Connection between 2 switches: do all networks need to be TAGGED?

[Raoulvb]

I have a network with multiple VLAN subnets coming from one port of my router into the first GS308E (port has PVID 999) and I have my main/management network coming into another port (PVID=1) on the same GS308E from an untagged port on my router.

On another floor in my house I have a second GS308E and currently i have 2 cables between these:

One cable forwards the TAGGED VLANs (all VLANs tagged on the ports and their PVID set to 999).

A second cable connects the 2 with both ports untagged and PVID = 1.

This all works well.

But now i need to add a 3rd switch after the second and I have only one cable.

So forwarding all tagged VLANs will be the same, but what about the management network.

I see 2 options: set PVID=1 on both outgoing and incoming ports and set them as UNTAGGED for VLAN=1.

OR I set both ports with VLANID=1 as Tagged as well (so ALL VLANs tagged) and PVID to 999 or so?.

Which is best?

thanks,

Raoul

[schumaku · Accepted solution]

Look, there is no right or wrong. In an enterprise network different factors apply, muh more can be done there for various security considerations. On a small home or small business network, simplicity and reasonable management is key.

In absence of capture all and default staging or re-staging network where unknown and untrusted clients will be assigned to for further actions - ways beyond of the infrastructure and management capabilities in a small environment - having the default network direct and untagged available on a trunk is useful, think about troubleshooting, think about extending and migrating the infrastructure, think about an ad-hoc switch replacement is certainly much better than ending in hours or days of downtime.

More bandwidth can be added by LAG, by devices with faster link speeds - and not by  adventurous ideas which might work this moment. 

[schumaku]

Dar Raoul,

Two links between the same switches is - even f these are carrying different VLANs - is a recepie to a nightmare. For such a configuration, we would need at least Smart switches with STP, RSTP, and MST (MSRP) for supporting multiple instances, eg. one by network (VLAN).

It does not matter which VLAN ID is configured as untagged/PVID on a physical network link (or a LAG) - as long as it's the same and only one on both ends.

Of course, you can also run all VLAN tagged on a trunk, but there s no need.

Regards,

Kurt

[Raoulvb]

Hi Kurt,

my thinking here was to prevent speed limitations, so one full gigbit speed for my main network, and one shared by VLANs which have all devices which do not need high speed (none are streaming).

And this works, maybe by accident.

Anyway, if you recommend to only use one line, then my real question is even more important (which you did not answer or I do not understand what you wrote about "it does not matter......"):

Should I set this up as UNTAGGED for main (VLAN 1) and TAGGED for the others, or should I also set the port connecting the 2 switches to TAGGED for VLAN1? I read somewhere on in an article about this topic that all lines between switched should be fully tagged...

thanks,

Raoul

[schumaku · Accepted solution]

Look, there is no right or wrong. In an enterprise network different factors apply, muh more can be done there for various security considerations. On a small home or small business network, simplicity and reasonable management is key.

In absence of capture all and default staging or re-staging network where unknown and untrusted clients will be assigned to for further actions - ways beyond of the infrastructure and management capabilities in a small environment - having the default network direct and untagged available on a trunk is useful, think about troubleshooting, think about extending and migrating the infrastructure, think about an ad-hoc switch replacement is certainly much better than ending in hours or days of downtime.

More bandwidth can be added by LAG, by devices with faster link speeds - and not by  adventurous ideas which might work this moment. 

[Raoulvb]

Thanks Kurt !!!

that helps.

Thinking of hours or days of down-time....thinking of what my wife will say.... oh boy. I know what I will do 😉

thanks again!! Really appreciate your fast answers.

regards,

Raoul