`DMIRror`

Manage directed port mirroring

DMIRror

Shortest form: dmir.

Set up per-port mirroring (“directed mirroring”): copy packets received and/or sent on some ports to a destination port or trunk.

dmirror <ports>                              show mirroring of <ports>
dmirror SHow                                 show every port that mirrors
dmirror <ports> Mode=<OFF|ON|Ingress|Egress|All>
        [DestPort=<port>] [DestModule=<modid>] [DestTrunk=<tgid>]
        [MirrorTagProtocolID=<tpid>] [MirrorVlanID=<vid>]

<ports> is a port list such as xe0, ce1,ce2 or all (see pbmp). The CPU port (cpu0) can be a destination. Ingress mirrors received packets, Egress sent packets, and All both.

The shell behaves differently from the built-in help in these ways:

The help shows Mode as optional. In fact it is required whenever any option is given; otherwise the shell prints must specify a mode.
The help says “DestTrunk overrides DestModule/DestPort”. In fact giving both DestPort and DestTrunk is refused (cannot specify both DestPort and DestTrunk). Any mode other than OFF needs one of them (missing DestPort or DestTrunk).
dmirror show works but is not in the help.
The mirror TPID and VLAN are applied only when both are given and the destination is a local port, not a trunk.

Warning

Mode=OFF removes every mirror destination on those ports, both ingress and egress, including mirror sessions (SPAN/ERSPAN) that SONiC configured. Setting a mirror uses the same hardware mirror resources as SONiC’s mirror sessions. Neither change is visible to SONiC.

Seeing mirrored traffic with tcpdump: Capture port traffic with tcpdump.

Unvalidated — Copy everything received on xe0 to the CPU (prints nothing on success)

drivshell> dmirror xe0 mode=ingress destport=cpu0

Unvalidated — Stop mirroring on xe0 (also removes any other mirror on xe0)

drivshell> dmirror xe0 mode=off

Hardware-validated — Show the mirror state of one port

drivshell> dmirror xe0
 xe0: -

With a port list and no options, dmirror prints one line per port, for example xe0: Mirror ingress to local port cpu0, or xe0: - when the port does not mirror. A trunk destination shows as to trunk group <n>, and a configured mirror VLAN is appended as (TPID=…, VLAN=…).

dmirror SHow

Show every port that mirrors, one line per port in the format above. If no port mirrors, it prints DMIRror: No mirror ports configured (the prefix is the command’s table name, not what you typed). A SONiC switch without mirror sessions prints this line. Safe.

Hardware-validated

drivshell> dmirror show
DMIRror: No mirror ports configured

Built-in help

Parameters: <ports> [Mode=<Off|On|Ingress|Egress|All>]
    [DestPort=<port>] [DestModule=<modid>] [DestTrunk=<tgid>]
    [MirrorTagProtocolID=<tpid>] [MirrorVlanID=<vid>
    DestTrunk overrides DestModule/DestPort.
    TPID and VLAN are set only if DestPort is a local port.