Packet loss on Cisco Layer-2 Switch connected through Cambium PTP820 MW multi hop Link

Hello All,

I need your help to fix one of the weired issue I am facing.
Currently, I have a simple Layer-2 Network with multiple VLANs on Cisco Switches on two locations connected through Cambium PTP820 MW Radios with multihop Radio Sites over distance of almost 100 kilometers. The subject MW link is delievering 100 Mbps bandwidth connection. End to end MW Radios are configured as Trunk to accomodate multiple VLAN traffic and MW Radios are connected to switches at both end through SFTP outdoor Ethernet CAT-6 cable and DC POE injector.

When we try to do an extended ping from A-End Switch to MW Radio management IP at point B, we get no ping drop but if we do an extended ping from A-End Cisco Switch to Cisco Switch at point B connected to MW Radio at Point B, we get packet loss. It is just not packet loss on extended ICMP ping, customer is also complaning about packet drops/ loss on their VLAN through B-End Cisco Switch connected to B-End MW Radio.

We are getting no CRC’s / Errors on B-End switch interface connected to B-End MW Radio and we also replaced switch, Ethernet Cables, DC POE injector and grounding is done properly for Tower. Our current Firmware is 10.5 with 40 MHz channel.

Below extended ICMP Ping results for your review as:
A-End-Switch#ping <B-END mw radio management ip > repeat 500
Type escape sequence to abort.
Sending 500, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 100 percent (500/500), round-trip min/avg/max = 1/4/17 ms
A-End-Switch#ping <B-END switch management ip connected to b-end mw radio> repeat 300
Type escape sequence to abort.
Sending 300, 100-byte ICMP Echos to, timeout is 2 seconds:
Success rate is 85 percent (256/300), round-trip min/avg/max = 1/7/25 ms

The solution worked fine without any packet loss for couple of weekes when we inititally deployed but since last few months we are having packet loss on B-End Switch.

Below is the switches trunk port sample configuration which are connected to A/ B-End MW Radios.
Interface Gi1/0/24
switchport mode trunk
switchport nonegotiate
bandwidth 110000
no logging event link-status
logging event trunk-status
power inline never
srr-queue bandwidth limit 90
no cdp enable
ip dhcp snooping trust
I would appreciate if someone can help us to point us to the right direction to fix this issue.

Thanks & regards,

Riaz Ahmed

I have forwarded this to our support and development teams.

Thanks, appreciate your response and help in this matter

Hi riaz,

Are you using an 80 MHz channel size?  There's a known problem with the 10.3 software that results in high packet loss on 80 MHz channels and possible lower packet loss at smaller channel sizes.  Could you try upgrading to the latest 10.5 software?



Hi Steve,
Thanks for your reply.

We are using 40 MHz channel and Firmware version on all Mw Radios are 10.5.

Please do advise further to fix this packet loss issue.

Thanks & regards,


Hi Riaz,

We'll have to look into this problem a little more.  Could you open a case with our support team at  We can setup a remote session and review your configuration.