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Is the Distribution Layer Still Needed? 72

arnie_apesacrappin wonders: "I'm in the process of designing the network for a new building in what I would consider a small to medium sized company. It is on the scale of tens of access layer switches, not hundreds. There is a ongoing argument about the need for a distribution layer. My position is that with today's layer 2/3 switches in the core, the distribution layer is outdated for a network of this size. The layer 2/3 core can provide all the aggregation services of the old distribution layer and the routing/filtering functionality of the core with better price and performance. My opponents can only argue that having a distribution layer is the standard. So, are there good reasons for having a distribution layer in a small to medium network? If you were going to argue against the distribution layer, what points would you make?"
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Is the Distribution Layer Still Needed?

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  • by grub ( 11606 )

    Quit trying to be clever. Proper use of L3 equipment around the LAN and judicious use of VLANs is smart. Current equipment will let you design in redundencies for failed hardware so trying to aggregate all your networking smarts to a central point of failure is not cool. Frankly it sounds like you're trying to impress management without thinking of the ramifications.
  • What? (Score:4, Funny)

    by Bootle ( 816136 ) on Wednesday April 06, 2005 @11:05AM (#12154210)
    All your technical mumbo jumbo is leaving me bamboozilified. Could ya tone it down a tad?
    • Re:What? (Score:2, Funny)

      by Anonymous Coward
      Mr. President, what have we told you about posting on Slashdot?
  • It can be done. (Score:4, Interesting)

    by FreeLinux ( 555387 ) on Wednesday April 06, 2005 @11:11AM (#12154288)
    Removing the distribution layer is perfectly possible. The main requirement though, is having sufficient processing power and redundancy on the core to handle the access layer's connections.

    Basically, if you eliminate distribution, you have to have a lot more processing power and lots more ports in the core. Depending on the network's size and distribution it will probably be more costly to build such a robust core. Also, don't forget that this thing is certain to grow. Can it scale easily and cost effectively with the more robust core? There will come a point that it will not scale effectively and the distribution layer will have to be introduced.
    • Re:It can be done. (Score:5, Insightful)

      by Kaamoss ( 872616 ) on Wednesday April 06, 2005 @11:16AM (#12154334) Homepage
      That's the real key, if the network can't be scalable then you're not setting your self up to do further work for the company. When you give someone a solution it should have the ability to grow with them. In the end it's almost allways cheaper to go with the more complete solution than the simple one.
    • Re:It can be done. (Score:1, Insightful)

      by Anonymous Coward
      Smaller layer 3 devices around the LAN allows for more scalability than a central beast.
  • by Schezar ( 249629 ) on Wednesday April 06, 2005 @11:23AM (#12154420) Homepage Journal
    The very concept was never spoken of at university (Rochester Institute of Technology), nor has it ever come up in work (IBM).

    Those three "layers" are abstractions, nothing more. The "distribution" layer is simply a term for traffic shaping and optimization. It's very useful in eliminating excess resource use on beleagured routers. Eliminating the layer is nothing more than simplifying your backbone architecture. There is no "layer" to eliminate except the theoretical one.

    It always amazes me how Cisco-certified (not making any acusations here) network techs speak an entirely different language from university-educated ones. They talk about Cisco-specific concepts like they're set in stone universally, and use Cisco jargon for common and/or basic concepts.

    There are other options besides Cisco, and not every network fits within the nomenclature of Cisco Jargon. You'd do yourself an immense favour to lean more about generic architecture concepts.

    I don't want to sound mean, but a Cisco cert is about as useful as an MSCE.
    • heh i go there, and well spoken...
    • I love the fact that the very next posting after this one starts with "To preface, I am a CCIE, so I know a little about these things."

      To the CCIE's defense, he gave a balanced and reasoned opinion that was not rife with Cisco jargon.

      I, on the other had, find it interesting to talk to university educated CS majors (I graduated with a BA in Math, but have worked as an SA and programmer for 17 years) who use lingo (especially pattern nomenclature) and discuss concepts (stateless session beans, oooooooooh) o
      • I've had experiences that negate both of these presuppisitions. At the small University where I went, I literally watched the ethernet equipment being installed. I then used it to do most of my assignments via a remote X session to the lab computers, from my dorm room. Professors looked at me dumbfounded when I told them why I wasn't attending labs any more. They wondered what I had "hacked" in order to be able to do that.

        When I applied for a job at the same University as Network-something-or-another y
        • Thank for articulating what frustrates me day in and day out.
        • I love the irony you bring to light about university settings.

          One would think those working for and under university level expectations, and job applications requiring EVERY-SINGLE-JOB-YOU-EVER-HAD to be listed with it, to be somewhat on the ball about how to do things, at least efficiently.

          But, no.

          What is often forgotten is that universities are rarely anything less than a bureaucracies. Therefore you, as I and my classmates, might get a "Unix Administrator" who is unaware of the web interface t

    • Is the real purpose of the "Distribution Layer" to distribute revenue to Cisco?

      Reading TFA and the other posts, I can see the point of reaching for that degree of networking control in a big enterprise. At the other end of the scale - the home LAN level, network bandwidth is practically where nuclear-generated electricity once promised to be - too cheap to measure. I went from 10Mb to 100Mb because it was cheap and available, not because of need, and any future migrations will likely be the same.

      You're ob
    • Yeh, but did your fancy university classes teach you how to route appletalk with EIGRP? Huh? Huh? Did you learn how to bridge CDP across legacy switches? Did you even learn why open standards like OSPF may not be the best choice in a modern high-powered network, you savage? I think not.
    • I think you're underrating the value of a CCNA, but you're right that the program doesn't present alternatives and uses different terminology than the Real World. That's what bugged me about it while I was taking the program; the education was OK, the indoctrination was a pain. Of course, the real problem is folks who (like those the original poster is arguing against) accept the Cisco Gospel at the expense of actual needs analysis.
    • Absurd! (Score:3, Funny)

      by wonkavader ( 605434 )
      Nothing could be more useless than an MSCE.
    • The very concept was never spoken of at university (Rochester Institute of Technology), nor has it ever come up in work (IBM).

      Thank [insert-diety-here] someone cleared this up for me. I thought I was well-versed in networking, but this article left me wondering what classes or books I missed. Now the answer is clear - Cisco. I make it a point to never attach myself to a brand-centric technology or concept.

      Again, thank you.
  • You don't need it (Score:4, Informative)

    by Anonymous Coward on Wednesday April 06, 2005 @11:26AM (#12154467)
    To preface, I am a CCIE, so I know a little about these things.

    You are correct that the layer 3 switches offer a different perspective on how networks can be drawn today.

    It used to be that big switches would sit in the computer room, with clunky slow routers sitting on top of them, acting as Routers-On-a-Stick, with some sort of trunk connecting them to the core switch.

    I think the easiest design that will give you the most benefit would be to just trunk a link to whatever closet, and use a cheap layer 3 switch (perhaps Extreme or a similar variety) in the data closet, for end user hookups.

    Have gateways set up on the switch, use a default route pointing back to the core, and divide up the ports to whatever VLANs you ported over--I prefer to have a management VLAN and a few ports set up for that, maybe an extra one for SPAN/Mirroring if necessary.

    The end user traffic would likely never be routed until it reached the core, unless you'd like to trunk the core traffic over to the closet. Then the access layer switch could route to the core subnet if necessary and save the core switch(es) the effort of doing such routing. If you have a small business, it wouldn't make much difference either way--many chassis based layer 3 switches do 64Gb per second routing with their fabric, and it is unlikely anyone would notice a delay from the routing in the closet or in the core.

    Again, it depends on how you want it to look and how you want trouble shooting to be. But you are absolutely correct--a distribution layer is no longer necessary. I would consider it, really, to be the Core/Distribution and then Access Layers, or the Core and Distribution/Access Layers.

    You still are using the concept of the distribution layer, but it has merged with another layer, depending on your design.

    Oh, and don't forget about spanning tree :) You still need that.
  • No clear choice. (Score:3, Informative)

    by redelm ( 54142 ) on Wednesday April 06, 2005 @11:33AM (#12154548) Homepage
    Yes, with a fully switched network the major driver for a distribution layer (traffic congestion & collision domain size) has gone away. However, other reasons like expandibility, damage isolation and traffic isolation still remain. For a price. Pick your poison.

  • Some people seem to have to make networks overly complicated but in most enterprises, a simple and clean architecture is the best policy.

    It basically comes down to switching at the core and routing at the edge. No need for all the jargon.

    • Enterprises have problems where developers need to operate in the same offices as finance or sales. The needs of the groups are very different (e.g. developers need simulated development environments which won't take out accounting, accounting needs very limited and controlled access to very special systems... ) and any one of the employees may be operating off-site through a VPN or shifting sites daily.

      Moving the employees around the network hardware isn't acceptable anymore. The network needs to be fl

  • From your description, I would say that eliminating a separate distribution layer would be just fine. A central layer-3 switch with enough ports to service all the users and infrastructure would be adequate for your network in most cases. You probably will end up with a distribution layer of sorts anyway as people put 4 and 8 port switches on desks for various reasons.

    Speaking from the $$$ side, it looks like you have priced out both options and the core-only network would be cheaper. In that case, more po

  • Layer 3 Switch? (Score:2, Interesting)

    by adamjaskie ( 310474 )
    The fuck is a layer 3 switch? I keep hearing this term. I was taught that hubs work on Layer 1 (physical), switches on Layer 2 (data link layer - i.e. dealing with MAC addresses) and routers on Layer 3 (network - i.e. dealing with IP addresses). Is "Layer 3 Switch" just cisco for what everyone else calls a "Router"?
    • Re:Layer 3 Switch? (Score:4, Informative)

      by Lars T. ( 470328 ) <Lars.Traeger@goog l e m a> on Wednesday April 06, 2005 @12:14PM (#12155114) Journal
      Layer 2 and Layer 3 Switch Evolution - Volume 1, Issue 2, September 1998 []
      Layer 3 switching is a relatively new term, which has been ?extended? by a numerous vendors to describe their products. For example, one school uses this term to describe fast IP routing via hardware, while another school uses it to describe Multi Protocol Over ATM (MPOA). For the purpose of this discussion, Layer 3 switches are superfast rout-ers that do Layer 3 forwarding in hardware. In this article, we will mainly discuss Layer 3 switching in the context of fast IP routing, with a brief discussion of the other areas of application.
    • Google turned up an answer in less time than it took to type your question. Basically, yes a layer 3 switch will route packets based on IP addresses. Apparently there are layer 4 switches as well (think protocols like HTTP, FTP, SMTP, etc)
    • Re:Layer 3 Switch? (Score:1, Insightful)

      by rf600r ( 236081 )
      I was taught that hubs work on Layer 1 (physical), switches on Layer 2 (data link layer - i.e. dealing with MAC addresses) and...

      You were taught incorrectly, or, perhaps a more plausible possibility is that you learned incorrectly. Ethernet hubs and switches are both Layer 2 devices. Your best bet is to read /. for a while and resist posting. You may learn something from this very thread.
      • I thought that Hubs were L1 devices, but only when they don't have multiple speeds. Eg. If I have a 100BT hub that only runs at 100BT, then its a true hub and would be an L1 broadcast style route.

        I fully agree though that when dealing with hubs that are for instance 10/100BT then they are forced to concider how to slot in each request between backplanes. The 10 devices work as a single hub, and the 100 devices work as another hub. There is also switching logic which bridges the two together. Usually the up
      • A hub is most certainly NOT a layer 2 device. All a hub does is re-transmit the data across multiple ports. It doesn't even look at the data. A switch actually looks at the frames, and sends them to only the port that needs it. I do not know where this would fit in with dual-speed hubs, however.
        • Dual speed hubs are sort of a lie.

          The operate at the speed of the slowest connected device.

          So, let's say ( for some bizzare reason ) you have a 10/100/1000 multi-speed hub.

          If you plug a 10mb device in, all ports run at 10mb.

          Since it's rebroadcast across all channels, there is no way to do "buffering" of a 10mb port usually.... which is what a multi-speed switch will "usually" do.

          buffer, or slow connections across any set of ports talking slower.
          • Actually, the more common implementation is that of a 2 port switch, where any of the physical ports are dynamically assigned to either the highspeed or lowspeed side of a 2 port switch to handle the buffering.

      • The only thing anybody should ever learn from reading posts on Slashdot is that almost nobody actually knows what they are talking about.

        Read mine; that's all the proof you'll need.
    • Re:Layer 3 Switch? (Score:3, Informative)

      by Zapman ( 2662 )
      You are sort of right. A 'router' is capable of working with multiple subnets, but traditionally, only has a few interfaces. A 'switch' (or hub) is traditionally only able to deal with 1 subnet, but has lots of 'interfaces' (ports).

      Switches have grown up, since the advent of VLAN's, they've been able to 'route' between vlans, and have expanded to OSPF, and other high end routing protocols, while keeping the port count. These higher end switches don't usually have WAN ports (T1, T3 type), or the ability
      • What is the point of VLAN?
        I have never found a need to set that on my switch, and every place I have even been that uses them all it does is get in the way of proper installation of HACMP clusters.
        • > What is the point of a VLAN?

          If you are utilizing chassie level switches, you'll run into them. The point is to have different IP subnets on the same 'switch', and have the switch route appropriately (or not as needed by the network design... without the routing piece, a host on VLAN 1, can't see a host on VLAN 2. That might be how you want it.)

          If you have a chassie with 8 blades of 48 ports each, it's unlikely that you want all of them to be on the same subnet, so you have VLAN's.
        • What is the point of VLAN?

          The advantages of multiple physical networks without the disadvantage of having to physically install multiple physical networks.

          Note that if you're not in an environment where multiple physical networks would not be an advantage (or even a consideration) VLANs are probably not of interest to you.

    • Yes, it's technically a router, but has lots of ports, like a switch. It's useful for doing QoS at the IP layer instead of the MAC layer, without having to translate between the two at the endpoints (workstations), which typically have crappy support for MAC layer QoS.
    • You were taught wrong. A bridge is a device that routes on layer 2.

      A switch is a device that does the operations in hardware as opposed to software. Generally a switch will run on layer 2 because it is much easier to put the layer 2 protocols in hardware, but sometimes they will work in layer 3. (actually most layer 3 switches are a combonation, doing the common tasks in hardware, but things less common in slower software)

      Unless specified otherwise, most switches today operate on layer 2, so nobody use

      • I should mention that most layer-2 switches to not have the spanning tree stuff that bridges have, so they are not the same thing. A switch is a smart hub, in that it doesn't send traffic to everyone, but it isn't smart enough to find loops in the network and deal with them. Now that networks run only routeable IP this isn't a big deal. Back when the transition from bridges to switches was made, was the tail end of the time when your network was likely to run some protocol that wasn't router friendly,

      • "Route" is a special term which applies only to layer 3 protocols.

        Software/hardware doesn't matter.

        A bridge was an older peice of hardware designed to connect two broadcast domains, useful for nasty protocols like NetBEUI.

        A switch was a multiport bridge. the MAC tables in modern switches are quite capable of bridging. I've been told that older switches had very limited MAC tables so the distinction between a bridge with two ports and a huge MAC table v.s. a switch with a huge number of ports and a s

  • by jsailor ( 255868 ) on Wednesday April 06, 2005 @12:00PM (#12154929)
    You didn't state the size of your network other than to say small-to-mid size, but most small to mid-size networks can run fine without a distribution layer. You're also correct that it is an artifact of 1996-1999 switching technology limitations and large vendor propaganda that sells ports. You need to be careful about:

    1. how you link your merged core/distribution switches: if your access uplinks are layer 2, you then have to span VLAN across core/distribution switches. If you plan on having your access switches perform layer 3 routing look into the costs your vendor may charge for that functionality. Some charge as much as $10,000 for the license.

    2. Be careful you grow your VLANs and spanning trees. Definitely use per-VLAN spanning trees. Also seriously consider rapid spanning tree or vendor specific hacks (uplinkfast, backbone fast, etc.)

    3. Use server access switches. Seriously consider redundant control processors in these.

    4. Seriously consider redundant control and switch fabrics for the the core/distribution switches. In the three-layer model, this was not as much of a requirement. Also seriously consider the failover time associated with the redundancy you bought. Times ranges from stateful/1 second failover to 90 second reboots to the redundant processor.

    5. If you do layer 3 routing and the access layer be very careful with your routing protocol design and avoid black-holes. Run through all failure scenarios and make sure you're covered.

    6. Consider where you want to perform filtering for security, QoS, etc. By eliminating the distribution layer, you're forcing this the access layer. (arguably it belongs there, but think about how many places you'll be configuring and monitoring)

    7. Most importantly, consider the costs after you've considered the above. You may find out that you're not saving much. Most of my clients do save, but some find out that after they've added redundancy and possibly upgraded switch models they are close the same cost.

    8. Consider your support group. What are they used to? Can they adapt? Can they handle the added functionality that's been pushed to the core or access switches.

    Again, I have clients with 1500 nodes running fine with a combined core/distribution. I also have a clients with 200 nodes that mandated three layers. IMHO the break point is somewhere around 1000-1500. As always every place is different, be careful, plan and you'll be fine.

    • I think the key reason to have that middle layer is for scalability these days.
      Buying 15 smaller switches, and collapsing/trunking 200 switches onto 15/30 Gig/10Gig uplinks to a core means my core only needs 15/30 ports, instead of 200+. Sure, you don't *need* it, if you can afford the port density of that size on your core, but any decent sized network is going to be pressed for that kind of cash :)
      It's significantly cheaper/easier to provided redundancy for 30 GigE ports than it is to provide redundancy
  • Think about what you'll need tomorrow, or three-five years from now. Then think about whether you'll be able to scale your design without rebuilding...

    Alot of vendor supplied designs are made assuming that you are going to grow exponentially... which may or may not be your case.
  • by dtfinch ( 661405 ) * on Wednesday April 06, 2005 @01:25PM (#12156167) Journal
    We just have a stack of 24 port gigabit switches. 4 ports on each switch is set up as a trunk to connect them together, effectively turning them into one giant, fast, very cheap gigabit switch. Looking at the Cisco diagram, this might be considered our distribution layer.

    We normally have one port on the switches for each system, with the exception that in some locations we have smaller switches to allow them to share a line, so that we don't have to rewire the building. We also use some smaller switches as repeaters to parts of the building too far away to connect directly to the central switches. Those small switches outside of the server room, along with all our servers and systems, might be considered our access layer.

    Then we have a tiny linksys router, intended for home use, connecting the entire building to the internet. I know, it sounds scary, and unprofessional, but it seems plenty capable of filling the bandwidth of a T1 and tracking as many simultaneous tcp connections as we use. We'll consider replacing it at the first sign of trouble. I guess this is our core layer.

    I suppose that whatever you use at the top level to connect your systems to create a single network can be called your distribution layer. The switches may get cheaper over the years, but it's the same thing. If you just have a chain of 8 port switches running around the building, then your distribution layer is a bunch of 8 port switches.

    However you design your distribution and access layers, your main goals should probably be to minimize line problems (mostly due to distance) and avoid bottlenecks. You seem concerned about price, so if you decide to use 100mbit switches to keep the price down, I recommend that get the kind that have gigabit uplinks and plug them into a gigabit switch, and plug your servers into the gigabit switch as well. Otherwise, your effective bandwidth will be 100mbit total rather than 100mbit per user.
  • by Jjeff1 ( 636051 ) on Wednesday April 06, 2005 @01:32PM (#12156266)
    For a school, they have 5 buildings on a campus. Within each building was 1 to 5 wiring closets. A total of 900 ports or so. Their requirements were simple, they wanted speed, multicast support, and some access control between VLANs. IP only.

    I'm a consultant and work with hardware from just about anyone, so it makes no difference who they bought. We were hired to design a network for this school using various vendors equipment. Primarily to compare costs.

    In the end, they went with a solution from HP. A single 5300xl in each building connected to a bunch of 48 port edge switches in each closet. Their server room has a 5300xl with a couple Gig blades and a second 48 port Gigbit switch.

    What really decided the issue was cost. They didn't need support for all the assorted protocols and features you get with cisco, and they didn't want to pay for it. With cisco, you had a 6500 series monster in the datacenter, then a distribution switch in each building, and a bunch of edge switches.

    The HP solution was well under a third of the cost of the cisco solution, also free lifetime next day replacement warranty on hardware. For the money they saved, they can afford to have a shelf full of spares, including a spare core switch.

    Personally, instead of looking at what model you want to use, look at what you need your network to do, then talk to your prefered vendors and see who can do it at the best price point.
  • As we regress to the Network is the Computer model (aka the network is a mainframe with intelligent terminals and completely virtualized services), the distribution layer becomes more and more important.

    Aside from the benefit of building the physical layout to represent (as much as possible) the hierarchical virtual topography in aiding troubleshooting, the Cisco Campus/DS layered design allows for the layering of services without having to swap out switches e.g. bringing routing to the switch port isn't g
    • Note: i sat in on a roundtable with Charlie Ciarcarlo (the Cisco CTO) a few weeks ago. Cisco intend to virtualise bloody everything. Their stated intention is to move intelligence from the edge/periphery back into the network. This will break the (to paraphrase) "Network of Stupid Networks" model for the free market explosive growth of the internet. I have doubts that it will do anything other than drive revenue into Cisco networks but am interested in the GRID computing as stepping stone model. Ciscos road
  • Count your blessings. You'd be amazed at how many small to medium sized companies (2000+ employees) have one Cisco router in a rack somewhere and use consumer grade linksys or d-link 10/100 switches everywhere else.

    For sending email and word docs around, you really don't need the whole Cisco hierarchy. On the other hand, If you're sending uncompressed production video around, it's not enough.
    • (2000+ employees) have one Cisco router in a rack somewhere and use consumer grade linksys or d-link 10/100 switches everywhere else.

      If you have such a network, please post pictures. The Slashdot populace would LOVE to see that beast. Shudder
      • I don't work there no more (disclaimer: my leaving had nothing to do with their network architecture).

        But I know a network consult who has described to me far worse scenarios:
        - Unstable networks that don't behave the same if the various elements are powered up in a different order
        - People bringing in their own wifi equipment and creating and routing new subnets on their own initiative, and the network admin people don't see it for a couple of MONTHS
        - Cheapo hubs that assume all equipment is at least FDX 10
        • And when the crappy consumer grade stuff fails they can swap in a new one for cheaper than two weeks maintenance on a cisco box.

          And that, in a nutshell(tm), is what I absolutely hate about the "high end" stuff. The fact that the up-front cost to gain ownership of the physical device is one thing, but the hefty recurring fees to get ANY kind of support (including, as far as I can tell, bug-fixes, security updates, and so forth) get insane very quickly. Especially when you're presumably willing to pay the

          • Please read a Cisco vulnerability announcement. You will see toward the base the procedure to get a free update that fixes the vulnerability if your equipment is not covered by smartnet. I quote:
            Customers who purchase direct from Cisco but who do not hold a Cisco service contract and customers who purchase through third-party vendors but are unsuccessful at obtaining fixed software through their point of sale should get their upgrades by contacting the Cisco Technical Assistance Center (TAC). TAC conta
        • Oh yeah! Welcome to the REAL world. I work in a non-profit. Sounds familiar. But hey, it works!
  • by wikinerd ( 809585 ) on Wednesday April 06, 2005 @01:58PM (#12156617) Journal

    The term "distribution layer" is defined by Cisco, which is just a corporation. There is no standard where you will encounter this term.

    The most well-known networking standards are the OSI model [] and the TCP/IP model []. Neither of these standard models include the term "distribution layer", which means nothing by itself: Is it about physical-electrical distribution, data distribution or information distribution?

    I personally dislike "standards" or tech-speak set by corporations and I believe international bodies and computer scientists should be preferred when it comes to standards and technical jargon: Imagine two computer scientists, one using Cisco-speak and the other knowing only Microsoft-speak, how are they going to communicate? It's impossible! - unless they both adopt a common language like these proposed in the OSI or TCP/IP model.

    I personally can communicate network concepts using the OSI model, and I am completely unaware of Cisco-speak. In an attempt to answer your question, I will assume that by "distribution" Cisco means "routing", which translates to "Internet layer" in TCP/IP-speak and is related to the Internet Protocol, while in ISO-speak it translates to "Network layer". If my understanding is correct, then the answer is that no matter how small your network is, you will want to use routing, for example for connecting your small network to the Internet. Even if the routing functionality is included in a device of another layer, or even when it is implemented in software, it will always be there, no matter whether the users or even the administrator can see it, especially if you are going to use the TCP/IP protocol suite.

    • Distribution does not mean routing. Distribution means policy. Cisco's model is to do very fast, efficient routing at the core, and fast switching at the access layer and leave all of the heavy policy processing in the distribution layer. This is a VERY scalable model, and it also happens to lead to a lot of switch sales... From what I saw of Cisco's own network (late 90's) they didn't even follow the idea themselves for satelite offices. In the satelite offices I admin'd we had one or more routers, connect
    • Did you just seriously write three full paragraphs saying that you don't know what you're talking about?

      The OSI and TCP/IP models are not even remotely analagous to the Cisco model of Core / Distribution / Access. OSI and TCP are describing network stacks, the Cisco model is describing a suggested physical network topology. Since your assumptions are unbelievably false, and you haven't bothered to do even the most cursory amount of research, the rest of your bits are wasted. Way to go.

  • Back in my early days of HS, i had the fancy to grab an A+ cert, followed by a CCNA and MCSE...
    I studied for the A+... then the changed the test and I didn't bother.
    I read a few MCSE books... got bad vibes.

    I took a CCNA course (semesters 1 2 and 3), picked up every last vender-neutral concept I could. Then the thing started selling Cisco specific concepts, moving away from concept and towards (cisco specific) implementation, teaching you to hawk cisco gear as much as know the (cisco-bent) basics.

    I quit.

    • Well, there are two things I want to say here:

      1- As for whether distribution layer is needed or not, I aggreed with an earlier post (somewhere up the page) that this is just an abstraction. By "distribution layer" you mean the place where filtering and access control (i.e. policy networking) is happening. So IMO it all depends on whether or not such functionality is required in your company.

      2- I've seen a few posts bahsing cisco concepts and certs in this article. Personally I have been through a few
  • We got to move buildings. Great experience if you can get the company to foot the bill.

    We ended up using a distribution layer because it made the config easier, and centralized a lot of complexity, and didn't cost an arm and a leg in fiber uplink ports. We utilized Extreme Networks 7i switches as distribution (44 gig fiber links), which (compared to core chassie blades for the same fiber density) were cheep. We then uplinked each distribution layer switch (2 of them) to the 4 core chassies. This cost 8

Never worry about theory as long as the machinery does what it's supposed to do. -- R. A. Heinlein