[Pc_Support] Re: ABS 8-Port, 5-Port GbE Switch -- VSC7388, VSC7385 (Blog article)

[Bryan J. Smith]

Derek Konigsberg <octo at logicprobe.org> wrote:
> Of course you need a router (or layer-3 switch) for that purpose. 

Yes.  And instead of putting in a dedicated router that will have
serious performance issues at >>10Mbps speeds -- let alone must leave
the switch fabric to do such -- I'd rather have wire-speed forwarding
in a $300-800 device.

Instead of $100 here, $200 there, router here, etc...

> What I'm saying is that most of the switches in your network have
> no need for MLS (multi-layer switching / layer-3 switching /
> routing / whatever you want to call it).

Which brings us back to our discussion with regards VLANs based on
1500 byte frames and 9000 byte frames.  _Transparent_, [near]
_full_wire_speed_ communication between nodes of 1500 byte and 9000
byte frames.  ;->

> However, such L2-only switches often still have a need for 
> features like VLANs (port-based and trunking) that tend to not
> exist on dumb switches.

I'm talking about:

A)  8-24 ports GbE (possibly with 100Mbps ports) layer-3 backbone
with 20+Gbps switch fabric

B)  Servers and performance workstations directly on that layer-3
backbone, largely talking 9000 byte jumbo frames

C)  Drop 5-8 port dumb switches for a room/cube-concentration for
general network usage with standard 1500 byte jumbo frames

> In Cisco-speak,

Oh boy ...

> we'd only consider L3 switches at the "distribution layer",

First off, that's _legacy_ '90s Cisco-speak.  ;->

Secondly, Cisco's new model is based on VoIP at the desktop, which
brings in QoS and layer-3/4 management at the desktop.

> but we still want VLAN capabilities at the L2-only "access layer".

Again, _legacy_ '90s Cisco-speak.  ;->
Cisco's _new_ model is, again, layer-3/4 at the desktop.  ;->

But regardless of all that, I'm talking about _desktop_ switches. 
Something I drop in between 4-7 systems/cubes, but still manage on a
_dedicated_ layer-3 switch port.

> In fact, I think my favorate product that illustrates a demand for
> such a capability is the 3Com NJ220.  It is a 5-port switch (1 is
> an uplink) with VLAN capabilities, built into a WALL PLATE.  The
> whole idea is that your office can have 4 ethernet ports on 4
> different networks, when only one physical cable is running down
> the wall. 

But how do you manage the wall-plate?
Furthermore, do you _know_ how much those things are?!
$30 per 100Mbps/port -- YIKES!!!

Listen, I'm _all_ for a _fully_ switched stack, but it is
_cost_prohibitive_ in many SMB setups of 50 nodes or so.  Not only is
layer-3 almost as cheap as layer-2 today, but you do _not_ need
managed layer-2 (or 3 for that matter) throughout your network.  That
will _always_ be a repeat case of _overkill_ for SMB setups of 50
nodes or so.

In a SMB of 50 nodes or so, you put layer-3 in your 20+Gbps switched
backbone, removing the need for _any_ other layer-3 device.  You then
connect servers and power workstations directly to that backbone. 
You can then use localized desktop switches as layout/expansion
dictates for regular users.

Cost is _sub-$1,000_ for 20+Gbps aggregate performance.


-- 
Bryan J. Smith     Professional, Technical Annoyance
b.j.smith at ieee.org      http://thebs413.blogspot.com
----------------------------------------------------
*** Speed doesn't kill, difference in speed does ***