17

The sending device uses the subnet mask to determine if the remote host is in it's local network or not. If the IP is within the subnet of the local machine, it uses ARP to determine the MAC address of the remote host. If it's outside, it queries it's local routing table to find the next hop of that IP, and sends out an ARP query to find the MAC address ...


8

To complement the other answers: The first thing a host (or router, which is just a host with multiple interfaces and packet forwarding between interfaces enabled) does is check its routing table. The most basic routing table will usually have: one entry for the local network, pointing to the relevant interface one default route, pointing to the default ...


6

Does anyone know what this is? As Ron Maupin already wrote, "EtherType" fields with values up to 1500 are interpreted as "length of the data", which is the number of valid data bytes following the EtherType field. ("valid" means: Not including padding bytes at the end of the frame). 0x0036 means that 54 data bytes are following the "EtherType" field. ...


4

You seem to be referring to 10GBASE-T. 10GBASE-R variants use 64b66b PCS encoding at 10.325 GBd. Basically, 10GBASE-T uses PAM-16 signalling = 16 discrete voltage levels - theoretically representing four bits of information. Two consecutive signal levels are combined in a two-dimensional checkerboard DSQ128 pattern for seven bits of information. These are ...


4

There are multiple types of Ethernet frames. The common ones today are Ethernet-II and 802.3 ethernet. They both start the same but diverge when they get to the ethertype/length field. From Wikipedia "Ethernet frame" The "Ethertype or length" field is how you tell whether it is EthernetII or 802.3. If the field is less than 1500 then it means that the ...


3

There are 3 pieces of information that your computer needs in order to do this. In a typical setup, they're all provided by DHCP. If you assign a static IP address, you have to provide them all to make this work. We're going to start off providing the both pieces of data that are missing. We'll set the subnet mask of both networks to 255.255.0.0. We'll set ...


3

An EtherType/Length value up to 1500 (0x05dc) indicates the frame's payload length. The values 1501-1535 (0x05dd-0x05ff) are undefined, real Ethertype values start at 1536 (0x600). The receiving switch is probably ignoring the rest of the frame and since the supposed FCS doesn't match, it drops the error frame. You'll need to use a larger value and take ...


3

Let me address question 2: Most argument says that if you dont adjust MTU then fragmentation will occur! So if we dont adjust MTU everything will work fine and fragmentation will occur any other. But at least things will work? Isn't it? There can be a big problem it there is an MTU mismatch between two connected devices. If routers A and B are ...


2

Direct answers to your questions are either not possible without more information or might not really help you. I'll try to explain: The maximum transfer unit is the largest IP packet size that can be sent on a given interface. With Ethernet, the MTU is generally 1500 bytes. Ethernet's maximum frame size is 1518 bytes for untagged standard frames - 18 ...


2

The Cisco 2610 is not only end-of-life (in 2012) but it's also rated at just 20,000 packets/s, so there's little sense putting GE ports in it (there's only a 16-port FE module). You seriously need to replace that router. Is this possible or am I best off keeping these separate from my main network simply for learning purposes and upgrading to a Gigabit ...


2

Do Cisco SG300 switches perform CRC error correction? No, nor do any other Ethernet switches.[*] The Ethernet frame's frame check sequence algorithm cannot correct errors, it can only detect them - as long as multiple bit errors don't cancel each other out. Erroneous frames are dropped. FCS errors do not cause link loss on the physical layer at any time. ...


2

It may help to distinguish what is happening at the IP level (and would behave differently if you were using a different protocol at the routed layer), what is happening at the Ethernet level (and would behave differently if you were using a different protocol at the link layer), and what is happening in the middle (the packet encapsulation, as well as the ...


1

1) Can I use PPP to connect to my router from PC? If no, then why? That depends. If you have network interfaces in your PC and router that support PPP, then yes. 2) Why I need PPPoE? Where it is used (in which situations)? PPPoE is needed for a link where the other end is running PPPoE. For example, many ISPs offering xDSL will use PPPoE, so you must ...


1

"fragment free" only makes sense if you have half duplex links, which means nowadays it is basically obsolete. Noone running a high-performance network today would use a half duplex link for anything important and half duplex links will almost certainly be running at a lower speed than the network backbone, so they would have to be store and forward switched ...


1

MAC identifies which device. IP identifies where that device is located. I know your name, but not where you live, so I can't send you that 100 dollar bill I promised to send to you using the postal service. You are correct about that within only 1 LAN you know exactly where each device is. So technically, only a Mac addres table would be enough to get ...


1

The reason is that those uncoded bits already have very good quality (low BER). Leaving them uncoded can reduce the overhead introduced by FEC.


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