Inter-VLAN speeds on DEC695 & DEC750

[Coastal9772]

I'm looking at either one of these models and am wondering what the inter-vlan routing speeds are?

[meyergru]

I cannot say for the DEC695, but for the DEC750, I can reach 3 GBit/s on a single 10 GBit Interface. I assume that the 1 GBit can easily be saturated on the DEC750 and that is probably what you ask because the DEC695 does not have 10 GBit in the first place.

Considering the negligible price difference between the two, I would always choose the DEC750.

[Coastal9772]

Hi, no 10Gb here. Thank you for the help.

[meyergru]

If you use 1 GBit, remember that when you use multiple VLANs on the same interface, the bandwith is shared between them, such that routed inter-VLAN traffic passes the interface twice. Which is why I prefer higher bandwith for local interconnections.

[Coastal9772]

I appreciate the insight. I do have some knowledge of intermediate networking but am somewhat new to VLANing.
I was planning on having the 4 or 5 VLANs on one port on the appliance. Is there an alternative?
 

[meyergru]

Sure. If you have enough interfaces available, you can spread the VLANs over muliple interfaces. Say, if you have two VLANs, you could have each one on one port. If you have only one WAN, you could spread 3 VLANs over the 3 remaining ports if your appliance has 4 of them. Or you could have your main LAN on a physical port whereas a guest and IoT VLAN share another port.

Another possibility is to use link aggregation to the switch if it has the capability.

Apart from that, many devices nowadays offer more than 1 GBit bandwidth - e.g. 2.5 GBit. Alas, the Deciso boxes do not offer this (other than using a special SFP+ transceiver on the DEC750 or 850).

[Coastal9772]

Looking at the 750 or the dc2750 (not sure I'm willing to speed the extra $100+ on the 1U unit as nice as it would be in the rack), they have 3 RJ45, I would use 0 for the WAN and 1 for say the primary VLAN and possibly 2 for Guest. Would that mean that I would be using an extra port on my switch to tag it for that VLAN?
Port 24 on switch would go to Port 2 on the 750 and be tagged with VLAN 2,3,4 and Port 23 on switch would go to Port 3 on the 750 and be tagged in 5? Is that how it works? The switch does support LAGG as well but that is beyond my understanding at this point.

[meyergru]

Yes. Pretty much so. The definitions on the switch and firewall interfaces should match. As I said, you might as well LAGG the ports and use the LAGG as the basis for your VLANs on both the switch and the firewall - provided the switch supports that.

In that case, the LAGG is logically an interface which offers larger bandwidth and provides uniform accesss to VLANs, much as a single interface. You can simply layer this.