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9

Bluetooth devices are required to have a unique device address, assigned from the same registry as Ethernet and Wifi MAC addresses. Quoting the Bluetooth specification version 5.0 volume 1: Each Bluetooth device shall be allocated a unique 48-bit Bluetooth device address (BD_ADDR). The address shall be a 48-bit extended unique identifier (EUI-48) ...


7

MAC spoofing is more about LAN disruption than stealing information. I think you have a mistaken idea about routers. Routers do not route to MAC addresses, and on a LAN, a router is simply another host. On a LAN, packets are encapsulated in a frame, and are switched based on the frame. The packet doesn't contain MAC addresses, only the frames do. Switches ...


7

It is as you said. The computer with that MAC address will receive the ethernet frame, since on layer 2 it's all good. Then, looking at layer 3, it will discard the IP packet, since the IP address is incorrect.


7

Welcome to Network Engineering! There is no standard for MACSec and 802.1Q, so manufacturers have come up with their own solutions. Cisco calls it "WAN MACSec," and does it this way: The WAN MACsec offering is standards based but offers additional capabilities not found in earlier MACsec capabilities. More specifically, MACsec can be leveraged by ...


7

Is your home postal address an abstraction? When someone send you a paper mail, they put your address on the envelope, then put the envelope in the mailbox (the first "router"). Then this mail goes from one hop to another through different means: from the mailbox to the local post office (second router), by car from the local post to a sorting center (...


7

First part of the question is whether there is a standard that prohibits use of IPv4 unicast addresses with multicast MAC address in an ethernet frame ? The problem here is that you are dealing with two different standards on different network layers that are defined and maintained by two completely different groups. Ethernet is IEEE 802.3, but IP is ...


6

First a word about: I understand word persistent as following : no one else can occupy wire at the time of persistent connection. So this connection is only one-to-one. But this is not right. Persistent connection can be established while other packets are going through the same wire. This is circuit-switched network vs packet-switching network ...


6

The basic function of a switch is transparent bridging - for this, it doesn't need any MAC address of its own. However, if you need to talk to a switch - ie. a managed switch - then that switch requires an address; usually that is a MAC address and an IP address [*]. STP is only supported on managed switches and in addition, an STP bridge is required to ...


6

MACsec provides security on the point-to-point link level. MACsec and 802.1X sit (more or less) in between the physical layer (L1) and the data link layer (L2). The key management is between the layer-1 (point-to-point) link partners, usually a host and its uplink switch port, not between (possibly more distant) layer-2 nodes. MACsec doesn't impact layer-2 ...


5

The narrow answer is no, there's no "ethernet ping" which is normally implemented. Your network termination unit appears to be a switch, presumably switching between your local copper and fibre ethernet; this is consistent with your description that the next-hop ISP router is down the fibre ethernet. If the ISP has configured several of the switch ports ...


5

The reason it is optional is that in 802.11 RTS and CTS are management frames. Management frames are sent at the lowest base/basic/required data rate supported by all clients associated to the ESS, which is typically much lower than the data rates used for normal unicast traffic. The reason for this is that only the data rates that are configured as base/...


5

Yes, if your switch supports spanning-tree protocol(either legacy spanning tree protocol, rapid-pvst+ or MST) your switch will have a mac address since spanning-tree protocol uses bridgeID to elect the root bridge and bridgeID consists of the bridge-Priority, a unique mac address and system-id which is basically the vlan number. Also if a switch has a ...


5

IP is an abstraction, but not the way you're describing it. In the OSI and TCP/IP models, layers abstract the layers below them. For example, an application protocol, like http, just expects a stream of bytes. Http doesn't know or care how the bytes arrive. Everything that happens below the application layer is abstracted. Media, data rates, clock speed, ...


5

The data will get lost. At the very latest, the last router in the chain will send a "Who has X" ARP request and get no answer, so it will not be able to deliver the packet. Or, if it still has the MAC address in its ARP cache, it will send the frame to a MAC address that no longer exists on the network, and the frame will just end up being ignored ...


4

The RFC doesn't address your second scenario. The reason for this is that Host C sending to Host A may not be on the same network as Host A. Host A having an ARP cache entry in that case doesn't make sense since Host A will never look for Host C in its ARP cache. Host A will always know Host C is not on its network, so it will always look for its own ...


4

Put every device in a different VLAN: device 1: vlan 11, device 2: vlan 12, ... Put a different IP network for each device: device 1: 192.168.1.11/24 device 2: 192.168.2.11/24 ... Then put your host in a trunk with all the vlans. Having an interface on your PC to each vlan would do the trick: int eth0.11: ip address 192.168.1.1/24 int eth0.12: ip ...


4

Bluetooth devices are assigned addresses similarly to Ethernet - an organizationally unique identifier (OUI) of 3 bytes followed by another 3 bytes assigned by the vendor. The Bluetooth address of a given device is almost certainly independent of an Ethernet MAC address. Bluetooth OUI lookup tools can be found on Google. Each device on a Bluetooth ...


4

Ethernet uses the "MAC-48" address space by IEEE. It is/was used for Wi-Fi, Bluetooth, Fibre Channel, SAS, ATM, Token Ring (and some others) as well. This gives us the opportunity to bridge all of these media together - more or less easily, frame formats/capabilities can differ significantly.


4

Ethernet layer 2 doesn't correct errors, it only detects them by frame check sequence (FCS). The algorithm for FCS is CRC with the polynomial G(x) = x32 + x26 + x23 + x22 + x16 + x12 + x11 + x10 + x8 + x7 + x5 + x4 + x2 + x + 1. CRC cannot detect certain paired (even-number) bit error combinations - with a stable connection, these are very rare. A flaky ...


4

Consider the following network, with correct addressing, masks and the obvious routes. B K |.2 |.? 10.0.0.0/24 ===+===+===+================ |.1 R |.1 10.0.1.0/24 ===+===+===+=======+======== |.2 |.? |.4 A J X Case 1: Local A sends packet to X with correct IP source address but incorrect source ...


4

From Wikipedia: ARP has been implemented with many combinations of network and data link layer technologies, such as IPv4, Chaosnet, DECnet and Xerox PARC Universal Packet (PUP) using IEEE 802 standards, FDDI, X.25, Frame Relay and Asynchronous Transfer Mode (ATM). IPv4 over IEEE 802.3 and IEEE 802.11 is the most common usage. ARP is used for different ...


3

As mentioned in your question about Bluetooth, IP can run over a wide range of underlying transport technologies - many of which are quite dissimilar to Ethernet. There are a bunch of easy legacy examples - mapping Ethernet across point-to-point links via PPP or HDLC doesn't require a notion of MAC addressing. Similarly on multi-point media types like ...


3

If a PC wants to send to another PC through a switch and does not know its MAC address, that means all PCs on network will receive it and see it!! Hosts on a LAN with a protocol that uses MAC addresses, e.g. ethernet, maintain an ARP table. A host on such a broadcast domain may eventually learn all the MAC addresses of the other hosts on the LAN in ...


3

Since you're quoting me, allow me to answer your question. I don't think it's contradictory at all. While it's true that tunneling protocols* don't fit the OSI model, the process of encapsulation remains the same. The original protocol data unit (PDU) is contained within another PDU, such that the inner PDU's structure and semantics (meaning) can be ...


3

On a Cisco IOS DHCP server, it is pretty simple. In the DHCP pool configuration, use the address command to assign an IP address to a MAC address: address <ip-address> hardware-address <mac-address> Preassigning IP Addresses and Associating Them to a Client: Preassigning IP Addresses and Associating Them to a Client Perform this task to ...


3

For A to detect B, it has go into "monitor mode" and listen on every channel (there's no guarantee B is even on the same channel) for 802.11 headers. But doing so means A is no longer associated with the WLAN. B might be sending out probes requests, but that also isn't guaranteed. Even if it is, you still have the problem of identifying B if you don't ...


3

I'll try to answer each of your questions, one after the other. But the premise is that an arp entry will get generated on a host, only when it sees an ARP response. Hosts dont typically do mac-learning from all frames. Switches do that function. A send a arp request to B B send a arp reply to A A arp table updated. The right thing to say is A does not ...


3

Assuming your are talking about a common TCP/IP over Ethernet network. 1 - this is not the case, if the destination is on the same network, the connection is made directly to the destinaiton without involving the gateway 2 - ARP is defined by RFC826 in which it is stated: ar$tha: Hardware address of target of this packet (if known). [...] If ...


3

It doesn't work. I'm assuming 192.168.2.2 uses a subnet mask of /24 or /16. With no route to 10.0.2.3 and no default gateway, A has no way to send the packet. You're correct in that ARP requests are only made for local destinations, they can't cross a router. If you can set up both PCs with a mask of /0 (= all IPs are local) it'll work both ways. PC A will ...


3

Packet forwarding decisions will always depend on the defined routes. There's only 3 outcome: Route defined, network reached: Forward (ARP request sent to find destination MAC address). Route not defined, default gateway: Forward (ARP request sent to find default gateway MAC address). Route not defined, no default gateway: Drop. Without a router (gateway), ...


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