PMP450x System Release 24.2 is now available at https://support.cambiumnetworks.com/files/pmp450 and it will be available on cnMaestro cloud within 24hours.
Legacy 450 APs (P12 APs) are not supported in Release 24.2. The last officially supported release for this hardware is Release 24.1.1. Operators using P12 APs should remain on 24.1.1 or consider migrating to supported hardware.
Important update on FSB 9083
In Field Service Bulletin FSB 9083, Cambium advises operators about a certificate upgrade for cnMaestro Cloud. This security update takes effect on March 3, 2025.
To maintain connectivity to cnMaestro Cloud, the AP/BHM must have an accurate date and time. The source of the date/time does not matter - it may be:
- Configured through an NTP server
- Obtained via GPS synchronization
- Manually set in the AP/BHM GUI under Configuration → Time
Steps for operators without a proper date/time configuration
-
Upgrade to Release 24.2
- Upgrading AP/BHM radios to Release 24.2 official updates the radio date to the latest of the software build date, the hardware build date, or a default software-configured time.
- 450 Legacy APs and BHMs (P12 radios) do not support Release 24.2, so operators using these radios must choose an alternative solution.
- If connectivity to cnMaestro is already lost, operators may use an alternative upgrade method such as CNUT or the Tools → Firmware Upgrade Utility.
-
Manually configure an NTP server
- Configure an NTP server on each AP/BHM.
- This action requires a reboot and may be set via SNMP if preferred.
-
Use GPS Synchronization for time
- Connect a GPS sync source or, in the case of 450v, 450 Legacy AP/BHM, 450b BHM, or MicroPoP, use onboard GPS to obtain time.
-
Manually set the date/time
- Set the date/time manually through Configuration → Time in the AP/BHM GUI.
Long-term recommendation
Relying on the default date update in 24.2 software serves only as a temporary solution. Frequent certificate updates are expected, so every deployed AP must have a reliable time source to ensure long-term connectivity to cnMaestro Cloud.
A successful cnMaestro connection between an AP/BHM and cnMaestro Cloud or an NTP-synced On-Premises installation provides an accurate time to the AP/BHM once the link is established. However, as of Q1 2025, an accurate date on the AP/BHM is required for a successful SSL connection before the AP/BHM-to-cnMaestro link can be established.
New Features
Follow-Me support for both component carriers on PMP 450v
The Follow-Me feature in Cambium PMP 450 updates the scanning lists for all SMs under an AP when the AP’s bandwidth or center frequency changes. It also forces SMs to prioritize scanning on the updated bandwidth and center frequency for faster recovery over the air.
Previously, Follow-Me support for the PMP 450v applied only to the first component carrier. As a result, the AP did not send center frequency changes for the second component carrier to SMs, requiring manual updates to each SM’s scan list.
Release 24.2 extends Follow-Me support to both component carriers on the 450v AP. SMs now receive updated scan lists for both carriers automatically.
Follow-Me applies only to SMs that are online under the AP at the time of modification.
Deeper Virtual Circuit (VC)
Release 24.2 includes an optimization to the Virtual Circuit (VC) queue depth. In previous releases, each VC was limited to 64 packets per frame, which impacted throughput in certain scenarios. The improvements depend on the frame configuration, bandwidth, number of SMs under test, modulation, traffic profile packet sizes, and link conditions, including retransmissions.
Key scenarios where improvements are observed:
-
Single SM tests:
- Performance improves in single SM link tests or end-to-end single SM speed tests.
-
Higher modulation levels and retransmissions:
- Links operating at lower modulation levels typically experience RF limitations rather than VC queue depth limitations.
- Links with higher MAC layer retransmissions are more likely to benefit. For example, a link operating at 8X modulation with significant retransmissions experiences improvements compared to the same link capped at 6X modulation or a link at 8X modulation with clean RF and no retransmissions.
-
Long frame configurations:
- Platforms such as 450i/450b/450m with 30MHz and 40MHz bandwidths, 75% or 85% DL ratios, and 5ms frame sizes show improvements.
- Platforms such as 450v experience better performance in single SM link tests at any frame size when using carrier aggregation bandwidth combinations greater than 40MHz.
-
Smaller packet sizes:
- Traffic profiles with smaller packet sizes are more likely to benefit when used with the above configurations and test scenarios.
To maximize the benefits of this feature, set the VC queue depth to 256 using a single configuration parameter on the Configuration > Radio page of the AP/BHM.
To restore performance similar to pre-24.2 software, set the queue depth to 64. A setting of 128 is also available for operators who want to experiment with different VC queue depth configurations.
With 24.2 BETA-4 or later, all AP types supported in 24.2 have the VC queue depth set to 256 by default after the upgrade.
450 Legacy SMs (P11 SMs) operate only at a VC queue depth of 64. All other SM hardware types support 128 and 256 queue depths. In sectors with a mix of legacy and newer SMs, set the VC queue depth to 128 or 256. The software applies higher queue depths to 450v/450b/450i SMs, while legacy 450 SMs continue to operate at 64 deep.
Uplink interference cancellation for 3GHz 450m
The beamforming technology in 450m APs manages interference in both uplink and downlink directions. With Release 24.2, Cambium introduces additional software to identify and mitigate uplink interference for 3GHz 450m APs. This enhancement is similar to the interference cancellation software for 5GHz 450m APs, which was introduced in Release 22.0.
No software license is required to use this feature. Enable the feature through a configuration setting on the Configuration → Radio page of the AP.
Enabling this feature forces all uplink traffic to be scheduled in Single User MIMO (SU-MIMO) mode, similar to the 5GHz interference cancellation feature. This feature is most effective in 450m sectors with uplink interference where MU-MIMO scheduling is not heavily utilized—sectors with lower uplink multiplexing gains.
This feature does not mitigate interference from other Cambium PMP radios that are time, frequency, and bandwidth-synced with the affected sector.
Alpha trials for this feature started in Q3 2024 and have been successful. Since Release 24.2 BETA-4, the feature is disabled by default on upgrade. In earlier 24.2 Alpha SIT builds, it was enabled by default.
Additional enhancements in Release 24.2
| Platforms | Tracking | Description |
|---|---|---|
| 450v SM | CPY-19282 | The AP now sends AFC SI information to 6 GHz 450v SMs, storing it for quick reconnection. If the SM briefly disconnects, it can use AFC standard power to reconnect to the AP, improving speed and reliability. |
| 450v AP | CPYV-889 | The AP now displays uplink per-CC modulation rates. Previously, software displayed per-CC modulation rates only in the downlink direction. |
| 450m APs, 450b SMs | CPY-19424 | Uplink efficiency improvements on 450m enhance aggregate sector MU-MIMO throughput in the uplink direction compared to Release 24.2 BETA-4, improving transmission efficiency. |
| All PMP AP/BHM products | none | Release 24.2 introduces an enhancement that automatically configures Server 1 to pool.ntp.org and updates the default time to March 2025 if no NTP server is set on the AP/BHM. These changes help prevent certificate validation failures when connecting to cnMaestro Cloud. For more details, refer to the Important update on FSB 9083 section above. |
| All | CPY-19220/CPY-19395 | The results from link tests run from Tools → Link Capacity Tests have always been measured at the physical (PHY) layer. In most cases, this measurement closely matches end-to-end throughput, such as results from external speed tests. However, in certain scenarios, PHY layer throughput appears noticeably higher, especially on 450v APs. To improve accuracy, Cambium now reports packet layer throughput instead of PHY layer throughput in the basic link test selections on the AP GUI. |
| All | CPY-19395/CPY-19447 | As mentioned above, in release 24.2, Cambium updated the link test output to display packet layer throughput instead of RF layer throughput to prevent overscheduling from affecting results. Packet layer throughput better represents the expected end-to-end performance. However, this change makes direct comparison between Release 24.2 and prior releases more difficult. To address this, both RF layer throughput and packet layer throughput now appear in two separate tables in Release 24.2. See the additional details below this table |
Updated SNMP OIDs
The following SNMP OIDs now report packet layer throughput:
- Downlink:
.1.3.6.1.4.1.161.19.3.3.18.2.5.0 - Uplink:
.1.3.6.1.4.1.161.19.3.3.18.2.6.0
For operators who still need PHY layer throughput for comparison with past releases, the following OIDs remain available:
- Downlink PHY Throughput:
.1.3.6.1.4.1.161.19.3.1.2.2.5.0 - Uplink PHY Throughput:
.1.3.6.1.4.1.161.19.3.1.2.2.6.0 - Although the MIB definitions indicate these OIDs are deprecated, they remain functional and can be used for this purpose.
Both packet layer throughput and PHY layer throughput now appear in separate tables on the AP UI. These changes apply to all link test options except Link Test with Multiple LUIDs.
The UI output for Link Test with Multiple LUIDs continues to report PHY layer throughput, and the matching SNMP OIDs remain unchanged:
- Downlink:
.1.3.6.1.4.1.161.19.3.3.18.5.3.0 - Uplink:
.1.3.6.1.4.1.161.19.3.3.18.5.10.0
Problems and limitations corrected in Release 24.2
| Products Affected | Tracking | Description |
|---|---|---|
| 450m APs | CPY-19408 | The 450m crashed due to the canopy process when running 24.1.1 with Proportional Scheduler or Airtime Fairness. |
| CBRS | CPY-19406 | Fixed an issue where the internal CBRS target frequency did not update when changing AP bandwidth via SNMP, which sometimes caused CBRS grants to be unexpectedly relinquished after an AP reboot. |
| 450v | CPY-19218 | Fixed an issue where SM session drops occurred in an operator lab due to a “bad session power adjust” on 450v APs. |
| CBRS | CPY-19160 | Fixed an issue where the CBRS TxExpire Relaxation feature caused SM state-triggered channel hunts to be delayed by up to 30 minutes. |
| All APs | CPY-19359 | Fixed an issue where the channel change history table incorrectly logged a 10 MHz bandwidth entry. |
| CBRS | CPY-19314 | This improvement added a new Delete CPI Data Permanently button on the CBRS page of 3GHz CBRS-capable SMs. It provided a cleaner procedure for removing or relocating SMs from a sector, reducing the risk of a race condition that left the SM registered in the SAS. For more details, refer to the CBRS Consolidated Procedures Guide, version 1.8.7 |
| 450v | CPYV-723 | Fast Rate Adaptation now supports all component carriers in 450v. |
Known issues and Limitations in Release 24.2
| Products Affected | Tracking | Description |
|---|---|---|
| All 450m sectors | N/A | When upgrading a 450m sector from Release 24.1.1 or earlier to Release 24.2, operators must consider the following:
|
| All SM and AP platforms | N/A | Link tests now display both packet layer throughput and physical layer throughput. This improves accuracy in Release 24.2, but in some cases, 24.2 link test results show lower values than in previous releases. This is an improvement, not a software bug. See the detailed explanation in the prior section for JIRAs CPY-19395 and CPY-19220. |
| 450m AP | N/A | Note on CPY-19079: Lower downlink grouping size is observed with 24.2 SMs compared to 24.0.1. Release 24.1 and 24.1.1 had advised operators to be cautious when upgrading SMs under 450m sectors due to concerns that throughput might be slightly degraded. Cambium has determined that a specific SM code fix in 24.2 causes a modulation level increase. In pre-24.2 software, this modulation increase can improve throughput or cause slight degradation if retransmissions reach VC queue depth limits. Throughput improves when higher VC queue depths are configured, particularly with 450v, 450i, or 450b SMs. For 450 legacy SMs, throughput may improve or degrade depending on link conditions. This advisory has now been removed in Release 24.2. |
| 450v SMs | CPY-19505 | Although 450v SM hardware supports SFP modules, Cambium does not recommend using them with 24.2 or earlier software. 450v APs do support Cambium-branded SFP modules. |
| 450v SMs under 450m AP | N/A | Using a timing source—at least a 1-second pulse—is considered best practice for all AP/BHM deployments, though it is not strictly required in most cases. However, when using 450v SMs under a 450m AP, do not use Generate Sync on the AP, as this may prevent 450v SMs from successfully locking onto the AP beacon. This issue is more likely to occur when operating at 10 MHz or 5 MHz bandwidths. This issue is not specific to Release 24.2 and also applies to earlier software versions. |
| 450v AP | CPY-19322 | EMAC errors and watchdog resets occur on certain 450v APs when using the Copper/Main port for connectivity. Some operators have reported these resets at specific 450v AP sites. Symptoms include occasional watchdog resets, Fatal Error Resets, and EMAC errors in the event log and Ethernet debug log, such as: 12/25/2024 : 04:08:11 CDT : 0 : EMAC0: Allocated TX DMA ring1, 1000 entries at 0x48322e00 - 0x4832aae0 12/25/2024 : 04:08:11 CDT : 0 : EMAC0: Allocated RX DMA ring1, 1000 entries at 0x4832ab00 - 0x483327e0. If these issues persist, Cambium recommends replacing the Ethernet connection with a fiber SFP connection for improved stability. This issue is not specific to Release 24.2 and has been observed in earlier software versions. |
| 450 legacy SMs running under 450v APs | CPY-18753 | 450 legacy SMs running software earlier than Release 24.2 under a 450v AP sometimes rate adapt downward to a low modulation when no traffic is present. When traffic starts, the rate increases to its expected operating value. This behavior has minimal impact on performance. |
A note on SFP support for 450v and 450m
Cambium is updating the PMP 450 Hardware and Installation Guide and the SFP Specification Document to clarify SFP module support. These updated versions are expected to be released soon. The key clarifications are:
- 450v APs: Cambium formally supports four Cambium-branded modules:
- 10Gbps SMF
- 10Gbps MMF
- 1Gbps SMF
- 1Gbps MMF
- 450m 5GHz: Cambium formally supports two Cambium-branded modules:
- 1Gbps SMF
- 1Gbps MMF
- 450m 3GHz: Cambium formally supports one Cambium-branded module:
- 1Gbps MMF
Although MMF is highly recommended for 3GHz 450m, Cambium recognizes that some operators have strict requirements that necessitate SMF. In such cases, Cambium will list a third-party Solid Optics module as a suggested alternative in the updated PMP Installation Guide.
Cambium does not recommend removing existing deployments of third-party SFP modules. If an operator’s current third-party modules have performed well, Release 24.2 does not introduce any software changes that prevent continued use.
Although 450v SM hardware supports SFP modules, Cambium does not recommend using them with Release 24.2.