Multilayer core switch design

eniaceniac Member Posts: 9 ■□□□□□□□□□
in CCDA & CCDP
Hello guys,

I am experiencing some difficulties to understand the main advantages of multilayer core switch design over L2 core switch design . icon_sad.gif

Could you guys be so kind to share little bit of your best practices and help me figure it out?

Thks a lot !!
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Comments

  • networker050184networker050184 Mod Posts: 11,962 Mod
    If your core is all L2 then you will have broadcast traffic flowing over your core and through the whole network. The core should forward traffic at a high rate between switchblocks and not be burdnend by broadcast traffic. You should cut broadcast traffic at the switchblock which is why it is recomended to have a L3 link to the core. Also if its all L2 you will not be able to communicate between VLANs which would not be good.
    An expert is a man who has made all the mistakes which can be made.
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  • GT-RobGT-Rob Member Posts: 1,090
    ^ on the nose. Think of a layer 3 switch like a fast router.
    http://frozenrouter.blogspot.com
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  • tech-airmantech-airman Member Posts: 953
    eniac wrote:
    Hello guys,

    I am experiencing some difficulties to understand the main advantages of multilayer core switch design over L2 core switch design . icon_sad.gif

    Could you guys be so kind to share little bit of your best practices and help me figure it out?

    Thks a lot !!

    eniac,

    Let's go through this step by step. What's the benefit of having a core layer versus not having a core layer?
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  • eniaceniac Member Posts: 9 ■□□□□□□□□□
    tech-airman wrote:
    eniac wrote:
    Hello guys,

    I am experiencing some difficulties to understand the main advantages of multilayer core switch design over L2 core switch design . icon_sad.gif

    Could you guys be so kind to share little bit of your best practices and help me figure it out?

    Thks a lot !!

    eniac,

    Let's go through this step by step. What's the benefit of having a core layer versus not having a core layer?

    Well,without Core layer all other areas would be isolated!!!
    The concept is expanded to mean the center of the network:
    -In order to switch packets as quickly as possible to optimize communication within the network the core layer doesn't perform any packet manipulation
    -Typically the network core layer is responsible for the rapid transfer of data and interconnection of various distribution and access layers.Therefore the core layer should be design to have redundant paths and other fault-tolerant criteria.
    -the core devices must provide alternate paths and load balancing;
    -also high level of availability and reliability
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  • tech-airmantech-airman Member Posts: 953
    eniac wrote:
    tech-airman wrote:
    eniac wrote:
    Hello guys,

    I am experiencing some difficulties to understand the main advantages of multilayer core switch design over L2 core switch design . icon_sad.gif

    Could you guys be so kind to share little bit of your best practices and help me figure it out?

    Thks a lot !!

    eniac,

    Let's go through this step by step. What's the benefit of having a core layer versus not having a core layer?

    Well,without Core layer all other areas would be isolated!!!
    The concept is expanded to mean the center of the network:
    -In order to switch packets as quickly as possible to optimize communication within the network the core layer doesn't perform any packet manipulation
    -Typically the network core layer is responsible for the rapid transfer of data and interconnection of various distribution and access layers.Therefore the core layer should be design to have redundant paths and other fault-tolerant criteria.
    -the core devices must provide alternate paths and load balancing;
    -also high level of availability and reliability

    eniac,

    When you mention "...all other areas would be isolated..." which functional area(s) and modules are isolated without a Core layer?
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  • NetstudentNetstudent Member Posts: 1,694
    We are now in a 20/80 standard of data flow. That is, 20% of user traffic should be local while 80% should be remote or cross the core. Because of this, we use funtional areas like the Data center(server farm) module, distribution module, and internet module. We are able to modularize and consolidate the network resources because we have a high speed, highly redundant L3 core that connnects it all together.

    Without L3 characteristics, the network would be too flat, as other have stated. Also layer 3 redundancy protocols have a faster convergence time than layer2 protocols like STP or RSTP.
    There is no place like 127.0.0.1 BUT 209.62.5.3 is my 127.0.0.1 away from 127.0.0.1!
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  • eniaceniac Member Posts: 9 ■□□□□□□□□□
    tech-airman wrote:
    eniac wrote:
    tech-airman wrote:
    eniac wrote:
    Hello guys,

    I am experiencing some difficulties to understand the main advantages of multilayer core switch design over L2 core switch design . icon_sad.gif

    Could you guys be so kind to share little bit of your best practices and help me figure it out?

    Thks a lot !!

    eniac,

    Let's go through this step by step. What's the benefit of having a core layer versus not having a core layer?

    Well,without Core layer all other areas would be isolated!!!
    The concept is expanded to mean the center of the network:
    -In order to switch packets as quickly as possible to optimize communication within the network the core layer doesn't perform any packet manipulation
    -Typically the network core layer is responsible for the rapid transfer of data and interconnection of various distribution and access layers.Therefore the core layer should be design to have redundant paths and other fault-tolerant criteria.
    -the core devices must provide alternate paths and load balancing;
    -also high level of availability and reliability

    eniac,

    When you mention "...all other areas would be isolated..." which functional area(s) and modules are isolated without a Core layer?

    .....major areas of the Enterprise network including data center,extranet, internet edge,Campus WAN/MAN.by isolated , I mean will not provide efficient access to headquarters and other divisions within a company.
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  • tech-airmantech-airman Member Posts: 953
    eniac wrote:
    tech-airman wrote:
    eniac wrote:

    Well,without Core layer all other areas would be isolated!!!
    The concept is expanded to mean the center of the network:
    -In order to switch packets as quickly as possible to optimize communication within the network the core layer doesn't perform any packet manipulation
    -Typically the network core layer is responsible for the rapid transfer of data and interconnection of various distribution and access layers.Therefore the core layer should be design to have redundant paths and other fault-tolerant criteria.
    -the core devices must provide alternate paths and load balancing;
    -also high level of availability and reliability

    eniac,

    When you mention "...all other areas would be isolated..." which functional area(s) and modules are isolated without a Core layer?

    .....major areas of the Enterprise network including data center,extranet, internet edge,Campus WAN/MAN.by isolated , I mean will not provide efficient access to headquarters and other divisions within a company.

    eniac,

    In reference to the Enterprise Composite Network Model, the following functional area and modules would be isolated from each other without a core layer:
    1. Enterprise Campus functional area
      [list=1:d8ac2546d1]
    2. Building Distribution module
    3. Edge Distribution module
    4. Server Farm/Datacenter Distribution module
    [/list:o:d8ac2546d1]

    So the Core Layer is important because it interconnects those three modules. Now what are the benefits of a Layer 2 core versus no core? What are the consequences of a Layer 2 core?
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  • eniaceniac Member Posts: 9 ■□□□□□□□□□
    tech-airman wrote:


    eniac,

    In reference to the Enterprise Composite Network Model, the following functional area and modules would be isolated from each other without a core layer:
    1. Enterprise Campus functional area
      [list=1:e611ddd81b]
    2. Building Distribution module
    3. Edge Distribution module
    4. Server Farm/Datacenter Distribution module
    [/list:o:e611ddd81b]

    So the Core Layer is important because it interconnects those three modules. Now what are the benefits of a Layer 2 core versus no core? What are the consequences of a Layer 2 core?

    tech-airman,



    Even that L2 switched core could provide the simplest and most efficient throughput"

    - switches in L2 core can not be linked to avoid any bridging loops.
    - STP must run to prevent L2 loops.This causes traffic on same links to be blocked.As
    well as additional downtime in case of link goes down.
    -because of broadcast traffic on core-layer VLANs,bandwidth on the core can be wasted
    unnecessarily;

    what else?
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