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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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Scenarios in which a host (e.g. Debian) would update its ARP table [closed]

For security reasons, I'd like to know for which of the following scenarios would a host (Debian for example) update its ARP table: It receives a gratuitous ARP for IPs that are not in its ARP table ...
AhmedWas's user avatar
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2 votes
1 answer
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cisco catalyst 6500 not honoring static ip assignments

I have a catalyst 6500 sup720 running 15.1(2)sy6 and i have attempted to have a set of mac addresses to get a specific ip from dhcp. below is what shows on the bindings. 10.1.4.200 01e0.508b....
Kendrick's user avatar
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1 answer
119 views

Too many mac addresses in a switch - Cisco Packet Tracer

The image of a network im refering to is above. In Cisco Packet Tracer after having used a command ping 192.168.1.3 from pc1 to pc3, when I check mac addresses in both SW1 and SW2 using show mac ...
pieceofpaper's user avatar
-1 votes
1 answer
40 views

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 ...
user1047228's user avatar
0 votes
2 answers
254 views

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 ...
Brasley's user avatar
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1 answer
81 views

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 ...
Dylan Prost's user avatar
0 votes
2 answers
508 views

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 ...
Paul's user avatar
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2 answers
342 views

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?
BHP's user avatar
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1 answer
214 views

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 ...
freman1952's user avatar
1 vote
1 answer
60 views

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 ...
Daniel Marschall's user avatar
6 votes
6 answers
9k views

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 ...
Tomasz's user avatar
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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. ...
Konejointune's user avatar
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0 answers
28 views

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 ...
Aviv Aviv's user avatar
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1 vote
1 answer
356 views

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....
N.C.'s user avatar
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4 votes
1 answer
118 views

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. ...
Gilbert Wong's user avatar
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1 answer
1k views

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 ...
Albert's user avatar
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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 ...
William's user avatar
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0 answers
11 views

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 ...
imnglwhatheheckw's user avatar
0 votes
2 answers
185 views

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 ...
Mhd Ghd's user avatar
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2 answers
255 views

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 ...
saba's user avatar
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1 answer
345 views

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 ...
potatoNetwork's user avatar
1 vote
3 answers
155 views

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 ...
Anas Programmer's user avatar
1 vote
1 answer
473 views

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 ...
Mehdi Charife's user avatar
1 vote
1 answer
88 views

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 ...
Mehdi Charife's user avatar
0 votes
2 answers
105 views

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 ...
Mehdi Charife's user avatar
0 votes
1 answer
274 views

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:...
SebMa's user avatar
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1 vote
0 answers
17 views

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 ...
Mbaku Baki's user avatar
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3 answers
412 views

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 ...
Stan's user avatar
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1 vote
1 answer
279 views

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 ...
AtNarrow's user avatar
1 vote
1 answer
222 views

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 ...
AlazOz's user avatar
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3 votes
2 answers
4k views

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 (...
The Footsie's user avatar
3 votes
3 answers
2k views

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 ...
LoneWolf47's user avatar
1 vote
1 answer
163 views

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 | | | ...
BlackFlag's user avatar
0 votes
0 answers
23 views

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 ...
CM_Key's user avatar
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0 votes
1 answer
74 views

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 ...
Norb Batt's user avatar
8 votes
6 answers
5k views

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 ...
Shadi's user avatar
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1 vote
3 answers
631 views

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 ...
S. M.'s user avatar
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1 vote
0 answers
265 views

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 ...
meta_warrior's user avatar
3 votes
1 answer
66 views

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. ...
Vexea's user avatar
  • 55
0 votes
2 answers
926 views

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 ...
S. M.'s user avatar
  • 398
0 votes
1 answer
146 views

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....
S. M.'s user avatar
  • 398
0 votes
2 answers
67 views

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 ...
David Frucht's user avatar
3 votes
2 answers
3k views

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 ...
SimonC's user avatar
  • 133
-1 votes
2 answers
154 views

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? ...
Umair Shahid's user avatar
5 votes
1 answer
5k views

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 ...
Engineer999's user avatar
5 votes
1 answer
221 views

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 ...
heddha's user avatar
  • 53
4 votes
1 answer
561 views

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?
Caine Kiewit's user avatar
0 votes
1 answer
2k views

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
Subscribe me's user avatar
0 votes
3 answers
337 views

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 ...
Seif Ashraf's user avatar
0 votes
1 answer
327 views

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 ...
Brian Yeh's user avatar
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