StudyNet

Heap CRM

siti_mch@yahoo.co.id (AksaSoft) — Thu, 20 Mar 2008 07:35:14 PDT

Heap CRM
A customer relationship management (CRM) application should make your life simpler not more complicated. Heap is designed to be simple. It has simple functions like messaging, calendars and contacts; but it ties them all together so you can see the relationships between these items. You can easily run reports on this data, or if you wish, export the data. Heap does what you need then gets the heck out of your way.

Main Features:
- Dashboard
- Messages
- Calendar
- Contacts
- Reports (Now with Goals)
- Event Templates (Sales-force Automation)
- E-Mail Integration (Now with E-Mail History)
- Specialized iPhone Interface

The International Travel Agency

siti_mch@yahoo.co.id (AksaSoft) — Mon, 03 Sep 2007 13:13:19 PDT

The labs in this course reference the fictitious International Travel Agency (ITA) , which maintains a global data network . The ITA business scenario provides a tangible, real-world application of the concepts introduced in the labs. Use the diagram of ITA's WAN topology to familiarize yourself with the company and its network

Making the network accessible but secure

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:37:23 PDT

Making the network accessible but secure

Accessible networks allow users to connect easily over a wide variety of technologies. Campus LAN users typically connect to routers at the access layer through Ethernet or Token Ring. Remote users and sites depend on one of several WAN services. The variety of WAN services will differ from area to area. Because cost and geography play a significant role in determining what type of WAN services an organization can deploy, Cisco routers support all major WAN connection types. As shown in the figure, these include circuit-switched (dialup) networks, leased lines (dedicated), and packet switched networks.

Dialup and dedicated access - Cisco routers can be directly connected to basic telephone service or digital services such as T1/E1. Dialup links can be used for backup or at remote sites that need occasional WAN access, while dedicated leased lines provide a high-speed, high-capacity WAN core between key sites.

Packet switched - Cisco routers support Frame Relay, X.25, Switched Multi-megabit Data Service (SMDS), and ATM. With this variety of support, the WAN service, or combination of WAN services, to deploy can be determined based on cost, location, and need.
Often, the easier it is for legitimate remote users to access the network, the easier it is for unauthorized users to break in. An access strategy must be carefully planned so that resources, such as remote access routers and servers, are secure. If a company enables users to telecommute via dialup modem, the network administrator must secure access routers with access lists or an authentication protocol such as the Password Authentication Protocol (PAP) or the Challenge Handshake Protocol (CHAP). These protocols require the user to provide a valid name and password before the router permits access to other network resources.

Making the network adaptable

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:36:10 PDT

Making the network adaptable
An adaptable network can gracefully handle the addition and coexistence of multiple routed and routing protocols. EIGRP is an exceptionally adaptable protocol because it supports routing information for three routed protocols: IP, IPX, and AppleTalk.
The Cisco IOS also supports route redistribution, which is described in Chapter 7, Route Optimization. Route redistribution allows routing information to be shared (i.e., redistributed) among two or more different routing protocols. For instance, RIP routes can be redistributed into an OSPF area.

Mixing routable and non-routable protocols
A network delivering both routable and non-routable traffic has some unique problems. Routable protocols (e.g., IP) can be forwarded from one network to another based on a network-layer address. Non-routable protocols (e.g., SNA) do not contain any network-layer address and cannot be forwarded by routers. Most non-routable protocols also lack a mechanism to provide flow control and are sensitive to delays in delivery. Any delays in delivery or packets arriving out of order can result in session loss. An adaptable network should accommodate both routable and non-routable protocols.

Making the network efficient 2

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:35:13 PDT

Making the network efficient 2
The Cisco IOS also supports the following bandwidth optimization features:
Dial-on-demand routing (DDR)

Switched access

Route summarization

Incremental updates
Dial-on-Demand Routing
An organization cannot always afford dedicated WAN circuits, or even Frame Relay, for every remote site. At sites that require only occasional WAN connectivity, dial-on-demand routing (DDR) offers an efficient, economical alternative. As shown in the figure, a router configured for DDR will listen for interesting traffic and wait to build the WAN link. When the router receives interesting traffic (as defined by the administrator), it places a call to activate the link, which is commonly ISDN.

Route Summarization
The number of entries in a routing table can be reduced if the router uses one network address and mask to represent multiple networks or subnetworks. This technique is called route aggregation, or route summarization. Some routing protocols automatically summarize subnet routes based on the major network number. Other routing protocols, such as OSPF and EIGRP, allow manual summarization. You will learn more about route summarization in the next chapter.

Incremental Updates
Some routing protocols, such as OSPF and EIGRP, send routing updates that contain information only about routes that have changed. These incremental routing updates use the bandwidth more efficiently than simple distance-vector protocols, which transmit their complete routing table at fixed intervals, regardless of whether a change has occurred

Making the network efficient

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:34:13 PDT

Making the network efficient
An efficient network does not waste bandwidth, especially over costly WAN links. To be efficient, routers should prevent unnecessary traffic from traversing the WAN and should minimize the size and frequency of routing updates. The Cisco IOS includes several features designed to optimize a WAN connection:
Access lists

Snapshot routing

Compression over WANs

The following sections describe each of these features.
Access Lists
Access lists, also called access control lists (ACLs), can be used to prevent traffic that the administrator defines as unnecessary, undesirable, or unauthorized. You may apply one access list on an interface for each protocol, per direction (i.e., in or out). Different filtering policies can be defined for IP, IPX, and AppleTalk. Access lists can also be used to control routing updates, apply route maps, and implement other network "policies" that improve efficiency by curtailing traffic.

Snapshot Routing
Distance-vector routing protocols typically update neighbor routers with their complete routing table at regular intervals. This is done even when nothing has changed in the network's topology. If a remote site relies on a dialup technology, such as ISDN, you can not expect the WAN link to remain active 24 hours a day. In fact, the tolls associated with ISDN make heavy use cost-prohibitive. However, if RIP routers expect updates every 30 seconds by default, the ISDN link would have to be reestablished twice a minute to maintain the routing tables. This hardly seems efficient, especially after employees have gone home for the night. Although it is possible to adjust RIP's timers, the Cisco IOS provides a much better solution to maximize network efficiency in this situation; snapshot routing.

Snapshot routing allows distance-vector routers to exchange their complete tables during an initial connection, but then wait until active periods on the line before again exchanging routing information. The router takes a snapshot of the routing table, which it uses during quiet periods while the dialup link is down. In other words, the routing table is kept frozen so that routes will not be lost because an update has not been received. When the link is re-established (usually because the router has identified interesting traffic that needs to be routed over the WAN), the router again updates its neighbors.

Compression
The Cisco IOS supports several compression techniques that can maximize bandwidth by reducing the number of bits in all or part of a frame. Compression is accomplished through mathematical formulas, or compression algorithms. Unfortunately, routers must dedicate a significant amount of processor time to compress and decompress traffic. This increases latency. For this reason, compression proves an efficient measure only on links with extremely limited bandwidth.

Making the network responsive

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:32:48 PDT

Making the network responsive
A network's responsiveness is typically measured by its end users as they access the network to perform day-to-day tasks. Today's users expect network resources to respond quickly, as if network applications were running from a local hard drive. You must tailor networks to meet the needs of applications, especially delay sensitive applications such as voice and video. The Cisco IOS offers traffic prioritization features to tune responsiveness in a congested network. Routers can be configured to prioritize certain kinds of traffic based on protocol information, such as TCP port numbers. As shown in the figure, traffic prioritization ensures that packets carrying mission-critical data take precedence over less important traffic.
If the router schedules these packets for transmission on a first-come, first-served basis, users could experience an unacceptable lack of responsiveness. Therefore, an end user sending delay-sensitive voice traffic, may be forced to wait too long while the router empties its buffer of a long train of queued packets.

The Cisco IOS addresses priority and responsiveness issues through queuing. The question of priority is most important on routers that maintain a slow WAN connection and therefore experience frequent congestion. Queuing refers to the process that the router uses to schedule packets for transmission during periods of congestion. By using the queuing feature, you can configure a congested router to reorder packets so that mission-critical and delay-sensitive traffic is sent out first. These higher priority packets are sent first even if other low-priority packets arrive first. The Cisco IOS supports four methods of queuing, as described in the following sections: first-in, first out (FIFO) queuing; priority queuing; custom queuing, and weighted fair queuing (WFQ). Only one of these queuing methods can be applied per interface because each method handles traffic in a unique way.

Making the network reliable and available

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:31:34 PDT

Making the network reliable and available

A reliable and available network provides users with 24-hours-a-day, 7-days-a-week access. In a highly reliable and available network, fault tolerance and redundancy make outages and failures invisible to the end user. The high-end devices and telecommunication links that ensure this kind of performance come with a steep price tag. Network designers constantly have to balance the needs of users with the resources at hand.
When choosing between high performance and low cost at the core layer, you should opt for the best available routers and dedicated WAN links. You must design the core to be the most reliable and available layer. If a core router went down, or if a core link became unstable, routing for the entire internetwork might be adversely affected.

Core routers maintain reliability and availability by rerouting traffic in the event of a failure. Networks that can deal with failures quickly and effectively are said to be robust. To build robust networks, the Cisco IOS offers several features that enhance reliability and availability. These include support for scalable routing protocols, alternative paths, load balancing, protocol tunnels, and dial backup. The following sections describe these features.

Scalable Routing Protocols
Routers in the core of a network should converge rapidly and maintain reachability to all networks and subnetworks within an Autonomous System (AS). Simple distance-vector routing protocols, such as RIP, take too long to update and adapt to topology changes to be viable core solutions. Compatibility issues sometimes require that some areas of a network run simple distance-vector protocols such as RIP and Routing Table Maintenance Protocol (RTMP, an Apple Computer proprietary routing protocol). Whenever possible, a scalable protocol such as Open Shortest Path First (OSPF) or Enhanced Interior Gateway Routing Protocol (EIGRP) should be implemented, especially in the core layer.

Alternate Paths
Redundant links maximize network reliability and availability, but they are expensive to deploy throughout a large internetwork. Links in the core layer should always be made redundant, but other areas of a network may also need redundant telecommunication lines. If a remote site exchanges mission-critical information with the rest of the internetwork, that site would be a candidate for redundant links. To provide another dimension of reliability, an organization may even invest in redundant routers to connect to these links. A network that consists of multiple links and redundant routers will contain several paths to a given destination. If a network uses a scalable routing protocol, such as OSPF or EIGRP, its routers will maintain a map of the entire network topology. This will allow the routers to reroute traffic quickly by selecting an alternate path. In fact, EIGRP maintains a database of all alternate paths just in case the preferred route is lost.

Load Balancing
Redundant links do not necessarily remain idle until a link fails. Routers can distribute the traffic load across multiple links to the same destination. This process is called load balancing. It can be implemented using alternate paths with the same cost or metric (equal-cost load balancing), or over alternate paths with different metrics (unequal-cost load balancing). When routing IP, the Cisco IOS offers two methods of load balancing: per-packet and per-destination load balancing. If process switching is enabled, the router will alternate paths on a per-packet basis. If fast switching is enabled, only one of the alternate routes will be cached for the destination address and all packets in the packet stream bound for a specific host will take the same path. Packets bound for a different host on the same network may use an alternate route. This way, traffic is load-balanced on a per-destination basis.

Per-packet load balancing requires more CPU time than per-destination load balancing. On the plus side, per-packet load balancing allows load balancing that is proportional to the metrics of unequal paths, rather than round-robin path selection, which can help utilize bandwidth efficiently.

Tunnels
Consider an IP network with Novell NetWare running IPX at a handful of remote sites. One way to provide IPX connectivity between the remote sites is to route IPX in the core. Even if only two or three offices sparingly use NetWare, this will create additional overhead associated with routing a second routed protocol (IPX) in the core. It would also require that all routers in the data path have appropriate IOS and hardware to support IPX. For this reason, many organizations have adopted "IP only" policies at the network core because IP has become the world's dominant routed protocol.

Tunneling allows an administrator a second and more palatable option: configure a point-to-point link through the core between the two routers using IP. When this link is configured, IPX packets can be encapsulated, or packaged, inside IP packets. IPX can then traverse the core over IP links, and the core can be spared the additional burden of routing IPX. Using tunnels, administrators increase the availability of network service.

Dial Backup
Sometimes two redundant WAN links are not enough, or a single link needs to be fault-tolerant, but a full-time redundant link is too expensive. In these cases, a backup link can be configured over a dialup technology, such as ISDN, or even an ordinary analog phone line. These relatively low-bandwidth links remain idle until the primary link fails.

Dial backup can be a cost-effective insurance policy, but it is not a substitute for redundant links that can effectively double throughput by using equal-cost load balancing.

Five characteristics of a scalable network

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:30:31 PDT

Five characteristics of a scalable network

Although every large internetwork has unique features, all scalable networks have essential attributes in common. A scalable network has five key characteristics:
Reliable and available - A reliable network should be dependable and available 24 hours a day, 7 days a week. In addition, failures need to be isolated, and recovery must be invisible to the end user.

Responsive - A responsive network should provide Quality of Service (QoS) for various applications and protocols without affecting a response at the desktop. For example, the internetwork must be capable of responding to latency issues common for Systems Network Architecture (SNA) traffic but still allow for the routing of desktop traffic, such as Internetwork Packet Exchange (IPX), without compromising QoS requirements.

Efficient - Large internetworks must optimize the use of resources, especially bandwidth. Reducing the amount of overhead traffic, such as unnecessary broadcasts, service location, and routing updates, results in an increase in data throughput without increasing the cost of hardware or the need for additional WAN services.

Adaptable - An adaptable network is capable of accommodating disparate protocols, applications, and hardware technologies.

Accessible but secure - An accessible network allows for connections using dedicated, dialup, and switched services while maintaining network integrity.
The Cisco IOS offers a rich set of features that support network scalability. The remainder of this chapter outlines specific IOS features that work to promote these five key characteristics of a scalable network.

Access layer example

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:29:44 PDT

Access layer example
In the figure, routers at the access layer are deployed to permit users at Site A and remote sites Y and Z to access the network.
Access routers generally offer fewer physical interfaces than distribution and core routers. For this reason, Cisco access routers, which include the 1600, 1700, 2500, and 2600 series, feature a small, streamlined chassis that may or may not support modular interfaces.

Two 2621s have been added to the access layer of the example network at Site A. These 2621 routers have two Ethernet interfaces: one that the users' end stations will connect to via a workgroup switch or hub, and one that connects to Site A's high-speed campus backbone.

Each remote site in the example requires only one Ethernet interface for the LAN side and one serial interface for the WAN side. The WAN interface connects via Frame Relay or ISDN to the distribution router in the wiring closet of Site A. For this application, the 2610 router provides a single 10-Mbps Ethernet port and will work well at these locations. These remote sites, Y and Z, are small branch offices that must access the core through Site A. Therefore, Dist-1 A is acting as a WAN hub for the organization. As the network scales, dozens of remote sites may access the core by connection to distribution routers at the WAN hubs, Site A, Site B, and Site C.

Distribution layer example

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:28:04 PDT

Distribution layer example

The following rules will protect the core from unnecessary or unauthorized traffic. Distribution-layer routers need fewer interfaces and less switching speed than their counterparts in the core because they should handle less traffic. Nevertheless, a lightning-fast core is useless if a bottleneck at the distribution layer prevents user traffic from accessing core links. For this reason, Cisco offers robust, powerful distribution routers, such as the 4000, 4500, and, most recently, the 3600 series router. These routers are modular, so interfaces can be added and removed depending on need, although the smaller chassis of these series are much more limiting than those of the 7000, 7200, and 7500 series.
Exactly how will these distribution-layer routers bring policy to the network? You can configure them to use a combination of access lists, route summarization, distribution lists, route maps, and other rules to define how a router should deal with traffic and routing updates. Many of these techniques are covered later in this course.

The figure shows two 3620 routers have been added at Core A (in the same wiring closet as the 7507). This means that you can use high-speed LAN links to make the connections between our distribution routers and the core router. Depending on the size of the network, these links may be part of the campus backbone and will most likely be fiber running 100 or 1000 Mbps. In this example, Dist-1 and Dist-2 are part of Core A's campus backbone. Dist-1 serves remote sites, while Dist-2, serves access routers at Site A. If Site A employs VLANs throughout the campus, Dist-2 may be responsible for routing between them.

Both Dist-1 and Dist-2 use access lists to prevent unwanted traffic from reaching the core. In addition, these routers summarize their routing tables in updates to Core A, keeping Core A's routing table as small and efficient as possible.

Core layer example

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:25:59 PDT

Core layer example

As the center of the network, the core layer is designed to be fast and reliable. Access lists are avoided in the core because they add latency, or delay. Moreover, end users should not access the core directly. Consider an apple; you can not get to the seeds in an apple's core without going through the skin first. In a hierarchical network, end users' traffic should reach core routers only after those packets have passed through the distribution and access layers, where access lists may be applied.
Because core routing is done without access lists, address translation, or other packet manipulation, it may seem as though the least powerful routers would work well for so simple a task. However, the opposite is true. The most powerful Cisco routers serve the core because they have the fastest switching technologies and the largest capacity for physical interfaces.

Marketed by Cisco as enterprise core routers, the 7000, 7200, and 7500 series routers feature the fastest switching modes available. The 12000 series router is also a core router, but it is designed to meet the core routing needs of Internet service providers (ISPs). Unless your company is in the business of providing Internet access to other companies, you are not likely to see a 12000 series router in your telecommunications closet.

Unlike some routers, such as the Cisco 2500 series, the 7000, 7200, and 7500 series routers are modular, so interface modules can be added as needed. The large chassis of this series can accommodate dozens of interfaces on multiple modules for virtually any media type, which makes these routers scalable, reliable core solutions.

One way that core routers achieve reliability is through using redundant links, usually to all other core routers. When possible, these redundant links should be symmetrical (i.e., they should have equal throughput) so that equal-cost load balancing can be used. That is why core routers need a relatively large number of interfaces. Another way that core routers achieve reliability is through redundant power supplies. Core routers usually feature two or more "hot-swappable" power supplies, which may be removed and replaced individually without bringing down the router.

The figure presents a simple core topology using 7507 routers at three key sites in an enterprise. Each Cisco 7507 is directly connected to every other router by two links, which makes this configuration a full mesh. Core links should be the fastest, most reliable, and most expensive leased lines in the WAN: T1, T3, OC3, or better. If redundant T1s are used for this WAN core, each router needs four serial interfaces for two point-to-point connections to each site. Ultimately, the design requires even more than this because other routers at the distribution layer will also need to connect to the core routers. Fortunately, you can easily add interfaces to the 7507s because they are modular.

You can see that with the high-end routers and WAN links involved, the core can become a huge expense, even in a simple example such as this. Some designers will choose not to use symmetrical links in the core to reduce cost. In place of redundant lines, packet-switched and dial-on-demand technologies, such as Frame Relay and ISDN, may be used as backup links. The trade-off for saving money by using such technologies is performance. For instance, if you use ISDN BRIs as backup links, you lose the capability to do equal-cost load balancing.

The core of a network does not have to exist in the WAN. In some cases, a LAN backbone may also be considered to belong to the core layer. Campus networks, or large networks that span an office complex or adjacent buildings, might have a LAN-based core. In this case, switched Fast Ethernet and Gigabit Ethernet are the most common core technologies, and they are usually run over fiber. Enterprises switches, such as the Catalyst 4000, 5000, and 6000 series, shoulder the load in LAN cores because they switch frames at Layer 2 much faster than routers can switch packets at Layer 3. In fact, as modular devices, these switches can be equipped with route switch modules (RSMs), adding Layer 3 routing functionality to the switch chassis.

The three-layer hierarchical design model

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:24:27 PDT

The three-layer hierarchical design model

A hierarchical network design model breaks the complex problem of network design into smaller, more manageable problems. Each level, or tier, in the hierarchy addresses a different set of problems so that network hardware and software can be optimized to perform specific roles. Devices at the lowest tier of the hierarchy are designed to accept traffic into a network and then pass traffic up to the higher layers. Cisco offers a three-tiered hierarchy as the preferred approach to network design.
In the three-layer network design model, network devices and links are grouped according to three layers: core, distribution, and access. Like the Open System Interconnection (OSI) reference model, the three-layer design model is a conceptual framework, an abstract picture of a network.

Layered models are useful because they facilitate modularity. Since devices at each layer have similar and well-defined functions, administrators can easily add, replace, and remove individual pieces of the network. This kind of flexibility and adaptability makes a hierarchical network design a scalable network design.

At the same time, layered models can be difficult to comprehend because the exact composition of each layer varies from network to network. Each layer of the three-tiered design model may include a router, a switch, a link, or some combination of these. In fact, some networks may combine the function of two layers into a single device, or may omit a layer entirely.

The following sections look at each of the three layers in detail.

The Core Layer
The core of the network has one purpose: to provide an optimized and reliable transport structure by forwarding traffic at very high speeds. In other words, the core layer should switch packets as fast as possible. Devices at this layer should not be burdened with access-list checking, data encryption, address translation, or any other process that stands in the way of switching packets at top speed.

The Distribution Layer
The distribution layer sits between the access and core layers and helps differentiate the core from the rest of the network. The purpose of this layer is to provide boundary definition by using access lists and other filters to limit what gets into the core. Therefore, this layer defines policy for the network. A policy is an approach to handling certain kinds of traffic, including routing updates, route summaries, VLAN traffic, and address aggregation. You can use policies to secure networks and to preserve resources by preventing unnecessary traffic.

If a network has two or more routing protocols, such as Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP), information between the different routing domains is shared, or redistributed, at the distribution layer.

The Access Layer
The access layer feeds traffic into the network and performs network entry control. End users access the network via the access layer. As a network's "front door," the access layer employs access lists designed to prevent unauthorized users from gaining entry. The access layer can also give remote sites access to the network via a wide-area technology, such as Frame Relay, ISDN, or leased lines.

Router function in the hierarchy

Because each layer (core, distribution, and access) has a clearly defined function, each layer demands a different set of features from routers, switches, and links. Routers that operate in the same layer can be configured in a consistent way because they all must perform similar tasks. In fact, the router is the primary device that maintains logical and physical hierarchy in a network, so proper and consistent configurations are imperative. Cisco offers several router product lines, each with a particular set of features tailored for one of the three layers:
Core layer - 12000, 7500, 7200, and 7000 series routers -

Distribution layer - 4500, 4000, and 3600 series routers -

Access layer - 2600, 2500, 1700, and 1600 series routers -
The following sections revisit each layer and examine the specific routers and other devices used there.

The three-layer hierarchical design model

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:23:27 PDT

Overview of Scalable Internetworks

siti_mch@yahoo.co.id (AksaSoft) — Mon, 14 May 2007 11:19:35 PDT

Overview of Scalable Internetworks

Only a few years ago, TCP/IP networks relied on simple distance-vector routing protocols and classful, 32-bit IP addressing. These technologies offered a limited capacity for growth. Today, network designers must retool, work around, or completely abandon these early technologies to build networks that can handle rapid growth and constant change. This course explores networking technologies that have evolved to meet this demand for scalability.
In networking, scalability is the capability to grow and adapt without major redesign or reinstallation. Allowing for growth seems simple enough, but it can be difficult to do without significant and costly redesign. For example, a network may provide a small company with access to e-mail, the Internet, and shared files. What would happen if that company tripled in size and demanded streaming video or e-commerce? Would the original networking media and devices adequately serve these new applications? Organizations can ill afford to completely re-cable and redesign their networks every time workers are moved, new nodes are added, or new applications are introduced.

Good design is the key to a network's capability to scale. More often than not, it is a poor design, and not an outdated protocol or router, that prevents a network from scaling gracefully. To be scalable, a network design should follow a hierarchical model. This chapter discusses the components of the hierarchical network design model and the key characteristics of scalable internetworks.