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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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3answers
43 views

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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0answers
29 views

“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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2answers
36 views

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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3answers
48 views

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 ...
4
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3answers
664 views

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
71 views

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 ...
1
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1answer
263 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 ...
3
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2answers
56 views

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 ...
1
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1answer
53 views

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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2answers
78 views

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
37 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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3answers
59 views

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
25 views

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
27 views

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
65 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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2answers
57 views

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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2answers
48 views

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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0answers
41 views

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
47 views

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 ...
3
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5answers
381 views

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
88 views

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 ...
0
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1answer
39 views

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. ...
4
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1answer
355 views

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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1answer
32 views

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 ...
2
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1answer
72 views

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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0answers
23 views

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 ...
3
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1answer
64 views

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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2answers
222 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 ...
0
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1answer
88 views

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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3answers
150 views

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 ...
1
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1answer
102 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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2answers
257 views

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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2answers
153 views

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 ...
4
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1answer
114 views

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 ...
0
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1answer
35 views

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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2answers
119 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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2answers
55 views

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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2answers
929 views

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 ...
1
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3answers
257 views

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 ...
2
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2answers
208 views

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 ...
2
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1answer
109 views

Can I curl a Cisco sg300 switch to get running config, MAC address table, int des, etc.?

I'm auditing switch interface descriptions at work. I work nights and sometimes people during the day shut down their computers when they leave, so I don't see which computers are on interfaces when I'...
2
votes
1answer
37 views

Should igmp table lookup misses flood to all ports?

With igmp snooping, upon receiving a multicast packet it looks up the table and decides which ports to forward the packet. What I'm wondering is, if there is not an entry in the table for that ...
7
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3answers
702 views

Does a switch always get a MAC address from a PC?

I was wondering if there is a possibility that a switch won't get the needed MAC address to it's CAM. For example, if the used protocol is UDP, where the sender doesn't need an answer back from the ...
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1answer
269 views

If ip address of a PC is dynamic is mac address static? [closed]

I am trying a open a specific port on my PC with defining ip address, since my ip is dynamic I am wondering if it is possible to do it with defining mac address and send packets based on mac-address ...
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1answer
74 views

Mac Address Representation wireshark

I'm a little confused. I just learned about two different mac address representations(hexadecimal and bit-reversed representation) in IEEE 802 When hexadecimal representation is used the octets are ...
3
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0answers
127 views

Distributed Trunking Inconsistent MAC table

Good afternoon. I've recently faced a problem in an HPE Distributed-Trunking Switch-to-Switch Square-Topology. Image 1 (shows the essential part of the architecture that consists of 4 switches ...
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2answers
211 views
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1answer
44 views

Only 1 device of 2 on my network can be accessed and the one available changes over time(these have different IP addresses) [closed]

Got like 2 dozen devices on a given network. Recently I've changed a module on 2 devices, and this resulted swapping their IP addresses, which wouldn't matter in my case. device A has IP b of device ...
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1answer
129 views

MAC address table [duplicate]

I believe this is a very simple question for you, but a interesting one for me, so I hope I don't mind you with my first question here, noob question. We have two switches. SW1 and SW2. First of all:...
5
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1answer
115 views

Cisco MAC Sticky Ports

So I have setup a sticky port on my switch with 1 allowed MAC for an access point. It has grabbed the Mac of the AP and after testing the port with a pc it shutdown the port as it should. But then I ...