big network question

2 network questions( little bit confused about that)

1-which device will reduce the impact of network traffic without dividing the LAN?
a router of a bridge?
2-a hub operates at the physical layer: true or false?

Thanks by advance.

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malcybood

farhanier1 wrote:

2 network questions( little bit confused about that)

1-which device will reduce the impact of network traffic without dividing the LAN?
a router of a bridge?
2-a hub operates at the physical layer: true or false?

Thanks by advance.

1 - A bridge or a switch will do this.....adding a router divides networks.....Adding switches or bridges creates more collision domains which improves bandwidth. Think of each interface on a router as a new network.

Switches and bridges create more collision domains (each port on the bridge or switch is a collision domain) and each PC connected to either port of these devices have dedicated bandwidth to this port. You can also create VLANs on the switch which creates new broadcast domains.

2. A hub with i.e. 8 ports is 1 collision domain and all PCs would be operating in one collision domain and scrapping for the same bandwidth. Hubs are Layer 1 Physical layer of the OSI model.

Here's a good link to explain the differences

http://www.practicallynetworked.com/networking/bridge_types.htm

pradeep_jagtap

Q1:- A network bridge connects segments, but incongruously it breaks up the traffic by filtering data frames, which are packets of data that are transmitted across the network. Each frame contains the physical addresses of the sending node and the receiving node. When a data frame is transmitted across a network, it visits every node in the segment. Each node checks to see whether the frame is meant for it, and if so it accepts the frame; if not, the node discards it. As you can probably guess, this adds up to a lot of traffic as more devices are added to a segment.
Bridges let you determine how many frames will go to what network nodes on the segments that the bridge is connected to. The bridge learns the physical address of each device connected to those segments and stores the location in an internal lookup table. When a frame is received from either segment connected to the bridge, it looks into the table to determine whether that frame’s destination address is located on the segment from which it was received or on the other segment. If the destination is on the same segment that the bridge received the frame from, the bridge discards the frame; otherwise, the bridge forwards the frame. Keep in mind that data will still be sent to every node on the originating segment—the bridge will only keep the frame from being sent to the other segment it is connected to

Q2:- The physical layer is responsible for the transmission of raw data in the form of a stream of bits across physical media. Layer 1’s specifications comprise the media interface, the physical topology, and the signaling methods used across the media. Layer 1 conveys the bit stream data through electrical impulses, light, or radio signals. The bit stream travels throughout the network at the most basic electrical level. To do this, the physical layer must define the cable media (or wireless mode), the network interfaces, and all physical aspects of the network. Examples of physical-layer protocol definitions include Asynchronous Transport Mode (ATM), Gigabit Ethernet, and the RS-232 interface. Note that both ATM and Gigabit Ethernet contain specifications that cross into the Data Link layer. It is very common to find protocols that encompass more than one layer.