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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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1answer
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Setting Destination MAC address for RTP/UDP packets

I have a requirement where I have to send the UDP packet to a destination multicast IPv6 address. In addition to that the packets must also have corresponding destination multicast MAC address set. I ...
3
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1answer
30 views

Finding MAC address with OUI List

I'm in the process of labeling the interfaces of my Cisco 3750G with descriptions referencing the device type that is associated with that port. I understand that I am able to run a show mac address-...
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1answer
64 views

Getting the IP Address from a device

I got some kind of "router" from another department and they want to know the IP address. I connected it for "testing" purpose on the switch at our place. I know the switch and port its connected to ...
4
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1answer
379 views

Why would a switch ever send an ARP request for a MAC address when it can just wait for the first packet to be received from a device?

I've been reading 'Windows Networking Fundamentals' and in that book it says that a switch can learn what MAC address is associated with a particular port when the connected device makes its first ...
2
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1answer
30 views

Why the ARP packet contains values like “Physical Address length” etc?

From what i know,MAC addresses are made of 48 bits,while IPv4 addresses are 32 bits Why are there these header fields? Are there MAC addresses with more or less 48 bits?
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3answers
117 views

Is IP an abstraction

If packets "hop" from network device to network device across networks using MAC addresses, resolved by ARP, does this suggest that IP is essentially an abstraction? By abstraction, I mean, the ...
1
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1answer
35 views

MAC Address Filtering Fortinet v6.0

I am having trouble configuring mac filtering. I do not use DHCP but am trying to figure out a way to set a mac address on a port and create a rule to block that specific mac address. So when I try ...
2
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2answers
76 views

Obtaining packet switch-port information via a mirrored port?

When sampling a mirrored port of a switch, is there any means of determining the switch-port information of the packet? Since Ethernet packets do not contain this information, I assume the answer is ...
-1
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1answer
39 views

Mac Address Flapping and switches

Is mac address flapping the reason why switches don't exchange switching information just like routers exchange routing information?
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2answers
55 views

Client timeout for Cisco IOS Static DHCP Pool

I'm not a network admin, but I have an old Cisco Catalyst 3560 for my network. I've successfully set up a DHCP Pool: ip dhcp pool 192.168.0.0 network 192.168.0.0 255.255.255.0 default-router 192....
1
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1answer
63 views

What is the meaning/translation of a MAC address?

For an instance : 00:0a:95:9d:68:16 I wonder if 00, 0a, 68 or 16 etc, has some specific meaning or can be translated, like giving the vendor information, date of issuing etc?
2
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1answer
49 views

MAC Address not resolving when IPSec VPN in place

I've created an IPSec VPN connection between two Mikrotik routers. They are connecting via IKEv2. Inside our two networks, we have a printer spooler which needs the printer's MAC address to verify it'...
2
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1answer
46 views

Is a network interface supposed to have no more than one MAC address?

Is a network interface supposed to have no more than one MAC address? Since a network interface is free to have more than one IP addresses, is IP address a way of multiplexing MAC address, if a ...
4
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1answer
297 views

Will the Sticky MAC access policy prevent unauthorized hubs from connecting to a network?

We have Meraki MS 250 switches. I have discovered some personal hubs attached to the network and want to ensure these devices wont work on the network to discourage the behavior. From what I can see,...
0
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2answers
53 views

How is Ethernet traffic sent between computers with multiple switches in-between? [duplicate]

I've wondered how Ethernet packets sent from Laptop-A to Laptop-B on the local network segment are delivered, when multiple switches are in-between. For hubs, that just replicates the packet on all ...
0
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1answer
20 views

How does a system know the local gateways MAC address for given IP address [duplicate]

Assuming you have the following network structure. Knowing the IP address of the WWW-Server, system A wants to send an IP packet. As I understand the destination MAC address has to be in the same ...
0
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1answer
52 views

Wireshark remote hosts

I configured a rip network. I connected two PCS to router 1, router 1 is connected to router 2 and PC 3 is connected to router 2. When I pinged PC 3 and looked at this in wireshark, in the source it ...
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0answers
38 views

Juniper EX4300 / MAC limiting SNMP trap

I have the following device and configuration: Model: ex4300-32f Junos: 17.3R3-S3.3 show configuration groups GLOBAL-SNMP { snmp { client-list MANAGERS { 10.8.9.0/28; } community TEST-COMMUNITY ...
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0answers
20 views

Information passed through an access point to a router

We have WiFi routers that control access through ACL's. We would like to use Access Points (AP) to increase the range of the WiFi routers. Does the AP pass the MAC address of the client to the ...
6
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2answers
178 views

How to display entire MAC address table on HP switches

I want to display the whole MAC address table without needing to press 'space' for the next page, so that if there are 50 entries in the table I'd be able to view them with a single command. I'm ...
7
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4answers
1k views

Does every host on the LAN share the same ARP table, or do hosts keep them individually?

I'm just learning about ARP. I'm a little bit confused. My confusion is better explained in a scenario. Host A is communicating with Host B. Host A knows Host B's IP address, but not it's MAC address....
2
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1answer
125 views

MAC Table vs ARP

I understand that for a switch to learn a MAC address, if host A wanted to send data to Host B the switch learns host A MAC and places it in the MAC table. If it doesn't know where the MAC (for Host B)...
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3answers
261 views

Switch and mac address table

I thought that a switch learnt the mac addresses by the computers sending out packets. However when I configured 2 switches, and 2 pc's, 1 pc connected to 1 switch, the other pc connected to the other ...
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3answers
86 views

Is an IP address assigned only to something with a Mac address?

From https://en.wikipedia.org/wiki/IP_address An Internet Protocol address (IP address) is a numerical label assigned to each device connected to a computer network that uses the Internet Protocol ...
3
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1answer
79 views

Port security on a cisco switch - predefined source MAC address and maximum number of MAC addresses

With port security on a Cisco switch, if you configure 1 source MAC address, does that also set the maximum MAC addresses to only one?
2
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2answers
86 views

How does a router know the destination mac?

so if I send a packet from a host to another from the same network we know the mac address of both the source and destination. However if the receiver is in a remote network the destination mac ...
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2answers
24 views

What is the bridging decision when getting ARP request?

Setup: Assume I have 3 VMs. VM1 VM2 and VM3. VM2 has two interfaces, say eth1 and eth3. eth1 is connected to VM1 physically and eth3 to VM3. I create a bridge on VM2 using brctl with eth1 and eth3. ...
3
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3answers
123 views

Is it possible to perform a Layer 2 (MAC address) traceroute?

I understand the difference between layer2 & layer3 and MAC & IP. I understand address resolution protocol, etc. But is there any way to do a traceroute that will show Layer 2 information? For ...
0
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2answers
78 views

Why we need ARP when each device has its own IP address?

I don't really understand Address Resolution Protocol (ARP). Why we need ARP when each device has its own IP address?
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1answer
48 views

locally vs universally administered MAC address? [duplicate]

Difference between locally and universally administered MAC address? What is the purpose of locally administered MAC address?
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3answers
150 views

If ARP uses broadcast, can I find out MAC-Address AND IP with it?

I have a peripheral device, connected via Ethernet to my Ubuntu. I would like to find out its IP, and untofetunately no it is not cached in my ARP table. ARP broadcasts the messages to every ...
0
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1answer
72 views

Private IP vs MAC

What I know is that when we connect to another IP, our Public IP gets shared to the outside world, and when they address us they use our Public IP (gateway), and then the gateway directs the ...
2
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2answers
33 views

LANs with no router,just a switch(or hub)

Can a LAN be implemented just with a switch? If so,how is the communication completed?just by MAC addresses? When sending a frame from the source to the destination,and inbetween there is a switch,...
3
votes
1answer
179 views

Cisco ARP cache rewrites?

I know that the Cisco's default ARP entry expiration is 240 minutes, however how does the ARP table mechanism work when a different MAC address is seen using the same IP? In other words, if I move ...
3
votes
1answer
75 views

Changing MAC Address

On learning about MAC addresses i came across U/L bit in the first octet. Further on i learned that MAC address could be spoofed. If U/L bit switches according to MAC address modification , how ...
4
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3answers
569 views

What is responsible for dropping Layer 2 frames that's not addressed to it?

It's my understanding that if a network interface card (NIC) receives a Layer 1 packet, it will extract the Layer 2 frame from it, checks its destination MAC address, and if it is not addressed to it (...
0
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1answer
85 views

will wireless devices' MAC address be saved on layer 2 switch?

So I know that basically switches work like this (assuming 2 PCs are connected via Ethernet port) - the switch will store the mapping of the 2 PCs' MAC address and the switch ports in which they ...
4
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1answer
52 views

What are the various standard and industry practice ways to express a 48-bit MAC address?

My team builds software that allows MAC Addresses as user input. These addresses are often copy and pasted from various platforms in a variety of formats. Wikipedia documents MAC Address Notational ...
2
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1answer
30 views

Global Unicast in IPv6 Neighbor Discovery

I have a very small pcap file in which Neighbor Discovery is performed for Global Unicast Addresses. That is, IPv6 addresses of both neighbors as I can see in Wireshark start from 2001:. Both IPv6 ...
6
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2answers
399 views

How to connect a special device in a network

I have a question which is puzzling me. I have a couple of custom electronic devices (are identical, one is a master and the other is a slave) which implement only up to level 2 of the ISO/OSI layer, ...
4
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3answers
379 views

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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2answers
75 views

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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2answers
77 views

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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1answer
77 views

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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2answers
365 views

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 ...
4
votes
1answer
40 views

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 ...
3
votes
1answer
420 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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3answers
85 views

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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3answers
985 views

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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3answers
726 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 ...