Zyxel XGS4600, set lower mtu

Smartqwerty

Good afternoon
I have an XGS4600 switch and another switch (HP) that need to be paired at the VLAN level.
I configured 2 VLANs, gave addresses to both switches, everything works ok.
However, by the time of installation in the product network, it turned out that there would be other equipment between the switches in bridge mode with a maximum MTU of about 1420.
I tested whether the switches would work without setting the MTU and so far I got zero results.
My HP switch allows me to set the MTU for both the level 3 interface (not used by me) and the VLAN interface (level 2), which are planned to be used.
Can I lower the MTU on the Zyxel XGS4600 switch?

Zyxel_Kay

Hi @Smartqwerty

Regarding your inquiry about adjusting the MTU size on the Zyxel XGS4600 switch, unfortunately, it's not possible to change the MTU size on this switch model. Our switch supports the standard MTU size of 1500 bytes. While it should be possible to forward packets with an MTU of 1420 bytes without issues.

For further investigation, we set up a topology:

PC (packet MTU size 1420) — Switch XGS4600 — Firewall

Then, we conducted a ping from the PC to the Firewall with a packet size of 1420 bytes, and the result was successful with no packet loss observed.

To assist you better, could you please provide us with the following information?

1. A detailed network topology illustrating how the switch is connected and what devices are connected to it.
2. How is the traffic being forwarded within your network?
3. What is the model of your HP switch?

This will help us understand your setup more comprehensively and provide you with more tailored assistance.

Zyxel_Kay

Hi @Smartqwerty

Regarding your inquiry about adjusting the MTU size on the Zyxel XGS4600 switch, unfortunately, it's not possible to change the MTU size on this switch model. Our switch supports the standard MTU size of 1500 bytes. While it should be possible to forward packets with an MTU of 1420 bytes without issues.

For further investigation, we set up a topology:

PC (packet MTU size 1420) — Switch XGS4600 — Firewall

Then, we conducted a ping from the PC to the Firewall with a packet size of 1420 bytes, and the result was successful with no packet loss observed.

To assist you better, could you please provide us with the following information?

1. A detailed network topology illustrating how the switch is connected and what devices are connected to it.
2. How is the traffic being forwarded within your network?
3. What is the model of your HP switch?

This will help us understand your setup more comprehensively and provide you with more tailored assistance.

Smartqwerty

Good afternoon.
We investigated out the problem for a long time, the problem was not in the Zyxel switch.
The problem is in the equipment installed by ITsec guys between my switches, I tried to assemble it with switches and routers from other vendors, including the ability to lower the MTU - nothing has changed.

Thank you for your answer, this is not the first time I come here and I really like your support - installing a stand based on the case of an ordinary user is cool!