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.
343
questions
0
votes
1answer
33 views
152 bit hardware address in dhcp binding?
When listing MAC addresses on a Cisco ISR DHCP service, I get a long list of hardware addresses, one per IP address, but for one IP I get an address so long it runs onto three lines. The other ...
3
votes
2answers
2k views
Why the first octet of a MAC address always end with a binary 0?
I stumbled upon a piece of code on GitHub: https://github.com/adeverteuil/bash-ula-generator/blob/master/gen-ula.sh
# Generate an EUI64 from the MAC address
# as described in RFC 3513
# https://tools....
0
votes
1answer
49 views
How data travel from a node to a destination IP address? [duplicate]
Let's say I have a lot of devices which connect to a single switch, and the switch itself connects to a router which provide Internet connection.
Whenever an application on a node needs to ...
0
votes
1answer
25 views
Why we need Mac address to send Packets? [duplicate]
While sending a packet network layer attach the source and destination Ip addresses to it. But Data link layer need a destination Mac address in order to send the data through router or within a ...
0
votes
3answers
69 views
Does a router send its own mac address or the mac address of the user?
When a request is made, does the router send its own mac address or the mac address of its user? Does it send the mac address at all?
My specific case is the following: I am getting a 4g sim card to ...
0
votes
1answer
33 views
Is it possible to propagate MAC address back to sender?
Let me first to tell me what I know, please correct me if I am wrong.
I know when Ethernet frame travels across the internet then Layer 3 data (Source and Destination IP) remains same and Layer 2 ...
1
vote
1answer
101 views
Cisco Nexus 6k mac move detection not working
My device is cisco Nexus 6001 Chassis (one unit dc switch)
# show version
...
kickstart: version 7.2(1)N1(1)
system: version 7.2(1)N1(1)
...
I've configured mac move detection:
# conf t
# mac ...
0
votes
1answer
21 views
Broadcast Timer [duplicate]
This question is regarding in the process of L2 MAC Address learning.
As we know, if a sender sends a packet to some receiver host which switch doesn't know, it will broadcast for learning.
Assume an ...
0
votes
2answers
102 views
Different MAC addresses [closed]
What happens if a host on the network receives an IP packet with a MAC source address that differs from the MAC address in the local ARP table for that source IP.
The ARP table entry for that IP was ...
0
votes
1answer
127 views
What happens when a switch receives a packet with an unknown source MAC address?
The CAM table cannot be populated with the source address so other action must be taken. Is the switch going to drop the packet?
1
vote
4answers
105 views
How can I search for MAC addresses on local network without referencing any IP addresses [closed]
I think there is an IoT device on my network that has lost its IP address or IP address has been corrupted by a power surge. I want to scan MAC address to see if it is still 'hiding' on my network. I ...
0
votes
1answer
41 views
Is destination MAC address is always end point MAC address? [duplicate]
To simplify if the destination is on a separate network would the source still does ARP request or does it uses default GW's MAC as destination MAC?
2
votes
1answer
55 views
Is this possible (NAT??)
I have a device on another network, say it's IP is 10.1.1.1
I want to ping it from my own network, say host 192.168.1.1, but I want to ping an address in my local segment to do so,so 192.168.1.2.
Is ...
0
votes
2answers
110 views
Confusions regarding byte and bit ordering of Ethernet Frame
I understand the concept of Endianess regarding numbers because there the bit significance is well defined. But when applied to things like Ethernet frame or Mac address, things are so clear to me, ...
0
votes
1answer
32 views
ARP table updated when receive message
I'm studying networking and I have a question about when an ARP table should update.
Consider this scenario:
Host A has the MAC address of host B in its ARP table.
Host B's ARP table is empty.
...
0
votes
1answer
44 views
ARP behaviors between hosts connected via switches
In a scenario like the following, where different hosts are connected via switches only, I'm not sure how the ARP packets will look like when A wants to send an IP packet to B.
I assumed all the ...
2
votes
1answer
100 views
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
votes
1answer
50 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-...
0
votes
1answer
67 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
votes
1answer
480 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
votes
1answer
32 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?
1
vote
3answers
134 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 ...
2
votes
1answer
614 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
votes
2answers
77 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
votes
1answer
44 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?
2
votes
2answers
71 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
vote
1answer
65 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
votes
1answer
59 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
votes
1answer
61 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
votes
1answer
361 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
votes
2answers
69 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
votes
1answer
28 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
votes
1answer
63 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 ...
4
votes
0answers
71 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 ...
0
votes
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
votes
2answers
191 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
votes
4answers
2k 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....
3
votes
1answer
393 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)...
4
votes
3answers
317 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 ...
1
vote
3answers
120 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
votes
1answer
88 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
votes
2answers
145 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 ...
0
votes
2answers
43 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
votes
3answers
442 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
votes
2answers
86 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?
0
votes
1answer
175 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?
1
vote
3answers
267 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
votes
1answer
311 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 ...
3
votes
2answers
37 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
266 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 ...
