Impossible to chain TL-SG108E switches in home network with no specific configuration

Impossible to chain TL-SG108E switches in home network with no specific configuration
Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 16:03:09 - last edited 2018-08-28 16:59:51

 

Hello, 

 

Due to the architecture of my house, I have to chain switches. I bought 3 managed TP link on Amazon TL-SG108E switches to have a proper configuration in the future, but right now it does not work.

 

To add more info

  • I have only managed switches TL-SG108E : two v3 and one V2.
  • I have 3 because I have to connect basement to First floor; then to second floor.
  • I have computer science background (15 years ago); so I get the basics but I have no applied experience here
  • I bought managed because those were super cheap for 1G 8 ports, and plus eventually I want to setup QoS
  • I bought them because In french there's an expression "who can do more can do less"
  • At the moment, I dont need VLANs, nor QoS 

 

To talk about configuration I did after I reset the switches to factory settings:

  • ISP box is a Fritzbox 7490 with stock configuration -> this is normally the only DHCP server; IP address is 192.168.178.1

  • Only 1 port is used of the ISP Box and goes to the 1st switch

  • The Wifi is enabled and used
  • I have recent cables - at least cat 5e cables, max length is 15 meters
  • I made sure I used the latest available firmware for all 3 switches
  • I assigned a static and unused IP addresses to each, gateway to the IP of the Box for all switches DHCP is deactivated for all switches
  • I wrote down the MAC address to not make any mistakes
  • I did a factory reset of my ISP box - just in case
  • I did not want to activate VLAN ,but it seems in the interface that I have to leave one enabled at least: MTU / Port based / 802.1Q

 

This is looking like: ISP box ---> Switch "basement (v3) —> Switch "TV" (v2) —> Switch "Desktop" (v3)

 

About what’s connected:

  • switch basement —> I have a NAS, and a computer
  • Switch TV -> I have TV, playstation, TV box , Apple TV, and a laptop I can plug
  • Switch desk -> two computers, Apple TV

 

Here are my findings  / what I tried

  • There’s internet at the switch basement. All is OK
  • There’s not internet from switch TV (all devices connected to TV and Desktop)
  • If I unplug the Desktop switch —> nothing changes
  • if I reduce to the strict minimum the number of devices connected --> nothing changes
  • If I switch the TV and Desktop; same results --> here I was suspecting a conflict with V2 and V3.
  • If I replace the switch TV by an unmanaged switch -> I have internet everywhere
  • If I add an unmanaged switch between the Basement and TV-> I have internet at the devices connected to the TV, but really really slow (1-2 Mbit)
  • From the PC connected to switches TV and Desktop -> I never see the switch basement -- But I suspect this is because I am not connected to it directly although that's not the same bevavior as if I use the PC connected to desktop;
  • I see both desktop and TV switches

 

Hope that makes sense to someone… I am quite lost; It seems like Switch basement is OK but somehow is not able to talk to another manager switch I have.

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#1
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Re:Re:Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration-Solution
2018-08-25 21:35:27 - last edited 2018-08-28 16:59:51

Next, check the cables. Connect a laptop to the cable feeding the middle switch, then test with the switch. Also check the middle switch stand-alone, with your laptop and a second device connected to it.

 

You need to isolate the error step-by-step, isolating every switch which doesn't work from the network. Also make double sure that you have factory defaults and only the IP set. But even with the IP set, check the switch stand-alone.

 

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Re:Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 16:14:27 - last edited 2018-08-25 16:14:53

Which IP addresses did you assign to the switches? Since TL-SG108E are managed switches, you need to assign an unqiue IP address to each.

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Re:Re:Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 16:39:05
I assigned static and unused IP to each: 192.168.178.197, : 192.168.178.198 and : 192.168.178.199
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Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 18:43:40 - last edited 2018-08-25 18:44:58

If you assign IPs and save the config (two steps!), everything should be fine to be able to chain the switches if default settings are o.k. for the moment, albeit it would be better to connect all three switches to the FritzBox directly. But chaining should work anyway. Different versions of the switch do not affect this.

 

If you forgot to save the config, the switch's IP will fall back to the factory-default IP 192.168.0.1 when being rebooted.

 

Regarding VLANs: don't enable MTU VLAN. Either disable all VLAN settings or enable 802.1Q VLANs and leave the port settings at default (= all ports members of Default_VLAN 1).

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Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 19:45:34 - last edited 2018-08-25 19:47:15

Hi, thanks. Not Chaining is not possible. IP adresses are well configured. I know about the 2 steps.

 

I cannot disable all Vlans apparently, do you suggest I can? Do you know how?

thanks for the suggestion about VLAN, I suppose that this config should be the exact same for all switch, right? 

 

do you know why replacing the switch “TV” by an unmanaged make everything work?

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Re:Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 21:20:49 - last edited 2018-08-25 21:29:52

freddb wrote

I cannot disable all Vlans apparently, do you suggest I can? Do you know how?

thanks for the suggestion about VLAN, I suppose that this config should be the exact same for all switch, right? 

 

After factory reset, port-based VLANs are enabled, but all ports are in the same VLAN 1. This is effectively the same as no VLAN enabled.

Same in 802.1Q VLAN mode if all ports are members of only one (Default) VLAN 1, provided they are left untagged.

 

In other words: having all ports as untagged ports in only one VLAN is the same as having all ports in no VLAN (unmanaged switch).

 

But in Multi-Tenant Unit mode (MTU) you have one uplink (port 1 or whatever port you select for the uplink), which is member of all VLANs and 7 other VLANs on TL-SG108E, one for each remaining port (2-8). Therefore, in this mode the VLAN is always enabled and you can disable it only by switching to either port-based VLAN mode or 802.1Q VLAN mode.

 

do you know why replacing the switch “TV” by an unmanaged make everything work?

 

 

Then probably the TV switch is either misconfigured (in MTU VLAN mode) or it's broken. Test wether you can reach all switches' web UIs from your system connected to the FritzBox, then test remaining systems. I have a similar setup (FritzBox -> T1600G ->TL-SG108E v2 -> TL-SG105E v3, also chained until the direct connection over Ethernet cable will be deployed soon) and it works fine.

 

 

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Re:Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 21:28:06

I did “enable 802.1Q VLANs and leave the port settings at default”

 

it did not work. 

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Re:Re:Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration-Solution
2018-08-25 21:35:27 - last edited 2018-08-28 16:59:51

Next, check the cables. Connect a laptop to the cable feeding the middle switch, then test with the switch. Also check the middle switch stand-alone, with your laptop and a second device connected to it.

 

You need to isolate the error step-by-step, isolating every switch which doesn't work from the network. Also make double sure that you have factory defaults and only the IP set. But even with the IP set, check the switch stand-alone.

 

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Re:Re:Re:Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 21:44:59

Thanks for the follow-up, and explaination.

 

I did triple check that all 3 switches have the same VLAN configuration. We can simplify to a 2 switches configuration more in details if that helps.

 

The following: FritzBoz --> Cable1 ethernet 10m --> Switch "basement" --> cable2 10m -- > Switch "TV" --> computer

 

In that configuration, from my computer, I have a network but "unidentified" where I cannot get an IP. Unless I replace Switch TV by an unmanaged.

 

- Whatever of the 3 switches I place at "basement" and "TV" the same behavior persist: I have internet from the "cable2", if I put any of the 3 managed switch it does not work, if I put the unmanaged it works.

 

It feels like the basement switch puts a flag in the packets, that the unmanaged switch kills or ignore, and if that's a managed switch then the flag prevents the packet from going further.

 

 

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Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 21:56:46 - last edited 2018-08-25 21:58:06

If you leave the managed switch at factory settings, it will behave as an unmanaged switch, except that it has an IP. If using more than one managed switches or a router using the same IP, you have to change the IPs of the switches.

 

Maybe, the switch making problems fools you when saving the config. See post #5 of this thread regarding the famous "Save Config" bug of TL-SG108E. It has been fixed in latest firmware for TL-SG108E of January 2018, but this was published only as update to v3 hardware. Anyway, you can flash a TL-SG108E v2 hardware with the firmware for a v3.

 

As for the test, use static IPs assigned to your laptop/PC. Don't depend on DHCP or the network, there are too many unknown factors! Always test a device you might consider broken in stand-alone mode and check wether you can reach the web UI and other devices connected to this single switch w/o network connection etc. Then re-connect it to the network if you have proofed that the switch itself works.

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Re:Re:Re:Re:Re:Re: Impossible to chain TL-SG108E switches in home network with no specific configuration
2018-08-25 22:06:13

Ok I made a new finding.

 

Until now I thought it was impossible to chain two managed switches but if I replace the “basement” switch by the unmanaged, I was able to chain two managed switches and at the end of the chain, I had a computer where I could access Internet.

 

this way  I thought I had identified a faulty switch, but if I keep only the 2 managed switches and move up in the chain (removing the unmanaged), then again I have no internet. 

 

so now I am puzzled. 

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