I'm contemplating enabling Jumbo frames for a specific network/VLAN (a dedicated storage network). Ports are spread across two switches, linked together using a LAG, which is configured to carry all relevant VLANs (trunking).
I presume the cross-switch LAG ports need to be configured for Jumbo frames? Will this negatively impact the VLANs carried over the same LAG which retain standard frames?
Below is an attempt at depicting the situation; let's say we want to enable Jumbo frames for VLAN 15 but retain standard MTU for VLAN 10, so on each switch (and connected NICs), we'd set the MTU to 9000 for ports 2, 3 & 4. So the cross-switch trunking LAG (on ports 3 & 4) carries both the standard MTU VLAN (10) and the Jumbo MTU VLAN (15). Will this cause any issue?
_______________________________ _______________________________
| | | |
---|-port 1/ VLAN 10(u) | | port 1/ VLAN 10(u)-|---
| | | |
---|-port 2/ VLAN 15(u) | | port 2/ VLAN 15(u)-|---
| | | |
| === SWITCH 1 === | | === SWITCH 2 === |
| | | |
| LAG1/port 3/VLAN 10+15(t)-|------|-LAG1/port 3/VLAN 10+15(t) |
| | | |
| LAG1/port 4/VLAN 10+15(t)-|------|-LAG1/port 4/VLAN 10+15(t) |
|_____________________________| |_____________________________|
(note: (u)=untagged ; (t)=tagged VLAN port - not that I think this matters (?))
This may be obvious - the term Maximum Transfer Unit suggests just this: it's a "max", as opposed to a mandated frame size - but it would be good to get it black on white by someone in the know...
I guess the LAG part is a bit of a red herring; the question would equally apply with a single trunking port across switches.
In case this matters, switches are Netgear ProSafe managed: GS748Tv5 and GS724Tv4
Cheers!
