1/28/2010 Network Plus Network Device Review

Physical Layer Devices Repeater –Repeats all signals or bits from one port to the other –Can be used extend network –Can connect copper to fiber (media converter) Hub –Multi-port repearter –Central device used on Star networks –Creates a Collision Domain –Intelligent or Managed hubs

Data Link Layer Devices Work with frames and recognize MAC addresses Bridge –Connects two (or more) collision domains –Learns all MAC addresses on each domain –Passes frames when necessary

Data Link Layer Devices Switch –Multi-port Bridge –Can be used to eliminate or greatly reduce network collisions and increase security –Today used in place of Hubs on Star Networks

Broadcast Domain Necessary for computers to find MAC address given an IP address or name A broadcast is a packet with destination MAC of all 1s Used by Address Resolution Protocol protocol to build ARP table All devices in broadcast domain receive ARP broadcast and requested device returns its MAC address.

VLANs Create multiple broadcast domains in switch structure. Reduce broadcast traffic Increase security Requires a layer 3 switch

VLAN Trunking Process of using one port to carry traffic from multiple VLANS by placing tags on the data frames

Creating Mesh Networks Provide redundant paths using switchs or routers

Spanning Tree Protocol (STP Prevents broadcast loops Uses 802.1d for STP or 802.1w for RSTP

Network Layer Devices Layer 3 switch Router Wireless Access Point

Layer 3 Switches Route datagrams based on IP address –Used to connect local network to Interner –Home WAP Route frames based on broadcast domain. –Used with VLANs –Devices all on same network broadcast ARP –Switch checks ARP broadcast for IP address and directs broadcast to the appropriate VLAN or broadcast domain.

Routers Direct packets to other networks based on information in router tables More complex then layer 3 switches Types of routers –Interior Routers Used within a organization’s MAN –Exterior Routers Used on Internet by ISPs –Border Routers Connect LAN or MAN to Internet

Routing Protocols Routers use tables that contain information on network paths Router table needs to be created and maintained –Static By network administrator Small networks –Dynamic Requires special protocols

Wireless Access Points Use IEEE standard and act as Layer 3 switch Can do some Layer 4 firewalling to filter packets based on port numbers Can be configure in Bridge mode Perform switching, routing, and firewall functions

That’s all folks