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  1. #1081
    Service Manager 5,000+ Posts
    Need some advice on learning networking

    BillyCarpenter's Avatar
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    Re: Need some advice on learning networking

    It should also be noted that there's a big difference between a production and SOHO network. I mean, if you only have a couple of routers, switches and servers, you need not concern yourself with optimizing spanning tree. But if you're running a lot of virtual servers in a Data Center, that's a different story.

    It used to be that in a basic college campus network that 70% of traffic flowed north and south. In other words: From the server to client.

    That's not the case these days. It's just the opposite with 70% of traffic flowing from east to west. In other words: From one virtual server to another. The data flow must be super fast and needs to take the best path. Hence: Optimal Spanning Tree.
    Embrace the process, not the outcome.

  2. #1082
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    Need some advice on learning networking

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    Re: Need some advice on learning networking

    I'm starting to notice a pattern. THE SHORTEST PATH.


    The shortest path in OSPF (routing table) and the shortest Spanning Tree (Layer 2).

    It makes sense if you think about it. I mean, when we get in our car, we don't take the longest route to our destination do we? Of course not.


    When it comes to networking, everything goes back to Math. But this type of math is way over my head. We're talking about algorithms.
    Embrace the process, not the outcome.

  3. #1083
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    Need some advice on learning networking

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    Re: Need some advice on learning networking

    Here's a question. Let's see if anyone has the answer?


    By default, Spanning Tree runs on every port. But if we have a single computer on port 5, it's impossible for a loop to exist. So, why have spanning tree running on that part?
    Embrace the process, not the outcome.

  4. #1084
    Service Manager 5,000+ Posts
    Need some advice on learning networking

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    Re: Need some advice on learning networking

    Quote Originally Posted by BillyCarpenter View Post
    I'm gong over port security and it suddenly hit me that there's a lot of networks out there that are highly vulnerable.

    When the ports are left open and unprotected, someone could introduce a mac address flooding attack. The switch only has so much memory and it will crash when flooded. There's a couple of different ways of dealing with this but I'm still going over it.


    I'm done with port security. It's cool stuff but very easy to configure.

    I've heard some of you talk about this. You go to network jack that's working and you plug in your device and it doesn't work. Why? Because the jack (switchport) is configured to work with only one specific mac-address. Actually, we can allow more than 1 mac-address but you get the point. If anyone plugs in a device with an unknown mac address, the port automatically shuts down. We can configure it to cut back on in a certain time or we can configure it so that we manaully have to bring it back up.

    There's also Port Filters. I'll save that for now.
    Embrace the process, not the outcome.

  5. #1085
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    Re: Need some advice on learning networking

    Quote Originally Posted by BillyCarpenter View Post
    I'm done with port security. It's cool stuff but very easy to configure.

    I've heard some of you talk about this. You go to network jack that's working and you plug in your device and it doesn't work. Why? Because the jack (switchport) is configured to work with only one specific mac-address. Actually, we can allow more than 1 mac-address but you get the point. If anyone plugs in a device with an unknown mac address, the port automatically shuts down. We can configure it to cut back on in a certain time or we can configure it so that we manaully have to bring it back up.

    There's also Port Filters. I'll save that for now.
    The ports can be configured for specific types of devices like say printers. If a printer is connected to a port that is configured for use by a computer, it won't work.

  6. #1086
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    Need some advice on learning networking

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    Re: Need some advice on learning networking

    Quote Originally Posted by slimslob View Post
    The ports can be configured for specific types of devices like say printers. If a printer is connected to a port that is configured for use by a computer, it won't work.


    I'm pretty sure that is achieved by using an ACL (Access Control List).

    Cisco provides basic traffic filtering capabilities with access control lists (also referred to as access lists). You can configure access control lists (ACLs) for all routed network protocols (IP, AppleTalk, and so on) to filter protocol packets when these packets pass through a device. You can configure access lists on your device to control access to a network; access lists can prevent certain traffic from entering or exiting a network. This module provides an overview of access lists.

    You can get very specific with an ACL. You can grant or block by protocol, also.
    Embrace the process, not the outcome.

  7. #1087
    Retired 10,000+ Posts slimslob's Avatar
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    Re: Need some advice on learning networking

    Sorry I didn't find this earelier bur here is a White Paper Ricoh put out in 2010 on using Wireshark. rfg042515.pdf

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