Planning trunk capacity for multiple GbE switches
- by wuckachucka
Without measuring throughput (it's at the top of the list; this is just theoretical), I want to know the most standard method for trunking VLANs on multiple Gigabit (GbE) switches to a core Layer 3 GbE switch.
Say you have three VLANs:
VLAN10 (10.0.0.0/24) Servers: your typical Windows DC/file server, Exchange, and an Accounting/SQL server.
VLAN20: (10.0.1.0/24) Sales: needs access to everything on VLAN10; doesn't need access to VLAN30 and vice-versa.
VLAN20: (10.0.1.0/24) Support: needs access to everything on VLAN10; doesn't need access to VLAN20 and vice-versa.
Here's how I think this should work in my head:
Switch #1: Ports 2-20 are assigned to VLAN20; all the Sales workstations and printers are connected here. Optional 10GbE combo port #1 is trunked to L3 switch's 10 GbE combo port #1.
Switch #2: Ports 2-20 are assigned to VLAN30; all the Support workstations and printers are connected here. Optional 10GbE combo port #1 is trunked to L3 switch's 10 GbE combo port #2.
Core L3 switch: Ports 2-10 are assigned to VLAN10; all three servers are connected here.
With a standard 10/100 x 24 switch, it'll usually come with one or two 1 GbE uplink ports; carrying over this logic to a 10/100/1000 x 24, the "optional" 10 GbE combo ports that most higher-end switches can get shouldn't really be an option.
Keep in mind I haven't tested anything yet, I'm primarily moving in this direction for growth (don't want to buy 10/100 switches and have to replace those within a couple of years) and security (being able to control access between VLANs with L3 routing/packet filtering ACLs).
Does this sound right? Do I really need the 10 GbE ports? It seems very non-standard and expensive, but it "feels" right when you think about 40 or 50 workstations trunking up to the L3 switch over 1 GbE standard ports. If say 20 workstations want to download a 10 GB image from the servers concurrently, wouldn't the trunk be the bottleneck? At least if the trunk was 10 GbE, you'd have 10x1GbE nodes being able to reach their theoretical max.
What about switch stacking? Some of the D-Links I've been looking at have HDMI interfaces for stacking. As far as I know, stacking two switches creates one logical switch, but is this just for management I/O or does the switches use the (assuming it's HDMI 1.3) 10.2 Gbps for carrying data back and forth?
