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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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How can I encode port number in dst_Mac?

Im new to SDN and Openflow so I am a little bit confused. How can I modify the destination Mac address with ovs-ofctl with purpose to encode the output port of the switch?
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Is there any relation between MAC addresses of a dual band (2.4 and 5 GHz) router?

I have a use case where I need to determine whether two MAC addresses belong to the same router with dual band connection 2.4 GHz and 5 GHz. When I did some study, I found that the MAC address of ...
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Reliable “Decentralized” approaches for MAC spoofing?

Among all techniques proposed to detect MAC spoofing, is there a reliable and decentralized approach such that we can detect this type of attack strongly? Some of proposed approaches are as follows: ...
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Does Switch need its own MAC address?

I saw a post say Switch do not need its MAC address, unless it's an administrable Switch for managing. but I found the spanning-tree protocol need a MAC address of Switch to form STP Root Bridge ID. ...
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What's the `CPU Interface` of Switch?

What's the CPU Interface of Switch? in the 2960-24TT Switch, there is a CPU Interface in it. Switch#show interfaces | begin CPU Hardware is CPU Interface, address is 0002.1669.5897 (bia 0002.1669....
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How to find the switch IP address based on MAC address?

On PC, the extra network adapter is configured as static 192.168.2.1. A switch with DHCP enabled is connected to 192.168.2.1 and if I login using the console (RS232) I see that it has 169.254.x.x ...
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Is it a protocol of flooding to find the MAC address?

Is it a protocol of flooding to find the MAC address? As we know, if the switch can not find a MAC address, it will flooding to every switchport except the entry port to find the corresponding MAC ...
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143 views

Port Security Or 802.1X Authentication On Non-Server Network

I have a closed network of 3 switches and 40 computers. 35 of those computers (Windows 7 x64 Professional) need to be plugged into any of the 24 ports on 2 of the switches at any time depending on the ...
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How did one go from IP to MAC in classful networks?

This is more of a question asked out of curiosity than for practical reasons, but it's bugging me, because it might point to a lack of understanding elsewhere. Back when classful IP addresses were ...
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Need help understanding how packets travel across the internet

I've been learning about networks recently at a new job, and I did a presentation on what I've learnt so far. When I was describing the relationship between the datalink and network layer, I mentioned ...
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Cisco Switch ports and MAC addresses

Good morning, How do I find out which port on a Cisco switch is connected to a particular MAC address? I recently took over Network Administrator position and trying to clean up and organize. Thank ...
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“MAC address change detection” in “Wireless Sensor Network”?

According to this answer : https://networkengineering.stackexchange.com/a/53058/36813 in a Cisco environment, we can use port-security to prevent hosts from changing MAC address on a port. Assume we ...
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Why two hexadecimal digit can only stand 8 bits in MAC address?

This is one of my network adapter, the MAC address is: a0:99:9b:17:52:07: en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500 ether a0:99:9b:17:52:07 inet6 fe80::c48:...
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Dynamically learned MAC address seems to never expire

I have a user getting error "No logon servers available" at login on a Windows machine. Topology is this: R1--SW1--IP phone--PC1 I cannot ping PC1 neither from its gateway R1 nor from SW1 (access ...
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Do routers change MAC address of packets when forwarding

Lets say host A wants to send a packet to host B through R1(interface 1 then 2) and R2 (interface 3), so my questions is: When the packet is forwarded inside R1 (from interface 1 to interface 2), ...
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1answer
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Finding the source MAC address in Router Advertisements [closed]

What is the source MAC address in the Router Advertisement packets received on the interface eth1? -i have ran tcpdump -i eth1 and tcpdump -n -i eth0 icmp6 -ifconfig eth1 and tried using the HWaddr ...
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288 views

Is there a way to “Pass through” a MAC address on a Cisco Switch?

We have two systems connected together, and the end system (system 2) relies on differentiating packets via MAC address from system 1 (it has two routes). For testing purposes, we want to put a ...
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Possibility of using Cisco “port security” in sensor networks?

Is it possible to use Cisco port security (to prevent a host changing its Mac address) in sensor networks? In a more general question, is Cisco port security platform independent? Meaning that it is ...
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1answer
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Possibility of recognising a computer in the network that has changed its mac address?

Consider a computer with Mac address (physical address) A, joins a network, and then it changes its Mac address to B. So, the network is able to recognise such a computer?
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Determine whether the MAC address is of a router or the destination computer?

In a given Ethernet frame containing the HTTP GET message can we tell apart whether the MAC address of the destination is of a router or end host? The link to ethernet-ethereal trace :: https://drive....
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1answer
38 views

Why don't switch MAC addresses conflict

Switches apparently have a base MAC and self-generate MAC value for each port from that base. If a company that makes both switches and processor boards builds a switch and assigns it MAC "N" and ...
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Why do we need an ethernet MAC address? [duplicate]

Don't think it's a duplicate. I've searched really many articles and couldn't find the satisfying answer. I understand : how ARP works MAC address is an unique address for each NIC IP is network ...
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1answer
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switch filter a frame

I was reading a text book, it says suppose a host A sends a frame with destination address DD-DD-DD-DD-DD-DD arrives at the switch on interface x. The switch indexes its table with the MAC address DD-...
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1answer
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How does MAC spoofing happen? [closed]

I know how to change my MAC address, but I want to know how does this happen, or how the programs that do so work.
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1answer
125 views

Setting MAC source address to broadcast

How would a network behave if one were to set the source address of an Ethernet frame to the broadcast address FF:FF:FF:FF:FF:FF? Obviously, one would have to manually alter the relevant field in the ...
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Why do we allow Mac-Address to be changed by software?

In CISCO routers, they provide a provision to change the MAC-Address. My question is MAC-Address is supposed to be a burned-in address i.e. a permanent address. If we allow the mac-address to be ...
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Why router interface need IP addresses while IP is constant during the journey?

A beginner question, I've recently read in Cisco CCNA R&S 200-125 official cert guide that the packet leaves the PC with a destination IP of PC2 (the target) but with the MAC of PC2 in case of PC2 ...
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Same mac addresses for all the IPs [closed]

So I'm on a public wifi network and I'm trying to do intrusive testing. The issue is that while doing arp scan all the IPs are returning the same mac addresse.
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2answers
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How does a wireless repeater ascertain the destination MAC address of a wireless client?

While diving into the depths of wireless networks I have come across the different address fields in the MAC header of 802.11 network frames. A few thought experiments later I was confused about a ...
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5answers
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Is there a Layer 2 address advertising protocol?

I needed help in understanding if LLDP/CDP is the Layer 2 equivalent to RIP or say any Layer 3 route advertising protocol. If not,is there a protocol that advertises the MAC Address Tables among ...
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2answers
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what is the MAC address of a device plugged in to a specific port on my Fortinet firewall?

I have a Fortinet FG-60E firewall running FortiOS v6.0.1. A wireless access point is connected to one of the ports (internal3). There are currently no other clients connected to the wireless access ...
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1answer
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Frame transfer from one switch to another configured with VLANS

Hi, My question is related to the Vlan. And this question would consist of 2 parts. 1)Would Switch 1 know all the devices present in Vlan 2 or Vlan 3, including the ones present in the Switch 2. ...
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Can I assign any MAC address in my internal network?

A piece of hardware I am working for contains a small network, which includes about 13 devices. This network is dedicated and only internal available. Due a factory error, a certain type of those ...
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externally work around randomised mac addresses

we have a few devices here at our business that need to be connected to the network, however as an 'inbuilt' feature they randomise their mac address every time they turn on, both via the Ethernet and ...
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1answer
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Why switch has records in mac-table when i just set ip address to the hosts which connected to the switch?

I created a new switch and connected to two hosts in GNS3.Like this: Host1--->LS<---Host2, i think the mac-table in the switch should be empty before i sent data between two hosts. But when i just ...
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MAC address not found in BSSID List

I'm trying to connect my device to a router but it fails. While debugging, I found this error message in the logs "MAC address not found in BSSID List" What does it mean? I know that the BSSID is ...
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1answer
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Switch MAC learning problem

I'm doing some research on switching algorithms using a Level 1 GSW-2476 switch and I have a problem regarding MAC learning. As far as I know, a switch stores the source MAC address of each incoming ...
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436 views

How router knows MAC address of its next hop when the forwarding table only has egress interface

Say a source sends a packet to its destination via router A and router B. In the forwarding table of router A, it will only have the mapping between the IP address of destination and that of one of ...
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Which MAC should be used: device MAC or Interface MAC?

My L3 switch has ~30 interfaces. If you look at the output below there are two MAC addresses showing in the results of the show interface command. The hardware address is the same for all interfaces. ...
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Empty mac address value [closed]

Is there some MAC address value, that can be used to denote that device does not have MAC set (something like 0.0.0.0 for IP).? I thought of ff:ff:ff:ff:ff:ff, but afraid that it could be meaningful ...
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1answer
245 views

Practical difference between MAC-48 and EUI-48

As mentioned at Wikipedia, The distinction between EUI-48 and MAC-48 identifiers is purely nominal: MAC-48 is used for network hardware; EUI-48 is used to identify other devices and software. (...
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Gratuitous arp and unicast flooding

we have few 100s of access switches connecting to a core 10k in IRF. Here all our access is pretty much dumb does only L2 job. So what happens now is unicast flooding, technically MAC ages out, ...
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How to make virtual devices on GNS3 be able to ping the physical host

I have had this problem already and figured out its reason. Basically the problem is that the virtual devices on GNS3 cannot ping the physical host and also the physical host cannot ping the virtual ...
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1answer
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Possibly an issue with MAC aging

I've got three switches, one core switch/router (Brocade 6450) and two access switches (HP 2530) which are connected to the core switch. I also have a number of devices connected to the access ...
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1answer
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Users broadcasting who they are in WLAN and cell-phone networks

In the same way that wifi-enabled devices and wireless APs broadcast their MAC addresses (FF:FF:FF:FF:FF:FF), do cell-phones/smartphones also broadcast such an ID too to connect to a cell tower? That ...
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194 views

Endpoint MAC address change detection [closed]

A question regarding a host behavior when gateway mac address has changed (although it deals with Windows, I think it's the best forum). Assuming a windows host sending trafic to a destination IP, ...
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Network layer : the working of ARP( address resolution protocol)

If the switches have MAC tables, then what is the need of ARP table in the host systems that stores MAC addresses of other end systems?
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How physical addresses change hop to hop?

I've been reading Data Communication book by Forouzan it says that "The physical addresses will change from hop to hop, but the logical addresses usually remain the same." So, according to this ...
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What is the need of two addressing schemes (physical and logic address) in networking to identify a host? [duplicate]

In computer networking, each device/host is assigned 2 different unique address. One physical address, MAC and one logic address, IPv4/IPv6, to make communication possible between any 2 hosts in the ...
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What is the difference between CAM and FIB table?

As far I know, CAM table is Content Addressable Memory table where MAC address is stored FIB table is Forward Information Base table which is a dynamic table that maps MAC addresses to ports. Both ...