In networking 101 class, we learned there are layers that divide up networking. One of those layers is called the data link layer and from what I understand, it encodes the MAC network card address into the data. If this is true, why is it we need to enable port forwarding on our routers, if, for example, we want to host a web server?
204400
Apples and Oranges.\n\nMAC codes, data link, and port forwarding have nothing to do with each other.\n\nYou need port forwarding so your router knows WHICH PC is hosting the web site. So, when a user tries to access it from the internet, the router knows where to send him.\n\nThe router doesn't know or care where your website it.
434481
MAC address is the personal identifier of a network card.  It says who, not where.  Wireless uses MAC address because it is the perfect ID- It then assigns an IP to say where the signal goes.  It would be cool to have a net send for MAC, but I've never heard of it.
486739
Are you running a router? What brand?  Most port forwarding on home networks is done through the router, and will require setting up static ips instead of using a dhcp server.
372578
There is no advantage to having more than one network card in a computer unless the computer is being used as a server. Then the server software can create separate subnets to isolate two networks. For example, one side can be a network visible to the Internet while the other side is isolated and (hopefully) safe. The server can act as a gateway.\n\nI'm sure someone will come up with some obscure use for two network cards in one computer, but it's not going to do anything for you like double your speed, or anything like that.
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You're right, your existing access lists won't be able to operate on packets in labelled MPLS VPNs. You should move your access lists as close as possible to the source of traffic, possibly to the distribution/access layer routers. Network core is supposed to be switching data very quickly. In certain situations access lists are processes by the main processor (as opposed to the hardware ASICs) and can be very processor intensive and slow in the core routers. Move your access list closer to the source.
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router - this is often a bundle of services for building a local area network.  It will contain a gateway or bridge to an internet service provider, and contain a switch for internet sharing.  It will also contain a DHCP server, which assigns IP addresses to devices on the LAN/\n\nswitch - an Ethernet switch works like a hub, but automatically configures that port for the IP parameters that is needed by that port.   So if you are using a cross-over cable to connect to a computer, the switch will automatically cross-back, so it works.  This is the NO BRAINER HUB.\n\nhub - a network hub connects various devices to a network.  But it is a dumb device, so it is up to the user to plug in the proper patch cable or cross-over cable.\n\ngateway - in general, a gateway is a device that connects a local area network to a wide area network or internet service.\n\nbridge - this is a general term to describe the connection of multiple devices and protocols to direct network communication.\n\nAs you can see, a router does it ALL.  I recommend that you use a high speed switch if you want to expand the number of ports that your router provides.  \n\nOH RATZ....  I started fooling around with this stuff at a whopping 5MHz back in 1983 for the stock exchanges.  I rewrote some TCP/IP protocol stuff before most geeks ever heard of it.   It was all Digital Equipment and Intel that were banging heads in those days. \n\nGood luck and Happy Computing!
103989
It's basically one way to encapsulate data.  If you send a 1 MB transmission it is chopped into smaller bits so that it can be sent efficiently.  One way to do this is frame relay, another way is ATM.
437547
The next hops address will be used to find the mac address of the layer3 device (router). The frame contains the IP address is Sourcemac-NexthopMAC-SourceIP-DestinationIP. When the packet moves from router to router the IP remains same but the MAC changes to next hops MAC
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The transport layer usually turns the unreliable and very basic service provided by the Network layer into a more powerful one. There is a long list of services that can be optionally provided at this level. None of them are compulsory, because not all applications want all the services available. Some can be wasted overhead, or even counterproductive in some cases.\nInternet protocol suite Layer\nConnection-Oriented\n    This is normally easier to deal with than connection-less models, so where the Network layer only provides a connection-less service, often a connection-oriented service is built on top of that in the Transport layer.\nSame Order Delivery\n    The Network layer doesn't generally guarantee that packets of data will arrive in the same order that they were sent, but often this is a desirable feature, so the Transport layer provides it. The simplest way of doing this is to give each packet a number, and allow the receiver to reorder the packets.\nReliable Data\n    The underlying network may well be noisy, and the data received may not always be the same as the data sent. The Transport layer can fix this: typically by providing a checksum of the data which detects if there has been a glitch of some kind. Of course, error free is impossible, but it is possible to substantially reduce the numbers of undetected errors. This layer may also retransmit packets which have gone missing en route.\nFlow Control\n    The amount of memory on a computer is limited, and without flow control a larger computer might flood a computer with so much information that it can't hold it all before dealing with it. Nowadays, this is not a big issue, as memory is cheap while bandwidth is comparatively expensive, but in earlier times it was more important. Flow control allows the receiver to say "Whoa!" before it is overwhelmed. Sometimes this is already provided by the network, but where it is not, the Transport layer may add it on.\nByte Orientation\n    Rather than dealing with things on a packet-by-packet basis, the Transport layer may add the ability to view communication just as a stream of bytes. This is nicer to deal with than random packet sizes, however, it rarely matches the communication model which will normally be a sequence of messages of user defined sizes.\nPorts\n    Ports are essentially ways to address multiple entities in the same location. For example, the first line of a postal address is a kind of port, and distinguishes between different occupants of the same house. Computer applications will each listen for information on their own ports, which is why you can use more than one network-based application at the same time.\n\nOn the Internet there are a variety of Transport services, but the two most common are TCP and UDP. TCP is the more complicated, providing a connection and byte oriented stream which is almost error free, with flow control, multiple ports, and same order delivery. UDP is a very simple 'datagram' service, which provides limited error reduction and multiple ports. TCP stands for Transmission Control Protocol, while UDP stands for User Datagram Protocol. Other options are the Datagram Congestion Control Protocol (DCCP) and Stream Control Transmission Protocol (SCTP).\n\nSome things, such as connection orientation can be implemented at either Transport or Network layer. The idea is that the Network layer implements whatever set of options is easiest: for some underlying networks it is easiest to implement connectionless communication, while for others it is easiest to implement connection oriented communication. The Transport layer uses this simplest set of options to implement whatever combinations of options are actually desired.\n\n///
66995
Ok let's start with a review of the answers so far.\n\nImperial: "they're both used to provide internet connectivity."\n\nSorry that's not right. I can use a hub in a network with no Internet connectivity.\n\nMarker: "A router uses software to send the information directly to the intended port."\n\nI understand what your trying to say but it didn't come across right. A router uses internal software (firmware typically) to direct traffic to the correct network.\n\nexquisite Computers& PU's Q&A: "Router are used in wan as the hub is use in lan Thats the main difer in these"\n\nNOT! Dude please get some networking knowledge before making such wrong, blanket statements. I can have a router in my lan but it cannot perform the same task and a hub in my wan certainly doesn't.\n\nThe other answers are pretty good so I won't repeat what they said.\n\nTo answer your question you need a device that will at least do NAT and a hub cannot do this. Typically your probably looking for a home type DSL/Cable router. For businesses I would suggest something higher end and a asking for support from a local technology provider
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Ethernet is a wall connection, kind of a fatter phone line, it is for internet, or connecting to another computer. An  Ethernet card is a little 'card' that would go into your laptop so you can connect to this ethernet.\n\n   Your new laptop most likely already has the card. Look for a connection on the laptop that looks like a fat phone jack. It does the same thing as the wireless connection, except needs to be connected with a wire. Good for when you are at a location that has no signal (like in the lower floors on campus, usually surrounded by cement wich makes it hard to get a good signal).
14797
I assume you mean the OSI Seven-Layer Model.  The Levels are from top to bottom:\n\n(Taken from Connected: An Internet Encyclopedia)\n\n1. The Physical Layer describes the physical properties of the various communications media, as well as the electrical properties and interpretation of the exchanged signals. Ex: this layer defines the size of Ethernet coaxial cable, the type of BNC connector used, and the termination method.\n\n2. The Data Link Layer describes the logical organization of data bits transmitted on a particular medium. Ex: this layer defines the framing, addressing and checksumming of Ethernet packets.\n\n3. The Network Layer describes how a series of exchanges over various data links can deliver data between any two nodes in a network. Ex: this layer defines the addressing and routing structure of the Internet.\n\n4. The Transport Layer describes the quality and nature of the data delivery. Ex: this layer defines if and how retransmissions will be used to ensure data delivery.\n\n5. The Session Layer describes the organization of data sequences larger than the packets handled by lower layers. Ex: this layer describes how request and reply packets are paired in a remote procedure call.\n\n6. The Presentation Layer describes the syntax of data being transferred. Ex: this layer describes how floating point numbers can be exchanged between hosts with different math formats.\n\n7. The Application Layer describes how real work actually gets done. Ex: this layer would implement file system operations.\n\nMore here, http://www.freesoft.org/CIE/Topics/15.htm
21943
Well theres a couple things I'm thinking that might be going on. One is that you dont have DCHP (Dynamic Host Control Protcol) enabled on any of the networks, but you'd usually manually have to turn that off, basicaly what it does is the server that you connect to will change your network settings such as IP address DNS (Domain Naming Service) and defualt gatway settings. What comes to mind is that since you said you were tring to connect to different works, I think you may be connecting to networks that are encrypted, if a network is encrypted, then you'll need a encrytion key to connect to it. Try asking the person that managing the network what is going on, and if they have had the same problem with other machines. As for setting up your own home network, I know linksys does have an easy set up program aviable on their web site, along with forums and a live chat you can use.
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The Ping command just tells you whether a certain IP address is responding or not. It will not retrieve the MAC for you. Arp can be used to retrive MACs for you. But only of the current "workgroup". MAC addresses are irrelevant after the first hop. Thereafter only IP addresses are relevant. Hence, you can never retrieve MAC addresses of any nodes beyond the first hop. For this reason, MAC addresses arent even transmitted beyond the first hop.
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This would depend how you'll be connecting your router up and why.\n\nIf you are simply cascading them, and the second router will just act like a switch/hub, this'll be easy.  Meaning you really don't need its DHCP capability and your main purpose is just to expand your network. This is when you've connected the 2nd router to the 1st via ethernet port.\n\nJust make sure the 2nd router is 0n the same IP segment as the first router - e.g., 1st router is 192.168.1.1, then set the 2nd router as 192.168.1.2, and turn off the second router's DHCP capability. On the new models, you can find this on the Basic Setup page - it may say something like "Local DHCP Server".\n\nIf you're adding the 2nd router as a different part of your network, this is a bit more complicated.  Its just like what halfMt said.  I believe you may need to setup Static routing for your network.\n\nBest to email Linksys about this (good if both routers are Linksys, if not contact both manufacturers of your routers).
470669
the address bar should simply be a text box with a label saying address right beside it and maybe a go button. The coding for the go button I would not be able to tell you though, as then this starts to get more toward networking.
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the packet went through many routers. each routher has a dynamic table (yeah..some are statics, but very rare). every packet will be routed to the next router, for example went to want to send a packet to Yahoo! answers, it went through your LAN router, the routher check the receiver address and decide that it's not for a local host (it doesn't care if it for Yahoo! or Yeeha! whatsoever, as long it's not local), it will routed to the AP. the AP then do the same checking, whether it's local to the AP or not. and this process keeps going on until it reaches Yahoo!\nduring the process, the receiver and the sender IPs will be changed according to which network the packet is in. for example, the packet from Yahoo! to your PC will have the IP of your AP as the receiver, than at the AP it will betranlated into the router's IP, then at the router it will be translated to your IP.\n\nthe MAC address will never changed since it's about your physical address, not logical...