i have a problem with output drop between 2960 (stack3) with forti

[ilanmelkamo052621]

Hi everyone,

I'm facing an issue. I have two FortiGate devices connected in a cluster, and I have two sites connected via L2. The remote site is unable to reach the gateway, and I'm experiencing packet loss. On the 2960 switch, I can see packet loss on the LACP interface towards the FortiGate.

I have checked the infrastructure between the sites, and everything seems fine. I also checked QoS on the switch, and there is none configured. In a local test at the site where the firewall is located, everything works fine.

What could be the cause of the issue?

[ilanmelkamo052621]

this is my topology 

[MHM Cisco World]

Can I see 

Show ether channel summary 

MHM

[ilanmelkamo052621 · Accepted solution]

hey MHM

i attached the output with my 2960 

Pelleg-2960-BB-SW#show etherchannel summary
Flags: D - down P - bundled in port-channel
I - stand-alone s - suspended
H - Hot-standby (LACP only)
R - Layer3 S - Layer2
U - in use f - failed to allocate aggregator

M - not in use, minimum links not met
u - unsuitable for bundling
w - waiting to be aggregated
d - default port

Number of channel-groups in use: 6
Number of aggregators: 6

Group Port-channel Protocol Ports
------+-------------+-----------+-----------------------------------------------
1 Po1(SU) LACP Gi2/0/14(P) Gi2/0/16(P) Gi3/0/11(P)
Gi3/0/12(P)
2 Po2(SU) LACP Gi2/0/18(P) Gi2/0/20(P) Gi3/0/13(P)
Gi3/0/14(P)
10 Po10(SD) LACP Gi1/0/1(D) Gi1/0/2(D) Gi2/0/1(D)
Gi2/0/2(D)
11 Po11(SD) LACP Gi1/0/5(D) Gi1/0/6(D) Gi2/0/5(D)
Gi2/0/6(D)
12 Po12(SD) -
20 Po20(SU) LACP Gi1/0/10(P) Gi1/0/12(P) Gi2/0/10(P)

Pelleg-2960-BB-SW#show interfaces port-channel 2 | section drop
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 3644
0 unknown protocol drops

Pelleg-2960-BB-SW#show interfaces gigabitEthernet 2/0/18 | section drops
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 331
0 unknown protocol drops

Pelleg-2960-BB-SW#
Pelleg-2960-BB-SW#
Pelleg-2960-BB-SW#show interfaces gigabitEthernet 2/0/20 | section drops
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 2673
0 unknown protocol drops

Pelleg-2960-BB-SW#show interfaces gigabitEthernet 3/0/13 | section drops
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 640
0 unknown protocol drops

Pelleg-2960-BB-SW#show interfaces gigabitEthernet 3/0/14 | section drops
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
0 unknown protocol drops

Pelleg-2960-BB-SW#show mls qos
QoS is disabled
QoS ip packet dscp rewrite is enabled

[Joseph W. Doherty]

Do your LAG member interfaces show, roughy, equal usage and drops?

Switch QoS is disabled?

[Joseph W. Doherty]

Ah, those interface stats, of course, confirm drops, but without any context, as in relative to total packets offered.

They do show a disparity between member links, but over what time isn't provided either.

You've also confirmed QoS is disabled.  BTW, for drops, usually, most drops to least drops is: default QoS => no QoS => custom QoS.  Also BTW, the last might be as simple as increasing drop thresholds.

Also know, the 2960 series do not have much in the way of buffer hardware resources.

[ilanmelkamo052621]

?