T1500G-10MPS - Cannot handle more than 9 devices

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T1500G-10MPS - Cannot handle more than 9 devices

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T1500G-10MPS - Cannot handle more than 9 devices
T1500G-10MPS - Cannot handle more than 9 devices
2020-03-05 12:23:10 - last edited 2020-03-09 16:47:01
Model: T1500G-10MPS  
Hardware Version: V2
Firmware Version: 2.0.3 Build 20190424 Rel.38076(s)

We have 4 of these switches, all of which are having the same problem. When we connect more than 9 devices, the switch is not forwarding on packets. This means that we cannot use the passthrough capability on our SIP phones.

 

This is our configuration

Ports 1-6: 6 x Cisco 7975 phones + PC using passthrough (100Mb/s link)

Port 7: 1 UPS (100Mb/s link)

Port 8: Trunk to upstream switch - Cisco SG350X-24 (1000Mb/s link)

 

We're not using any VLANs and the power is well within budget (30W).

 

When I look at the MAC address table on the upstream Cisco switch, I see 10 MACs on the port that is connected to each TP-Link switch.

 

Some of the TP-Link switches can't even be connected to, because the 10 MAC addresses it's provided to the upstream switch are for the connected devices, so ARP requests aren't being responded to. In these cases, 10 of the devices have connectivity to the network.

 

On the switches that I can connect to, only 9 of the devices have connectivity to the network. When I look at the MAC address table on the TP-Link switch, I can see the addresses of all 13 devices on Ports 1-7, and a complete MAC address table on Port 8, but the upstream switch can only see 9 of the MACs (plus the MAC of the TP-Link switch).

 

So, the question is, is there a device limit for these (I can't believe that this is the case).

 

Edit: In addition, I connected a Wireless Access point to one of the ports, and this causes the same problem. Once 8 WiFi devices are connected to the AP, no more can connect. This is because it reaches the 10 port limit (1 Switch + 1 AP + 8 devices = 10). So it seems that there is a hard limit of 9 devices and that this switch is rendered useless if you intend on connecting a Wireless Access Point to it...

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Re:T1500G-10MPS - Cannot handle more than 9 devices-Solution
2020-03-09 15:58:58 - last edited 2020-03-09 16:47:01

@JohnBayly 

 

T1500G-10MPS supports 8K MAC address table. It's hard to believe that it only can connect up to 10 clients. As you said, T1500G-10MPS shows the whole MAC address but upstream switch only shows 9 MAC address. Maybe there is some features like port security function enabled on the upstream switch, make the downlink port be only able to learn 10 MAC addresses?

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Re:T1500G-10MPS - Cannot handle more than 9 devices-Solution
2020-03-09 15:58:58 - last edited 2020-03-09 16:47:01

@JohnBayly 

 

T1500G-10MPS supports 8K MAC address table. It's hard to believe that it only can connect up to 10 clients. As you said, T1500G-10MPS shows the whole MAC address but upstream switch only shows 9 MAC address. Maybe there is some features like port security function enabled on the upstream switch, make the downlink port be only able to learn 10 MAC addresses?

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Re:T1500G-10MPS - Cannot handle more than 9 devices
2020-03-09 16:46:22 - last edited 2020-03-09 16:46:56

@Andone Thanks for the reply. I discovered this myself on Friday, and hadn't gotten around to updating this thread. I happened to be logged onto the upstream (Cisco SG350X) switch in order to configure port mirroring and was lucky to see a notification that a Port Security rule had been hit :facepalm:

 

Trust me, I'm pretty mortified that I didn't realise what was going on, but in my defence I've had other switches / WAPs attached to the same switch and they didn't trigger the Cisco Port Security like the TP-Link switches did. When I have the time I'll look into the reason for that, but at least I've stopped banging my head against the wall.

 

Left for posterity, just in case somebody else makes the same mistake that I did...

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