Traditionally to detect and isolate network faults, ping and traceroute are used. But in a complex network with large number of U/E-CMP being availble, it would be difficult to detect and isolate faults in the network. Also detecting loss/reordering/duplication of packets becomes much harder. draft-lapukhov-dataplane-probe uses active probes to solve the above mentioned problems. UDP-Pinger with IOAM, would combine draft-lapukhov-dataplane-probe with IOAM-ietf-data and IOAM-ietf-transport to provide a more sophisticated way for detection/isolation of network faults and enable network telemetry.

UDP-Pinger for IPv6 does:

Crafts and sends Probe packets from source node to destination.
Probe packet is an IPv6 packet with HBH header to collect IOAM data and UDP header followed by payload.
UDP source and destination ports are varied to cover all possible paths in network as well as to simulate real application traffic.
IOAM Trace option is used to record the path Probe packets take and also for measuring latency.
IOAM E2E option is used to measure packet loss, reordering and duplicate packets.
UDP payload follows packet format in draft-lapukhov-dataplane-probe and is used on source/destination nodes to identify Probe/Reply packets.
Destination node on receiving Probe packet sends a reply back to source. Reply packet is formed by exchanging source and destination IP addresses and packet type in UDP payload.
Source node on receiving Reply packet can trace packet Path and measure latency, packet loss, reordering, duplication.
On detecting fault in network, Probe packets are sent with loopback flag set. On seeing loopback flag, each device in network along with forwarding the packet, also sends a copy back to source. With this Source node can corelate and detect the faulty node/link.

Configuration

Following section describes how to enable UDP-Pinger on a VPP node. Please note that IOAM configurations as mentioned in IOAM for IPv6 have to be made prior to starting any of the below configurations.

UDP-Pinger Enable/Disable

For configuring UDP-Pinger between two end-points, following parametrs need to be provided by using the CLI:

set udp-ping src <local IPv6 address>  src-port-range <local port range> 
dst <remote IPv6 address> dst-port-range <destination port range> 
interval <time interval in sec> [fault-detect] [disable]

src : IPv6 address of local node.
src-port-range : Port range for source port in UDP header. Syntax is <start_port>:<end_port>
dst : IPv6 address of the destination node.
dst-port-range : Port range for destination port in UDP header. Syntax is <start_port>:<end_port>
interval : Time interval in seconds for which Probe packets need to be sent out.
fault-detect : This is to enable IOAM loopback functionality on detecting a failure and to detect faulty node/link.
disable : Used for deleting a UDP-Ping flow.

Example:

To create a UDP-Pinger session:
set udp-ping src db00::1 src-port-range 5000:5002 dst db02::1 dst-port-range 6000:6002 interval 1 fault-detect

To delete a UDP-Pinger session:
set udp-ping src db00::1 src-port-range 5000:5002 dst db02::1 dst-port-range 6000:6002 interval 1 fault-detect disable

UDP-Pinger Data Export

For exporting network telemetry data extracted from UDP-Pinger sessions, below command is used. Data is exported as IP-Fix records.

set udp-ping export-ipfix [disable]

On enabling udp-ping export, UDP-Pinger data is exported as 
IP-Fix record to IP-Fix collector address as configured in
IP-Fix using the command:

set ipfix exporter collector <Remote IP Address> src <Local IP address>

Following data is exported from UDP-Pinger:

IOAM Trace information for each of UDP-Pinger flow
Roundtrip Delay
Packet loss count
Reordered Packet count
Duplicate Packet count

Example:

To enable export:
set ipfix exporter collector 172.16.1.254 src 172.16.1.229
set udp-ping export-ipfix

To disable export:
set udp-ping export-ipfix disable

Operational data

For checking the state of the UDP-Pinger sessions, below command can be used:

show udp-ping summary

Command displays follwing for each UDP-Pinger session:

IOAM Trace information for each of UDP-Pinger flow
Roundtrip Delay
Packet loss count
Reordered Packet count
Duplicate Packet count

Example:

vpp#show udp-ping summary
UDP-Ping data:
Src: db00::1, Dst: db02::1
Start src port: 5000, End src port: 5002
Start dst port: 6000, End dst port: 6002
Interval: 1

Src Port - 5000, Dst Port - 6000, Flow CTX - 0
Path State - Up
Path Data:    
pkt_sent : 400
pkt_counter : 400
bytes_counter : 458700
Trace data: 
pkt_sent : 400
pkt_counter : 400
bytes_counter : 45870
Trace data: 
path_map:

node_id: 0x1, ingress_if: 1, egress_if: 2, state:UP
node_id: 0x2, ingress_if: 0, egress_if: 2, state:UP
node_id: 0x3, ingress_if: 3, egress_if: 0, state:UP
node_id: 0x2, ingress_if: 4, egress_if: 9, state:UP
node_id: 0x1, ingress_if: 10, egress_if: 0, state:UP
pkt_counter: 400
bytes_counter: 45870
min_delay: 10
max_delay: 50
mean_delay: 15

POT data: 
sfc_validated_count : 0
sfc_invalidated_count : 0

Seqno Data:
RX Packets        : 400
Lost Packets      : 0
Duplicate Packets : 0
Reordered Packets : 0

Src Port - 5000, Dst Port - 6001, Flow CTX - 1
Path State - Down
Path Data:    
pkt_sent : 500
pkt_counter : 400
bytes_counter : 45870
Trace data: 
pkt_sent : 500
pkt_counter : 400
bytes_counter : 45870
Trace data: 
path_map:

node_id: 0x1, ingress_if: 1, egress_if: 2, state:UP
node_id: 0x2, ingress_if: 0, egress_if: 2, state:UP
node_id: 0x3, ingress_if: 3, egress_if: 0, state:Down
node_id: 0x2, ingress_if: 4, egress_if: 9, state:Down
node_id: 0x1, ingress_if: 10, egress_if: 0, state:Down
pkt_counter: 500
bytes_counter: 45870
min_delay: 50
max_delay: 500
mean_delay: 100

POT data: 
sfc_validated_count : 0
sfc_invalidated_count : 0

Seqno Data:
RX Packets        : 400
Lost Packets      : 100
Duplicate Packets : 20
Reordered Packets : 5

<So on for other source/destination port combination>