Configure and Monitor What Just Happened

The What Just Happened (WJH) feature, available on Mellanox switches, streams detailed and contextual telemetry data for analysis. This provides real-time visibility into problems in the network, such as hardware packet drops due to buffer congestion, incorrect routing, and ACL or layer 1 problems. You must have Cumulus Linux 4.0.0 or later and NetQ 2.4.0 or later to take advantage of this feature.

For a list of supported WJH events, refer to the WJH Event Messages Reference.

If your switches are sourced from a vendor other than Mellanox, this view is blank as no data is collected.

When WJH capabilities are combined with NetQ, you have the ability to hone in on losses, anywhere in the fabric, from a single management console. You can:

  • View any current or historic drop information, including the reason for the drop
  • Identify problematic flows or endpoints, and pin-point exactly where communication is failing in the network

By default, Cumulus Linux 4.0.0 provides the NetQ 2.3.1 Agent and CLI. If you installed Cumulus Linux 4.0.0 on your Mellanox switch, you need to upgrade the NetQ Agent and optionally the CLI to release 2.4.0 or later (preferably the latest release).

cumulus@:~$ sudo apt-get update
cumulus@:~$ sudo apt-get install -y netq-agent
cumulus@:~$ sudo netq config restart agent
cumulus@:~$ sudo apt-get install -y netq-apps
cumulus@:~$ sudo netq config restart cli

Configure the WJH Feature

WJH is enabled by default on Mellanox switches and no configuration is required in Cumulus Linux 4.0.0; however, you must enable the NetQ Agent to collect the data in NetQ 2.4.0 or later.

To enable WJH in NetQ:

  1. Configure the NetQ Agent on the Mellanox switch.

    cumulus@switch:~$ sudo netq config add agent wjh
    
  2. Restart the NetQ Agent to start collecting the WJH data.

    cumulus@switch:~$ sudo netq config restart agent
    

When you are finished viewing the WJH metrics, you might want to stop the NetQ Agent from collecting WJH data to reduce network traffic. Use netq config del agent wjh followed by netq config restart agent to disable the WJH feature on the given switch.

Using wjh_dump.py on a Mellanox platform that is running Cumulus Linux 4.0 and the NetQ 2.4.0 agent causes the NetQ WJH client to stop receiving packet drop call backs. To prevent this issue, run wjh_dump.py on a different system than the one where the NetQ Agent has WJH enabled, or disable wjh_dump.py and restart the NetQ Agent (run netq config restart agent).

Configure Latency and Congestion Thresholds

WJH latency and congestion metrics depend on threshold settings to trigger the events. Packet latency is measured as the time spent inside a single system (switch). Congestion is measured as a percentage of buffer occupancy on the switch. When specified, WJH triggers events when the high and/or low thresholds are crossed.

To configure these thresholds, run:

netq config add agent wjh-threshold (latency|congestion) <text-tc-list> <text-port-list> <text-th-hi> <text-th-lo>

You can specify multiple traffic classes and multiple ports by separating the classes or ports by a comma (no spaces).

This example creates latency thresholds for Class 3 traffic on port swp1 where the upper threshold is 10 and the lower threshold is 1.

cumulus@switch:~$ sudo netq config add agent wjh-threshold latency 3 swp1 10 1

This example creates congestion thresholds for Class 4 traffic on port swp1 where the upper threshold is 200 and the lower threshold is 10.

cumulus@switch:~$ sudo netq config add agent wjh-threshold congestion 4 swp1 200 10

Configure Filters

You can filter the WJH events at the NetQ Agent before it is processed by the NetQ system. Filtering is performed on a drop-type basis. You can filter the drop type further by specifying one or more drop reasons or severity. Filter events by creating a NetQ Configuration profile in the NetQ UI or using the netq config add agent wjh-drop-filter command in the NetQ CLI.

For a complete list of drop types and reasons, refer to the WJH Event Messages Reference.

To configure the NetQ Agent to filter WJH drops:

  1. Click (Upgrade) in a workbench header.

  2. Click Configuration Management.

  3. On the NetQ Configurations card, click Add Config.

  4. Click Enable to enable WJH, then click Customize.

  5. By default, all drop reasons and severities are selected. Uncheck any drop reasons or severity you do not want to use to generate WJH events, then click Done.

  6. Click Add to save the configuration profile, or click Close to discard it.

To configure the NetQ Agent to filter WJH drops, run:

netq config add agent wjh-drop-filter drop-type <text-wjh-drop-type> [drop-reasons <text-wjh-drop-reasons>] [severity <text-drop-severity-list>]

Use tab complete to view the available drop type, drop reason, and severity values.

This example configures the NetQ Agent to drop all L1 drops.

cumulus@switch:~$ sudo netq config add agent wjh-drop-filter drop-type l1

This example configures the NetQ Agent to drop only the L1 drops with bad signal integrity.

cumulus@switch:~$ sudo netq config add agent wjh-drop-filter drop-type l1 drop-reasons BAD_SIGNAL_INTEGRITY

This example configures the NetQ Agent to drop only router drops with warning severity.

cumulus@switch:~$ sudo netq config add agent wjh-drop-filter drop-type router severity Warning

This example configures the NetQ Agent to drop only router drops due to blackhole routes.

cumulus@netq-ts:~$ netq config add agent wjh-drop-filter drop-type router drop-reasons BLACKHOLE_ROUTE

This example configures the NetQ Agent to drop only router drops when the source IP is a class E address.

cumulus@netq-ts:~$ netq config add agent wjh-drop-filter drop-type router drop-reasons SRC_IP_IS_IN_CLASS_E

View What Just Happened Metrics

You can view the WJH metrics from the NetQ UI or the NetQ CLI.

  1. Click (main menu).

  2. Click What Just Happened under the Network column.

    This view displays events based on conditions detected in the data plane. The most recent 1000 events from the last 24 hours are presented for each drop category.

  1. By default the layer 1 drops are shown. Click one of the other drop categories to view those drops for all devices.

Run one of the following commands:

netq [<hostname>] show wjh-drop <text-drop-type> [ingress-port <text-ingress-port>] [severity <text-severity>] [reason <text-reason>] [src-ip <text-src-ip>] [dst-ip <text-dst-ip>] [proto <text-proto>] [src-port <text-src-port>] [dst-port <text-dst-port>] [src-mac <text-src-mac>] [dst-mac <text-dst-mac>] [egress-port <text-egress-port>] [traffic-class <text-traffic-class>] [rule-id-acl <text-rule-id-acl>] [between <text-time> and <text-endtime>] [around <text-time>] [json]
netq [<hostname>] show wjh-drop [ingress-port <text-ingress-port>] [severity <text-severity>] [details] [between <text-time> and <text-endtime>] [around <text-time>] [json]

Use the various options to restrict the output accordingly.

This example uses the first form of the command to show drops on switch leaf03 for the past week.

cumulus@switch:~$ netq leaf03 show wjh-drop between now and 7d
Matching wjh records:
Drop type          Aggregate Count
------------------ ------------------------------
L1                 560
Buffer             224
Router             144
L2                 0
ACL                0
Tunnel             0

This example uses the second form of the command to show drops on switch leaf03 for the past week including the drop reasons.

cumulus@switch:~$ netq leaf03 show wjh-drop details between now and 7d

Matching wjh records:
Drop type          Aggregate Count                Reason
------------------ ------------------------------ ---------------------------------------------
L1                 556                            None
Buffer             196                            WRED
Router             144                            Blackhole route
Buffer             14                             Packet Latency Threshold Crossed
Buffer             14                             Port TC Congestion Threshold
L1                 4                              Oper down

This example shows the drops seen at layer 2 across the network.

cumulus@mlx-2700-03:mgmt:~$ netq show wjh-drop l2
Matching wjh records:
Hostname          Ingress Port             Reason                                        Agg Count          Src Ip           Dst Ip           Proto  Src Port         Dst Port         Src Mac            Dst Mac            First Timestamp                Last Timestamp
----------------- ------------------------ --------------------------------------------- ------------------ ---------------- ---------------- ------ ---------------- ---------------- ------------------ ------------------ ------------------------------ ----------------------------
mlx-2700-03       swp1s2                   Port loopback filter                          10                 27.0.0.19        27.0.0.22        0      0                0                00:02:00:00:00:73  0c:ff:ff:ff:ff:ff  Mon Dec 16 11:54:15 2019       Mon Dec 16 11:54:15 2019
mlx-2700-03       swp1s2                   Source MAC equals destination MAC             10                 27.0.0.19        27.0.0.22        0      0                0                00:02:00:00:00:73  00:02:00:00:00:73  Mon Dec 16 11:53:17 2019       Mon Dec 16 11:53:17 2019
mlx-2700-03       swp1s2                   Source MAC equals destination MAC             10                 0.0.0.0          0.0.0.0          0      0                0                00:02:00:00:00:73  00:02:00:00:00:73  Mon Dec 16 11:40:44 2019       Mon Dec 16 11:40:44 2019

The following two examples include the severity of a drop event (error, warning or notice) for ACLs and routers.

cumulus@switch:~$ netq show wjh-drop acl
Matching wjh records:
Hostname          Ingress Port             Reason                                        Severity         Agg Count          Src Ip           Dst Ip           Proto  Src Port         Dst Port         Src Mac            Dst Mac            Acl Rule Id            Acl Bind Point               Acl Name         Acl Rule         First Timestamp                Last Timestamp
----------------- ------------------------ --------------------------------------------- ---------------- ------------------ ---------------- ---------------- ------ ---------------- ---------------- ------------------ ------------------ ---------------------- ---------------------------- ---------------- ---------------- ------------------------------ ----------------------------
leaf01            swp2                     Ingress router ACL                            Error            49                 55.0.0.1         55.0.0.2         17     8492             21423            00:32:10:45:76:89  00:ab:05:d4:1b:13  0x0                    0                                                              Tue Oct  6 15:29:13 2020       Tue Oct  6 15:29:39 2020
cumulus@switch:~$ netq show wjh-drop router
Matching wjh records:
Hostname          Ingress Port             Reason                                        Severity         Agg Count          Src Ip           Dst Ip           Proto  Src Port         Dst Port         Src Mac            Dst Mac            First Timestamp                Last Timestamp
----------------- ------------------------ --------------------------------------------- ---------------- ------------------ ---------------- ---------------- ------ ---------------- ---------------- ------------------ ------------------ ------------------------------ ----------------------------
leaf01            swp1                     Blackhole route                               Notice           36                 46.0.1.2         47.0.2.3         6      1235             43523            00:01:02:03:04:05  00:06:07:08:09:0a  Tue Oct  6 15:29:13 2020       Tue Oct  6 15:29:47 2020