information about devices

NOTES:
Physical layer Hubs, Repeaters, Cables, NIC
Data Link Layer Bridges, Switches, NICs
access point connects computers with wireless adapters to a network
16550 UART chip

needed to provide a modem connection of 115200 bps
most computers today have 16550 UART chips for both of their serial ports
these serial ports can run as fast as 256 Kbps

transceivers can convert media types(?)
gateway translates protocols


HUBS
hub connects multiple computers to create a single logical network segment
active hub boosts signal strength
a passive hub is limited to supporting distances of less than 30 meters (100 feet)
Ethernet hub directs the data packet to all hosts on the LAN segment
Token Ring hub (MAU) will only regenerate the signal to the next device in line



NICS
NICs work at both the physical and datalink layer
You have replaced a NIC in a workstation connected to a Token Ring network, but the workstation cannot communicate with the server. What is the most likely cause of this problem?
The NIC is set for the wrong speed.** (?)



SWITCHES
switches and bridges and maybe NICs work at the data link layer
a switch can replace a hub, not a mau, or transciever, or repeater
a switch must be able to read the MAC address of each frame it receives.
This information allows switches to repeat incoming data frames
only to the computer or computers to which a frame is addressed.
This speeds up the network and reduces congestion.



BRIDGES
used to join two network segments together
allows computers on either segment to access resources on the other.
can also be used to divide large networks into smaller segments.
can also connect networks that run at different speeds, different topologies, or different protocols
cannot, join an Ethernet segment with a Token Ring segment, because these use different networking standards.
operate at MAC sublayer of the Data Link layer
Bridges read the MAC header of each frame to determine on which side of the bridge the destination device is located,
the bridge then repeats the transmission to the segment where the device is located.



ROUTER
used to connect networks of different types, such as those using different topologies and protocols
operates at the netwok layer
can switch and route packets across multiple networks
determine the best path for sending data.
can be used to segment a large network,
and to connect local area segments to a single network backbone that uses a different physical layer and data link layer standard
can also be used to connect LAN's to a WAN's.



BROUTERS
operates in the Network layer and the Data Link layer
act like a BRidge for non-routable protocols (NetBEUI) and as Routers for routable protocols (TCP/IP)
can be used to connect 2 netbeiu nets and a tcp/ip+netbeiu net, and keep net segmented
connects network segments and allows full bandwidth on all ports
combination bridge, and router in one device.
more cost effective as both the bridge and router are combined together



GATEWAYS
used to connect networks using different protocols
operate at the network(?) layer of the OSI model.
In order to communicate with a host on another network, an IP host must be configured with a route to the destination network.
If a configuration route is not found, the host uses the gateway (default IP router) to transmit the traffic to the destination host.
default t gateway is where the IP sends packets that are destined for remote networks.
If no default gateway is specified, communication is limited to the local network.
Gateways receive data from a network using one type of protocol stack,
removes that protocol stack
and repackages it with the protocol stack that the other network can use
configure default gateway to allow nodes on one local network to communicate with nodes on another network
the default gateway for a computer is usually the address of the router
functions provided by a default gateway
Provides a route for packets with destinations outside the local subnet.
"Your default gateway does not belong to one of the configured interfaces."
run ipconfig
The default gateway has been misconfigured. The default gateway setting is an IP configuration setting.
if a client needs to send a packet that is not on the client's subnet, the packet goes to the default gateway



CSU/DSUs
combines the functionality of a channel service unit (CSU) and a data service unit (DSU)
used to connect a LAN to a WAN,
and they take care of all the translation required to convert a data stream between these two methods of communication.
DSU provides all the handshaking and error correction required to maintain a connection across a wide area link, similar to a modem
DSU will accept a serial data stream from a device on the LAN and translate this into a useable data stream for the digital WAN network.
It will also take care of converting any inbound data streams from the WAN back to a serial communication.
CSU is similar to a DSU except it does not have the ability to provide handshaking or error correction.
It is strictly an interface between the LAN and the WAN and relies on some other device to provide handshaking and error correction.




MAUs
Q. users connected to the new MAU can communicate with each other but not with users on the original MAU:
A. Connect the ring in port to the ring out port on each MAU.
if using two MAUs, the ring in port of one MAU should be connected to the ring out port of the other MAU.
Q. new MAU. Users are not able to connect to the LAN. The network analyzer shows connectivity from the NICs to the RJ-45 plugged into the MAU. The most likely cause?
A. The ring in and ring out are misconfigured between MAUs.



1.5.0 Network Devices-Data Link Layer
Data Link devices work with MAC addresses
A NIC works at both physical and data link layer
Bridge/Switch Modes
store-and-forward
1. packet is first gathered and stored in its entirety
2. switch then begins to transmit it on the outbound link
cut-through
1. switch starts to transmit the front of the packet
2. back of the packet continues to arrive

Bridges
Help prevent broadcast storms
STP (Spanning Tree Protocol)
designates the state of each interface on a bridge
Forwarding - all packages recieved and forwarded
Blocking - only status of other bridge messages pass




1.5.0 Network Devices-Network Layer
Routers: 3 methodologies
1. static routing
static routing info table
does not exchange info with other routers
2. distance vector routing
dynamic routing info table
uses RIP (Routing Information Protocol)
routing path based on distance, number of hops
maxium hops = 15
3. link state routing
dynamic routing info table
maintains a copy of every other routers LSP
LSP (Link State Protocol)
OSPF (Open Shortest Path First)
routhing algorithm, successor to RIP

difference between outlook express and Microsoft outlook

How to Decide Which Client Best Suits Your Needs

When choosing between Outlook Express and Outlook, users and organizations should base their usage decision on the following criteria:

Outlook Express

Choose Outlook Express if:
You require only Internet e-mail and newsgroup functionality (for versions of Windows later than Microsoft Windows 95, versions of Windows earlier than Microsoft Windows 95, Macintosh, and UNIX platforms).
You use or plan to use Office 98 for Macintosh, and you want to take advantage of the integration of Outlook Express with this version of the Office suite.

Outlook

Choose Outlook if:
You require advanced Internet standards-based e-mail and discussion group functionality.
You require integrated personal calendars, group scheduling, task, and contact management.
You require integrated e-mail and calendaring, cross-platform clients for versions of Windows later than Microsoft Windows 95, versions of Windows earlier than Microsoft Windows 95, and Macintosh platforms.
You use, or plan to use Office 97, Office 2000, Office XP or Exchange Server and want to take advantage of the integration of Outlook with this version of the Office suite, and the integration with Exchange Server.
You require robust, integrated run-time and design-time collaboration capabilities

how to configure pix firwall

How to Configure Cisco PIX Firewall Part I
Cisco
How to Configure PIX Firewall.

Abstract:

Please find below a step by step process to configure the PIX Firewall from scratch. A simple scenario is given here where you have a corporate network with a PIX Firewall connected to the Internet through the Outside Interface, Internal Network through the Inside interface and DMZ through the DMZ Network. This paper would assist you in a simple step by step, near complete configuration for a PIX Firewall running a midsized corporate network