41

This is an interesting question since I've never seen anything that authoritatively states the design decisions behind that choice. Everything that I've come across, whether on the Interwebs or from conversation with people smarter than me in this area, seem to indicate two possibilities: Future proofing Extra shielding Future Proofing By the time of the ...


40

Simply put, no, they are different: with a 10 GbE interface, you get a bandwidth of 10 Gb/s even for a single connection with 10x 1GbE interfaces (and using 802.ad protocol), a single connection/session is limited to 1 Gb/s only. On the other hand, you can serve 10 concurrent session each with a bandwidth of 1 Gb/s In other words, bonding generally does ...


39

For the same reason why the first and second pair are connected to pins 4, 5 and 3, 6: compatibility with telephone systems. In telephony main pair is the middle pair and second pair is the next one from middle (pins 2, 5 in RJ11 and 3, 6 in RJ45). If you're using Fast Ethernet or Ethernet, you can route telephone signal in regular cable and it will work ...


38

The I/O model in Windows is based on a stack of components. Data must flow through the various components of that stack that exists between the physical network card, and the application that will consume the data. Sometimes those various components inspect the data (a TCP packet for example,) as they flow through the stack, and based on the contents of that ...


31

You are correct that frequencies that high would be completely unmanageable. Sending one bit per frequency would cause problems for various types of radio transmissions as well. So we have modulation techniques which allow more than one bit to be send. A touch of terminology: baud, most people will remember that term from the days of telephone modems, is ...


27

It's at /sys/class/net/eth0/address (or more precisely /sys/devices/pciXXXX:XX/XXXX/net/eth0/address where the XXX is your PCI bus ID, but this varies between systems). (Incidentally, I found this with find /sys -name eth0 and looking at the files in the directories identified.)


27

The diagram on Wikipedia is horrible. Hopefully what I'm about to write is clearer. The maximum payload in 802.3 ethernet is 1500 bytes. This is the data you're trying to send out over the wire (and what the MTU is referring to). [payload] <- 1500 Bytes The payload is encapsulated in an Ethernet Frame (which adds the Source/Destination MAC, VLAN tag, ...


26

Ok so after posting this question last night night I continued to do some research the only real solution I came across seems to have taken care of the problem. Disabling TSO, GSO and GRO using ethtool: ethtool -K eth0 gso off gro off tso off According to a post found here: http://ehc.ac/p/e1000/bugs/378/ From what I understand this will or can cause a ...


24

It's just a 110 wiring block. More or less a type of punch down block. (According to a quick Googling, that wiring block is generally Cat5e compliant these days, so you could use it for a 100Mbit network connection). Instead of a patch panel Which has a set number of jacks pre-sized and pre-wired to a certain standard (like RJ45 jacks or RJ 12 jacks or ...


21

The Physical Coding Sublayer is responsible for delimiting the frames, and sending them up to the MAC layer. In Gigabit Ethernet, for example, the 8B/10B encoding scheme uses a 10 bit codegroup to encode an 8-bit byte. The extra two bits tell whether a byte is control information or data. Control information can be Configuration, Start_of_packet, ...


20

ARP only works between devices in the same IP subnet. When device A with IP address A needs to send a packet to device B with IP address B, the first thing it does is consulting its routing table to determine if IP address B belongs to a subnet it can directly reach through its network interface(s); if it does, then devices A uses ARP to map IP address B to ...


20

You say "WPA2" but I suspect you're not looking for encryption but, rather, authentication. (If you are looking for encryption then skip to the edit at the end of this answer.) I strongly suspect you're looking for is 802.1X authentication. 802.1X allows you to have wired (and wireless) clients authenticate before being granted access to the network. All ...


20

10gb/s via x10 1gb/s ports I am answering only for completeness sake and to save you some headaches. I have over 20k servers doing something similar to this and I can tell you it is a bad idea. This method adds a lot of complexity that will cause operational problems later on. We did this with 4 1gb nics per server. At the time it actually made more ...


19

Question is a bit broad but i believe it's still valid for this site. A good initial site survey is very important. Depending on the scale of this, you may need a professional networking company to run the survey for you. I will assume that this has a learning purpose so i'll list what we do when we go to a new site. Disclaimer: a proper network survey is ...


18

Stop it, you're making me feel old. ;) Ethernet was originally designed to connect to shared media. There used to be devices called "hubs." Outwardly, hubs look almost the same as switches do today, but the way that they forward frames is fundamentally different. Nearly every Ethernet switch will build a database that maps MAC addresses to RJ-45 ports. ...


18

How does it work? Like this: As Tim pointed out, it takes advantage of the fact that (100Mbit or slower) ethernet connections only use two of the pairs, so one jack can effectively carry two signals. Of course just because it works doesn't mean it's a Good Thing. Given the opportunity you should plan on rewiring your panel (and possibly the rest of your ...


16

Test the ports thoroughly before trying to use them. I can't speak for your predecessor, but one reason I've seen that done (with cut ends or empty crimped ends) is to "mark" bad or sketchy/lossy ports on a switch; it's a great way to see at a glance that a port should not be used.


15

Source MAC = A Destination MAC = C Why: When A needs to send data to another host it first determines whether or not the detination host is on the local network. Upon determining that the destination is not local, A sends the data to it's configured default gateway, which is C. Why not B? Because switches (bridges) when operating at layer 2 don't modify ...


13

That cable is not a serial to Ethernet cable. It is a female DB-9 to 8P8C plug serial cable. Cisco uses 8P8C connectors that are the same as copper Ethernet for console access to their equipment. That cable would normally go from 9pin serial on your computer to the router console which is also serial. I'm guessing since you thought it was serial to ...


13

According to AMD's spec the destination doesn't have to be the all-ones address. It can also be the receiving station's address or a multicast address. The payload is a different story. It must be the sequence ff:ff:ff:ff:ff:ff followed by the receiving station's MAC address repeated 16 times. The presence of absence of the station's entry in the switch's ...


13

FCoE doesn't run over regular Ethernet though, it requires Data Centre Ethernet/Bridging - an evolution of Ethernet that is only current supported on a very limited number of, typically high-end, switches such as Cisco's Nexus range. THIS is a great, and surprisingly short, book that would pretty much tell you everything you'd need to know about the subject ...


12

Solved. The issue is with SCCM 2012 SP1, a service called: ConfigMrg Wake-Up Proxy. The 'feature' does not existing SCCM 2012 RTM. Within 4 hours of turning this off within the policy, we saw steady drops in CPU usage. By the time 4 hours was up, ARP usage was merely 1-2%! In summary, this service does MAC address spoofing! Cannot believe how much havoc ...


11

Welcome to the strange and mysterious world of jumbo frames! It's normal that jumbo frame ethernet gear has MTU > 1518 and < 65K byte and you have to find a setting that is the lowest common denominator across your L2 domain to enable proper jumbo traffic. My guess is that your ping/ICMP implementation only works for 8192 bytes payload, so 8164 + 28 (...


11

LACP itself doesn't provide the ability to bond across multiple switches; it bonds across multiple ports on a single ethernet switch, and depending on the vendor there might even be restrictions on which ports on a switch can be bonded together. Some vendors have proprietary protocols (typically called MLAG) that allow for bonded ethernet channels across ...


11

VLAN's are a layer 2 feature, while IP/DHCP is a layer 3 one, I just wanted to make that clear but they have a lot to do with each other in this scenario. Basically all you really need to do is ensure that your L2/3 switch/router is configured to allow your DHCP server to not only route to/from all VLANs but provide a 'DHCP Helper' service so that all ...


11

4-pair UTP cable with RJ-45 connectors was invented for audio telephone use. Its adoption and evolution as a medium for high-speed digital data communications has been a matter of convenience: adapting pre-existing mass-produced products for new uses rather than devising a completely new technical standard specific to one new application. The way this ...


11

Those are PadJack Locks.: http://www.padjack.com/wp-content/uploads/2013/01/padjack_sv_sm1.png They can't be removed without breaking them. They don't come from Dell that way, someone else installed them. They're meant to be difficult to removed, and tamper-evident. If I remember correctly the back end has a "top" and "bottom" that you pry up/down (apart)...


11

There is no single protocol for managing switches or other network devices. There are a few systems which allow a single management interface, which is then translated into the native configuration for the device (hopefully with some degree of fidelity); but these are neither standardizes or widely deployed.


10

The answer is that both schemes are around (and will probably remain around for the foreseeable future of CAT5 cable) for hysterical raisins. (The Wikipedia article alludes to the history here) Basically the T568B standard is dead & deprecated at this point, but my advice is that in the absence of any specific guidance (i.e. when you're not using a ...


10

Packet switching in the network gear will always process vLAN information if it is supported. So having vLANs or not, makes no difference in switching speed. If the packet has to be routed by a L3 router, then there may be a penalty incurred. Similarly if the packet has to be forwarded to a router, you'll have even more penalty incurred for that process. ...


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