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Does the source MAC address change when a router forwards a packet?
Exam Alert: Remember that the source and destination IP address do not change throughout the process while the source and destination MAC address changes at each segment. You will see multiple questions about this on the CCNA exam! The MAC address is only locally significant and changes each hop.
Does router change MAC address?
It’s only possible to change a router’s MAC address if the router has the MAC Clone feature — most routers do. You can easily change the MAC address of a router via the MAC clone feature.
Does router change IP address of packet?
Pure routers do not change IP addresses. They just pass the IP packet to whatever physical network is likely to transport it to its destination.
What happens to MAC addresses as a packet travels from one network to another?
When a packet crosses a subnet boundary (e.g. by reaching a LAN’s router), the MAC address is discarded because it means absolutely nothing outside of the subnet in which it originated. It is not possible to recover the MAC address of somebody else’s machine if your only method of getting to them involves a router.
Can a router have multiple MAC addresses?
Wi-Fi Router and Access Points have multiple MAC addresses, not just one. They have multiple network interfaces: the WAN port. the LAN port (in some routers)
What happens if 2 devices have the same MAC Address?
In order for a network device to be able to communicate, the MAC Address it is using must be unique. If two devices have the same MAC Address (which occurs more often than network administrators would like), neither computer can communicate properly. On an Ethernet LAN, this will cause a high number of collisions.
Does a router use MAC addresses?
MAC addresses are used to communicate on the local area network. All a router uses a MAC for is to send traffic inside the LAN to the correct device. To answer this question you need to know how routers do the forwarding decisions.
How are MAC addresses changed by routers for forwarding?
Host A and B are in different subnets, and their default gateways are Router A and Router B vlan interfaces. My question is when Router A forward the packets to Router B, does it change packets’ source MAC to it outgoing interface MAC and destination MAC to Router B’s incoming interface MAC?
How does packet forwarding work in an IP router?
⑥ The packet processor at the line card #2 refers to the ARP table, and finds out the MAC address of the next hop 20.1.1.1 is b2. ⑦ So, according to the QoS policy (scheduling algorithm), it takes the packet out of the egress packet buffer, and forwards to ge2/1 port.
What happens to the MAC address of a packet?
MAC addresses only have meaning within an Ethernet network. Logically what happens at R1 is. The destination MAC address is checked. For a Unicast MAC address* if it doesn’t match the frame is dropped by the network card, if it does match the Ethernet frame is stripped and the packet is passed up to the IP stack.
Can a switch change the source MAC address?
If the switch were to change the source MAC address, the destination host would use this MAC address for any responses (including updating any ARP entries with bad data). This would result in the same situation I already described, just for all return traffic. Could mechanisms be developed to do this?