Networking Devices

Network Connectivity Devices
1. hubs
  1. =physical star and logical bus, utilizes CSMA/CS, forwards all broadcasts, not recommended for today's networks
2. Network Interface Card (NIC)
  1. NIC is installed in your computer to connect your computer to the network. It provides the physical, electrical, and electronic connections to the network media. Has 2 LED's (usually one for connection, other for activity)
3. Bridges
  1. connects two similar network segments together, breaking up collision domains. Software based (vs switches=hardware based. not common over switches today
4. Switch
  1. connect network segments together. recognize MAC address and forward to only that segment (if not recognize, fwd to all segments accept receiving). layer 2 device. (note layer 3 switch=router)
    1. switches that can add IP address for telnetting, adding VLAN, SNMP, and can configure a port for VOIP=managed switch
    2. switches that can't do the above=unmanaged switches.
5. router
  1. used to connect many, sometimes disparate, network segments together, combining them into what we call an internetwork. A well-configured router can make intelligent decisions about the best way to get network data to its destination. layer 3 device. sometimes act as a firewall.
6. firewall
  1. protects your LAN resources from invaders that prowl the Internet for unprotected networks, while simultaneously preventing all or some of your LAN’s computers from accessing certain services on the Internet. either a stand-alone “black box” or a software implementation placed on a server or router. has 2 connections-one to internet (public side) and one to LAN (private side). 2 firewalls surround servers that are both public and private (like email servers) called DMZ
7. Interface Configuration on routers/switches
  1. switches
    1. configure ports (all enabled by default), duplex (set to duplex auto by default) and speed (set to auto). good to troubleshoot last two if connection error. newer switches detect ethernet cable type
  2. router
    1. ports shut down by default. must configure duplex, speed, and IP address
8. DHCP Server
  1. DHCP servers assign IP addresses to hosts. If DHCP server on other segment, use unicast or directed broadcast to transmit. Client requests IP address, a subnet mask, a lease time (the amount of time before the IP address and other DHCP information expires on the client), the IP address of the DHCP server, the default gateway (router), the DNS server IP address (it gets two), the domain name used by DNS, and some NetBIOS information. can also be configured with a reservation list so that a host always receives the same IP address.
Specialized network related devices
1. multilayer switch
  1. switches on Open Systems Interconnection (OSI) Layer 2 like an ordinary network switch but provides routing. differences are the hardware inside and the operating system
2. Load Balancer
  1. load balancer can actually send incoming packets to multiple machines hidden behind one IP address. Depending on your needs, you can set rules based on the least load, fault tolerance, the fastest response times, or just dividing up (balancing) outbound requests for smooth network operations. great in ecommerce with multiple server
3. DNS server
  1. FQDN resolution. domains=.com (commercial), .mil (military), .ca (canada), etc. Pointer Records (PRT) resolves IP to FQDN. MX=mail exchange recores=can have multiple servers as same mail recipient for redundancy. Canonical Name record (CNAME) used to add ftp.whatever.com to same FQDN as www.whatever.com. AAAA records for authentication (RADIUS or TACACS+).
  2. Name resolution by: HOSTS file (meaning you stati- cally type in all names and IP addresses on each and every host), a request broadcast on the local network (Microsoft’s favorite—why ask a server when you can just broadcast, right?), DNS, and Microsoft’s Windows Internet Naming Service (WINS)
  3. Dynamic DNS=hosts register IP address as they are assigned by DHCP
4. proxy server
  1. handles its client-machine requests by forwarding them on to other servers. connect to the specific server that can fulfill the request for the client that wants it. can cache info to increase performance
  2. caching proxy= information from a client’s or clients’ earlier request speeding up bandwidth/performance
    1. web proxy=creates a web cache=page loads faster, fills in information (user, billing/shipping), and filter websites
5. encryption devices
  1. more choice of encryption methods and stronger encryption options. en/decryption process is very processer intensive and interferes with other functions that those routers and servers might be performing.
6. content filter
  1. filters spam, objectionable content, offloads the work from servers or routers
7. VPN concentrator
  1. accepts multiple VPN connections from remote locations
planning/implementing SOHO using network segmentation
1. requirements?
  1. how many comps, internet?, share resources?
2. cause congetstion=Too many hosts in a broadcast domain, Broadcast storms, Multicasting, Low bandwidth, Adding hubs for connectivity to the network
  1. fix this via network segmentation
3. switches break up into collision domains, routers break up into broadcast domains and provide WAN services
4. router functions =Packet switching, Packet filtering, Internetwork communication, Path selection
5. environmental conditions have to be right
  1. can't be too hot and shut down CPU's
  2. can't be too dry, for static elec will build up, and can't be too humid, for connections will corrode and shorts will occur.
6. Layer 2 switches is hardware-based-uses Application specific integrated circuit (ASIC). Keeps MAC address on filter table. If mystery MAC address, a broadcast occurs and responder is added to filter table. hubs allow only one device per network segment to communicate at a time whereas switches allow every connection to communicate at the same time.
7. Hub-multiport repeater. reamplifies or regenerates that signal and then forwards the digital signal out all active ports without looking at any data.

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Networking Devices

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	Created by Joshua Snider over 10 years ago