CCNA focuses on networks for SMEs (small and medium enterprises).
A hierarchical design model is recommended.
Easy to manage and expand.
Problems are resolved quickly.
hierarchical network design divided into three layers.
Core, (CL).
Distribrution (DL).
Access (AL).
Each layer provides specific functions.
This "modularity" facilitates the scalability and performance.
Access Layer (AL): the lowest
Interfaces with the terminal(User).
Includes routers, switches, bridges, hubs and wireless access points.
Provides a means of connecting devices to the network and control who can communicate over the network.
Distribution Layer (DL):
Aggregates data received from TO before the transfer of CL for routing.
Controls the flow of traffic with the policy and outlines broadcast domains with VLANs defined in the AL.
Allow VLAN traffic segmentation (separate subnets).
DL-switchestypically high-performance devices, high availability and redundancy to ensure reliability.
Core Layer (CL):
The high-speed backbone or internetwork.
Key to the cohesion between the devices at the distribution level? must be highly available and redundant.
Often combined with Internet resources.
Fm TFC aggregates all devices, so it must be able to quickly transfer large amounts of data.
Note: the smaller networks often combine the distribution andCore layers.
Three Laye3rs logic is divided into a clearly defined hierarchy.
It 'much more difficult to see these layers physically.
Advantages of a hierarchical network:
Scalability:
Hierarchy of networks very well.
The modular design allows you to replicate design elements.
Expansion is easy to program and implement.
Redundancy:
As a network grows, the availability is increasingly important.
Availability increases dramatically with hierarchicalNetworks.
For example, Al-connect switches to switches 2 DL. When DL switch fails, the AT-switch, switch to another.
Redundancy is limited to the level of access. Normally, the devices do not connect to multiple switches.
Performance:
Properly designed networks can achieve near wire speed btw all devices.
Safety:
AL-switch can be configured to control devices can connect to the net to give.
More advanced security policyAvailable from the DL.
AL Some switches support L3 capability, but usually it is the task of DL-switch, because it can process more efficient.
Manageability:
Changes can be repeated for all devices in a layer, probably because they perform the same functions.
Distribution of new switches will be simplified as configurations can be adopted with few changes.
Consistency within each layer simplifies debugging.
Maintainability:
Because ofits modularity and scalability are accustomed to hierarchical networks easily.
This also means that networks are less expensive.
In other designs will be the network management is growing increasingly complicated.
Principles of Hierarchical Network Design:
hierarchical design is no guarantee of good design.
simple guidelines to help distinguish BTWN well-designed and poorly thought through hierarchical networks.
Network diameter:
In general, the first thingassayed.
Reaching the number of devices through a package to its destination.
Small diameter ensures low latency and predictable.
Bandwidth aggregation (added):
combined to give the links btw switch to throughput.
Cisco has a proprietary technology called Link Aggregation EtherChannel.
aggregated links are provided by different dashed lines with an oval or a single dashed line with an oval.
May be at any level (less frequently used @AL).
Redundancy:
The redundancy can be provided in a number of options.
For example, 2x or 2x connections BTWN equipment devices.
redundant links can be expensive.
Redundancy design starts in the AL. Ensure that accommodate all network devices? 3 LR switches.
This helps determine the DL-3 switch? CL-switch.
What is a converged network?
SMEs are increasingly running voice, video and data.
The convergence process is the combination of these.
ARecently this possibility was limited to large companies.
Legacy (older) devices hindered convergence.
Since analog phones has not been replaced, you can see and legacy PBX systems and IP-based PBX.
Convergence is now easier and cheaper.
With a convergence is to manage a single network.
It costs less to deploy and manage.
IT cabling to be simplified.
Convergence also creates new opportunities.
You can wire the voice and videodirectly into the PC of an employee.
You do not need a phone or expensive video equipment.
Soft phones (Cisco IP | Communicator) offer a high degree of flexibility.
With the software, companies can quickly convert to converged networks with low cost of capital.
With cheap webcams for video conferencing can be added.
Separate voice, video and data networks:
voice networks include telephone lines run to a PBX (Private BDXT Exchange) isolation switch in a wiring closet Telco PSTN(Public Switch Telephony Network).
fm Cabinet Telco often separate the data and video cabinets.
New phone? a new line for the telephone system.
With a network of properly designed hierarchical voice lines with little or no impact will be.
Now the sense that networks can accommodate BW, converges.
Exploring the hierarchical network switches:
Tk-flow analysis:
The process of measurement and analysis of BW use to optimize performance, planning and HWImprovement.
To select the appropriate gear in a hierarchical network, you must spec flows by TFC, users and servers.
The networks should be designed with an eye toward growth.
Powered by the TFC-flow analysis software.
If port density and price check sufficient transmission capacity to ensure growth.
Analysis Tools:
Many TFC-flow analysis tools are available.
SolarWinds Orion NetFlow 8.1 CE analysis.
User Community Analysis:
Identifies users grpingsand its impact on net return.
Influenced port density and flow of TFC, influences the selection of network switches.
Typically, users are grped the work function.
For example, human resources and finance a plan to another.
Each department. have different users and needs, and requires access to various network resources.
Select Options, connections enough to meet the needs and enough to satisfy the department pwrful TFC.
Good network design also factors inGrowing.
Examine the TFC generated by end-user applications.
Some communities of users create a lot of others do not.
The position of the user community, which influences the data is stored and server farms.
Users agree to close their servers, you can reduce the diameter of the network, reducing the impact on other users.
However, the use is not always bound by their physical location or office.
The stored data and data analysis server:
Data can be servers, SAN,NAS units bu tape or disc or other component.
Contains both client-server and server / server TFC.
TFC Client-server typically passes through several switches.
forward prices BW-aggregation and-switch can help eliminate the bottlenecks for this type of TFC.
Some server applications to generate a high volume server btw.
These servers are shoule neighbors (ie, secure data centers shown).
TFC entire switch data center is usually very high.
Requires higherImplementation switches.
Topology diagram:
A graphic representation of a network infrastructure.
Shows how all the switches are connected together, including those designed to connect ports.
It shows where and how many switches are in use.
They can also contain information about the density and GPRS device.
Helps to visually identify potential bottlenecks.
Very difficult to create after the fact.
Switch Features:
Switch form factors:
fixed configuration or modularstackable or non-stackable.
Thickness is measured in rack units. (This is 1U, 3U).
Fixed Config switch - hardware can not be added.
Modular Switches - Chassis allows line cards containing multiple ports.
The larger frame, more modules can be supported.
stackable switches:
Can be linked together via a special cable that provides high-bandwidth backplane throughput btw switches.
Cisco StackWise technology allows you to interconnectnine switches with fully redundant backplane connections.
Stacked switches operate effectively as a single large switch.
Desirable, where fault tolerance and availability are critical BW and a modular switch is too expensive.
Performance:
Port density:
port density per switch is three doors available.
roots are typically fixed ports 1000!
large corporate networks do require high-density modular switches to the optimum use of space and PWR.
AlsoAvoid bottlenecks uplink.
A series of solid swtches consume a lot of additional ports for switch aggregation BW btw.
Compete in a modular switch aggregation is less problematic because the chassis backplane, the BW.
Forwarding Rates:
The processing capacity of a switch in bps.
Switch product lines are labeled for shipping rates.
If this is too low, can not take his wire-speed on all ports.
= Wire speed that each port is capable of(10Mbps etc.).
For example, switch to 48 GbE ports at wire speed = 48 Gb / s of the TFC.
If the switch only supports 32 Gbps (internal), can not operate at full wire speed on all posrts simultaneously.
Access switches normally not required full wire speed, because they are limited by their physical and uplink to the DL.
Link Aggregation:
Determine whether to aggregate ports enough to support the required BW.
switch port 24-GbE EC was up to 24 Gbps.
If youconnected to the network through a single cable, you can only forward 1 Gbps for the rest of the network.
The wire speed is 01:24 for each of the 24 devices.
Links to support the aggregation of these bottlenecks up to 8 ports to reduce grped where up to 8 Gbps.
can be constructed with 10-GbE uplink rates of return high.
Cisco uses the term EtherChannel ports = aggregates.
Power over Ethernet (PoE):
PoE can provide a power switch onExisting Ethernet.
Wireless AP can be used by IP phones and some of them.
Allows greater flexibility for equipment installations.
Adds significant costs to the switch.
PoE switch labeled with "V" for volts.
Layer 3 functions:
Typically, the switches operate at L2, and, above all, deal with MAC addresses.
L3 switches provide advanced features.
L3 switch = Multi Layer Switch.
switch functions in a hierarchical network:
Access Layer SwitchFeatures:
Port Security - the first line of defense for a network.
How many and which devices are allowed to connect.
All Cisco switches support port Layer Security.
VLAN component - of converged networks.
Voice TFC is usually given in a separate VLAN.
Port Speed:
Fast Ethernet is sufficient for most voice and data TFC.
PoE - much more expensive, so use only when necessary.
Link Aggregation - on all 3 lvls supported.
QoS - VoIP needs.
DistributionLayer Switch offers:
Collect all data-switch-switch and forwards them to the CL.
Provides inter-VLAN routing.
DL-switches have a capacity to manufacture than AL.
Need Help L3 inter-VLAN routing.
Security Policy:
Need L3 so advanced security policies can be applied.
ACL control the flow through a network of TFC.
ACL filter switches allow TFC.
ACLs are CPU-intensive because each packet inspection and must match ACLRules.
Placing on the ACL DL also reduces the 3 options that require additional configuration mgmt.
Policy-based connectivity and access to departmentaléworkgroup base coat.
Quality of service:
DL-switches must be implemented priorities for the next fm TFC maintenance AL Switches, QoS.
If not all devices support QoS, reduced benefits, -. poor performance and quality.
DL-switches are under high demand.
Need redundancyadequate availability.
DL-switches are typically used in pairs.
Recommend that they support multiple, hot-swappable power supply PWR.
Finally, they must link aggregation and aggregate broadband connection back to basic support.
Core Layer Switch Features:
CL is the backbone for high speed.
The transmission rate depends on the number of networked devices.
If you choose to inadequate controls on nuclear, you are faced with potentialBottleneck slowing down all the questions TFC.
CL should be aggregated to support 10 GbE switch.
L3 redundancy has a faster convergence of L2, so sure, CL-L3 switches support functions.
CL switches should support provides full redundancy.
QoS is the center for high-speed WAN access is often more important prohibitivel expensive.
Switches for SMEs:
Identify uses Cisco SMB applications.
The features of Cisco Catalyst switches:
You can not just choose oneTurn on the size of a company.
Companies are often integrated cross with other institutions.
In 6500 makes sense as an AL-switch, where there are hundreds of users in an area such as the stock market.
Cat Express 500 - forward prices = 8.8 to 24 Gbps.
Cat 2960 - L3, QoS, PoE is 16 to 32 Gbps.
Cat 3560 - enterprise-class, PoE, QoS, 32-128 Gbps.
Cat 3750 - piled high performance.
Cat 4500 - DL midrange modular - up to 136 Gbps.
Cat 4900 - Data Center.
Cat6500 - DL & CL - up to 720 Gbps.
Miscellaneous:
MDF - main distribution function.
Gi 0E1 - short for Gigabit Ethernet.
Spanning Tree - Protocol allows redundant paths, but stopped to avoid some links, switching loops.
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