Articles

Types of Drive Interfaces

Hard drives and optical drives are manufactured with different interfaces that are used to connect the drive to the computer. When you install a storage drive in a computer, the connection interface on the drive must be the same as the controller on the motherboard. Some common drive interfaces are as follows Integrated Drive Electronics (IDE), also called Advanced Technology Attachment (ATA), is an early drive controller interface that connects computers and hard-disk drives. An IDE interface...

Call Control and Transport Protocols

Microwave Transmission Node

Voice communication over IP is a mix of call control signals and voice conversations coded and possibly compressed into IP packets. Both reliable (connection-oriented) and so-called unreliable (connectionless) transmissions are required for voice communication. Reliable transmission guarantees sequenced, error-free, flow-controlled transmission of packets. However, because reliable transport is connection-oriented, it can delay transmission and reduce throughput. TCP provides reliable transport...

Disable IP Source Routing

On occasion, it's used for troubleshooting. However, a hacker mighi attempt to communicate with one of your hosts by inserting himself or herself as an intermediary stop between two legitimate host addresses. Figure 6-11 illustrates the scheme. Figure 6-11 A Hacker Attacking with IP Source-Routing Figure 6-11 A Hacker Attacking with IP Source-Routing The hacker. II, pretends to be an intermediary hop in a source-routed path from Host B to Host A. H creates a...

Configuring DNS Rewrite

Using the Static Command for DNS Rewrite Note Using the nat command is similar to using the static command except that DNS Rewrite is based on dynamic translation instead of a static mapping. Using the Alias Command for DNS Rewrite The alias command causes the security appliance to translate addresses on an IP network residing on any interface into addresses on another IP network connected through a different interface. The syntax for this command is as follows hostname(config) alias...

How Data Flows through the OSI Layers

Data Flow Osi Model

To get a better understanding of how the OSI layers function, it is important to know how data flows between the layers. In this section, we'll trace the data as it flows through the layers of the OSI model. As you will see in this section, each layer adds (or encapsulates) some form of header or trailer. (Layer 2, the Data Link layer, is responsible for adding a trailer.) Figure 2.2 shows the data flow from Device A to Device B. Note The example in Figure 2.2 demonstrates how end user packets...

Partitions and Calling Search Spaces

Months The Year Worksheets

A partition is a group of dialable patterns with similar accessibility. Any dialable pattern can be assigned to a partition. All phone numbers are in the null partition by default, and all devices have access to the null partition. As soon as a phone number is assigned to a different partition, the devices in the network will not be able to access that phone number without the configuration of a calling search space (CSS). A CSS defines which partitions are accessible to a particular device. A...

Modulation Techniques and How They Work

In short, the process of modulation is the varying in a signal or a tone called a carrier signal. Data is then added to this carrier signal in a process known as encoding. Imagine that you are singing a song. Words are written on a sheet of music. If you just read the words, your tone is soft and does not travel far. To convey the words to a large group, you use your vocal chords and modulation to send the words farther. While you are singing the song, you encode the written words into a...

Acronyms and Abbreviations

This element lists abbreviations, acronyms, and initialisms used in this book and in the internetworking industry. Many of these acronyms and other terms are also described in the Cisco Internetworking Terms and Acronyms resource, available at http www.cisco.com univercd cc td doc cisintwk ita . Authentication, authorization, and accounting Algebraic code-excited linear prediction Application and Content Networking System Adaptive Differential Pulse Code Modulation American National Standards...

Case Study Route Tagging

Dblink Oracle

Figure 14.17 shows a situation in which routes from several routing domains, each running a separate routing protocol, are being redistributed into a single transit domain running OSPF. On the other side of the OSPF cloud, the routes must be redistributed back into their respective domains. Route filters can be used at the egress points from the OSPF cloud into each domain to permit only the routes that belong to that domain. However, if each domain has many routes or if the routes within the...

Debugging T30 Fax Messaging

The most frequently used tool for troubleshooting fax relay problems is the IOS command debug fax relay t30 all-level-1. This command displays the T.30 messaging that is passing through the Cisco voice gateway from the perspective of the gateway's DSP. Output that is equivalent to this IOS command can be found on Cisco non-IOS gateways using the procedures discussed at the end of this section. Before using this command, you should have already determined that the Cisco voice gateways are...

Resolving Problems at the Physical or Data Link Layer

Chapter 7, Isolating a Problem at the Physical or Data Link Layer, lists several common symptoms of problems occurring at the physical or data link layer. Table 13-1 provides a summary of those symptoms for your review. Table 13-1 Common Symptoms of Physical and Data Link Layer Problems Table 13-1 Common Symptoms of Physical and Data Link Layer Problems Common Symptoms of Problems Occurring at the Physical Layer Common Symptoms of Problems Occurring at the Data Link Layer No component above the...

QoS and BGP Interaction

Logicals Leicht Kostenlos Zum Ausdrucken

This topic describes the interaction between QoS and BGP. This topic describes the interaction between QoS and BGP. When using QPPB, the QoS feature works independently from BGP routing. BGP is only used to propagate the QoS policy. In QBBP configurations, you specify whether to use IP precedence or the QoS group ID obtained from the source (input) address or destination (output) address entry in the route table. You can specify either the input or output address. This topic describes CEF...

Interaction Between OSI Layers

Imagine a Web browser displaying a Web page that it received from a Web server. Before that happened, the browser somehow interacted with the software implementing other layers of TCP IP on the client computer, causing a request to flow to the server. Likewise, the broswer application somehow communicated with the Web server application, telling the server what Web page the browser wanted to display. A fancy way to describe these two ideas that is interaction between OSI layers. The process of...

MGCP Configuration Server

When you are using the Configuration Server feature, the gateway- and interface-specific MGCP configuration commands are provided by CUCM in the form of an Extensible Markup Language (XML) configuration file that is downloaded by the Cisco IOS gateway from the CUCM TFTP server. This is the recommended approach to integrate Cisco IOS MGCP gateways with CUCM. The Cisco IOS gateway dynamically loads the necessary MGCP configuration commands from the XML file downloaded from the TFTP server. When...

Example 952 show isdn status Command Output

Global ISDN Switchtype basic-ni ISDN BRIO interface dsl 0, interface ISDN Switchtype basic-ni Layer 1 Status TEI 70, Ces 1, SAPI 0, State MULTIPLE_FRAME_ESTABLISHED TEI 71, Ces 2, SAPI 0, State MULTIPLE_FRAME_ESTABLISHED Spid Status spidl configured, spid1 sent, spid1 valid Endpoint ID Info epsf 0, usid 2, tid 1 TEI 71, ces 2, state 5(init) spid2 configured, spid2 sent, spid2 valid Endpoint ID Info epsf 0, usid 4, tid 1 Layer 3 Status 0 Active Layer 3 Call(s) Activated dsl 0 CCBs 0 The Free...

Configuring Analog Voice Ports

Leverlink Series Belt Tensioners

The three types of analog ports that you will learn to configure are In North America, the FXS port connection functions with default settings most of the time. The same cannot be said for other countries and continents. Remember, FXS ports look like switches to the edge devices that are connected to them. Therefore, the configuration of the FXS port should emulate the switch configuration of the local PSTN. For example, consider an international company that has offices in the United States...

Link State and Advanced Distance Vector Protocols

In addition to distance vector-based routing, the second basic algorithm used for routing is the link-state algorithm. Link-state protocols build routing tables based on a topology database. This database is built from link-state packets that are passed between all the routers to describe the state of a network. The shortest path first algorithm uses the database to build the routing table. Figure 3-26 shows the components of a link-state protocol. Understanding the operation of link-state...

Different Types of Switch Ports

com Access Ports belong to and carry the traffic of only one VLAN Trunk Ports carry the traffic of multiple VLANs and by default is a member of all VLANs in the VLAN database. Both ISL and 802.1Q trunk ports are supported Tunnel Ports designed for service providers who carry traffic of multiple customers across their networks and are required to maintain the VLAN and Layer 2 protocol configurations of each customer without impacting the traffic of other customers. Both 802.1Q tunneling and...

Load Balancing with OSPF

Calculate Cost Ofospf

Load balancing is a standard functionality of Cisco IOS Software that is available across all router platforms. It is inherent to the forwarding process in the router, and it enables a router to use multiple paths to a destination when it forwards packets. The number of paths used is limited by the number of entries that the routing protocol puts in the routing table. Four entries is the default in Cisco IOS Software for IP routing protocols except for BGP. BGP has a default of one entry. The...

Advertising BGP Routes to Neighbors

The previous section focused on the tools that BGP can use to inject routes into a local router's BGP table. BGP routers take routes from the local BGP table and advertise a subset of those routes to their BGP neighbors. This section continues focusing on the BGP table because the BGP route advertisement process takes routes from the BGP table and sends them to neighboring routers, where the routes are added to the neighbors' BGP tables. Later, the final major section in the chapter, Building...

Well Known Multicast Addresses

IANA controls the assignment of IP multicast addresses. To preserve multicast addresses, IANA is reluctant to assign individual IP multicast addresses to new applications without a good technical justification. However, IANA has assigned individual IP multicast addresses to popular network protocols. IANA has assigned several ranges of multicast IP addresses for specific types of reasons. Those types are as follows KEY Permanent multicast groups, in the range 224.0.0.0-224.0.1.255 POINT...

TCP and UDP Reactions to Packet Loss

UDP and TCP behave very differently when packets are lost. UDP, by itself, does not react to packet loss, because UDP does not include any mechanism with which to know whether a packet was lost. TCP senders, however, slow down the rate at which they send after recognizing that a packet was lost. Unlike UDP, TCP includes a field in the TCP header to number each TCP segment (sequence number), and another field used by the receiver to confirm receipt of the packets (acknowledgment number). When a...

IP Phone Auto Registration

Auto Registration Cucm

Auto registration allows CUCM to issue extension numbers to new IP phones, which is similar to the way in which the DHCP server issues IP addresses. With auto registration configured and enabled, when a new IP phone boots and attempts to register with CUCM for the first time, CUCM issues an extension number from a configured range. After CUCM issues the extension, it adds the phone to its configuration database with the used device ID (MAC address) and the assigned extension. If a specific...

External Phone Number Mask

Cisco External Mask Number Getting Spam

The external phone number mask is a DN configuration attribute. The external phone number mask of the first DN of the phone is also used for the following functions Change the display of the main phone number at the top of the LCD screen. A DN of 15001 with an external phone number mask of 21255XXXXX would result in a displayed phone number of 212 551-5001. Any user on the phone can instantly identify the PSTN direct inward-dialing number by viewing the LCD of the phone. Automated alternate...

CUCM Digit Prefix and Stripping

The Digit Prefix feature prepends digits to a number. Any phone keypad digits from 0 to 9, and the * and digits, can be prepended to the calling or called numbers. The Digit Prefix feature can be applied to a calling-party or a called-party number and configured under the corresponding transformation setting in the route-pattern, route-list, or translation-pattern configuration. Figure 12-6 displays the calling- and called-party prefix configuration available at the route-pattern, route-list,...

Distribution Layer Functionality

This section describes distribution layer functions and the interaction of the distribution layer with the core and access layers. The distribution layer represents both a separation between the access and core layers and a connection point between the diverse access sites and the core layer. The distribution layer determines department or workgroup access and provides policy-based connectivity. Following are the characteristics of the distribution layer Distribution layer devices control...

Configuring H323 Gateways

Options for setting up an H.323 gateway include the following Enable H.323 VoIP call services (required) Configure an interface as an H.323 gateway interface (required) Configure codecs (optional) Configure Dual Tone Multifrequency (DTMF) and fax relay (optional) Adjust H.225 settings (optional) Depending on the deployment scenario, you might be configuring only the required features or many of the options available for an H.323 voice gateway. Figure 5-12 offers a sample topology that needs to...

Modified Deficit Round Robin

MDRR is a queuing feature implemented only in the Cisco 12000 series router family. Because the 12000 series does not support CBWFQ and LLQ, MDRR serves in place of these features. Its main claims to fame are better fairness than legacy queuing methods such as priority queuing and custom queuing, and that it supports a priority queue (like LLQ). For the CCIE Routing and Switching qualifying exam, you need to understand how MDRR works at the conceptual level, but you don't need to know how to...

Worksheet 8103 Answer Broadband Questions

Which types of signals are carried over a DSL cable Voice and data 2. What is the typical upload speed of a satellite broadband connection 50 Kbps to 1 Mbps 3. Which type of broadband technology is referred to as CATV Cable TV 4. Which cable type is used by a CATV broadband connection RG-59 Coaxial cable 5. ISDN uses existing telephone copper wires to send and receive which types of signals Voice, video, data 6. Which technology is usually an alternative when cable or DSL is not available...

Network Design Methodology

Network Methodology

The network design methodology presented in this section is derived from the Cisco Prepare, Plan, Design, Implement, Operate, and Optimize (PPDIOO) methodology, which reflects a network's lifecycle. The following sections describe the PPDIOO phases and their relation to the network design methodology, and the benefits of the lifecycle approach to network design. Subsequent sections explain the design methodology in detail. Design as an Integral Part of the PPDIOO Methodology The PPDIOO network...

Case Study ACMC Hospital IP Addressing Design

Cisco Hospital Network Design

This case study is a continuation of the ACMC Hospital case study introduced in Chapter 2, Applying a Methodology to Network Design. Use the scenarios, information, and parameters provided at each task of the ongoing case study. If you encounter ambiguities, make reasonable assumptions and proceed. For all tasks, use the initial customer scenario and build on the solutions provided thus far. You can use any and all documentation, books, white papers, and so on. In each step, you act as a...

Identify the Names Purposes and Characteristics of Motherboards

The motherboard is the main printed circuit board. It contains the buses, or electrical pathways, found in a computer. These buses allow data to travel between the various components that comprise a computer. A motherboard is also known as the system board, backplane, or main board. Figure 1-4 shows a variety of motherboards. The motherboard accommodates the central processing unit (CPU), RAM, expansion slots, heat sink fan assembly, BIOS chip, chip set, and the embedded wires that interconnect...

Mesh Versus Hierarchical Mesh Topologies

Partial And Full Mesh Topology

Network designers often recommend a mesh topology to meet availability requirements. In a full-mesh topology, every router or switch is connected to every other router or switch. A full-mesh network provides complete redundancy, and offers good performance because there is just a single-link delay between any two sites. A partial-mesh network has fewer connections. To reach another router or switch in a partial-mesh network might require traversing intermediate links, as shown in Figure 5-3....

H323 Endpoint Support

H.323 phones support multiple lines and can be audio, video, or data networking endpoints. H.323 terminals are synonymous with endpoints. The H.323 terminal language is used in the H.323 standard. CUCM supports voice calls from H.323 terminals natively. CUCM can also integrate with H.323 video endpoints using an H.323 gatekeeper. Cisco Unified Communications IP Telephony, Part 2 explains the H.323 video integration in further detail. H.323 phones do not register with CUCM. H.323 devices are...

Atomic Aggregate and Aggregator Attributes

The Atomic Aggregate attribute informs BGP peers that the local router is using a less specific (aggregated) route to a destination. If a BGP speaker selects a less specific route, when a more specific route is available, it must attach the Atomic Aggregate attribute when propagating the route. The Atomic Aggregate attribute lets the BGP peers know that the BGP speaker used an aggregated route. When you use the Atomic Aggregate attribute, the BGP speaker has the option to send the Aggregator...

DHCP Starvation Attacks

As the name implies, a DHCP starvation attack is where a DHCP server is sent so many DHCP requests that eventually there are no more IP addresses available to allocate to legitimate devices, hence rendering the network unusable. A DHCP starvation attack works by broadcasting DHCP requests with spoofed MAC addresses. As you have seen, there are many tools available on the Internet to send out these sorts of frames. The end result may involve the attacker installing their own DHCP server and...

Cisco Unity Express Configuration

Unity Cisco Cli

This section examines the configuration needed for Cisco Unity Express to communicate with Cisco Unified CME. This includes the final Cisco Unity Express CLI configurations and the Cisco Unity Express web initialization. The CME CLI configurations needed for interoperability between Cisco Unified CME and Cisco Unity Express are also discussed. Cisco Unity Express Post-Installation Configuration After an installation or upgrade of Cisco Unity Express software, the system will run the...

CUCM Initial Configuration

After you install CUCM, some initial configuration has to be done before starting to deploy endpoints. This initial configuration includes the items in Table 5-1. Table 5-1 Publisher Server Required Services Table 5-1 Publisher Server Required Services Basic network settings have already been configured during installation, but some of them should be revisited (use of external NTP and DNS servers), and network settings that are not configurable during installation (for example, enabling DHCP...

The show ip eigrp topology Command

This command shows the topology table. It allows for the analysis of DUAL. It will show whether the successor or the route is in an active or passive state. The syntax is as follows show ip eigrp topology autonomous-system-number ip-address mask Example 7-3 shows the output of this command. Example 7-3 show ip eigrp topology Output IP-EIGRP Topology Table for process 100 Codes P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - Reply status P 140.100.56.0 255.255.255.0, 2 successors,...

Best Practices for Hierarchical Layers

Spans And Layers Best Practices

Each layer of the hierarchical architecture contains special considerations. The following sections describe best practices for each of the three layers of the hierarchical architecture access, distribution, and core. When designing the building access layer, you must take into consideration the number of users or ports required to size up the LAN switch. Connectivity speed for each host should be considered. Hosts might be connected using various technologies such as Fast Ethernet, Gigabit...

IP Virtual Reassembly

A buffer overflow attack can occur when an attacker continuously sends a large number of incomplete IP fragments, causing the firewall to lose time and memory while trying to reassemble the fake packets. IP virtual reassembly is an interface feature that when turned on, will automatically reassemble fragmented packets coming into the router through that interface. Cisco recommends that you enable ip virtual-assembly on all interfaces where traffic comes into the router. To enable virtual...

Load Balancing with EIGRP

Typically, networks are configured with multiple paths to a remote network. When these paths are equal or nearly equal, it makes sense to utilize all the available paths. Unlike Layer 2 forwarding, Layer 3 forwarding has the capability to load-balance between multiple paths. That is, the router can send frames out multiple interfaces to reduce the amount of traffic sent to a single network connection. The key to this feature is that the network paths must be of equal cost (or nearly equal for...

Hardening Cisco IP Phones

The IP phone is a target for attacks, just like all other components of the network. IP phone endpoints should be protected in a similar manner to servers in the environment. IP phones have default settings that make them vulnerable to attacks. There are several options available to harden IP phones and thus protect them against various attacks and infiltration methods. The product-specific configuration parameters of Cisco IP Phones are set by default to achieve the greatest functionality but...

Understanding the PSTN

Pstn Connections

All the signaling standards and communication methods discussed in the previous section typically focus around the connection to one, massive voice network known as the public switched telephone network (PSTN). If you have ever made a call from a home telephone, you have experienced the results of the traditional telephony network. This network is not unlike many of the data networks of today. Its primary purpose is to establish worldwide pathways allowing people to easily connect, converse,...

Link State Versus Distance Vector Routing Protocols

This section describes the two most common and relevant routing protocols that TCP IP has available for use, namely RIP and OSPF. Controversy surrounds the debate over link-state versus distance vector routing algorithms regarding which is better. NOTE Link-State and distance vector routing protocols are also known as interior gateway protocols (IGPs) this concept is discussed later in the discussion of OSPF and border gateway protocol (BGP) interoperability. Chapter 7, Summarization, discusses...

Rstp Bpdu Flag Byte

Rstp Stages

Topology Change ACK Agreement Forwarding Learning f 00 Unknown _ 01 Alternative Backup 10 Root RSTP (802.1w) uses type 2, version 2 BPDUs, so an RSTP bridge can communicate with 802.1D on any shared link or with any switch running 802.1D. RSTP sends BPDUs and populates the flag byte in a slightly different manner than the manner used by 802.1D. An RSTP bridge sends a BPDU with its current information every hellotime period (2 seconds by default), even if it does not receive any BPDUs from the...

DeJitter Buffer Delay

De-jitter buffer delay is the third voice delay component. Jitter happens in data networks. You can control it, and minimize it for jitter-sensitive traffic, but you cannot eliminate it. Buy why talk about jitter in the section on delay Because a key tool in defeating the effects of jitter, the de-jitter buffer (sometimes called the jitter buffer) actually increases delay. The de-jitter buffer collects voice packets and delays playing out the voice to the listener, to have several ms of voice...

Tail Drop Global Synchronization and TCP Starvation

Global Synchronization Graph Example

Tail drop occurs when a packet needs to be added to a queue, but the queue is full. Yes, tail drop is indeed that simple. However, tail drop results in some interesting behavior in real networks, particularly when most traffic is TCP based, but with some UDP traffic. Of course, the Internet today delivers mostly TCP traffic, because web traffic uses HTTP, and HTTP uses TCP. The preceding section described the behavior of a single TCP connection after a single packet loss. Now imagine an...

Determining Your Events per Second

Although the numbers presented in Table 3-3 might not be realistic in your network, they do give you an idea of which types of devices tend to send the most events. The noisiest devices on your network are likely in this order 3 Intrusion detection systems intrusion prevention systems (IDS IPS) 4 Virtual Private Network (VPN) devices 7 Other devices, such as databases, operating systems, antivirus software, desktop and server protection software (such as Cisco Security Agent), and so on This...

Threats to and Attacks on Routers

Information theft Examples of attack techniques IP fragmentation attacks for DoS Some general threats to routers include (but are not limited to) unauthorized access, session hijacking, rerouting, masquerading, DoS, eavesdropping, and information theft. Unauthorized access may occur when one of the following occurs Session hijacking may occur if an attacker can insert falsified IP packets after session establishment via IP spoofing, sequence number prediction and alteration, or other methods....

Install a CPU and a Heat Sink Fan Assembly

Heat Sink Assembly Motherboard

The central processing unit (CPU) and the heat sink fan assembly may be installed on the motherboard before the motherboard is placed in the computer case. Figure 3-2 shows a close-up view of the CPU and the motherboard. The CPU and motherboard are sensitive to electrostatic discharge. When handling a CPU and motherboard, make sure that you place them on a grounded antistatic mat. You should wear an antistatic wrist strap while working with these components. When handling a CPU, do not touch...

Configuring Device Pools

This topic describes device pool configuration. (.'it -I' j clbr iri- -c- jc Lev cc Us - ppl zitb -cf in I i-jui IT f t*ty fafidirM (.'it -I' j clbr iri- -c- jc Lev cc Us - ppl zitb -cf in I i-jui IT f t*ty fafidirM UeviLf Kuul Ari uriu fU iriKiriLiers-* C Fv I J < I I clz'r- P e De-.-Devin- - Pnal Settings L'JV Jt -LlI .ct 1 C zee CalMircq 'C I H I-.-' I --H 1 -I I . J Fi- j I nT Ss-t ec Tcr pl c i iolh.i.il.'1 ni ii_. HH *i j h h fir ill i -i-j l i Hi i ri M-m -in .r-.- . ri. 111 . '.l'.' '...

Network and Feature Services

Simple Budgeting Templates For Household

A CUCM cluster can consist of up to 20 servers. Each server can fulfill different tasks, such as running a TFTP or DHCP server, being the database publisher, processing calls, providing media resources, and so on. Depending on the usage of a server, different services have to be activated on the system. There are two types of services on CUCM servers Network services Network services are automatically activated and are required for the operation of the server. Network services cannot be...

Identify Common Problems and Solutions

Computer problems can be attributed to hardware, software, networks, or some combination of the three. You will resolve some types of computer problems more often than others. A stop error is a hardware or software malfunction that causes the system to lock up. This type of error is known as the blue screen of death (BSoD) and appears when the system is unable to recover from an error. The BSoD is usually caused by device driver errors. The Event Log and other diagnostic utilities are available...

Clock Rates DCE and DTE

When a network engineer needs to add a point-to-point leased line between two routers, he contacts a service provider and orders the circuit. As part of that process, the customer specifies how fast the circuit should run, in kilobits per second (kbps). While the circuit is being set up by the telco, the engineer purchases two CSU DSUs, installs one at each site, and configures each CSU DSU. He also cables each router to the respective CSU DSU using the cables shown in the previous section....

Documenting Traffic Flow on the Existing Network

Documenting traffic flow involves identifying and characterizing individual traffic flows between traffic sources and stores. Traffic flows have recently become a hot topic for discussion in the Internet community. A lot of progress is being made on defining flows, measuring flow behavior, and allowing an end station to specify performance requirements for flows. To understand traffic flow behavior better, you can read Request For Comments (RFC) 2722, Traffic Flow Measurement Architecture. RFC...

CUCM Transformation Masks

Dialing transformations allow the call-routing component to modify either the calling (initiator) or called (destination) digits of a call. Transformations that modify the calling number (automatic number identification, ANI) are calling-party transformations transformations that modify the dialed digits (dialed number identification system, DNIS) are called-party transformations. Transformation masks use mask operations that allow the suppression of leading digits, the modification or...

Configuring Active Standby Failover on the Cisco ASA

Anti Nmda Receptor Encephalitis

Maintaining appropriate redundancy mechanisms within infrastructure devices is extremely important for any organization. The Cisco ASA supports active-active and active-standby failover. NOTE When the active unit fails, it changes to the standby state while the standby unit changes to the active state. The unit that becomes active takes ownership of the IP addresses and MAC addresses of the failed unit. The unit that is now in standby state takes over the standby IP addresses and MAC addresses....

Identifying the Scope of a Network Design Project

One of the first steps in starting a network design project is to determine its scope. Some of the most common network design projects these days are small in scope for example, projects to allow a few people in a sales office to access the enterprise network via a VPN. On the other hand, some design projects are large in scope. Ask your customer to help you understand if the design is for a single network segment, a set of LANs, a set of WAN or remote-access networks, or the entire enterprise...

Hierarchical IP Address Design and Summarization

A hierarchical IP address design means that addresses are assigned in a hierarchical manner, rather than randomly. The telephone network provides a good analogy. This network is divided into countries, which in turn are divided into areas and local exchanges. Phone numbers are assigned based on location. For example, in North America, 10-digit phone numbers represent a 3-digit area code, a 3-digit central office code, and a 4-digit line number. So if you are in Europe and you want to call...

Peerto Peer Communication

Desktop Protocol Stack

For data to travel from the source to the destination, each layer of the OSI reference model at the source must communicate with its peer layer at the destination. This form of communication is referred to as peer-to-peer communication. During this process, the protocols at each layer exchange information, called protocol data units (PDU), between peer layers, as shown in Figure 1-23. Data packets on a network originate at a source and then travel to a destination. Each layer depends on the...

Voice Mail Integration

Planar Fitting

CUCM can integrate with Cisco Unity via either Skinny Client Control Protocol (SCCP) or Session Initiation Protocol (SIP). Cisco Unity telephony integrations are configured with the Cisco Unity Telephony Integration Manager (UTIM). In addition to the option of adding multiple clusters by adding additional integrations for each new CUCM cluster in Cisco Unity, CUCM supports Annex M.1, Message Tunneling for Q Signaling (Q.SIG), which allows administrators to enable Q.SIG on intercluster trunks...

Neighbor Unreachability Detection

If a node to which another is communicating fails, it is not very beneficial to detect the failure before the upper layers do. If a router in the path to the destination fails, however, there may be an alternative router to use, and it would be extremely helpful to be able to detect that failure before the upper-layer protocol does. Neighbor reachability is verified in one of two ways from hints from the upper-layer protocols or from responses to Neighbor Solicitations. Forward-direction...

The Eigrp Packet Header

Packet Format

Figure 8.28 shows the EIGRP header, which begins every EIGRP packet. Figure 8.28. The EIGRP packet header. Figure 8.28. The EIGRP packet header. Version specifies the particular version of the originating EIGRP process. Although two software releases of EIGRP are currently available, 11 the version of the EIGRP process itself has not changed since its release. 11 Because of the improvements to its stability beginning with IOS 10.3(11), 11.0(8), and 11.1(3) use of the later version of EIGRP is...

The show isis database Command

The show isis database command shows the LSPs held in the local database. The LSP ID shows the system ID of the generating router and whether this LSP is from a router or a pseudonode. The last octet shows whether the LSP was too large to fit into one PDU a nonzero value in this field indicates that this is a fragment of an LSP. The number states the fragment number. Because IS-IS is a link-state protocol, the database should be identical on every router of the same level within the area. The...

T38 Fax Relay and Modem Passthrough Configuration for MGCP

A common scenario for handling regular faxes along with modems or SG3 fax devices at the same time is to use a fax relay protocol for the fax traffic and modem passthrough for the modem or SG3 fax traffic. Although this scenario can be configured for the H.323, SIP, MGCP, or SCCP voice signaling protocols using T.38 or Cisco fax relay, Example 10-5 shows how this scenario is configured specifically for an MGCP voice gateway running NSE-based T.38 fax relay and modem passthrough. Example 10-5...

Automated alternate routing AAR

Automated alternate routing (AAR) provides a mechanism to reroute calls through the PSTN or other network by using an alternate number. Cisco CallManager automatically reroutes calls through the PSTN or other networks when Cisco CallManager blocks a call due to insufficient location bandwidth. With automated alternate routing, the caller does not need to hang up and redial the called party. When a call is made from the device of one location to the device of another location, location bandwidth...

SMTP Commands and Sample Sessions

The easiest way to grasp how SMTP works is to look at a basic SMTP session. Example 6-1 details how a simple e-mail is transmitted between two mail devices using SMTP. 220 smtp-outbound.cisco.com ESMTP Sendmail 8.12.10 8.12.6 Fri, 20 Oct 2006 250 smtp-outbound.cisco.com Hello 192.168.1.1 , pleased to meet you MAIL FROM < testuser cisco.com> 250 2.1.0 testuser cisco.com Sender ok RCPT TO < myfriend example.com> 250 2.1.5 myfriend example.com Recipient ok 354 Enter mail, end with . on a...

SIP Third Party IP Phone Support in CUCM

CUCM supports RFC 3261-compliant third-party SIP phones. Support for third-party SIP phone features varies greatly from Cisco SIP IP Phone features. Third-party phones have only RFC 3261 SIP Version 2 support, whereas Cisco SIP Phones have many Cisco SCCP features that have been rewritten to work in a native SIP protocol stack. Two different types of third-party SIP phones can be added to CUCM. Third-party SIP phones may be added as basic or advanced phones. Third-party SIP basic phones support...

BIOS and the BIOS Setup Program

The BIOS setup program is stored in the system ROM chip. It varies greatly from computer to computer. Today's BIOS setup programs include many options. To organize them, they are often grouped together. Most BIOS setup programs are menu based, including standard CMOS setup, advanced chipset setup, power management, PCI configuration, and peripheral configuration. The standard CMOS setup includes the information for the date, time, floppy drives, hard drives, keyboard, and video card. The...

E1 vs E2 external routes

External routes fall under two categories, external type 1 and external type 2. The difference between the two is in the way the cost (metric) of the route is being calculated. The cost of a type 2 route is always the external cost, irrespective of the interior cost to reach that route. A type 1 cost is the addition of the external cost and the internal cost used to reach that route. A type 2 route is always preferred over a type 1 route for the same destination. This is illustrated in the...

Default Routes and the ip classless Command

When a router needs to route a packet and there is no route matching that packet's destination in the routing table, the router discards the packet. Default routing lets the router forward the packet to some default next-hop router. Default routing is that simple However, two configuration options for default routing make it a little tricky. Also one other option changes the algorithm of how the router decides whether there is a routing table match, which affects when the default route is used....

Commands to Influence OSPF Routing Decisions

You can control routing updates within OSPF in multiple ways. Recall that OSPF calculates a cost to a destination based on a formula involving bandwidth. To influence route decisions, you can either change the bandwidth on the interface, which in turn will affect the cost of the link, or directly change the cost of the interface. OSPF also supports the direct changing of the administrative distance with the distance command, much like EIGRP. OSPF also uses the passive interface command to...

Multihoming the Internet Connection

The generic meaning of multihoming is to provide more than one connection for a system to access and offer network services. The term multihoming is used in many specific ways also. A server, for example, is said to be multihomed if it has more than one network layer address. Content delivery networks can multihome application layer data and services. The term multihoming is increasingly being used to refer to the practice of providing an enterprise network more than one entry into the...

WAN Transport Technologies

Dual Sonet Rings Atm Switching

Table 5-1 compares various WAN technologies, based on the main factors that influence technology selection. This table provides typical baseline characteristics to help you compare the performance and features offered by different technologies. Often, the offerings of the service provider limit your technology decisions. NOTE Some WAN technology characteristics differ between service providers Table 5-1 is meant to illustrate typical characteristics. Table 5-1 WAN Transport Technology...

Characterizing Types of Traffic Flow for New Network Applications

As mentioned, a network flow can be characterized by its direction and symmetry. Direction specifies whether data travels in both directions or in just one direction. Direction also specifies the path that a flow takes as it travels from source to destination through an internetwork. Symmetry describes whether the flow tends to have higher performance or QoS requirements in one direction than the other direction. Many network applications have different requirements in each direction. Some data...

The aaa authentication enable default command

After enabling AAA globally on the access server, you need to define the authentication method lists and apply them to lines and interfaces. These authentication method lists are security profiles that indicate the service, PPP, dotlx, or login and authentication method. Up to four authentication methods (local, group TACACS+, group RADIUS, line, or enable authentication) may be applied to a line or interface. A good security practice is to have either local or enable authentication as the...

Comparison of IGMPv1 IGMPv2 and IGMPv3

Table 16-5 compares the important features of IGMPvl, IGMPv2, and IGMPv3. First Octet Value for the Query Message Destination Address for the General Query Joining multicast group address and source address Is Report Suppression Mechanism Available Can Maximum Response Time Be Configured Can a Host Send a Leave Group Message Destination Address for the Leave Group Message Can a Router Send a Group-Specific Query Can a Host Send Source-and Group-Specific Reports Can a Router Send Source- and...

Guidelines for Creating an Enterprise Network

When creating an Enterprise network, divide the network into appropriate areas, where the Enterprise Campus includes all devices and connections within the main Campus location the Enterprise Edge covers all communications with remote locations and the Internet from the perspective of the Enterprise Campus and the remote modules include the remote branches, teleworkers, and the remote data center. Define clear boundaries between each of the areas. NOTE Depending on the network, an enterprise...

Figure 35 Overlap of Multicast MAC Addresses

224.1.1.1 224,129.1.1 225.1.1,1 225,129.1,1 238.1,1.1 238.129.1.1 239.1,1.1 239.129.1.1 An Ethernet multicast MAC address has some overlap the same MAC address is assigned to 32 different multicast groups. If one user on an Ethernet segment subscribes to multicast group 225.1.1.1, and a nother user subscribe s to 225 .w29. 1.1, both users receive b ooh multicast streams. I n en gineering multicast networks on LAN segments, this overlap needs to be specifically watched for and engineered to...

Private Line Automatic Ringdown

Private line automatic ringdown (PLAR) is used when a phone should dial a predefined number as soon as the phone goes off-hook. PLAR is typically used with button-free security phones in elevators and stairways. Implement PLAR in CUCM by following these steps Step 1 Configure a translation pattern where the pattern is empty (null string pattern), and put it into a partition. Step 2 Configure the number to be dialed by the PLAR-enabled phone in the called-party transformation mask of the...

Transformation Examples

Multiple transformations might take place when placing a phone call. Using external phone number masks instructs the call-routing component to use the external phone number of a calling station rather than its DN for caller ID information. The external phone number mask is applied on an individual line basis through the Directory Number Configuration screen on the device. The route pattern matched for an outgoing call can apply another set of calling-party transformations before extending the...

The Layer 2 Roaming Process

As previously discussed, Layer 2 roaming happens when a user moves to another AP but stays on the same VLAN and the same IP subnet. As far as the user is concerned, nothing special has happened. The client isn't notified that he is roaming. He also keeps his IP address, and all active transmissions stay active. This process is handled within a single controller. This process is called intracontroller roaming and takes less than 10 ms. Behind the scenes, the client, when roaming to a new AP,...

The Pros and Cons of a Dedicated Management Network

Carrying management traffic out of band can quickly result in building a fairly sophisticated network that is dedicated just to network management. This network can exist in addition and in parallel to the network that you are trying to manage a dedicated network that allows your management systems to communicate with the network elements that they are managing. However, using out-of-band management communications does not necessarily imply the use of a dedicated management network that is...

Using a Top Down Network Design Methodology

The world we've made as a result of the level of thinking we have done thus far creates problems that we cannot solve at the same level at which we created them. To paraphrase Einstein, networking professionals have the ability to create networks that are so complex that when problems arise they can't be solved using the same sort of thinking that was used to create the networks. Add to this the fact that each upgrade, patch, and modification to a network can also be created using complex and...

The Class Selector PHB and DSCP Values

Classs Selector And Dscp Values

RFC 2475, which defines DiffServ, became an RFC in December 1998. Even today, some QoS features in IOS do not support DiffServ Some QoS features will never support DiffServ, because newer, better tools that can do the same thing may have been introduced. All tools that support Cisco's strategic direction for QoS configuration, using the Modular QoS command-line interface (MQC), support DSCP. However, depending on the tools you need to use, and the IOS revisions you use in your network, you may...

Cisco IP Phones Boot Sequence

The Cisco IP Phone has a standard startup process consisting of several steps. The steps are illustrated in Figure 7-2 and outlined as follows Step 1 PoE The Cisco IP Phone obtains power from the switch. The switch continuously sends a small voltage on the transmit pins. The voltage sent by the switch is then looped back in hardware from the IP phone back to the switch's receiving pins. The switch has now detected an in-line power-requiring device, and the Cisco switch generates the port's...

Protecting Cisco IOS from Intrusion

Now that you have a snapshot of modern security concerns, this section looks at Cisco IOS and the configuration commands you can use to deny intruders the ability to harm valuable network resources that are typically connected behind a Cisco router. In particular, this section covers how you can stop DoS attacks. Figure 8-2 displays a typical network scenario. You see how to configure the router, separating the public and private networks so that the private network is not vulnerable. Figure...

Enterprise Campus Modules

Enterprise Campus Network Design

This section introduces the Enterprise Campus functional area and describes the purpose of each module therein. It also discusses connections with other modules. An enterprise campus site is a large site that is often the corporate headquarters or a major office. Regional offices, SOHOs, and mobile workers might have to connect to the central campus for data and information. As illustrated in Figure 3-11, the Enterprise Campus functional area includes the Campus Infrastructure module and,...

CCIE Security Lab Exam FAQs

Hmmwv Gmv Parts

The following are some frequently asked questions about the difficult 1-day CCIE Security lab exam. 1. When did the lab format change from 2 days to 1 day October 2001. All CCIE certification labs worldwide now test candidates in the 1-day format. 2. Where can I take the CCIE Security lab exam Locations where you can take the CCIE Security lab exam follow Research Triangle Park (RTP), North Carolina, USA You can find more information at scheduling_lab_exam.html. 3. What is the maximum score and...

Media Resource Support

Put Call Hold Cucm Cube Call Flow

CUCM offers software-based media resources. Start the IP Voice Media Streaming application to activate the following The following media resources are available only in hardware Audio conferencing and MTP media resources can also be offered by hardware media resources. MoH is a special case. Because of the potential WAN bandwidth utilization of MoH, the multicast streams of the server are normally scoped at the headquarters. Survivable Remote Site Telephony (SRST) can stream one media resource...

The Hybrid Fiber Coaxial HFC Network

Hfc Node Fiber Tail

The first networks to include a fiber node-type technology were built beginning in 1990. CATV networks today are built exclusively using HFC design and older networks are being retrofitted to receive the benefits of HFC. As a result, most CATV networks today are based on fiber node-based architecture, but they also include elements of the older coaxial networks. The HFC network design helps reduce many of the amplification and attenuation issues and other issues associated with all coaxial...

Neighbor Stuck in Init STATE

The init state indicates that a router sees Hello packets from the neighbor, but two-way communication has not been established. A Cisco router includes the router IDs of all neighbors in the init (or higher) state in the neighbor field of its Hello packets. Example 3-15 shows sample output of the show ip ospf neighbor command. Example 3-15 Output from the show ip ospf neighbor Command For two-way communication to be established with a neighbor, a router must also see its own router ID in the...

Identify the Names Purposes and Characteristics of Input Devices

An input device is used to enter data or instructions into a computer. Here are some examples of input devices Digital camera and digital video camera Biometric authentication device The mouse and keyboard are the two most commonly used input devices. The mouse is used to navigate the graphical user interface (GUI). The keyboard is used to enter text commands that control the computer. Digital cameras and digital video cameras, shown in Figure 1-20, create images that can be stored on magnetic...

CUCM Installation and Upgrade Overview

Cucm Upgrade Process

CUCM can be upgraded from the various previous releases of Windows Server-based CUCM or appliance-based CUCM. Cisco CallManager Releases 3x and earlier for Windows Server have to be upgraded to Release 4.1(3) or later before upgrade to 6.0(1) is possible. Appliance-based CUCM releases earlier than 5.1(1) have to be upgraded to Release 5.1(1) before upgrade to 6.0(1) is possible. Figure 3-1 displays the various upgrade path options available for CUCM 6.0(1). Figure 3-1 CUCM Upgrade Paths Windows...

Configuring AAA Authorization

You can restrict the type of operation users can perform or the network resources they can access by using the AAA authorization service. After AAA authorization is enabled and configured, user profiles are stored on the local database or in a remote security server. From information in these profiles, users' sessions are configured after they have been authenticated. AAA supports five different methods of authorization TACACS+ User profile information is stored on a remote security server that...

Port Fast Uplink Fast and Backbone Fast

Uplinkfast

The Cisco-proprietary PortFast, UplinkFast, and BackboneFast features each solve specific STP problems. Table 3-5 summarizes when each is most useful, and the short version of how they improve convergence time. Table 3-5 PortFast, UplinkFast, and BackboneFast Used on access ports that are not connected to other switches or hubs Immediately puts the port into forwarding state once the port is physically working Used on access layer switches that have multiple uplinks to distribution core...

Route Summarization with VLSM

Routing Summarization

In large internetworks, hundreds or even thousands of network addresses can exist. In these environments, it is often not desirable for routers to maintain many routes in their routing table. Route summarization, also called route aggregation or supernetting, can reduce the number of routes that a router must maintain by representing a series of network numbers in a single summary address. This section describes and provides examples of route summarization, including implementation...

Media Resource Access Control

Root Cause Analysis Template Word

All media resources are located in a null media resource group by default. Usage of media resources is load balanced between all existing devices. Hardware resources are preferred in the selection algorithm based on their enhanced capabilities (multiple audio codec support) and the reduction of load on the CUCM. Media resource management controls and manages the media resources within a cluster. The Media Resource Manager (MRM) service enhances CUCM features by making it easier for CUCM to...

Multiplexing Using TCP Port Numbers

Cvc Port Port

TCP provides a lot of features to applications, at the expense of requiring slightly more processing and overhead, as compared to UDP. However, TCP and UDP both use a concept called multiplexing. So, this section begins with an explanation of multiplexing with TCP and UDP. Afterward, the unique features of TCP and UDP are explored. Multiplexing by TCP and UDP involves the process of how a computer thinks when receiving data. The computer might be running many applications, such as a web...