Understanding the 450i PMP

Can someone explain this to me?
We have a PMP network using all 450i radios in the 4.9Ghz band. The AP has 12 subscriber modules connected, all of which are low bandwidth users. One site, suddenly had its speeds cut down by about 2/3, from 15Mbps to 5Mbps.
In troubleshooting, this I attempted to adjust the MIR Bandwidth Settings and the Priority Settings at the problem site. I set those fields to their maximum rate allowed. In doing this, all of the other sites started timing out and the EIGRP routing started to bounce, until I returned to the original setting.
Can anyone explain why that would happen? I’m not sure if it was from the MIR change or Priority or both. It seems odd to me that any of those changes would knock the other subscriber modules offline, but I’m not that familiar with the Cambium 450i PMP equipment.
Thanks in advance!

Hi Phillip!

I would recommend opening a support ticket for the “troublesome” SM, however on MIR, here is some info that could be useful:

  1. MIR Settings: The MIR settings on each subscriber module dictate the maximum bandwidth that the SM can utilize. When you increased the MIR settings to their maximum rate for the problem site, you essentially allowed that particular SM to consume as much bandwidth as it could up to the maximum capacity of the AP (Access Point). This could lead to a situation where a single SM consumes the majority of the available bandwidth, leaving less available bandwidth for other SMs. This would not typically cause other sites to time out unless the bandwidth was so fully consumed by one or a few SMs that the others could not maintain their minimum required bandwidth.

  2. Priority Settings : The Priority settings determine the order in which packets are processed and forwarded by the AP. Higher priority traffic gets processed before lower priority traffic. Setting the problematic site to a higher priority could cause its traffic to be processed first, potentially at the expense of traffic from other SMs. In a bandwidth-constrained environment, this could indeed impact the performance of other SMs, possibly leading to timeouts and instability in EIGRP (Enhanced Interior Gateway Routing Protocol) routing if the network relies on timely delivery of routing protocol packets.

  3. Interactions Between MIR and Priority Settings : When both settings are adjusted to favor a single site, the combined effect can be more pronounced. The site with increased MIR and priority can monopolize both bandwidth and packet processing priority at the AP, exacerbating the impact on other SMs.

Hope this helps!

Regards
Kinan

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