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30

CAM (Content Addressable Memory) is memory that can be addressed by content, rather than a numeric memory address. You can look up the interface by presenting the memory with the MAC address. This is done in a single CPU cycle vs. the traditional programming of searching through a table, which will cost many CPU cycles. There is also TCAM (Ternary Content ...


22

I actually like the way the IPv6 RFC defines it: 2. Terminology node - a device that implements IPv6. router - a node that forwards IPv6 packets not explicitly addressed to itself. host - any node that is not a router. So in your list: router, printer, "Camera in network", switch A router is a node, a ...


20

Only one device is allowed to transmit at any given time. At any other given time, another device is allowed to transmit. How can you have a conversation at a dinner table if only person can speak at any time?


18

Some LAN protocols, on some media, are half duplex. That means that only one host on a LAN can send a frame at any given time. The classic example of this is the original ethernet, but the modern example is Wi-Fi. The original ethernet ran on coax, and it used CSMA/CD (Carrier Sense Multiple Access with Collision Detection) to detect collisions where two ...


17

EDITED I'm assuming you're considering using an IP block that is not registered to you. Otherwise, skip to the last paragraph. Besides being a very poor practice, if you use public addresses on your internal network, that means that you can never reach hosts that use those real addresses. You may think you'll never need to reach servers in some other part ...


14

CAM - Content Addressable Memory, referring to the memory used for the MAC address table. It works kind of reverse from RAM, you address it by giving it content and it returns you the address where the content is stored - which is then used to find the egress port for this address.


13

Link local addresses are used in one single network segment, they can't be routed. Unique local addresses can be routed, but only within one routing domain. So an ISP can choose to use ULA for services which can't be publicly accessible.


12

There is a historical reason for this, as @ronmaupin alludes to. In small networks, you don't need a layer 3 protocol. All the devices are directly addressable, so layer 2 addresses work fine. As networks got bigger and became interconnected, there was a need to know how to get from one network to another. That is the function of routing, which is done ...


12

Switches forward all packets it receives to the best of its ability. If is unable to send a packet immediately, the packet is queued in a buffer and if the queue is full, the packet is dropped. Typically a switch has input and output buffers per port instead of a common buffer for each port, so an overload of incoming traffic port doesn't affect the ...


11

First: What you describe is NAT, not firewalling. A firewall just filters what can go through, a NAT device changes addresses in packets. You almost answer the first question yourself. Yes, a NAT device needs to keep track of every session going through it. Most communication on the internet uses TCP or UDP. Both of these protocols use port numbers. A ...


11

An IP address on a true layer 2 only switch is used for management (accessing the CLI remotely, sending SNMP traps, logging, TACACS/RADIUS, etc.). The IP address on the switch is in no way required for the switch to actually do its job, which is to switch frames.


9

The two Windstream Routers each have an MPLS port: 192.168.1.2 = Host MPLS 192.168.2.2 = Remote MPLS The Windstream routers also each have an open internet port to which I have attached a Firewall Router for filtering the internet, making the internet gateways: 192.168.1.1 = Host Gateway 192.168.2.1 = Remote Gateway Problem ...


9

I'd suggest to remove ports from bridge if it is possible to add them to switch group. When your ports are bridged - all packets going through these interface are processed using CPU while, if they would have been in the same switch group, special switch chip would process those packets, decreasing load on CPU. So, in your case, you can make ether1 to be a ...


9

No, that's not correct. You don't need a router for two hosts to communicate using IP as long as they're in the same network.


8

IPv4 or IPv6 doesn't matter, except for the availability of addresses. These are examples using IPv4. Topology A is what most people do. Topology B is what Mike Pennington said. Topology C is what you can do if you get a few addresses from your ISP.


8

You need to understand the network layers. They are independent of each other. Ethernet and IPv4 are currently the dominant protocols, but that was not always the case, and IPv4 is being replaced with IPv6, which has very different addressing. Layer-2 protocols can carry many different layer-3 protocols, and layer-3 protocols don't care which layer-2 ...


8

I would imagine that with TCP A will resend the packages until it's gotten an acknowledgement for them all which would degrade A's performance because of having to resend packages all day long (need confirmation on that thought as well) but with UDP or other such protocols the question remains. TCP has "the sliding window mechanism that controls the ...


8

There is no single precise definition for a "link". A link can be a physical layer connection, two ports connected by a cable. A link can also be understood as general connectivity by data link layer, ie. point-to-multipoint (as in "does the VLAN link over that trunk?" or with an aggregated link). The TCP/IP model defines the link layer as the one below ...


8

It is merely a necessity constraint and personal preference. If a Network is being built that would only have 10, or 20, or 50, or even 100 hosts, there is no reason not to use a /24 from 192.168.0.0/16. This is why home networks typically use the 192.168.0.0 range. If a Network is being built that would (in all growth projections) only have up to 1000 or ...


7

Besides the unknown unicast flooding that you allude to, broadcasts are necessary to the operation of ethernet. Some protocols require broadcasts. For instance, hosts use ARP requests (broadcasts) to resolve layer-3 to layer-2 addresses. Multicasts are are flooded to every port in the broadcast domain, albeit IGMP snooping, if supported and configured, can ...


7

You are conflating many things here, so let's try to detangle the issues in your question. Data rate is data rate, regardless of the physical medium. A 1Gb connection has the same data rate whether it is fiber or copper. As @toddwilcox mentions, the advantages of fiber over copper are longer spans and electromagnetic isolation. Data rates are independent ...


7

NO. IP packets are encapsulated inside Ethernet frames. It's not one or the other.


7

With directly connected computers, both need to use the same speed when sending to each other. Transmitting and receiving with different speeds requires splitting up the data into packets and some kind of packet buffer in between the computers. Such a buffer is part of a network bridge (switches work like bridges) or a router. Repeaters (and hubs) have no ...


6

The answer to the question "When do you use link local addresses" the answer is "always". Link local addresses are present on all interfaces and are used for many essential link protocols such as neighbor discovery, duplicate address detection and router advertisement. Unique local addresses are the replacement for the deprecated site local address scope. ...


6

Wikipedia is your friend: LAN: A local area network (LAN) is a computer network that user interconnects computers in a limited area such as a home, school, computer laboratory, or office building using network media. In simple words, what unifies devices on one LAN: they are situated in the same area. Most commonly, one LAN is behind one router (not ...


6

Don't confuse the network layers. Each layer has a specific purpose. Also, don't assume that there is only one protocol for each layer. Layer-2 has many protocols, some of which use MAC addresses, and some which don't. Of those that use MAC addresses, some use 48-bit MAC addresses, and some use 64-bit MAC addresses. There are also multiple layer-3 protocols. ...


6

In addition to the completely correct answers about speed matching directly connected systems ... One of the fundamentals of the internet (including all the private routing portions) is that the indirectly connected fast host A can communicate perfectly well with slow host B, without even any knowledge of the layer 2 mechanisms. The separation of layers ...


6

I know that in the data link layer that is responsible ensuring that frames has been transmitted successfully by sending acknowledgement That is incorrect. There are very few data-link protocols that do this. The transport protocol is normally where acknowledgement takes place, but not all transport protocols do that. TCP does, but UDP does not. With a ...


6

A switch buffers frames - this is in contrast to a repeater hub that can't buffer anything. As @jcbermu has pointed out, both frames from A and B are first stored in their respective ports' receive buffers. The frame that is received in completeness first is then transferred to port D's transmit buffer and transmitted to D. The second finished frame is ...


6

Your understanding is correct, but your assumption that "no frames transmitted from either hosts, C and D." is likely wrong. Gratuitious ARP precisely address this concern. From Wireshark.org: The networking stack in many operating systems will issue a gratuitous ARP if the IP or MAC address of a network interface changes, to inform other machines on ...


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