Cambium PTP India: a 3-warehouse weekend cutover in Coimbatore

Last updated: 22 June 2026

Cambium PTP India is what we ended up calling the project. The mast at Singanallur was bright yellow. We do not buy yellow masts. The previous vendor had used a galvanised pole left over from a flag-pole job at a school. That was the first thing I looked at on Saturday morning. It told me half the story before anyone opened a laptop.

I am Naveen. I do networks. This is a 2026 Cambium PTP India deployment for a 3-site FMCG logistics firm in Coimbatore. One weekend. Three warehouses. A WMS that finally stopped lying to the drivers.

Why Cambium PTP India came up in a Coimbatore boardroom at all

The firm runs three sites. Peelamedu is the head office and the main godown. Singanallur is the sorting centre, 1.1 km away across a low-rise residential patch. Kalapatti is the receiving warehouse, 820 metres beyond Singanallur. No clean line of sight from Peelamedu to Kalapatti. Singanallur sits in the middle and sees both.

Each site had a 10 Mbps MPLS leased line at about Rs 13,000 per month. Rs 4.68 lakh a year total, plus an escalation clause nobody had read. Once a quarter one of the lines dropped for three hours and the WMS at that site went read-only. Trucks queued. Drivers shouted at the gatehouse.

The IT manager, a quiet man named Rakesh, had spent a year asking for fibre. The quote came back at Rs 28 lakh for the trench and the permissions. Six months of work. Two road crossings needed municipal approval and two of those said no. The CFO said, in Tamil, that we would dig when the rain stopped.

A Cambium Networks Private Limited regional partner came in with a different number. PTP 670 from Peelamedu to Singanallur. ePMP 4500 from Singanallur to Kalapatti. cnMaestro X for cloud management. Hardware about Rs 7.6 lakh. Install, masts and commissioning: Rs 1.8 lakh. cnMaestro X for 3 years: Rs 78,000 indicative. Spare radios and UPS: Rs 1.4 lakh. Rs 11.6 lakh all-in. No recurring telco bill. Payback in 14 months. I was the third opinion. They wanted somebody who had done this before and would tell them where it would break.

Saturday morning: the line-of-sight survey

I do not trust Google Earth alone for a line-of-sight call. A mango canopy that looks 12 metres on a satellite tile is 16 metres in real life, and it grows. The partner SE drove down from Chennai on Friday night with a Force 300-25 dish, a tripod, a laser rangefinder, and a small spectrum analyser. The labelmaker came out of my bag on the Peelamedu rooftop.

Peelamedu to Singanallur first. Roof to roof, 1.1 km. Fresnel zone clear at the calculated mast heights. RSSI minus 52 dBm. Modulation locked at 256-QAM. Link budget gave us 9 dB of fade margin. Yaar, that is comfortable. You want at least 6 dB in a Coimbatore monsoon.

Singanallur to Kalapatti was harder. The line passed over a single-storey school and brushed the upper edge of a coconut tree. We climbed the Singanallur water tank with the owner’s permission. Pushing the mast 1.4 metres higher cleared the canopy. Rs 18,000 extra. The CFO got the photo on WhatsApp and approved by lunchtime. Bas.

The spectrum analyser run mattered most. The 5 GHz outdoor band is usable in India for self-use backhaul under the TRAI delicensed-band framework. Two channels in the upper 5.8 GHz range came back empty. We marked one as primary, one as backup.

The cable room tells you more than the boardroom

At Singanallur the cable room door sat slightly ajar. Inside, a 12-port unmanaged switch with one cable looping back to itself and a patch cord labelled “do not unplug” in Tamil with no name and no date. The panel was honest. The labels were not.

At Kalapatti the cable room was a converted bathroom. The switch was a 2014 D-Link on a wooden shelf. Above it, an air conditioner dripping condensate on the wall behind. A faint green stain. Arre, this is the kind of thing that turns a Sunday outage into a Monday tribunal. We moved the switch to a new bracket and put a plastic shield above it. Twenty minutes. Two screws.

Peelamedu was the cleanest. A Cambium cnMatrix EX2028 was already in the rack. One spare SFP in the drawer. Labelmaker out. Labelmaker in. Tea.

Sunday morning: the cutover

We had told the operations head the WMS would be down for a maximum of three hours. We planned for two. We hit one hour forty-three minutes end to end, including the chai break the SE insisted on.

06:00, masts up from Saturday. We powered on the PTP 670 pair, fine-tuned with cnMaestro. Tweaked the Peelamedu dish 1.8 degrees and brought the link from minus 54 to minus 51 dBm. Throughput 412 Mbps full-duplex. The MPLS line we were replacing ran at 10.

07:30, the ePMP 4500 pair was up between Singanallur and Kalapatti. 820 metres, throughput 286 Mbps. The new mast height paid for itself.

09:00, we cut the WMS over. The first dispatch order on the new link printed at Kalapatti at 09:11. The driver did not notice anything had changed. That is what a good cutover looks like. Latency end to end came back at 4 milliseconds. The MPLS path had been 38. The WMS sync delay visible to the gatehouse, 90 seconds at peak, dropped to under 5 during the Monday morning truck rush.

Cambium PTP versus the two alternatives

This is the table Rakesh wanted for the CFO. Indicative numbers based on the Coimbatore quotes. Your numbers will vary.

The honest call matters. Wireless is not better than fibre. Fibre costs three times as much and takes six months. If you have line of sight, an empty channel, and a CFO who can sign one-time capex over a five-year fibre lease, wireless is cheaper. If you have a tree-heavy campus, fibre is the answer.

What I would do differently next time

I had specced one extra Force 300-25 per site as cold spares. The CFO struck them from the BOM and saved Rs 84,000. We compromised on a single shared cold spare at Peelamedu. Nine months in, no radio has failed. The day one does, the second site is 25 minutes away. I will spec the spare per site again and lose the argument again.

I started on cnMaestro Essentials instead of cnMaestro X. X gives per-link historical RSSI trending, which tells you a tree is growing into your Fresnel zone three weeks before it actually blocks the link. We upgraded after the first month. Pay for X on day one if your link runs over vegetation.

We did not segment the guest Wi-Fi at Singanallur from the WMS traffic on day one. The cnPilot APs shared a flat VLAN with the warehouse scanners for two weeks. I did not sleep well during those two weeks.

The DPDP question your auditor will ask

The WMS carries personal data of contract drivers and the gatehouse register. Under the DPDP Rules notified by MeitY, this firm is a Data Fiduciary and the data falls inside scope from 13 May 2027. The Rs 250 crore penalty ceiling is real. Show your auditor the encryption posture on the PTP link, the access control on cnMaestro, and the log retention on the firewall at each site. PTP 670 uses AES-128 by default. Turn on AES-256. Align policy to ISO/IEC 27001 and keep an incident playbook aligned to CERT-In timelines.

Naveen’s notes from the weekend

Frequently asked questions

How far can Cambium PTP 670 reach in Indian terrain?

Plan for 20 km comfortably, 40 km with extra mast height, and 80 km only when you can guarantee line of sight. For inter-warehouse links inside a city, you are usually under 5 km and the link budget is generous.

Do I need a TRAI licence to run a Cambium PTP India link?

5 GHz outdoor backhaul in the delicensed band is permitted for self-use under current TRAI rules. Higher bands and longer-distance links may need a frequency authorisation. The partner who plans your link will tell you which band needs paperwork.

Will Cambium PTP India survive an Indian monsoon?

Rain fade is real on 5 GHz over long links. Plan for a 6 dB fade margin minimum and 9 dB if you can. Below 3 km, monsoon-grade availability is achievable with a properly mounted lightning arrestor at each end.

Can I manage Cambium PTP from cnMaestro alongside my cnPilot Wi-Fi?

Yes. cnMaestro X handles PTP, ePMP and cnPilot APs in one console. Single login for the IT team. That is one of the real reasons people pick Cambium.

Where to go next

The parent Cambium Networks India product page has the full radio and switch matrix. The sibling story cnPilot Wi-Fi for an 8-branch Pune clinic covers indoor branch Wi-Fi. For cabling, see the Belden weekend story or the CommScope Systimax MDF re-cert. If DPDP is driving the project, the DPDP readiness assessment is the right first step.

P.S. Naveen here. The yellow mast at Singanallur was repainted matte grey three weeks after the cutover. The cable was never the problem. The cable is rarely the problem. Label everything twice.