Packet Drop Issue

[WaleedAmir]

We have an packet drop issue in our meraki mx84 when we active our cisco meraki in network and ping local IP gateway with packet size 18000 got packet drop on it also same time when we get an packet loss then we observe packet drops on public destinations IPs and also packet drop on our internet provider gateway. Neet support How can we solve this issue we check everything like fiber optic media convertor, LAN cable, Switches connectivity. Also for testing purpose we install mikrotik router for 1 day and see there is no packet loss observe on it. So there is an issue in meraki.

[BlakeRichardson]

@WaleedAmir  have you opened a support case with Meraki?

Your local LAN shouldn't be dropping packets by simply pinging your MR. How is your network setup is it a mostly flat network or do you hve routing between different subnets taking place on the MX?

Roughly how many users do you have on your network?

[WaleedAmir]

Hi,

Yes I am already open support case with meraki.

We run 1 IP subnet in our LAN that is 192.168.19.0/24 and we have approx 150 LAN users that are connected with Cisco 3560 switches and these switches are uplink with our main aggrigation switch and aggr switch uplink with meraki. my point is when we ping 192.168.19.1 -l 18000 -t from end user we observe packet loss due to this we face disconnection in browsing and on VOIP but on same side when we disconnect meraki and trun on our mikrotik on same network it work perfectly no packet drop observe on it.

[WaleedAmir]

One more thing that I forget to writen in my last reply, we use star topology our all access switches are uplink with our aggrigation switch and just aggrigation switch is directly connected with MX with fiber optic and our remainaing switches are also uplink to aggr with fiber optics. 

[PhilipDAth]

Have you got the port where the MX plugs into your switch configured for auto/auto, and have you also got the MX configured auto/auto?

This sounds like a classic duplex mis-match.

[PhilipDAth]

If you are doing a "don't fragment" ping then an 18000-byte ping should be dropped.  The MTU is typically 1500 bytes.

If you are doing a ping that allows packet fragmentation, then perhaps you are experiencing an MTU squeeze.  Perhaps you are using PPPoE and you're ISP only supports 1492 byte packets, and you need to lower your MTU.

To test this idea, try reducing the MTU on your test machine to something like 1400 bytes:

https://techamor.com/reducing-mtu-on-windows-10/ 

[WaleedAmir]

Hi,

When we connect standalone PC directly with ISP media convertor and ping some public IPs then Its work fine no packet drop observe on it only just when we ping with MX like from any end user that routed with MX then we face these type of issue. Such as drops on MX gateway that is 192.168.19.1 and also on public IPs with 18k ping size.