Networking Test 2
Request for Proposal Outline
-Background: overview of current network, new network and what you want it to accomplish -Network requirements: set of possible network designs, mandatory desirable and wish list, security and response time requirements -Service requirements: implementation plan, training courses, support service, performance guarantees -Bidding process: time schedule, ground rules, bid evaluation criteria -Info from vendor: experience with similar networks, hardware/software benchmarks, references
IPv4 Address
-4 byte (32 bit) addresses -Dotted decimal notation (Makes it easier for humans) -breaks address into 4 bytes and writes binary equivalnet -Often assigned in large group (used up address space quickly)
Routing Information Protocol (RIP)
-A dynamic distance vector interior routing protocol -Once popular on internet, now used on simple networks -Manager builds routing table using RIP -Routing tables broadcast periodically by all nodes -When a new added, RIP counts number of hops between computers and updates routing tables
Open Shortest Path First (OSPF)
-A dynamic link state interior routing protocol -Became more popular on internet -More reliable paths (traffic and error rate calculated) -Less burden on network - only updates sent (not entire routing table) and to only other routers (no broadcasting)
System Management Software
-Also called enterprise management software -Analyze device information record for diagnosis -Prevents alarm storms (for a failed circuit, many connected devices sending alarms) -Allows pinpointing of problem quickly
Types of Addresses
-Application Layer: URL (www.google.com) -Network Layer: IP Address (149.52.45.23) 4 bytes -Data Link Layer: MAC Address (00-0C-00-F5-03-5A) 6 bytes
Network Management Standards
-Application layer protocols defining type of information collected and format of messages -Simple Network Management Protocol (SNMP) -Common Management Interface Protocol (CMIP) : developed for OSI type networks
Packetization and Reassembly
-Application layer sees message as single block of data -TCP breaks message into smaller pieces -Delivers packets and puts them back together
Network Users
-Assess the number and type of users that will generate network traffic -Much network traffic comes from internet use (In the past, application programs accounted for most) -Future network upgrades will require understanding of the use of new applications (Effect of video on network)
Categorizing Network Needs
-Assess the traffic generated in each segment (Understand what is high volume and low volume) -Organize network requirements into mandatory, desirable, and wish-list requirements
Cost Assessment
-Assessment of costs of various physical network design alternatives -Complex process that requires analysis of factors: -Circuit costs, switches/routers, hardware, software, testing and maintenance, operation costs
Assignment of Network Layer Address (IP)
-Assigned by network managers or programs such as DHCP and placed in configuration files -Every network on the internet is assigned a range of possible IP addresses for that network
Estimating Circuit Traffic
-Average: total characters transmitted per day / circuit -Peak: maximum characters transmitted per two second interval (hope to design to peak) -Message Volume: Count messages in current network and multiply it with growth rate -Precision: not major concern, can lease another line or upgrade
Application Systems
-Baselining: Review applications currently used on network and identifying their location so they can be connected to the planned network -Include applications expected to be added to network -Also identify the hardware and software requirements and protocol type for each application (HTTP over TCP/IP or something)
TCP connections
-Before data is sent connection is established (SYN to establish connection and FIN to close) -Old Version: separate connection for every HTTP request -New Version: Open connection with HTTP request sent to server -Leave connection open for all subsequent requests -Close connection when the session ends
Programs for Dynamic Addressing
-Bootstrap protocol and Dynamic Host Control Protocol (DHCP) -Program on client establishes connection to server -Client broadcasts request for IP Address -Server responds with message with IP Address -Can also be timed (time expired -> new address)
First step of Needs Analysis
-Break network into 3 conceptual parts -Access layer: Lies closest to user, often a LAN -Distribution layer: Connects the access layer to the rest of the network, often a BN (small networks may not have) -Core layer: connects different parts of distribution together, often a WAN
Designing Clients and Servers
-Building block approach requires the specification of the computers needed in terms of standard units -Allocate base level clients to "typical" users -Allocate base level servers to typical applications -Assign advanced computers to high volume users and servers -"typical" unit is always changing with new technology
Session Management
-Connected oriented -Connectionless -Quality of Service
Connecting to a router
-Console port -Network interface port -Auxiliary port -ACL: Access control list
Designing circuits and devices
-Deciding on fundamental technology and protocols -Performs capacity planning, estimating the size and type of standard and advanced network circuits for each type of network (LAN, BN, WAN) -Assess current and future data transmitted on circuit -Focus on average and peak traffic
Decentralized Routing
-Decisions made by each node independently of on another -Information needs to be exchanged to prepare routing tables -Used by the internet
Centralized Routing
-Decisions made by one central computer -Used on small, main-frame networks
Objective of Needs Analysis
-Define geographic scope of network -Define applications and users that will use network -Goal is to produce network design that will: -Describe network elements needed to meet needs -Does not specify technologies at this stage -Focus is on functionality (high speed network)
QoS - Quality of Service
-Defines and assigns priorities to "classes of service" -Timley delivery of packets, -Required by some real time applications (facetime)
Device Latency
-Delay imposed by device in processing messages (high latency device takes long time, low latency device faster -Wire speed: virtually no delays -Computer processor key element effecting latency -More important for networks with high traffic
Simple Network Management Protocol (SNMP)
-Developed for Internet and LAN's -Agent: collects device info and responds to requests form manager -Management Information Base (MIB): database at device stored by agent -Network management station (NMS): Access MIB, sends control messages to agent -Problems: limited functionality, security, vendor extentions
Technology Design
-Development of a physical network (or set of possible designs) -Specify the computers (clients and servers) needed to support applications and users -Specify circuits and devices (routers, gateways) to connect to the computers
Network Management Software
-Device management software -System management software -Application management software
Network Devices
-Devices from different vendors will provide different capabilities (faster, more reliable) -Factors in network performance: Device latency, memory, load balancing, capacity management
Enhanced Interior Gateway Routing Protocol (EIGRP)
-Dynamic link state protocol (developed by cisco) -Records transmission capacity, delay time, reliability, and load time for all paths -Keeps routing table for its neighbors and uses information in its routing decisions as well
Distance Vector
-Dynamic routing algorithm -Uses least number of hops to decide route of a packet -Used by Routing Information Protocol (RIP)
Policy Based Management
-Enables managers to set priority policies for traffic to take effect when congested -EX: order processing to have highest priority -Configure devices using QoS to give application highest priority
Service Level Agreements
-Established between organizations and common carrier and ISPs -Specify the exact type of performance that the common carrier will provide (99%, 99.9% etc) -Specifies penalties if this agreement is not met
Vendor Selection Process
-Evaluate submitted proposals against specific criteria -Select winner(s) based on criteria -Multi vendor selections provide better performance, less expensive, but more difficult to manage (each vendor blames each other for problems)
Border Gateway Protocol (BGP)
-Exterior routing protocol -Used to exchange info between autonomous systems -Based on distance vector algorithm -Far more complex than interior routing protocols -Providing routing info only on selected routes -Security concern, cant maintain tables of every route
Network Design Tools
-First step: Enter a diagram of the existing network (created from scratch or discovered automatically) -2nd Step: Add info about expected network traffic and see if expected traffic can be maintained through simulations -3rd Step: Examine results to see throughput and delays and change design if necessary
Assignment of Application Layer Address (URL)
-For clients only (server does not need) -Assigned by network managers and placed in configuration files -Some servers may have several application layer addresses
Baselining
-Gain an understanding of the current operations in terms of application systems and messages -Provides clear picture of sequence of operations, processing time, current network, existing costs, needs
Dynamic Addressing
-Giving addresses to clients (automatically) only when they are logged into the network -Eliminates permanent addresses for clients -When computer is moved, new IP address is assigned -Uses a server to supply an IP address to clients on the network
Second step of Needs Analysis
-Goal is to produce a logical network design, describing network elements to meet needs or organization -Identify basic technical constraints -Identify constraints imposed by the current network infrastructure
Needs Analysis
-Goal is to understand why the network is being built what what users and applications it will support (improve poor performance, new applications, upgrade, standardize equipment based on vendor/protocol) -Goals differ depending on network (LAN and BN best to design in over capacity, WAN relies on leased circuits, build to capacity)
Device Memory
-Goes hand and hand with latency -High latency devices can store backup up packets in memory so they're not retransmitted causing extra traffic -Also important for servers, requests can be processed more quickly
Subnets
-Group of computers on same LAN with IP numbers using same prefix -Assigned addresses that are 8 bits in length -Assigned addresses could be more or less than 8 bits in length
TCP/IP Layers
-Host computers: Packets move through all layers -Gateway/Routers: Packet moves from physical layer to Data Link layer through the network layer -At each stop: Ethernet packet is removed and new one is created for next node -IP and above packets never change in transit (created by original sender and destroyed by final receiver)
Data Link Layer Resolution
-Identifying the MAC address of the next node (that packet must be forwarded) -Uses Address Resolution Protocol (ARP)
Types of Routing Protocols
-Interior routing protocols: operate within a network (autonomous system) and provide detailed info about each node -Exterior routing protocols: Operate between networks (autonomous systems)
Transport Layer Functions
-Linking to application layer -Segmenting -Session Management ( connection- oriented, connectionless, and QoS)
Transfer Control Protocol (TCP)
-Links the application and network layers -Performs packetization and reassembly (Breaks up large packets and numbers them before sending)
Internet Addresses
-Managed by ICANN -Manages assignment of both IP addresses and URL (application and network) -Assigned at same time -Manages some domains directly, and authorizes private companies to become domain name registrars
Designing for Network Performance
-Managed networks: Used managed devices that assists w network management though monitoring -Network circuits: traffic analysis, service legal agreemnt -Network devices: Device latency and memory, load balancing -Minimizing network traffic: content caching and delivery
Simulation
-Mathematical technique used to model behavior or a network -Can track number of packets and delays at each point in the network -May highlight potential trouble spots
Traditional Network Desgin
-Meet with users to determine needs and apps -Estimating data traffic on each part of the network -Designing circuits to support this traffic -Building and implementing network -Takes up to a year or two
Application Management Software
-Monitor applications based on device information -Focus on delays and application layer management
Phases of Building Block Design
-Needs analysis: Understand current and future needs (classify users and applications, specific technology) -Technology Design: Examine available technologies to meet needs. Provide more capacity to keep ahead of growth -Cost assessment: Cost of technology
Managed Network
-Networks that used managed devices -Requires both hardware and software -Hardware: monitor, collect, transmit -Software: store, organize, analyze
Remote Monitoring (RMON)
-Part of Simple Network Management Protocol (SNMP) -Provide network wide monitoring info to manager (rather than device wide) -Collect info on different layers to figure out cause of traffic -Collects stats bases on IP address (can see host-host traffic)
Network Circuits
-Play a critical role in designing network for max performance -Important to size the circuit and place them to match the traffic -Areas of concern: circuit loading and capacity planning, traffic analysis, service level agreements
Known address, same subnet (client)
-Prepare HTTP packet and send it to TCP -Place HTTP packet into TCP packet and send it to IP -Place TCP packet into IP packet and adds IP address -Uses subnet mask to see its on same subnet -Adds ethernet field and sends frame to web server
MAC Address Resolution
-Problem: Unknown MAC address of next node -Solution: Uses Address Resolution Protocol (ARP) -Operation: --Broadcasts message to all nodes on LAN asking which one has the IP address --Host with that IP address responds w/ MAC address --MAC address is stored and message is sent
Routing
-Process of identifying what path to have a packet take through a network from sender to receiver
Asynchronous Transfer Mode (ATM)
-Protocol supporting QoS -High Speed data link layer protocol
User Datagram Protocol (UDP)
-Protocol used for connectionless routing in TCP/IP suite that uses no acks and no flow control -Uses only small packet header w/ 4 fields -Commonly used for small messages -Can also be used for applications where a packet can be lost
Device Management Software
-Provide specific information about a device -Analyzes patterns of configuration, traffic, error conditions etc.
Connectionless Routing
-Provided by UDP -Sending packets individually without circuit -Each packet sent individually and will be routed separately and arrive at different times
Selection Process Deliverables
-RFP delivered to the vendors -Revised set of physical network diagrams (done after vendor is selected, final technology design) -Business case to support network design
Inadequacies of Traditional Design
-Rapidly changing technology of computers, networking devices, and circuits -Rapidly growing network traffic -Dramatic change in balance of costs (minimize staff managemnt time to operate rather than hardware cost)
Known address, same subnet (server)
-Receive ethernet frame, perform error checking and send back ACK -Process incoming frame successfully up the layers -Process HTTP request and send HTTP response -Process outgoing HTTP response down layers -Create and send ethernet frame
Sending message using TCP/IP
-Required network layer addressing information (Computer's IP address and subnet mask) -IP address of local DNS server and router on its subnet -Address info obtained from a configuration file or provided by a DCHP server
QoS in TCP/IP
-Resource Reservation Protocol (RSVP) -Real-Time streaming protocol (RTSP) -Real-Time Transport Protocol (RTP)
Internet Protocol (IP)
-Responsible for addressing and routing of packets -IPv4 and IPv6 -Maximum size of message depends on data link layer protocol
Transport Layer
-Responsible for end to end message delivery -Sets up virtual circuits when needed -Breaks message into smaller messages to send then puts them back together on the other end
Transport and Network Layers
-Responsible for moving messages from end-to-end -TCP/IP is most commonly used protocol
Autonomous System (AS)
-Routing protocol -A network operated by an organization (Indiana) -Protocols based on autonomous system
Unknown address (host)
-Sends UDP packet to local DNS server -Local DNS server knows destination hosts IP address (sends DNS response back to sending host) -If local DNS server does not know address, sends UDP packet to next highest UDP host and so on until its found
Network Needs Deliverables
-Set of logical network diagrams showing applications, circuits, clients, servers -categorized into "typical" or "high volume" -Logical plan conceptual plan for the network (No physical elements specified)
Connection Oriented Routing
-Setting up virtual circuit or TCP connection -TCP asks IP to route all packets along same route -Used by HTTP, SMTP, FTP
Internet Control Message Protocol (ICMP)
-Simplest and most basic -An error reporting protocol (reporting routing errors to message senders) -Limited ability to update routing tables
Selling Proposal to Management
-Speak their language and present the design in terms of easily understandable issues -Make a business case by focusing on organization needs and goals -Avoid technical issues and focus on reliability
QoS Routing
-Special kind of connectionless routing -Allows to let some things have priority over others -Defines classes of service each with different priority
Routers
-Special purpose devices used to handle routing decisions on the internet -Maintain their own routing tables -Determine paths, transmit packets -Contain: CPU, memory, ports / interfaces -Don't Contain: Disk drive, monitor, keyboard, mouse
Design Process
-Start with highest level (Drawing WAN connecting locations) -Next draw individual locations connected to WAN -Gather information and characteristics of the environment (legal requirements, regulations, building codes)
Managed Device
-Switches and routes -Monitors traffic flows -Monitors its status and other devices connected -Records various data on messages it processes -Sends these to a managers computer -Sends alarm if critical situation is detected (failing device or unusual traffic) -Problems detected and reported by the devices themselves before they become major problems
Linking to Application Layer
-TCP may serve several Applications at the same time -Use port numbers to determine which application to send data to
TCP/IP
-Transfer Control Protocol / Internet Protocol -Most common, used by every internet equipment -Developed in 1974 by V Cerf and B Kahn -Most common protocol suite -Reasonably efficient and error free
Server Name Resolution
-Translating destination's host's name to its corresponding IP Address -www.yahoo.com translated to 123.53.345.34 -Uses one or more Domain Name Service (DNS) server to resolve the address
Static Routing
-Type of decentralized routing -Uses fixed routing tables developed by network managers -Each node has its own routing table that is updated when computers are added or removed -Used on relatively small networks with few routing options that rarely change
Dynamic / Adaptive Routing
-Type of decentralized routing -Uses routing tables at each node that are updated dynamically -Based on routing condition information exchanged between routing devices
Request for Proposal (RFP)
-Typically used before making large network purchases -Detailed specification of equipment, software, services -Categorized into mandatory, desirable and wish-list -Ask vendors to provide system and see what their price is so you can compare vendors
Assignment of Data Link Layer Address (MAC)
-Unique hardware addresses placed on network interface cards by their manufacturers (based on standardized scheme)
Capacity Overbuilding Dilemma
-Upgrading network costs 50-80% more than building it right the first time (under capacity huge concern) -Most organizations intentionally build for over capacity to account for growth -Most end up using overcapacity in 3 years
Domain Name Service (DNS)
-Used to determine IP address for given URL -Provided through a group of name servers (Databases containing different directories of IP addresses) -Large organizations maintain their own name servers -Smaller organizations rely on name servers provided by their ISP's -When a domain name is registered, IP address of the DNS server must be provided to registrar for all URLs in this domain
Subnet Masks
-Used to make it easier to separate the subnet part of the address from the host part
Routing Table
-Used to make routing decisions -Shows which path to send packets on to reach a given destination -Kept by computers making routing decisions
IPv6 Address
-Uses 16 byte address (basically infinite addresses) -Addresses will be subdivided into hierarchical routing domains
Link State
-Uses a variety of information types to decide how to route packet -Link state info exchanged periodically by each node to keep every node in the network up to date -Provides more reliable, up to date paths -Used by Open Shortest Path First (OSPF)
Building Block Network Design
-Uses few standard components to reduce long run costs -Use few type of devices over and over, narrow product choice but deep throughout organization -Phases: Needs analysis, technology design and cost assessment (cycles through 3 phases until complete)
Known address, same subnet
Differences: -use subnet mask to determine its on different subnet -send outgoing frames to local subnet's GW -Local gateway operations: -Receive frame and remove ethernet header -Determine next node (via routing table) -Make new frame and send it to the destination GW -Destination gateway operations -Remove header, determine destination (By IP address) -Place the IP packet in a new ethernet frame and send it to its final destination
Network Layer Functions
Addressing: Each device on path must have address -Internet Address, assignment of addresses, translation between network address and other addresses Routing: Process of deciding which path packets should take
How DNS Works
If desired URL is in clients table: -- use corresponding IP address --Each client maintains a server address table If desired URL is not in client's table: --Sends DNS request packet to local DNS server --Server responds with corresponding DNS packet If desired URL in not in Local server's table: --Sends DNS packet to next highest DNS server --Usually DNS server at top level domain