Hi,
- hardware: CRS112-8G-4S
- RouterOS: 7.22
The switch is really just switching and the CPU load is low. There are six servers behind it (black boxes for me), and ISP uplink connected. All 1Gbps Ethernet.
I am seeing a very high number of tx-drop-packet and tx-drop-byte on my uplink interface. No other kinds of errors.
I am trying to understand what’s happening, but can’t actually find any clear definition of tx-drop-packet and tx-drop-byte in the docs. I suppose that the relevant line in the ROS → Wired connections → Ethernet docs is:
| tx-drop (integer) | Total count of transmitted frames that were dropped due to the already full output queue |
|---|---|
Is this correct? It seems to me this contains the drops across all the queues. There are Tx counters per queues, but the drop counters per queue are missing.
Interestingly, when I run /interface monitor-traffic ether7uplink, the tx-queue-drops-per-secondnever shows anything but 0, and the tx-bits-per-second is in higher tens or lower hundreds (mostly 50 - 200 mbps, although now I see a few bursts to about 800 mbps when I look at the WinBox graph). The tx-drop-* grows even in these 30-200 Mbps periods, outside of the visible 800Mbps spikes.
What I would like to understand is:
- Is this due to bursts leading to queue buffer overflow that are not visible on the graph?
- If so, why on the Traffic tab, why Tx/Rx Drops and Tx Queue Drops are 0?
- Is this hitting packet per second or bits per second ceiling?
- Can something be done about this problem? ISP say they don’t see any errors and don’t do any traffic shaping on this port.
- I briefly switched the port from
only-hardware-queuetomulti-queue-ethernet(mq pfifo, queue size 50 - the default), seemed make no difference.
- I briefly switched the port from
Looking forward to learning more about this!
This is a few minutes after resetting the counters:
> /interface ethernet print stats where name=ether7uplink
;;; uplink
name: ether7uplink
driver-rx-byte: 9 411 093
driver-rx-packet: 94 204
driver-tx-byte: 43 463 782
driver-tx-packet: 39 833
rx-bytes: 9 009 226 292
rx-too-short: 0
rx-64: 55 118
rx-65-127: 21 323 373
rx-128-255: 2 819 468
rx-256-511: 5 682 842
rx-512-1023: 1 205 103
rx-1024-1518: 2 418 144
rx-1519-max: 0
rx-too-long: 0
rx-broadcast: 54 188
rx-pause: 0
rx-multicast: 12 655
rx-fcs-error: 0
rx-align-error: 0
rx-fragment: 0
rx-overflow: 0
tx-bytes: 25 340 437 941
tx-64: 1 190
tx-65-127: 18 449 007
tx-128-255: 2 051 444
tx-256-511: 6 801 873
tx-512-1023: 1 271 487
tx-1024-1518: 13 014 507
tx-1519-max: 0
tx-too-long: 0
tx-broadcast: 1 128
tx-pause: 0
tx-multicast: 15 804
tx-underrun: 0
tx-collision: 0
tx-excessive-collision: 0
tx-multiple-collision: 0
tx-single-collision: 0
tx-excessive-deferred: 0
tx-deferred: 0
tx-late-collision: 0
tx-queue0-packet: 3 440
tx-queue1-packet: 41 585 668
tx-queue2-packet: 388
tx-queue3-packet: 12
tx-queue4-packet: 0
tx-queue5-packet: 0
tx-queue6-packet: 0
tx-queue7-packet: 0
tx-queue0-byte: 272 048
tx-queue1-byte: 25 340 133 505
tx-queue2-byte: 31 260
tx-queue3-byte: 1 128
tx-queue4-byte: 0
tx-queue5-byte: 0
tx-queue6-byte: 0
tx-queue7-byte: 0
tx-drop-packet: 87 394
tx-drop-byte: 115 580 817
tx-queue-custom0-drop-packet: 0
tx-queue-custom0-drop-byte: 0
tx-queue-custom1-drop-packet: 0
tx-queue-custom1-drop-byte: 0
policy-drop-packet: 0
custom-drop-packet: 0
current-learned: 18 446 744 073 709 551 612
not-learned: 0
More details:
> /system resource print
uptime: 5d16h7m34s
version: 7.22 (stable)
build-time: 2026-03-09 08:38:02
factory-software: 6.44.6
free-memory: 74.6MiB
total-memory: 128.0MiB
cpu: MIPS 24Kc V8.5
cpu-count: 1
cpu-frequency: 400MHz
cpu-load: 46%
free-hdd-space: 2968.0KiB
total-hdd-space: 16.0MiB
write-sect-since-reboot: 661
write-sect-total: 3362018
architecture-name: mipsbe
board-name: CRS112-8G-4S
platform: MikroTik
> /system routerboard print
routerboard: yes
model: CRS112-8G-4S
revision: r3
serial-number: HE108JN1WA6
firmware-type: qca8513L
factory-firmware: 6.48.6
current-firmware: 7.22
upgrade-firmware: 7.22
> /interface ethernet print detail where name=ether7uplink
Flags: X - DISABLED, R - RUNNING; S - SLAVE
0 RS ;;; uplink
name="ether7uplink" default-name="ether7" mtu=1500 l2mtu=1588 mac-address=48:A9:8A:35:03:C5 orig-mac-address=48:A9:8A:35:03:C5 arp=enabled arp-timeout=auto loop-protect=default loop-protect-status=off
loop-protect-send-interval=5s loop-protect-disable-time=5m auto-negotiation=yes advertise=10M-baseT-half,10M-baseT-full,100M-baseT-half,100M-baseT-full,1G-baseT-half,1G-baseT-full tx-flow-control=off
rx-flow-control=off bandwidth=unlimited/unlimited switch=switch1
> /interface bridge print detail
Flags: Y - MANAGED; D - DYNAMIC; X - DISABLED, R - RUNNING
0 R ;;; defconf
name="bridge" mtu=auto actual-mtu=1500 l2mtu=1588 arp=enabled arp-timeout=auto mac-address=48:A9:8A:35:03:BF protocol-mode=none fast-forward=yes igmp-snooping=no auto-mac=no admin-mac=48:A9:8A:35:03:BF
ageing-time=5m vlan-filtering=no dhcp-snooping=no ra-guard=no port-cost-mode=short forward-reserved-addresses=no max-learned-entries=auto mlag-peer-port=none mlag-priority=128 mlag-heartbeat=5s
> /interface bridge port print detail
...
6 H ;;; defconf
interface=ether7uplink bridge=bridge priority=0x80 path-cost=10 internal-path-cost=10 edge=auto point-to-point=auto learn=auto horizon=none hw=yes auto-isolate=no restricted-role=no restricted-tcn=no pvid=1
frame-types=admit-all ingress-filtering=no unknown-unicast-flood=yes unknown-multicast-flood=yes broadcast-flood=yes tag-stacking=no bpdu-guard=no trusted=no trusted-ra=no mvrp-registrar-state=normal
mvrp-applicant-state=normal-participant multicast-router=temporary-query fast-leave=no
> /interface ethernet switch port print detail
6 name="ether7uplink" ingress-customer-tpid=0x8100 egress-customer-tpid=0x8100 ingress-service-tpid=0x88A8 egress-service-tpid=0x88A8 learn=yes drop-secure-static-mac-move=no drop-dynamic-mac-move=no
allow-unicast-loopback=no allow-multicast-loopback=no action-on-static-station-move=forward drop-when-ufdb-entry-src-drop=yes isolation-leakage-profile=29 vlan-type=network-port allow-fdb-based-vlan-translate=no
allow-mac-based-service-vlan-assignment-for=all allow-mac-based-customer-vlan-assignment-for=all filter-untagged-frame=no filter-priority-tagged-frame=no filter-tagged-frame=no
egress-vlan-tag-table-lookup-key=egress-vid egress-vlan-mode=unmodified ingress-mirror-to=none ingress-mirroring-according-to-vlan=no egress-mirror-to=none
qos-scheme-precedence=ingress-acl-based,sa-based,da-based,dscp-based,protocol-based,vlan-based,pcp-based default-customer-pcp=0 default-service-pcp=0 pcp-propagation-for-initial-pcp=no egress-pcp-propagation=no
dscp-based-qos-dscp-to-dscp-mapping=yes pcp-or-dscp-based-qos-change-dei=no pcp-or-dscp-based-qos-change-pcp=no pcp-or-dscp-based-qos-change-dscp=no pcp-based-qos-drop-precedence-mapping=0-15:green
pcp-based-qos-dscp-mapping=0-15:0 pcp-based-qos-dei-mapping=0-15:0 pcp-based-qos-pcp-mapping=0-15:0 pcp-based-qos-priority-mapping=0-15:0 priority-to-queue=0-15:0,1:1,2:2,3:3
per-queue-scheduling=wrr-group0:1,wrr-group0:2,wrr-group0:4,wrr-group0:8,wrr-group0:16,wrr-group0:32,wrr-group0:64,wrr-group0:128 custom-drop-counter-includes="" queue-custom-drop-counter0-includes=""
queue-custom-drop-counter1-includes="" policy-drop-counter-includes=""
> /interface ethernet switch print
name: switch1
type: QCA-8511
bridge-type: customer-vid-used-as-lookup-vid
drop-if-no-vlan-assignment-on-ports:
drop-if-invalid-or-src-port-not-member-of-vlan-on-ports:
unknown-vlan-lookup-mode: svl
forward-unknown-vlan: yes
use-svid-in-one2one-vlan-lookup: no
use-cvid-in-one2one-vlan-lookup: yes
mac-level-isolation: yes
multicast-lookup-mode: dst-ip-and-vid-for-ipv4
override-existing-when-ufdb-full: no
unicast-fdb-timeout: 5m
ingress-mirror0: switch1-cpu,unmodified
ingress-mirror1: switch1-cpu,unmodified
ingress-mirror-ratio: 1/1
egress-mirror0: switch1-cpu,modified
egress-mirror1: switch1-cpu,modified
egress-mirror-ratio: 1/1
fdb-uses: mirror0
vlan-uses: mirror0
mirror-egress-if-ingress-mirrored: no
mirror-tx-on-mirror-port: no
mirrored-packet-qos-priority: 0
mirrored-packet-drop-precedence: green
bypass-vlan-ingress-filter-for:
bypass-ingress-port-policing-for:
bypass-l2-security-check-filter-for: