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photon2
photon2
12/5/2012 | 2:52:31 AM
re: Alcatel Router Revenues Surge
Well since the we've degraded to bridging vs switching, what I've been looking for (for awhile) is the comprehensive difference today between a router and switch. My definition has been the line where WAN services take place, BGP must be enabled beyond 2 peers, and multicast support is available. But I'm sure that's not all of it....any suggestions in a simple checklist without the 'vendor bent'?
paolo.franzoi
paolo.franzoi
12/5/2012 | 2:52:30 AM
re: Alcatel Router Revenues Surge

ATM PVCs were not a requirement of ATM networks. It was a poor implementation and the technology supported SVCs and PNNI. So, I come back to it was the boxes and not the technology. The boxes were designed to support handsful of high value connections and apply zillions of rules to these connections. The technology did not require that to be true. The application of the technology was such to deploy this over high value interfaces of very small numbers.

When ATM was taken to consumer access, this needed to change and the boxes did not change. That is not the technology's fault. Which is actually your claim. If DSLAMs had used PNNI and SVCs to set up new users than there was no need to set up ATM PVCs. ATM PVCs were not a requirement for that application.

I am simply stating that number of point to point connections is the reason that a particular technology failed. I dispute this claim. I point to my example. ATM did not automate its connections. That was a product problem.

I think the voice network is a great analogy...BGP wishes it had the simplicity of area codes.

seven
Sisyphus
Sisyphus
12/5/2012 | 2:52:30 AM
re: Alcatel Router Revenues Surge
> The statement was that ATM is hard to manage
> because of the number of point to point
> connections. I dispute this point absolutely
> at any layer. ..

But Seven -

ATM PVCs had to be set up manually. SVCs never quite made it, MPLS came too late to save the day and aid the scaling issue. It was indeed an N**2 problem, and had scaling issues. I saw it first hand...

The voice network supports millions of dynamic connections indeed, but those are set up and torn down by users, there is no administrative overhead involved in setting up those connections - just in setting up a static network topology where connections get set up by users as they need.

There is a fundamental difference, and I still think the voice network is not a god analogy, not for L2 Ethnernet nor for ATM... and not for L3, for that matter.
paolo.franzoi
paolo.franzoi
12/5/2012 | 2:52:30 AM
re: Alcatel Router Revenues Surge

Sis,

The statement was that ATM is hard to manage because of the number of point to point connections. I dispute this point absolutely at any layer. I dispute that it was dificult to scale as it was done with many employees who had difficulty reading and writing. Call me when you can manage a BGP router network with such employees.

The complexity of managing these networks is QoS and trying to solve all problems with a single infrastructure.

seven

mtb826
mtb826
12/5/2012 | 2:52:29 AM
re: Alcatel Router Revenues Surge
The fact that the 7450 functions as a PE for Ethernet services; switches VPLS or PW services over GRE, LDP, or RSVP-TE (I believe that is called an LER); support POS as well as Ethernet interfaces, can also switch MPLS (I believe that is called an LSR ); supports all required IGP protocols within the core to function as an LER and LSR; does not maintain a global L2 FIB or support STP except in the context of VPLS; VLANs have only local significance; why would you not call it a router? If (or should we say when?) Juniper or Cisco had such a box you'd call it a router, wouldn't you?

Face it folks, Alcatel is in the game.
turing
turing
12/5/2012 | 2:52:29 AM
re: Alcatel Router Revenues Surge
I think routing/switching is no longer objective, but subjective terms.

I still believe the classical definitions:
A switch forwards based on L2 (802 MAC, ATM VPI/VCI, whatever) addresses in an L2 bridge table, and doesn't fragment/reassemble the packets, doesn't change contents of packets, and for all intents and purposes shouldn't care whether it's L2 packets are carrying IP, IPX or Appletalk. In ieee 802's case (e.g., ethernet switches) it's a bit more specific in that it shouldn't change MAC addresses, but can partition based on vlans, could particiapte in spanning tree and its derivatives as a bridge node, etc.

A router does not have to run a single routing protocol, just like switches don't have to run spanning tree. (although in the latter case usually because people don't want it to) A router merely has to forward based on the ip dest address, changes the L2 addresses since L2 is terminated by it, technically should decrement the TTL, could/should do fragmentation/SARing or at least enforce an MTU, etc. For ethernet L2 it would be the broadcast domain edge, and appears as an ethernet LAN endpoint.

An L3 switch in my book is a router, or at least a logical equivalent of a switch where the separate VLANs are "connected" by an internal router engine. It's just that some people think it's an L2 switch even when they make it route between VLANs, and others think it's an L3 switch even when they only have 1 VLAN configured on it or no inter-VLAN forwarding.
Tony Li
Tony Li
12/5/2012 | 2:52:29 AM
re: Alcatel Router Revenues Surge

Actually, BGP with area codes would push us into the realm of geographic addressing. While that would greatly simplify the protocol itself, the regulation necessary to implement the approach would be intractable. The result would be a series of exceptions, which would lead to a combination of both 'area code' and 'longest match' forwarding, which would be a level of complexity far above where we are today.

Tony
turing
turing
12/5/2012 | 2:52:28 AM
re: Alcatel Router Revenues Surge
But I would hardly call an ethernet switch connection-oriented.

The distinction of router switch physically is still important and does still mean hardware differences for vendors - especially if you mean ATM switches vs. routers. I find there is also still a big difference in the cost structure between routers and ethernet switches and although some of that is just positioning and markets, some of it is real hardware differences.

I agree with you in principle. But to me when a vendor tells me they're a router it has a very different meaning for a network than a switch, for most technical groups of the organization.
turing
turing
12/5/2012 | 2:52:28 AM
re: Alcatel Router Revenues Surge
When these new "all-ethernet" devices were coupled with cut-through forwarding modes, they didn't want to be lumped into the old "bridge" product category.

Actually if I recall right, they started using the term when the started being able to forward from one port to another while simultaneously forwarding between two other ports.

Cut-through I thought was a bit later, no? (cut-through being the ability to start transmitting out the destination port before waiting for the whole receive packet to arrive, instead of store-and-forward)

They also desperately wanted to distance themselves from cpu-based bridges with only a few ports, as they had lots of ports and hardware ASICs to do bridging much much faster. Somehow router vendors never figured out how to make that distinction - its still a router whether it's a Juniper T640 or a Proteon GlobeTrotter.

tmc1
tmc1
12/5/2012 | 2:52:28 AM
re: Alcatel Router Revenues Surge
More flames for the fire:

There is also considerable difference in the HW and SW design also. While an L3 switch can do routing, it is usually lacking in some of the things that are required by a router. It has been leveraged from an enterprise switching environment, is VLAN-centric and cost is a very important design limitation. In many cases an L3 switch lacks the memory sizes, interface support, reliability design, testing and development that are needed for high-end edge or core routing functions. The people developing L3 switches frequently do not understand the requirements of high-end routing or do not have enough dedicated resources working full time on making such a product. They just slap some new "high-feature" NPA/FPGA blades in and try to add MPLS, etc.

I have worked on both successful L3 switching products and routing products and they are like night and day in design and testing because the mission of each is so different.

For this reason I agree that no enterprise switch should be considered a true router although it can do simple routing just fine. The 7450 is a true router under this criteria IMHO because it is leveraged from a good, proven router (the 7750) and not from an enterprise switch.
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