Table of Contents
How does an Ethernet switch forward frames?
To forward the frame, the switch examines the destination MAC address and compares it to addresses found in the MAC address table. If the address is in the table, the frame is forwarded out the port associated with the MAC address in the table.
When a switch receives an Ethernet frame what does it do with it?
To do this, the switch learns which devices, called stations in the standard, are on which segments of the network by looking at the source addresses in all of the frames it receives. When an Ethernet device sends a frame, it puts two addresses in the frame.
How does a switch process a frame?
A switch works in the middle of the network. It connects multiple devices. It uses MAC addresses of the sender and receiver devices to process the frame. When a switch receives a frame, it reads the source address of that frame and stores it into a table known as the CAM table.
Which port does switch use to send frames to the host?
*The switch found the same destination mac-address in the “port 2”, for that reason, the ICMP packet is sent out of the port 2 where PC3 is located.
What decision does the switch make when it receives a frame?
In store-and-forward switching, when the switch receives the frame, it stores the data in buffers until the complete frame has been received. During the storage process, the switch analyzes the frame for information about its destination.
How do I send an Ethernet frame?
Method
- Overview.
- Select the required EtherType.
- Create the AF_PACKET socket.
- Determine the index number of the Ethernet interface to be used.
- Construct the destination address.
- Send the Ethernet frame.
- Send the frame (using sendto)
- Send the frame (using sendmsg)
Do switches always broadcast?
For broadcasts to work as intended the switch must handle broadcasts as a special case, and must send broadcasts to all other connected ports. If a switch receives a message that is sent to that destination MAC address then the switch knows it is a broadcast and will forward the message to every other connected port.
What does a switch on an Ethernet network do if it receives a unicast frame with the destination MAC address that resides at the same switch port as the source frame?
What will an Ethernet switch do if it receives a unicast frame with a destination MAC that is listed in the switch table? The switch will forward the frame to a specific port. If the destination is a broadcast or multicast, the switch will forward the frame to all ports except to the port the frame was received.
How does a Ethernet switch forward a frame?
If the destination address is in the table, and is known to be reachable on the same port that the frame was received on, the switch will filter (drop) the frame. Otherwise, the switch will forward the frame out of the port corresponding to its destination address in the forwarding table.
How does an Ethernet switch or bridge work?
An Ethernet switch or bridge relays Ethernet frames between devices connected to different ports. It thereby links multiple hosts (or smaller network segments each with multiple hosts) into a single connected network. When a frame arrives at a switch or a bridge, the source address of the frame is noted.
How is the source address of an Ethernet switch determined?
As each frame is received on each port, the switching software looks at the source address of the frame and adds that source address to a table of addresses that the switch maintains. This is how the switch automatically discovers which stations are reachable on which ports. Figure 1-2 shows a switch linking six Ethernet devices.
What does a switch do with the frames it recieves?
Switch is a layer 2 device. So this means it deals with frames (builds and examines them). So when it receives a frame, it looks inside to see where the destination mac address is. But since the mac address is on some further away network, and not directly connected to the switch, how in the world can it decide which way to send it?