Interfaces can stay in always in suppressed/damping status if the link has LOCAL-FAULT on it. Interface will remain in down state.
Interfaces can stay in always in suppressed/damping status if the link has LOCAL-FAULT on it.
Sample Interface Configuration:
interfaces {
et-0/0/0 {
mtu 9192;
hold-time up 3000 down 0;
damping {
half-life 30;
max-suppress 900;
reuse 1;
suppress 1050;
enable;
}
We can see that Interface is in suppressed state.
Physical interface: et-0/0/0, Enabled, Physical link is Down
. . .
Ethernet-Switching Error: None, Loopback: Disabled, Source filtering: Disabled, Flow control: Enabled
Hold-times : Up 3000 ms, Down 0 ms
Damping : half-life: 30 sec, max-suppress: 900 sec, reuse: 1, suppress: 1050, state: suppressed
Current address: d8:53:9a:18:7d:8d, Hardware address: d8:53:9a:18:7d:8d
Last flapped : 2025-08-07 03:41:46 UTC (00:22:29 ago)
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Policed discards: 0, L3 incompletes: 0, L2 channel errors: 0,
L2 mismatch timeouts: 0, FIFO errors: 0, Resource errors: 0
Output errors:
Carrier transitions: 6, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0,
Active alarms : LINK
Active defects : LINK, LOCAL-FAULT
We can enable the debug “debug interface flaps” or “undebug interface flaps” from the FPC shell and see that suppressed state should be cleared in 342645ms (around 342 seconds or 5 minutes and 42 seconds) but as per the above output we see that the suppressed state is there for the more then 22 mins.
Interface debug from the FPC shell:
[Thu Aug 7 03:53:46.219 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 03:53:46.501 LOG: Warning] T6E(0/0) link[40 0] UP, phy_link_ok: 61520 mac_local_fault:0 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 03:53:46.501 LOG: Debug] IFD: et-0/0/0 cat 5 cleared alarm LINKDOWN
[Thu Aug 7 03:53:46.501 LOG: Debug] IFD: et-0/0/0, on up timed list
[Thu Aug 7 03:53:46.503 LOG: Debug] IFD: et-0/0/0, up/down timer started
[Thu Aug 7 03:53:48.462 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 03:53:48.492 LOG: Debug] IFD: et-0/0/0, Detected Flap Down State
[Thu Aug 7 03:53:48.492 LOG: Warning] T6E(0/0) link[40 0] DOWN, phy_link_ok: 0 mac_local_fault:1 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 03:53:48.492 LOG: Debug] IFD: et-0/0/0 cat 5 activated alarm LINKDOWN
[Thu Aug 7 03:53:49.503 LOG: Debug] IFD: et-0/0/0, up/down timer fired (3000)
[Thu Aug 7 03:53:49.503 LOG: Debug] IFD: et-0/0/0 down, St:0x00000001, Ac:0x00000001, Cl:0x00000000:
[Thu Aug 7 03:53:49.503 LOG: Info] ifp et-0/0/0 ifd_mdown: 918101916 ms
[Thu Aug 7 03:53:49.503 LOG: Debug] IFD: et-0/0/0, penalty: curr = 0.000186, new = 1000.000186, max = 1073764537, ttr=298973ms, elapse time = 714008
[Thu Aug 7 03:53:49.517 LOG: Debug] IFD: et-0/0/0, sent flap msg to RE, Down state
[Thu Aug 7 03:53:50.359 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 03:53:50.495 LOG: Warning] T6E(0/0) link[40 0] UP, phy_link_ok: 61520 mac_local_fault:0 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 03:53:50.495 LOG: Debug] IFD: et-0/0/0 cat 5 cleared alarm LINKDOWN
[Thu Aug 7 03:53:50.495 LOG: Debug] IFD: et-0/0/0, on up timed list
[Thu Aug 7 03:53:50.495 LOG: Debug] IFD: et-0/0/0, up/down timer started
[Thu Aug 7 03:53:52.493 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 03:53:52.542 LOG: Debug] IFD: et-0/0/0, Detected Flap Down State
[Thu Aug 7 03:53:52.542 LOG: Warning] T6E(0/0) link[40 0] DOWN, phy_link_ok: 0 mac_local_fault:1 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 03:53:52.542 LOG: Debug] IFD: et-0/0/0 cat 5 activated alarm LINKDOWN
[Thu Aug 7 03:53:53.495 LOG: Debug] IFD: et-0/0/0, up/down timer fired (3000)
[Thu Aug 7 03:53:53.495 LOG: Debug] IFD: et-0/0/0 down, St:0x00000001, Ac:0x00000001, Cl:0x00000000:
[Thu Aug 7 03:53:53.495 LOG: Info] ifp et-0/0/0 ifd_mdown: 918105910 ms
[Thu Aug 7 03:53:53.495 LOG: Debug] IFD: et-0/0/0, penalty: curr = 911.873148, new = 1911.873148, max = 1073764537, ttr=327023ms, elapse time = 3994
[Thu Aug 7 03:53:53.497 LOG: Debug] IFD: et-0/0/0, sent flap msg to RE, Down state
[Thu Aug 7 03:53:54.375 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 03:53:54.497 LOG: Warning] T6E(0/0) link[40 0] UP, phy_link_ok: 61520 mac_local_fault:0 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 03:53:54.497 LOG: Debug] IFD: et-0/0/0 cat 5 cleared alarm LINKDOWN
[Thu Aug 7 03:53:54.497 LOG: Debug] IFD: et-0/0/0, on up timed list
[Thu Aug 7 03:53:54.498 LOG: Debug] IFD: et-0/0/0, up/down timer started
[Thu Aug 7 03:53:56.407 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 03:53:56.462 LOG: Debug] IFD: et-0/0/0, Detected Flap Down State
[Thu Aug 7 03:53:56.462 LOG: Warning] T6E(0/0) link[40 0] DOWN, phy_link_ok: 0 mac_local_fault:1 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 03:53:56.462 LOG: Debug] IFD: et-0/0/0 cat 5 activated alarm LINKDOWN
[Thu Aug 7 03:53:57.497 LOG: Debug] IFD: et-0/0/0, up/down timer fired (3000)
[Thu Aug 7 03:53:57.497 LOG: Debug] IFD: et-0/0/0 down, St:0x00000001, Ac:0x00000001, Cl:0x00000000:
[Thu Aug 7 03:53:57.497 LOG: Info] ifp et-0/0/0 ifd_mdown: 918109914 ms
[Thu Aug 7 03:53:57.497 LOG: Debug] IFD: et-0/0/0, penalty: curr = 1742.959883, new = 2742.959883, max = 1073764537, ttr=342645ms, elapse time = 4004
[Thu Aug 7 03:53:57.499 LOG: Debug] IFD: et-0/0/0, sent flap msg to RE, Down state
Messages File:
Aug 7 03:41:51 jtac-ptx10002-60c-re0 fpc0 IFD: et-0/0/0, dampening: entering suppressed state
This is expected as the damping logic will not get evaluated till LOCAL-FAULT flag gets clear from the interface.
We can check it by removing the LOCAL-FAULT flag from the interface by putting a soft loop (set interfaces et-0/0/0 ether-options loopback) on the interface.
After soft loop configuration on the interface, we see damping state transition from suppressed to unsuppressed.
Physical interface: et-0/0/0, Enabled, Physical link is Up
Ethernet-Switching Error: None, Loopback: Enabled (local), Source filtering: Disabled, Flow control: Enabled
Damping : half-life: 30 sec, max-suppress: 900 sec, reuse: 1, suppress: 1050, state: unsuppressed
Last flapped : 2025-08-07 04:04:42 UTC (00:00:22 ago)
Carrier transitions: 7, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0,
Active alarms : None
Active defects : None
[Thu Aug 7 04:04:38.618 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 04:04:39.251 LOG: Warning] T6E(0/0) link[40 0] UP, phy_link_ok: 61520 mac_local_fault:0 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 04:04:39.251 LOG: Debug] IFD: et-0/0/0 cat 5 cleared alarm LINKDOWN
[Thu Aug 7 04:04:39.251 LOG: Debug] IFD: et-0/0/0, on up timed list
[Thu Aug 7 04:04:39.252 LOG: Debug] IFD: et-0/0/0, up/down timer started
[Thu Aug 7 04:04:42.254 LOG: Debug] IFD: et-0/0/0, up/down timer fired (3000)
[Thu Aug 7 04:04:42.254 LOG: Info] IFD: et-0/0/0, dampening: exiting suppressed state
[Thu Aug 7 04:04:42.273 LOG: Debug] IFD: et-0/0/0, sent flap msg to RE, Up state
[Thu Aug 7 04:05:17.262 LOG: Info] PORTDEV: [FPC:0 PIC:0]: ==> RECEIVED TPORT MAP CONFIG msg
[Thu Aug 7 04:05:17.318 LOG: Debug] IFD: et-0/0/0, Detected Flap Down State
[Thu Aug 7 04:05:17.318 LOG: Warning] T6E(0/0) link[40 0] DOWN, phy_link_ok: 0 mac_local_fault:1 mac_remote_fault: 0 asic_fault: 0
[Thu Aug 7 04:05:17.318 LOG: Debug] IFD: et-0/0/0 cat 5 activated alarm LINKDOWN
[Thu Aug 7 04:05:17.318 LOG: Info] ifp et-0/0/0 ifd_mdown: 918789997 ms
[Thu Aug 7 04:05:17.318 LOG: Debug] IFD: et-0/0/0, penalty: curr = 0.000411, new = 1000.000411, max = 1073764537, ttr=298973ms, elapse time = 680083
[Thu Aug 7 04:05:17.321 LOG: Debug] IFD: et-0/0/0, sent flap msg to RE, Down state
Aug 7 04:04:42 jtac-ptx10002-60c-re0 fpc0 IFD: et-0/0/0, dampening: exiting suppressed state
Now if we delete the soft loop from the interface, still the damping state remains unsuppressed.
Last flapped : 2025-08-07 04:05:17 UTC (00:14:28 ago)
Carrier transitions: 8, Errors: 0, Drops: 0, Collisions: 0, Aged packets: 0, FIFO errors: 0, HS link CRC errors: 0,
MTU errors: 0, Resource errors: 0