SolarCapture Nodes

Data Structures
struct	sc_arista_ts_node
	This node is to be used with Arista switches that are able to add hardware timestamps to packets. This is useful when SolarCapture is doing software timestamping, as it provides more precise timestamps. More...
struct	sc_batch_limiter
	Node to limit the maximum batch size sent to downstream nodes. More...
struct	sc_delay_line
	Node to delay upstream packets by a random time within a given time range. Randomness is achieved by performing a hash on the destination IP address and can be controlled using the num_lines argument. More...
struct	sc_filter
	Node to direct all matched packets to one output and all other packets to another output. The filter can be provided via a BPF string, or via a sc_pkt_predicate object. More...
struct	sc_reader
	Takes an input stream of data in PCAP format and outputs individual packets. More...
struct	sc_tap
	Forward input to output and a copy of input to the 'tap' output. If a BPF or predicate filter is specified, only packets matching the filter are duplicated to the 'tap' output. More...

Detailed Description

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Data Structure Documentation

struct sc_arista_ts_node

This node is to be used with Arista switches that are able to add hardware timestamps to packets. This is useful when SolarCapture is doing software timestamping, as it provides more precise timestamps.

Arguments:

Argument	Optional?	Default	Type	Description
kf_ip_proto	Yes	253	SC_PARAM_INT	The IP protocol used to send key frames.
log_level	Yes	"sync"	SC_PARAM_STR	The logging level of the node, must be set to one of "silent", "errors", "setup", "sync" or "verbose".
filter_oui	Yes		SC_PARAM_STR	Filter out timestamps with this OUI.
kf_device	Yes		SC_PARAM_STR	Filter keyframes by device field.
kf_eth_dhost	No		SC_PARAM_STR	Destination MAC address for the keyframes.
kf_ip_dest	No		SC_PARAM_STR	Destination IP address for the keyframes.
tick_freq	Yes	350000000	SC_PARAM_INT	Expected frequency in Hz of the switch tick.
max_freq_error_ppm	Yes	20000	SC_PARAM_INT	Max ppm between expected and observed frequency before entering no sync state.
lost_sync_ms	Yes	10000	SC_PARAM_INT	Time after last keyframe to enter lost sync state.
no_sync_ms	Yes	60000	SC_PARAM_INT	Time after last keyframe to enter no sync state.
no_sync_drop	Yes	0	SC_PARAM_INT	Toggle sync drop, set to 1 for on 0 for off.
strip_ticks	Yes	1	SC_PARAM_INT	Toggle the option for the node to strip switch timestamps. Set to 0 for off and 1 for on.

Named Input Links:

None

Output Links:

Link	Description
""	All packets that have not been filtered by the node are sent down this link.

Exposed Statistics:

Name	Type	Data Type	Description
max_host_t_delta	double	config	Max delta in seconds the node can compute a tick-delta over.
max_freq_error	double	config	Max ppm allowed between measured and expected tick frequency before entering no sync state.
lost_sync_ms	int	config	Time in milliseconds spent in lost sync state.
no_sync_ms	int	config	Time in milliseconds spent in no sync state.
exp_tick_freq	int	config	The expected tick frequency in Hz.
strip_ticks	int	config	1 if the node is stripping ticks 0 otherwise.
log_level	int	config	The log level.
tick_freq	double	magnitude	The measured tick frequency in Hz.
n_keyframes	uint64_t	pkt_count	Number of keyframes processed by the node.
n_filtered_oui	uint64_t	pkt_count	Number of packets filtered out by OUI.
n_filtered_other	uint64_t	pkt_count	Number of packets filtered out for other reasons.
n_skew_zero_ticks	uint64_t	pkt_count	Number of skew zero packets received.
n_lost_sync	uint64_t	pkt_count	Number of packets processed whilst in lost sync state.
n_no_sync	uint64_t	pkt_count	Number of packets processed whilst in no sync state.
n_kf_len_mismatch	uint64_t	pkt_count	Number of packets received where the keyframe length did not match.
n_kf_dev_mismatch	uint64_t	pkt_count	Number of packets received where the device field did not match.
n_kf_bad_fcs_type	uint64_t	pkt_count	Number of keyframes with a bad FCS.
kf_switch_drops	uint64_t	pkt_count	Number of keyframes dropped by the switch.
n_kf_big_gap	uint64_t	pkt_count	Number of large gaps between keyframes.
n_skew	uint64_t	ev_count	Number of skews.
enter_no_sync	uint64_t	ev_count	Number of times the node has entered no sync state.
enter_sync1	uint64_t	ev_count	Number of times the node has entered sync1 state.
enter_sync2	uint64_t	ev_count	Number of times the node has entered sync2 state.
enter_lost_sync	uint64_t	ev_count	Number of times the node has entered lost sync state.

struct sc_batch_limiter

Node to limit the maximum batch size sent to downstream nodes.

This node can work in one of two modes

• default – Send packets as soon as possible.
• on_idle – Only send packets when the node detects it is in an idle state.

Arguments:

Argument	Optional?	Default	Type	Description
max_packets	Yes	64	SC_PARAM_INT	The maximum number of packets in a batch.
mode	Yes	NULL	SC_PARAM_INT	Batching mode can be either NULL for default mode or "on_idle".

Named Input Links:

None

Output Links:

Link	Description
""	All packets are sent down this link.

struct sc_delay_line

Node to delay upstream packets by a random time within a given time range. Randomness is achieved by performing a hash on the destination IP address and can be controlled using the num_lines argument.

If num_lines = 1:

• usec/nsec must be a single value.
• All packets will be delayed by this amount.

If num_lines > 1:

• usec/nsec must be a range of values <min_delay>-<max_delay>.
• Non-IP packets are delayed by exactly <min_delay>.
• IP packets are assigned a line by hashing the destination IP address.
• For a given line in (0, ..., num_lines-1) the delay is <min_delay> + (<max_delay> - <min_delay>) * (line / num_lines)

Arguments:

Argument	Optional?	Default	Type	Description
num_lines	Yes	1	SC_PARAM_INT	Number of lines used in the hash.
usec	Yes	NULL	SC_PARAM_STR	Set this to a string of the form "\<min_delay\>[-\<max_delay\>]" to set the delay time of the node in microseconds.
nsec	Yes	NULL	SC_PARAM_STR	Set this to a string of the form "\<min_delay\>[-\<max_delay\>]" to set the delay time of the node in nanoseconds.

Note: One and only one of usec and nsec must be set.

Named Input Links:

None

Output Links:

Link	Description
""	All packets are sent down this link.

struct sc_filter

Node to direct all matched packets to one output and all other packets to another output. The filter can be provided via a BPF string, or via a sc_pkt_predicate object.

Arguments:

Argument	Optional?	Default	Type	Description
bpf	Yes	NULL	SC_PARAM_STR	Filter string in Berkeley Packet Filter format.
predicate	Yes	NULL	SC_PARAM_OBJ	An SC_OBJ_PKT_PREDICATE to use as a filter.

Note: Exactly one of bpf and predicate must be set.

Named Input Links:

None

Output Links:

Link	Description
""	Packets matched by the filter.
"not_matched"	Packets not matched by the filter.

struct sc_reader

Takes an input stream of data in PCAP format and outputs individual packets.

PCAP data can be sent to this node either by passing a filename or file descriptor, in which case the node will create a new ::sc_fd_reader node upstream, or by explicitly connecting a node that sends PCAP data.

Packets can be passed on to downstream nodes in one of three modes:

• none – Emit packets as they are read.
• all-input – Emit packets when node receives end-of-stream. There will be a failure at runtime if the pool is too small to hold the entire input file.
• all-buffers – Emit packets when the buffers are full or when the node receives end-of-stream.

Arguments:

Argument	Optional?	Default	Type	Description
prefill	Yes	"none"	SC_PARAM_STR	Mode used to read PCAP files, can be one of "none", "all-input" or "all-buffers".
signal_eof	Yes	1	SC_PARAM_INT	Set to 1 to pass end-of-stream after emitting all packets. Otherwise set to 0
filename	Yes	NULL	SC_PARAM_STR	If fd is not set this tells the node to create a ::sc_fd_reader node to read PCAP data from the given filename. If fd is set then this file is used for logging purposes only.
fd	Yes	-1	SC_PARAM_INT	Setting this tells the node to create a ::sc_fd_reader node to read PCAP data from the given file descriptor.

Named Input Links:

None

Output Links:

Link	Description
""	The converted unpacked sc_packet stream.
"input"	The PCAP format stream.

struct sc_tap

Forward input to output and a copy of input to the 'tap' output. If a BPF or predicate filter is specified, only packets matching the filter are duplicated to the 'tap' output.

The node can be placed in one of two modes:

• default:
  • Input packets are always forwarded to "" immediately.
  • If buffers are available, they are copied to "tap" immediately, otherwise they never go to tap.
• Reliable:
  • If buffers are available, all packets are forwarded to "" and "tap" immediately.
  • If not, they are delayed until buffers are available and then forwarded to "" and "tap" at that point.

Note: In reliable mode this node can potentially create a backlog large enough to provoke drops in an upstream node or VI.

Arguments:

Argument	Optional?	Default	Type	Description
snap	Yes	0	SC_PARAM_INT	Copy at most n bytes of the duplicated frames, set to 0 to disable.
reliable	Yes	0	SC_PARAM_INT	Set to 1/0 to enable/disable reliable mode.
bpf	Yes	NULL	SC_PARAM_STR	Filter to select packets to duplicate in BPF format.
predicate	Yes	NULL	SC_PARAM_OBJ	Predicate object to select packets to duplicate.

Note: At most one of bpf and predicate may be specified.

Named Input Links:

None

Output Links:

Link	Description
""	All packets are sent down this link.
"tap"	The copy of the input.