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infomation communication introdution
Transcript of infomation communication introdution
10’ Lee Ji Hye
10’ Song Jeong Soo
10’ Song Hye In
10’ Beak Won Mi
10’ Cho Jae Eun Contents What is Network Management? Planning First Second The First Job of Network Management is Planning the Technological Infrastructure, which consists of the Elements of the Network and How they Fit Together - Normal growth in application demand
- Disruptive applications
Applications that require massive network changes
Video requires higher network capacity
Voice requires high quality of service
- Organizational changes
- Changes in other aspects of IT (data center consolidation, etc.) Understand the Driving Forces for Change The first step in planning the technological infrastructure is to understand the current network in detail
Requires a comprehensive inventory what is analysis? How? third Gaps Analysis Identify gaps that will exist and that need to be closed
Characterize and document each
Create a plan for closing each gap fourth Options for Closing the Gaps - Multiple options must be considered
- Select roughly the least expensive option that will fully meet requirements
Base cost decisions on the total cost of ownership (TCO)
- Select based on scalability
The ability to grow cost effectively and sufficiently (See Figure 10-2) Scalability Traffic Management Traditional Traffic Management Methods As we saw in Chapter 4, even in a network with adequate capacity most of the time, there will be occasional momentary traffic peaks when traffic exceeds capacity.
Switches have to store frames in their memory buffers.
This creates latency in delivery.
If the buffer is too small for the delayed traffic, the switch must drop some frames. Install much more capacity than is needed most of the time
This is wasteful of capacity
Unacceptable in WANs, where capacity is expensive
Does not require much ongoing management labor Overprovisioning Priority Assign priority to applications based on sensitivity to latency
In momentary periods of congestion, switch sends high-priority frames through, holding back low-priority frames
Substantial ongoing management labor
Used heavily in WANs, where the cost per bit is too high to use overprovisioning In ATM, reserve capacity on each switch and transmission line for an application
Allows strong QoS guarantees for voice traffic
Wasteful if the reserved capacity is not sued
Usually, data gets the scraps—capacity that is not reserved for voice QoS Reservations Traffic Shaping Compression A fifth way to manage traffic is to use compression.
Here, 3 Gbps and 5 Gbps traffic streams go into the network.
Without compression, 8 Gbps of capacity would be needed.
With 10:1 compression, only 800 Mbps of capacity is needed.
A 1 Gbps line will be adequate Network Simulation Software Simulation Build a model, study its implications
More economical to simulate network alternatives than to build several networks and see which one is best Purposes ① Compare alternatives to select the best one
② Sensitivity analysis to see what will happen if the values of variables are varied over a range
③ Anticipating problem such as bottlenecks
④ Planning for growth to anticipate areas where more capacity is needed. Adding a new link The Simulation Process Step 1: Before the Simulation, Collect Data Data must be good
Otherwise, GIGO (garbage in, garbage out) Step 2: Adding Node Add node icons to the simulation Work Area
(clients, servers, switches, routers, etc.) Step 3: Specifiying the Topology Specify the topology by adding transmission linesbetween nodes (and specifying line speeds). Step 4: Configuring Elements Configure EACH node and transmission lines
(IP Time-to-Live value, etc.).
In this case, Frame Relay burst speed rate. Step 5: Adding Applications Add applications, which generate traffic data Step 6: Runnig the Simulation Examine the output to determine implications
Validate the simulation if possible (compare with actual data to see if it is correct) Step 7: What-If Analysis Do what-if analysis, trying different alternatives. Step8 : Application Analysis OPNET’s Application Characterization Environment (ACE) can do network and application simulation. TCP/IP Management IP Subnet Planning IP Addresses always are 32 bits long Subnrtting at the university of Hawai'i it divided the 16 bits over which it has discretion into an 8-bit subnet part and an 8-bit host part. The 2N-2 Rule If a part has N bits, it can represent 2N-2 subnets or hosts per subnet. Calculation fewer hosts per subnet.
more subnets mean fewer hosts, and more hosts means fewer subnets. Balancing subnet and Host part sizes Network Address Translation(NAT) A firm gets a block of IP addresses
NAT allows a firm to hide these “external” IP addresses NAT Operation Transparency NAT is Transparent to Internal and External Hosts Security with NAT, attackers learn only false,external IP addresses.
attacker cannot send attack packets to the internal hosts. Expanding the Number of Available IP Addresses Problem: companies may receive a limited number of external IP addresses from their ISPs There are roughly 3,000 possible ephemeral port numbers for each IP address So for each external IP address, there can be 4,000 connections Solution Private IP Address Ranges Reserved for use inside firms
May not be used outside firms
192.168.x.x (most popular)
172.16.0.0 through 172.31.255.255 Protocol Problems with NAT - IPsec, VoIP, etc. do not work properly with NAT
The protocol must know the true IP address of a host - Planning - TCP/IP management Planning the technological infrastrucure
traffic management methods
network simulation IP subnet planning
Network Address Translation(NAT) Thank You