Questions tagged [mac-address]
For questions about Media Access Control (MAC) address which is used as the OSI layer-2 address for many OSI layer-2 protocols.
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ISP ARP tables and routing [closed]
So I'm Network+ certified and have a beginners understanding of how network communication works, my head starts to split a bit though when I think about how the information is actually communicated ...
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If the destination MAC is changed every hop. When it arrives at the destination router, how will it know which device to deliver the packet to?
I learned that inside a packet there is information about the sender's public IP and MAC and the receiver's public IP and MAC, and that at each hop, the sender's and receiver's MAC are changed along ...
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Ethernet frame's source mac-address out of a port in an ARP request forwarded to an interconnected switch towards an end host
PC1 ----- (P1) SWITCH1 (P2) ----- (P2) SWITCH2 (P1) ----- PC2
Assume two network switches SWITCH1 and SWITCH2 are interconnected to each other through their ports P2 respectively present on each ...
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Is it possible to extract the source and destination IP addresses from a MAC header/frame?
I asked a similar question on SO, but was directed to post it here. For original context, see this SO post.
In short, I'm trying to extract the source and destination IP addresses of a received packet ...
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Is there a way to find all MAC addresses in an Ethernet network?
How can I find all MAC addresses connected to a LAN network? Is there a way or protocol to do this?
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Arp and flooding
it is my understanding that nodes are not aware of the mac address of other nodes they want to communicate with, when a frame is created to communicate node A with node B, the destination mac address ...
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Can ELI/AAI/SAI addresses be Multicast?
In a slideshow by IEEE regarding the Structured Local Address Plan (SLAP), I saw the following table:
SLAP local identifier
SLAP Quadrant
Z bit
Y bit
X bit
M bit
second hex digit
ELI
01
1
0
1
0
A
...
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How to solve problem with two devices with the same MAC address, connected to the switch?
I have two devices with the same MAC address (don't ask why, I can't solve it by replacing those devices or modifying MACs) connected to one switch. Of course both of them get the same IP from DHCP ...
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how do I fight/ protect and gather evidence if my router was copy Mac and my Mac was ported? [closed]
I learned recently that my devices including router had it's Mac address copied multiple times. I believe I'm going through a network hacking that uses the Mac addresses to drown my network services. ...
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Why are connected switches not a good substitute for the network layer? [duplicate]
Unless I am missing something, because switches can be chained together, I am not sure why the network layer is needed. Theoretically, one can dedicate a frame to any MAC address, and assuming there ...
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What is PPP and why does it not have a MAC address?
I just wanted clarification on what exactly PPP is and why it does not have a MAC address due to having seen that under a response to a question of how routers transverse packets to their destinations....
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What's the differences between sticky-config MAC & sticky MAC on Huawei SW？
In Port-security configuration，
port-security mac-address sticky-config xxxx-xxxx-xxx vlan x
port-security mac-address sticky xxxx-xxxx-xxx vlan x
1.All of them do not disappear after SW restarting. ...
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635
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Sharing same IP address inside LAN? [duplicate]
Q: if 2 devices A and B share same ip address in LAN, can device A retrive all messages whose destination is device B?
I think this depends on how the LAN is configured.
If it's wireless then device A ...
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Are ARP messages always used for the process of "Flooding" even when layer-3 is not involved? [duplicate]
I'm new to learning networking so please bear with me.
I've learned that ARP messages and flooding are used to find mac addresses when IP addresses are involved.
I've learned that when the mac address ...
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How do devices on a network communicate when they are only connected through a router? [duplicate]
This is in my router's routing table:
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
192.168.1.0 0.0.0.0 255.255.255.0 U 0 ...
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Failover with sticky MAC address on network switch
Introduction:
I am configuring a server to have two ethernet ports (one as primary, the other is redundant) connected to two different switches. In the switches, I enabled the sticky MAC address and ...
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What's the difference between host routes and network routes for layer 2 destination selection?
This problem usually occurs with servers, but the question itself is about network.
When I have a gateway with 10.1.1.1 and an interface with /24 network, the network routes are automatically ...
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trying to ping 192.168.2.2 from 192.168.1.1 pcs
im trying to ping pc2 from pc0 and it doesn't work
can anyone help tell me why?
pc0 is 192.168.1.1/24 and pc2 is 192.168.2.2/24.
The port connecting switch 0 is 192.168.1.100/24 and the port ...
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dynamic mac address added all hosts through the Do1Q tunnel
we have a nexus switch, we configure two customer ports in different switches with (mode Dot1Q tunnel)
as all traffic must have two VLAN tags, an inner tag, and an outer tag,
in our network, we ...
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Why specify the address of the default gateway in the routing table?
I’m struggling to understand the need of specifying the default gateway in the host’s routing table.
When a host is building a frame to be sent, it needs to specify two MAC addresses; one for the ...
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Does the host need to access the routing table to know if the destination IP address exists in the same network?
It is said that, in the process of building a frame, the host checks if the destination IP address exists in the same network. My question is concerning how the host performs this check. Does the host ...
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Where does a host save its IP address?
While building a particular packet to be sent across or outside the network, the host, at a certain point, needs to specify the MAC address of the interface through which the packet is going to be ...
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Why does the show arp returns a different IP than the PC's gateway on the Switch
I have a PC connected to a switch connected to a router : why does the show arp returns a different IP than the PC's gateway on the Switch ? :
PC $ arp -a | grep -w gateway
gateway (172.16.15.1) at 00:...
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Does a router need ARP to send data to router in anther netwrk, it already has the IP address of the interface right?why does it need the MAC address? [duplicate]
i am studying off this
https://www.practicalnetworking.net/series/packet-traveling/key-players/#arp
but my question is if ip address is for end to end communication , how is the end to end happening ...
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Lost the Static IP/network settings of a device
We have a physical device (lab instrument) that we can only connect to via ethernet. Unfortunately a static IP was set with network settings and these settings has been lost.
We connected our computer ...
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MAC OUI in Bits 3 to 24
One networks basics course the statement was made by lecturer for OUI (Organizational Unique Identifier) to be carried in MAC-address Bits 3 to 24. I wonder where the start bit number 3 from? It is ...
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What happens if the layer 2 destination MAC address mismatches?
I was wondering, what happens if I send a packet with layer 2 destination (say 1ebf) different that what will receive it, lets say a router (mac 22ff) recieves it. Will it drop the packet? Or ...
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Show port on Cisco switch that mac address is being dropped on
We use ISE to handle port security on our switches. When I see that there is a mac address being dropped by the switch it doesn't show what interface this mac is patched into.
#show mac address-table (...
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Can you send data in LAN without an IP?
From What I know, IPs are used to communicate b/w two different networks say LAN1 and LAN2... and MACs are used to communicate within a LAN.. I think this because my instructor says that Hubs and ...
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Does RSTP also maintain correct mac table entries?
I've got 4 switches connected in a circle and they all run RSTP. Lets assume the following:
switch A (root bridge) ------- switch D
| |
| ...
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What is the difference between a private IP and a MAC address? [duplicate]
I am taking a course preparing me for the Network+ certification. I wanted to know what the purpose of a private IP is when a MAC address exists. From what I understand, the MAC address is used to ...
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What are the IP/MAC addresses of requests between 2 different subnets? [closed]
Assume that networks 172.15.10.0/24 and 172.15.11.0/24 are connected through a router with interfaces 172.15.10.254 (MAC3) and 172.15.11.253 (MAC4).
If host A sends a packet through its network ...
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How Does A Layer 2 Switch Differentiate Between Different Networks?
I know that different IP-based networks can be connected to the same layer-2 switch. and I know each network's nodes can communicate just fine, however, no normal traffic can occur between two nodes ...
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Why switch uses Mac address during implementation of spanning tree protocol (STP)?
We know that layer2 switch doesn't use Mac address ,uses only certain port number to accept the frame.
But I have been read on book as well as internet that uses Mac address to find spanning tree for ...
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MACsec encryption feature on Cisco NX-OSv 9000 Virtual Software?
https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus9000/sw/7-x/nx-osv/configuration/guide/b_NX-OSv_9000/b_NX-OSv_chapter_01.html
The above link only stated some examples of features which ...
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How are IP broadcasts handled at lower levels
When I use a broadcast IP address, for example 198.255.255.255, what will happen when it gets passed down to the link-layer which will then look for the corresponding MAC address in your ARP table. ...
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How PPPoE uses addressing to know destination Mac address?
Case.1 We know that when router connected via point to point(PPP) protocol then ARP isn't used to know the destination Mac address.
Case.2 When two router connected via PPP as well as Ethernet which ...
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Understand router Ip address and Mac address, Switch Mac address
Scenario:1
Suppose external Router R1 has interface a connected with interface b of the site Router R2. And Router R1 using IP address 80.0.0.0/8 for a. Router R2 has 4 subnets 80.0.0.0/10, 80.64.0....
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using Cisco WIC-4ESW 4PORT ETHERNET WIC Card (L2 switching card) on a 1700 Cisco router, where the router stores the MAC address of connected devices?
Router is an L3 device, but some models (such as Cisco 1700 router), we can attach the WIC-4ESW which is L2 switching card.
as per the offical Cisco datasheet:
The WIC-4ESW interface card is a Layer 2 ...
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Mobile cellular Networks (GSM, LTE, 5G, ...) and MAC addresses
We've been provided with a new firmware for our telematics units, which connects to the Internet via a VPN provided by a mobile carrier; since this new firmware release, we've noticed that each and ...
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Multicast MAC using destination MACs
I am working on a routing algorithm which involves multicasts, my question is: Is there a possible way to convert a list of MAC addresses to a single multicast MAC address for configuration purposes?
...
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Does an unmanaged switch deal with IP addresses at all
My belief is that an unmanaged plug-and-play layer 2 network switch only deals with MAC addresses.
When computer A on a local network wants to communicate with computer B for example through the ...
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MAC collisions in Probe Requests
To find nearby routers, mobile devices send probe requests to coax the routers into sending probe responses.
Since modern devices don't use their actual MAC address anymore but instead rely on MAC ...
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Can a radio share a MAC address with the ethernet interface of an access point?
I have a situation where I have found the BSSID to have a MAC address congruent to the MAC address of the ethernet interface.
Is this possible?
Does this happen with all access points?
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How do we identify an address as a valid MAC address
If 000.a83.b1c.08e is a valid MAC address then why is 123.123.123.123 not a valid address?
Also if how do we identify its 32 bit long or 48 bit long
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Do hosts in the same LAN know their MAC addresses?
I am trying to learn about how ARP protocol works in LANs. So, here is the physical structure of my network:
So, when I try to ping PC3 from PC1, I expected the first packet to timeout because PC1 at ...
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How to determine if a network cable is bad on a LAN under an unmanaged switch with no DHCP?
Is there anyway to detect this via automation and software? I know if I can get access to the MAC address table on the switch I can see if there's a missing MAC address. I don't know if this is ...
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lan with multiple ip [duplicate]
If imagine lan assigned ip from from this range (192.168.1.0/24) then can we assign another ip from same subnet mask? If no why?
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Can wifi clients in same subnet talk to each other without a WAP?
I understand that a L2 device like WAP is needed to forward packets from one client to another within the same network (based on MAC mostly like in 802.11)
However my question is, if there is no WAP ...
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Is knowing MAC needed for talking to another device in same wifi network?
I have heard about ARP protocol for learning MAC address of other devices in a LAN for communicating with each other. However, I am bit confused about how it works in a typical infrastructure mode, ...
