticall carrier. Thiss then depends onthe line‐raate of the optical carrier anda the minimmum switchinng granularityy of the switcch. Assuming STS‐1for the lattter, we identtify the bit intterpretation ini the two fieelds as below::OC‐768bandwidth1 field:bandwidth2 field:

For an OCC‐768 line‐ratte, there is 1 possible starrting timeslott for an STS‐7768c signal, 4 possible sloots foran STS‐1992c signal, 16 possible slotss for an STS‐448c signal, 64 for STS‐12c, 256 for STS‐33c and 768 for STS‐1. Of theese, the banddwidth1 fieldd identifies all possible chhoices for STTS‐768c, STS‐‐192c and STTS‐48csignals. Thhe availabilityy of time‐slotts for the STS‐‐768c signal is shown by settingsall four bits 0‐3. For STS‐192c and STS‐48c the availabilityaoff the time‐sloot is indicatedd by setting thhe corresponding bit or zeeroing0‐55 indicate 6 possible chhoices of available startingg time‐slots forf anit if it is already being used. Bits 20STS‐12 siggnal (out of a total 64).The interpretaation of thesse bits meritss a more dettailed explanaation.When wee say 64 posssible starting time‐slot chooices, we meean that choiice 0 is time‐‐slot 0, choice 1 istime‐slot 12, and choicce 2 is time‐sslot 24 and soo on. The 64 choicesccan beb representeed in binary withw 6thbits. Thuss if bits 31‐266 of the bandwidth1 field are for example 110001, it represents the 49 choice ofstarting timetslot – ie. time‐slot 588. Similarlly, bits 56‐633 of bandwiddth1 and 0‐223 of bandwwidth2representt 4 possible starting time‐slot choices (8( bits each) for an STS‐3cc signal (out ofo a possible 256),and bits 24‐632represeent 4 possible choices (10 bitsb each) for an STS‐1 signnal.Lastly it should be notted, that whille the numbeer of choices we can repreesent for the lower rate signalsappears loow, this is generally not thhe case. This is because anny choice for a higher ratee signal repreesentsmultiple choicescfor a lower rate signal. For example, if as abbove the 49thh choice is ideentified for ann STS‐12c signal (starting timme‐slot 588), iti also represents 4 additioonal choices for an STS‐3cc signal – 588, 591,594, and 597, as well as 12 additional choices for an STS‐11 signal – 588, 589, 590 anda so on. Similarreasoningg can be followwed for OC‐1192 below:OC‐192Bits 20‐61 in bandwiidth1 represeent 7 choicees for an STTS‐3c signal (out of 64), and bandwwidth2representts 8 choices foor an STS‐1 signal (out of 192).1OC‐48With an OC‐48Osignal, we can repreesent all 48 possibleptime‐‐slots for STS‐‐1 signals, as well as all 166 STS‐3cs, and 4 STS‐12cs. SimilarlySwe canc representt all possible choices for alla possible signals in an OC‐12Osignal with just the banndwidth1 field.

3.4 Circuit Flow Cross‐Connect StructureThe logical equivalent of the ofp match structure from the packet switching spec is the ofp connectstructure in the circuit switching addendum. It is used to describe the circuit flow much like the matchstructure is used to describe the packet flow. When describing a cross‐connection, the following structofp connect is used within struct ofp cflow mod message (Section 3.5):/*Description of a cross-connection*/struct ofp connect{uint16 t wildcards;uint16 t num components;uint8 t pad[4];/* identifies which two ports to use below *//* identifies number of cross-connect to be made – ie. num array elems*//* for 64 bit alignment*/uint16 t in port[0];uint16 t out port[0];/* OFPP * ports – real or virtual *//* OFPP * ports – real or virtual */struct ofp tdm port in tport[0];struct ofp tdm port out tport[0];/* description of TDM channel */struct ofp wave port in wport[0];struct ofp wave port out wport[0];/* description of lambda channel */};OFP ASSERT(sizeof(struct ofp connect) 8 );The wildcards field simply identifies which fields in the ofp connect structure should be ignored whenlooking to cross‐connect an incoming port to an out‐going port. Note that of the 6 choices currentlydefined in the wildcards field, at least 4 need to be set, so that the 2 zeroed out wildcard flagscorrespond to a type of input port and a type of output port. Since the ofp connect structure is reallylike a header followed by variable length arrays, the num components field identifies the bytes tofollow./* Flow wildcards */enum ofp connect wildcards {OFPCW IN PORTOFPCW OUT PORTOFPCW IN TPORTOFPCW OUT TPORTOFPCW IN WPORTOFPCW OUT WPORT}; 1 1 1 1 1 1 0,1,2,3,4,5For example, a valid wildcard entry can be 0x003C indicating a regular input port to output portconnection. The num components identify in this case could be 2, indicating that the 4 bytesimmediately following the padding bytes, contain ports numbers for 2 in ports, followed by 4 bytes fortwo out ports. A TDM to TDM cross‐connection can be identified as 0x0033 and a lambda cross‐connection as 0x000F. In the former case, if num components is 2, it indicates that the 16 bytesfollowing the padding bytes, describe two in tports, followed by 16 bytes of two out tports. It is alsopossible to connect dissimilar port types as will be explained in the next section. As an example awildcard entry of 0x0036 would indicate cross‐connecting a regular input port (real or virtual) to a TDMport. Descriptions of TDM and wavelength ports are defined below;

/* Description of a TDM port */struct ofp tdm port {uint16 t tport;/* port numbers in OFPP * ports */uint16 t tstart;/* starting time-slot in binary */uint32 t tsignal;/* one of OFPTSG * flags */};OFP ASSERT(sizeof(struct ofp tdm port) 8 );/*Description of a wavelength port */struct ofp wave port {uint16 t wport;/* restricted to real port numbers in OFPP * ports */uint8 t pad[6];uint64 t wavelength;/* use of the OFPCBL * flags */};OFP ASSERT(sizeof(struct ofp wave port) 16 );As mentioned above, multiple ports can be cross‐connected on the switch with a single structofp connect. For example if we wish to make the following connections:tport 1, tsignal STS-3c, tstart 9 ÅÆ tport 3, tsignal STS-3c, tstart 9tport 5, tsignal STS-12c, tstart 24 ÅÆ tport 3, tsignal STS-12c, tstart 24tport 1, tsignal STS-3c, tstart 12 ÅÆ tport 3, tsignal STS-3c, tstart 0We can do so by defining the num components as 3, creating an array of ofp tdm port’s with the leftside of the above connections as in port, and the right side as out port and requiring thatcorresponding elements of the two arrays should be cross‐connected.3.5 Circuit Flow Add/Modify/DeleteModifications to the flow table in a circuit switch are accomplished via the OFPT FLOW MOD message.This message is the only new message type introduced by this spec. The enum ofp type is changed asbelow.enum ofp type {/* Immutable messages. */OFPT HELLO,OFPT ERROR,OFPT ECHO REQUEST,OFPT ECHO REPLY,OFPT VENDOR,/* Symmetric message *//* Symmetric message *//* Symmetric message *//* Symmetric message *//* Symmetric message *//* Switch configuration messages. */OFPT FEATURES REQUEST, /* Controller/switch message */OFPT FEATURES REPLY,/* Controller/switch message */OFPT GET CONFIG REQUEST,/* Controller/switch message */OFPT GET CONFIG REPLY, /* Controller/switch message */OFPT SET CONFIG,/* Controller/switch message *//* Asynchronous messages. */OFPT PACKET IN,OFPT FLOW EXPIRED,OFPT PORT STATUS,/* Async message *//* Async message *//* Async message *//* Controller command messages. */

OFPT PACKET OUT,OFPT FLOW MOD,OFPT PORT MOD,/* Controller/switch message *//* Controller/switch message *//* Controller/switch message *//* Statistics messages. */OFPT STATS REQUEST,OFPT STATS REPLY,/* Controller/switch message *//* Controller/switch message *//* Controller command messages for circuit switches. */OFPT CFLOW MOD/* Controller/switch message */};The associated struct ofp cflow mod is shown below:/* Circuit flow setup, modification and teardown (controller Æ datapath) */struct ofp cflow mod {struct ofp header header;unit16 t command;/* one of OFPPC * flags */uint16 t hard timeout;/* max time to connection tear-down,/ * if 0 then explicit tear-down required */uint8 t pad[4];struct ofp connect connect;/* 8B followed by variable length arrays */struct ofp action header actions[0];/* variable number of actions*/};OFP ASSERT(sizeof(struct ofp cflow mod) 24);The length field in the header is the total length of the message. The connect field describes the cross‐connections to be made and is of variable length. The number of bytes defining the cross‐connections tobe made can be inferred from the wildcards and num components field in struct ofp connect asdescribed in the previous section. The actions length can then be inferred by subtracting all precedingbytes from the length field in the header. The command field must be one of the following as defined inOF packet switch spec v0.8.9:enum ofp flow mod command {OFPFC ADD,/* New flow. */OFPFC MODIFY,/* Modify all matching flows. */OFPFC MODIFY STRICT, /* Modify entry strictly matching wildcards */OFPFC DELETE,/* Delete all matching flows, analogous to tearing down a circuit flow. */OFPFC DELETE STRICT, /* Strictly match wildcards and priority. */OFPFC DROP/* Terminate a circuit flow */};However, for circuit flows, we require that OFPFC MODIFY STRICT and OFPFC DELETE STRICT are usedto modify and terminate existing connections. Also note that there is no ‘idle timeout’ field in theflow mod struct as it normally not possible to tell in circuit switches, if the circuit is idle or not. We dohowever include a hard timeout field, which may find some uses in certain cases, where the duration ofa flow is pre‐determined. If this value is set to zero, circuit flows will be permanent and an explicitDELETE STRICT will be required to teardown the flow. Additionally, we have added an extra commandOFPFC DROP, which is used to s

n switch pa intain separ 2@stanford.edu) OpenFlow c specification g). This spec time‐slots, w interfaces an s OpenFlow his documen independent ircuit switch. for packet ification cov avelengths a d conversel protocol cha t should be v ly. We recomm switches o ers the