At 10/12/2012 10:23 AM, Tim Densmore wrote: >Hi Fred, > >Could you expand a bit on this? It sounds like you're describing what >I'd refer to as "virtual circuits" rather than "switching." Are you >setting up per-customer VLANs or something like that?
It helps if you think of it as "Ethernet-framed Frame Relay", rather than as Ethernet that hoary old LAN. So it's virtual circuit switching (the two terms are complementary, not contradictory). Each link between a pair of routers is a VLAN, which is a two-point virtual circuit. The term "VLAN" is a bit inappropriate nowadays, and the 12-bit size of the tag is inadequate for large networks, but that's what we get when recycling a mass-produced product. (Apparently AT&T ran out of tags on some of their switches.) The tag btw is solved by "Q-in-Q" nesting of tags, though most of the time it's a subscriber tag nested inside a provider tag. There's a real market gap not quite being filled by our usual WISP vendors MT and UBNT. MT has a new CPE router with SFP support. This would be great for a regional CE fiber network. Let's say you have a building (say, Town Hall) with multiple tenants in it, each with a separate IP network (say, Town administration, Police, and School Admin). You'd want to be able to drop off one fiber with separate VLANs (virtual circuits) for each network, isolating the traffic from each other. An MEF switch is cheaper than a real Cisco router but a Routerboard is cheaper yet! And it can't route since there are multiple independent networks there, each with its own routers and firewalls. Nor is bridging appropriate (not isolating). So a Carrier Ethernet (MEF) switching option would fill that bill. Of course the same software would work with a wireless feed to a shared-tenant building, not needing the SFP version. I suspect the pieces are all there, just not the assembly instructions or tools to facilitate it. It involves setting up VLANs and queues. >TD > >On 10/11/2012 06:35 PM, Fred Goldstein wrote: > > Switching, though, is what Frame Relay and ATM do, and now Carrier > > Ethernet is the big thing for fiber. It uses the VLAN tag to identify > > the virtual circuit; the MAC addresses are just passed along. Since > > it's connection-oriented (via the tag), it can have QoS assigned. I > > think it's theoretically possible to tag user ports, route on tags and > > set QoS on RouterOS, but it's not obvious how to do it all. Switching > > doesn't pass broadcast traffic; it provides more isolation and privacy > > than plain routing. Mesh routing then works at that layer, > > transparent to IP. It'll be "interesting" to set up. > >_______________________________________________ >Wireless mailing list >[email protected] >http://lists.wispa.org/mailman/listinfo/wireless -- Fred Goldstein k1io fgoldstein "at" ionary.com ionary Consulting http://www.ionary.com/ +1 617 795 2701 _______________________________________________ Wireless mailing list [email protected] http://lists.wispa.org/mailman/listinfo/wireless
