Resumen de las opciones de actuación a nivel de la UE

Modifications to a meter from the controller are done with the OFPT_METER_MOD message:

/* Meter configuration. OFPT_METER_MOD. */ struct ofp_meter_mod {

struct ofp_header header;

uint16_t command; /* One of OFPMC_*. */

uint16_t flags; /* Bitmap of OFPMF_* flags. */ uint32_t meter_id; /* Meter instance. */

struct ofp_meter_band_header bands[0]; /* The band list length is inferred from the length field in the header. */

};

OFP_ASSERT(sizeof(struct ofp_meter_mod) == 16);

The meter_id field uniquely identifies a meter within a switch. Meter are defined starting with meter_id=1 up to the maximum number of meters that the switch can support. The OpenFlow protocol also defines some additional virtual meters that can not be associated with flows:

/* Meter numbering. Flow meters can use any number up to OFPM_MAX. */ enum ofp_meter {

/* Last usable meter. */ OFPM_MAX = 0xffff0000,

/* Virtual meters. */

OFPM_SLOWPATH = 0xfffffffd, /* Meter for slow datapath. */

OFPM_CONTROLLER = 0xfffffffe, /* Meter for controller connection. */ OFPM_ALL = 0xffffffff, /* Represents all meters for stat requests

commands. */ };

Virtual meters are provided to support existing implementations of OpenFlow. New implementations are encouraged to use regular per-flow meters or priority queues instead.

ˆ OFPM_CONTROLLER: Virtual meter controlling all packets sent to the controller via Packet-in mes- sages, either using the CONTROLLER reserved port or in other processing (see 6.1.2). Can be used to limit the amount of traffic sent to the controller.

ˆ OFPM_SLOWPATH: Virtual meter controlling all packets processed by the slow datapath of the switch. Many switch implementations have a fast and slow datapath, for example a hardware switch may have a slow software datapath, or a software switch may have a slow userspace datapath.

The command field must be one of the following:

/* Meter commands */

enum ofp_meter_mod_command {

OFPMC_ADD, /* New meter. */

OFPMC_MODIFY, /* Modify specified meter. */ OFPMC_DELETE, /* Delete specified meter. */ };

The flags field may include a combination of following flags:

/* Meter configuration flags */ enum ofp_meter_flags {

OFPMF_KBPS = 1 << 0, /* Rate value in kb/s (kilo-bit per second). */ OFPMF_PKTPS = 1 << 1, /* Rate value in packet/sec. */

OFPMF_BURST = 1 << 2, /* Do burst size. */ OFPMF_STATS = 1 << 3, /* Collect statistics. */ };

The bands field is a list of rate bands. It can contain any number of bands, and each band type can be repeated when it make sense. Only a single band is used at a time, if the current rate of packets exceed the rate of multiple bands, the band with the highest configured rate is used.

/* Common header for all meter bands */ struct ofp_meter_band_header {

uint16_t type; /* One of OFPMBT_*. */

uint16_t len; /* Length in bytes of this band. */ uint32_t rate; /* Rate for this band. */

uint32_t burst_size; /* Size of bursts. */ };

OFP_ASSERT(sizeof(struct ofp_meter_band_header) == 12);

The rate field indicates the rate value above which the corresponding band may apply to packets (see 5.7.1). The rate value is in kilobit per seconds, unless the flags field includes OFPMF_PKTPS, in which case the rate is in packets per seconds.

The burst_size field is used only if the flags field includes OFPMF_BURST. It defines the granularity of the meter, for all packet or byte burst which length is greater than burst value, the meter rate will always be strictly enforced. The burst value is in kilobits, unless the flags field includes OFPMF_PKTPS, in which case the burst value is in packets.

The type field must be one of the following:

/* Meter band types */ enum ofp_meter_band_type {

OFPMBT_DROP = 1, /* Drop packet. */

OFPMBT_DSCP_REMARK = 2, /* Remark DSCP in the IP header. */ OFPMBT_EXPERIMENTER = 0xFFFF /* Experimenter meter band. */ };

An OpenFlow switch may not support all band types, and may not allow to use all its supported bands on all meters, i.e. some meters may be specialised.

The band OFPMBT_DROP defines a simple rate limiter that drop packets that exceed the band rate value, and uses the following structure:

/* OFPMBT_DROP band - drop packets */ struct ofp_meter_band_drop {

uint16_t type; /* OFPMBT_DROP. */ uint16_t len; /* Length is 16. */

uint32_t rate; /* Rate for dropping packets. */ uint32_t burst_size; /* Size of bursts. */

uint8_t pad[4]; };

OFP_ASSERT(sizeof(struct ofp_meter_band_drop) == 16);

The band OFPMBT_DSCP_REMARK defines a simple DiffServ policer that remark the drop precedence of the DSCP field in the IP header of the packets that exceed the band rate value, and uses the following structure:

/* OFPMBT_DSCP_REMARK band - Remark DSCP in the IP header */ struct ofp_meter_band_dscp_remark {

uint16_t type; /* OFPMBT_DSCP_REMARK. */ uint16_t len; /* Length is 16. */

uint32_t rate; /* Rate for remarking packets. */ uint32_t burst_size; /* Size of bursts. */

uint8_t prec_level; /* Number of drop precedence level to add. */ uint8_t pad[3];

};

OFP_ASSERT(sizeof(struct ofp_meter_band_dscp_remark) == 16);

The prec_level field indicates by which amount the drop precedence of the packet should be increased if the band is exceeded.

The band OFPMBT_EXPERIMENTER is experimenter defined and uses the following structure:

/* OFPMBT_EXPERIMENTER band - Write actions in action set */ struct ofp_meter_band_experimenter {

uint16_t type; /* One of OFPMBT_*. */

uint16_t len; /* Length in bytes of this band. */ uint32_t rate; /* Rate for this band. */

uint32_t burst_size; /* Size of bursts. */ uint32_t experimenter; /* Experimenter ID. */ };

OFP_ASSERT(sizeof(struct ofp_meter_band_experimenter) == 16);

The experimenter field is the Experimenter ID, which takes the same form as in the typical experi- menter structure (see 7.2.5). The rest of the band body is experimenter defined.