Certified Design Associate

Assigns tags to multiprotocol frames. Tag Switching integrates routing at Network Layer 3 and Switching at Data Link layer 2 to provide scalable high-speed switching. With Tag Switching tags are assigned to multiprotocol frames. Packets are assigned a label that tells the switching node how data should be forwarded across the network.

First In, First Out Queuing - store and forward functionality The only queuing type that is correctly defined is First In, First Out Queuing . First In, First Out queuing provides store and forward functionality. Packets are stored when the network gets congested and then forwarded in the order in which they are received. Priority Queuing ensures that critical applications are processed first. Packets are prioritized according to several factors including protocol, packet size and address. Custom Queuing allows applications with different bandwidth requirements to share network resources. Weighted Fair Queuing uses algorithms that reduce delay variables and produce predictable network response time. Weighted Fair Queuing enables light and heavy network applications to run equally well without heavy bandwidth demands taking all the network resources from lighter applications.

The ordering of access lists on a router is extremely important. When a router receives a packet, it will test each packet against each criteria in the access list statements. Once a match is found, the processing stops and no more statements are checked for a match. If for some reason, the packet does not match any of the criteria, the packet with be blocked with the implicit "deny all" statement.

Access lists should be designed with the more likely matching conditions at the top of the list. The Cisco IOS will test each access list from top to bottom until matching criteria is found. You should study your traffic flow and attempt to design the access lists with the criteria that will more than likely match at the top of the access list. If your router needs to check less conditions on the access list, then router performance will be enhanced.

IP extended = 100-199 IP standard = 1-99 The IP access list numbers are correct. The correct access list numbers for AppleTalk zone are 600-699, IPX standard 800-899 and IPX extended, 900-999. Cisco IOS release 11.2 allows an alphanumeric name for IP access lists. To use this feature, type "ip-access-list" followed by the key word "standard" or "extended" followed by the list name that you choose.

There are currently 3 main classes of addresses available for public use on the Internet. Class A, Class B and Class C. Class D and Class E addresses are used for private TCP/IP organizational usage. Class A network addresses range from 1.0.0.0 to 126.0.0.0. The first byte, 1-126 are the available network addresses for Class A. The last 3 bytes (24 bits)are all the allowable host addresses. To determine the amount of hosts available for a Class A address, calculate 2 to the power of 24 (number of bits in the host address area). The result is that there are 16,777,214 host addresses available for a Class A internet address. Class B network addresses range from 128.1.0.0 to 191.254.0.0. The first byte, 128-191 are the available network addresses for Class B. The last 2 bytes (16 bits) are all the allowable host addresses. To determine the amount of hosts available for a Class B address, calculate 2 to the power of 16 (number of bits in the host address area). The result is that there are 65536 host addresses available for a Class B internet address.
Class C network addresses range from 191.0.1.0 to 223.255.254.0. The first byte, 191-223 are the available network addresses for Class C. The last byte (8 bits) are all the allowable host addresses. To determine the amount of hosts available for a Class C address, calculate 2 to the power of 8 (number of bits in the host address area). The result is that there are 255 host addresses available for a Class C internet address. Class D addresses (224.0.0.0) are used for multicasting and Class E addresses (240.0.0.0 are used for experimental purposes The address 127.0.0.0 is used for local loopback and is not included in the internet addressing scheme.

Flow control is a technique that ensures that a transmitter does not overburden a receiving entity with data. As the receiving station buffers fill, a message is sent to the sending device to suspend transmission until the data in the buffers are processed at the receiving station.

J1 is the Japanese format signaling standard for the equivalent of 2.048Mbps. Also, 2.048Mbps is equivalent to 30 DS0s. A T1 is equivalent to 1.544 Mbps and 24 DS0s.

Integrated Services Digital Network (ISDN) is a digital service that is offered by regional telephone companies in many parts of the world. ISDN supports video and voice as well as data transmissions. ISDN is used as a redundancy for critical network links as well as to provide an alternative to slower analog dialup lines for home users. In the United States ISDN Primary Rate Interface is used for business and contains 23B channels and one D channel. The European Standard for ISDN Primary Rate Interface is 30B channels and one D channel. Each B channel is equivalent to 64 Kbps and each D channel is equivalent to 16 Kbps.

The seven layers of the OSI reference model are Layer 1 Physical, Layer 2 Data Link, Layer 3 Network, Layer 4 Transport, Layer 5 Session, Layer 6 Presentation, Layer 7 Application.

Multiplexing does allow multiple logical signals to be transmitted simultaneously across a single physical channel. T1 lines are very often multiplexed to provide appropriate bandwidth to applications and network components.

The International Organization for Standardization (ISO) is responsible for the seven layer network reference model, referred to as the OSI (Open Systems Interconnection) reference model. IOS is the acronym for the Internetwork Operating System from Cisco. IEEE (Institute of Electrical and Electronics Engineers) is a group that develops network standards. IETF (Internet Engineering Task Force) is a collection of groups that focus on developing Internet and TCP/IP standards.

Both Data Link addresses and Network addresses are needed to provide connectivity throughout an internetwork. Data link addresses are physical addresses and are provided in a frame format for transmission across a network. Network addresses are logical addresses that are sent in a packet format for network node address resolution and routing functions.

Address Resolution Protocol (ARP) is the internet protocol that is used to map an IP address to a MAC address. ARP is defined in RFC #826.

TCP is a connection-oriented, reliable protocol that provides full-duplex data transmission.

TCP provides a sequence number field for data acknowledgement. If there is no acknowledgement, then the fields are retransmitted. UDP has no sequence number field, and does not acknowledge data sent.

An area border router connects OSPF areas to a backbone network. Another acronym for ABR is available bit rate.

Asymmetric Digital Subscriber Line (ADSL) is a technology that provides higher bandwidth from network provider to the end user than from the end user to the network provider.

Border Gateway Protocol (BGP) is a routing protocol that has replaced Exterior Gateway Protocol (EGP) as the standard exterior routing internet protocol.

First In, First Out (FIFO) is a method used to describe the method for sending data. The first data packet in, is the first packet sent out.

Time Domain Reflectometer (TDR) is a network diagnostic device that sends a signal through a network medium component, usually a cabling to check for continuity and isolate physical network problems.

An IP datagram reserves 32 bits for the source IP address and 32 bits for the destination IP address. (Example 11000000 00000001 00000111 01000000 = 192.1.7.128)

If the network will grow in scale or user base, it's important to include design specification that take the anticipated growth into consideration. Also, legacy systems and applications, especially mainframe applications that may require different network capabilities should be considered. Finally, the business culture of a company is always important as it will frequently be a template for the internetwork design. Local weather patterns generally will not be a major concern.

OSPF is CPU and memory intensive. OSPF is easy on the link, heavy on the router; RIP is light on the router, heavy on the links. Using OSPF as the routing protocol uses a lot of router memory, but fewer links have to be remembered. The opposite is true for RIP.

Performance can be affected on Ethernet segments if the utilization is at or above 40% for extended periods of time.

The business culture will directly affect the internetwork design. An example of this would be the network designed to accommodate remote users that work from home. Also, messaging needs would be different if all users were allowed to communicate to anyone in the organization. A more hierarchical business culture may restrict messaging access or limit the amount of users connecting from home offices.

The first choice, changing the legal contract may be a consideration if you feel that you do not have enough information to accurately assess the network and the companies business needs. But generally, you should be able to get an overview of the health of the existing network by analyzing the backbone segments of the network. Meeting with the current staff to discuss ideas about the current network would probably prove a waste of time due to the subjective view based on their technical ability and day to day responsibilities. Estimating based on historical data can be dangerous since more than likely the network load or physical infrastructure has changed since the historical data was gathered.

When two stations on an Ethernet network attempt to send a frame at the same time, a collision occurs and the result of the damaged frames cause Cyclic Redundancy Check (CRC) errors. CRC error rate is determined by dividing the total number of CRCs (Cyclic Redundancy Check) characters by the total number of MBs transmitted, it is not the total number of errors reported. If you divide the number of MAC layer errors by the total number of MBs transmitted, you will get the MAC-layer error rate.

Cisco's NetFlow is the fulltime monitoring tool that will collect detailed statistics on your internetwork. Cisco IOS is the Internetworking Operating System software that enabled configuration for your Cisco network component. CiscoWorks does monitor device status and will enable network personnel to troubleshoot internetworking problems. Network Associates' Sniffer although a network analysis tool, is not a Cisco product.

When there are major protocols running on the customer's network such as IP, you may want to assess the bandwidth used by routing protocols, TCP-based applications, and UDP-based applications.

Gathering information about the customers current network applications is the first step when you characterize a customer's network. Although it's important to establish a good working relationship with the current network staff, getting advice from them may be something that is better left for another time. Both A and B are assumed. You would have already met with the client and the contract should already be signed if you are at the stage of characterizing their network.

User Datagram Protocol (UDP) does not offer windowing or flow control. The applications that run on top of UDP include: Simple Network Management Protocol (SNMP) : port 161 Remote-procedure call (RPC) : port 111 Domain Name Server (DNS) : port 53.

Latency is another name for network delay. The network delay is the time it takes from a frame being ready for network transmission until the time that the transmission is successful. Latency, or network delay is a function of a great deal of factors including protocol, media and network design.

All network traffic patterns are important. You will need to consider all geographical user groups and usage patterns to accurately design an enterprise network.

When characterizing your customer's existing network, it's important to document the current addressing schemes that are in place. It's possible that network protocols addressing assignments or schemes may limit the future scalability of the network.

MTBF = Mean Time Between Failure is used to describe the mean time between failures on a network segment or computer related device.

Some of the features of Cisco's Private Internet Exchange Firewall (PIX Firewall) are protecting internal network architecture from internet traffic, allows secure access to the internet ,and customer's can take advantage of a larger address pool for IP addressing schemes with Network Address Translation (NAT).

When you characterize an existing network and are using a network analyzer to gather protocol statistics, relative protocol usage is in relation to the other protocols on the network segment. Absolute protocol usage is in relation to the total amount of bandwidth available.

All the answers are part of characterizing a customer's network. Identify bottlenecks in the current network design, look at future growth of the current network especially taking a look a legacy systems and their impact on day to day operations. Also non-technical issues such as corporate politics and budget can and will greatly influence your network design.

It will be very important to understand the customer's technical expertise. You'll want to be able to talk to the customer at their level of understanding without insulting or completely confusing them with technical details. Also, it's important to know if the customer has a specific technology that they believe will solve all problems with the current network design. With this information, you can design a solution that will assure success for you and your customer.

A protocol analyzer will be the tool to determine local traffic, or any traffic on the customer's network. Traceroute and ping are excellent troubleshooting tools, and telnet will allow remote access to work on systems, but they will not provide detailed analysis of network traffic.

Since you are identifying performance requirements, you are investigating availability as the amount of time that the network is available which can be described as Mean Time Between Failure (MTBF).