ITEC 275 Computer Networks – Switching, Routing, and WANs. Week 4 Robert D’Andrea. Agenda. Learning Activities Logging into the VMware View Client Accessing the MIMIC Virtual Lab CCNA Introduce Cisco IOS Review week three Week four. VMware View. Select VMWare View Client icon
clear Reset functions
clock Configure serial interface clock
configure Enter configuration mode
connect Open a terminal connection
copy Copy from one file to another
debug Debugging functions (see also 'undebug')
delete Delete a file
disable Turn off privileged commands
disconnect Disconnect an existing network connection
enable Turn on privileged commands
erase Erase a filesystem
exit Exit from the EXEC
help Description of the interactive help system
logout Exit from the EXEC
no Negate a command or set its defaults
ping Send echo messages
reload Halt and perform a cold restart
show Show running system information
systat Display information about terminal lines
interfaces Interface status and configuration
ipv6 IPv6 information
isis IS-IS routing information
location Display the system location
logging Show the contents of logging buffers
modemcap Show Modem Capabilities database
privilege Show current privilege level
protocols Active network routing protocols
running-config Current operating configuration
startup-config Contents of startup configuration
terminal Display terminal configuration parameters
users Display information about terminal lines
version System hardware and software status
access-lists List access lists
aliases Display alias commands
backup Backup status
buffers Buffer pool statistics
clock Display the system clock
compress Show compression statistics
configuration Contents of Non-Volatile memory
controllers Interface controller status
dialer Dialer parameters and statistics
flash: display information about flash: file system
frame-relay Frame-Relay information
history Display the session command history
hosts IP domain-name, lookup style, nameservers, and host table
access-list Add an access list entry
alias Create command alias
banner Define a login banner
cdp Global CDP configuration subcommands
class-map Configure QoS Class Map
dialer-list Create a dialer list entry
enable Modify enable password parameters
end Exit from configure mode
exit Exit from configure mode
frame-relay global frame relay configuration commands
help Description of the interactive help system
hostname Set system's network name
interface Select an interface to configure
ip Global IP configuration subcommands
ipv6 Global IPv6 configuration subcommands
isdn ISDN configuration commands
key Key management
line Configure a terminal line
logging Modify message logging facilities
no Negate a command or set its defaults
policy-map Configure QoS Policy Map
router Enable a routing process
snmp-server Modify SNMP parameters
trunk Configure a trunk group
username Establish User Name Authentication
- Develop a set of network maps
- Learning the locations of major internetworking devices
- Identify all network segments
- Identify any standard methods for addressing and naming convention
-Types and lengths of actual cable and fiber
- Investigate architectural constraints
- Investigate environmental constraints
- Investigate important aspects of characterizing the network infrastructure.
How to begin characterizing?
Top-down method that shows high-level to low-level information.
WAN to LAN
Identify each campus network
Buildings, floors, and rooms
Location(s) of servers and main-frames
Location(s) of routers and switches
Location(s) of LANs and VLANs
Create a map that displays network services
- Develop network diagrams of the company
- Develop modular block diagrams
- Develop wiring within buildings
- Verify architecture and environmental constraints
- Develop any wireless installations with a wireless site survey
Baseline the existing network
A benchmark that is used as a foundation for measuring or comparing current and past values. For example, a company wanting to measure the success of one of its product lines can use the number of units sold during the first year as a baseline from which to evaluate subsequent sales growth. In business, baselines and benchmarks serve a similar purpose.
- Bandwidth used by applications
- Bandwidth used by protocols
- Involves identifying the sources and destinations
- Analyzing the direction of traffic
- Analyzing the symmetric of traffic
A user community is a group of workers who use a particular application. They can exist in a department or group of departments.
A User Communities chart should be utilized to record this type of information in.
A data store is an area in a network where application layer data resides. A data store can be a number of components; server, server farm, a storage-area network (SAN), main-frame, a tape backup unit, a digital video library, or where large quantities of data are stored.
- Identify and characterize individual traffic flows between traffic source and stores.
- To understand traffic flow better read RFC 2722.
- Measuring traffic flow behavior
Characterize the behavior of existing networks
Plan for network development and expansion
Quantify network performance
Verify the quality of network services
Assign network usage to users and applications
Traffic Flow Measurement: RFC 2722
This document provides a general framework for describing network traffic flows, presents an architecture for traffic flow measurement and reporting, discusses how this relates to an overall network traffic flow architecture and indicates how it can be used within the Internet.
- Flow has attributes
Routing path and routing options
Number of packets
Number of bytes
Addresses for each end of the flow
Characterizing the size of a flow by measuring the number of megabytes per second (MBps) with a protocol analyzer.
- Bidirectional and symmetric is when both ends of the flow send traffic at the same rate.
- Bidirectional and asymmetric is when the client sends small queries and servers send large streams of data.
- Broadcast flow is unidirectional and asymmetric.
Cisco NetFlow collects and measures data as it enters a router and switch interface, it’s source, and destination , IP address, source and destination TCP or UDP port numbers, packet and byte counts.
The objective is to document the megabytes per second between pairs of autonomous systems, networks, hosts, and applications.
Use the Network Traffic Flow on the Existing Network form to document this information.
- Terminal/host traffic flow (Telnet, asymmetric)
- Client/server traffic flow (Thin client, bidirectional and asymmetric)
- Peer-to-peer traffic flow (ftp, NFS, and HTTP, bidirectional and symmetric)
- Server/server traffic flow ( implement directory services, cache heavily used data, and to mirror data, bidirectional and symmetric)
- Distributed computing traffic flow (task manager, applications that require multiple computing nodes)
Involves two flows
Use the Network Application Traffic Characteristics form to identify traffic flow for new and existing network applications.
Traffic load information can help characterize networks with sufficient capacity for local usage and internetwork flows. Estimating traffic loads is difficult. Try to avoid bottlenecks in your network design.
The traffic load is the sum of all the data, all network nodes that are ready to send at a particular time. The goal is to design the network capacity to be more than adequate to handle the traffic load.
-The number of stations
-The average time that a station is idle between sending frames.
-The time required to transmit a message once medium access is gained.
- Identify user communities
- Revisit the size of the data objects sent by applications
- The overhead caused by protocol layers, and any other load caused by application initialization.
Address Resolution Protocol (ARP)
Dynamic Host Configuration Protocol (DHCP)
Internet Control Message Protocol (ICMP)
Domain Name System (DNS)
Multicast DNS (mDNS)
NetBIOS name queries ( runs on the session layer of the OSI model)
Network Time Protocol (NTP)
Simple Service Discovery Protocol (SSDP)
Service Location Protocol (SLP)
Simple Network Management Protocol (SNMP)
The Simple Network Management Protocol (SNMP) is by far, the dominant protocol in network management. A key reason for its widespread acceptance, besides being the chief Internet standard for network management is its relative simplicity. Implementing SNMP management in a networked device is far more straightforward than most other standard or non-standard approaches to network management. Despite that, SNMP application development has not been as simple as one would like. It has required significant effort to develop management applications to manage the variety of networked devices to be managed. This situation is now changing for the better, as more SNMP tools are available. There are also different versions of SNMP available, such as SNMP V1, SNMP V2c, and SNMP V3. With improved tools, SNMP is poised to deliver end-to-end management for all areas of the growing internet industry.
SNMP management has become the dominant standardized network management scheme in use today. The SNMP set of standards provide a framework for the definition of management information along with a protocol for the exchange of that information. The SNMP model assumes the existence of managers and agents. A manager is a software module responsible for managing a part or all the configuration on behalf of the network management applications and users. An agent is a software module in a managed device responsible for maintaining local management information and delivering that information to a manager via SNMP. A management information exchange can be initiated by the manager (via polling) or by the agent (via a trap). Agents function as collection devices that gather and send data about the managed resource in response to a request from the manager. UDP ports 161 and 162 are the default ports reserved for SNMP. The agent listens for requests and replies to them over port 161 and reports asynchronous traps on port 162, unless it is instructed to use different ports. SNMP accommodates resources that do not implement the SNMP software by means of proxies. A proxy is an SNMP agent that maintains information on behalf of one or more non-SNMP devices.
- A broadcast frame goes to all network stations on a LAN. Routers do not forward broadcasts.
IPv6: FF:FF:FF:FF:FF:FF (128 characters)
- A multicast frame goes to a subset of stations.
Cisco routers and switches running Cisco Discovery Protocol (CDP) on a LAN.
Allow users to be subdivided into subnets by associating switch ports with one or more VLANs. A VLAN can span many switches, broadcast traffic within a VLAN is not transmitted outside the VLAN.
Broadcast radiation is a term used to describe the affect of broadcasts spreading from the sender to all other devices in a broadcast domain. Broadcast radiation can impact your endpoints network performance.
Efficiency refers to whether applications and protocols use bandwidth effectively. Efficiency is affected by
- Frame size (maximum transmission unit (MTU))
- Interaction of protocols used by an application
- Windowing and flow control (recipient states in TCP packet how much data it is ready to receive (receive window).
- Error-recovery methods
File Transfer Protocol (FTP, TCP)
Simple Mail Transfer Protocol (SMTP, TCP)
Hypertext Transfer Protocol (HTTP, TCP)
Simple Network Management Protocol (SNMP, UDP)
Domain Name System (DNS, UDP)
Trivial File Transfer Protocol (TFTP, UDP)
DHCP server (UDP)
DHCP client (UDP)
remote Procedure Call (RPC, UDP)
Are the requirements flexible or inflexible
- Voice and video are inflexible applications regarding bandwidth. - Data transmissions a flexible when dealing with insufficient bandwidths.
- Constant bit rate (CBR)
- Real-time variable bit rate (rt-VBR)
- Non-real time bit rate (nrt-VBR)
- Unspecified bit rate (UBR)
- Available bit rate (ABR)
- Guaranteed frame rate (GFR)
Source end system reserves network resources in advance and requests a guarantee that the negotiated QoS be assured to all cells.
CBR service is intended to support real-time applications.
Connections are characterized in terms of a peak cell rate (PCR), sustained cell rate (SCR), and maximum burst size (MBS).
Intended for non-real-time applications.
Data flow is a burst
Does not specify any traffic related guarantees.
Use resource management (RM) cells to communicate back to the source any traffic flow changes.
Guaranteed Frame Rate Service (GFR)
GFR is designed for applications that require a minimum rate guarantee and can benefit from dynamically accessing additional bandwidth available in the network.
With the establishment of a GFR connection, an end system specifies a PCR, MCR, MBS, and MFS.
RSVP is considered a set up protocol used by a host to request specific qualities of service from the network for particular application flow. RSVP is used by routers to deliver QoS requests to other routers along the paths of a flow. RSVP requests resources being reserved in each node along the path.
Provides a client with a data flow with a QoS closely approximated to the QoS that the flow would receive on an unloaded network.
The controlled-load service is intended for applications that are highly sensitive to over-loaded conditions, such as real-time applications.
- RFC 2212 describes the guaranteed bandwidth and delay characteristics. - - Guaranteed service provides a firm limit on end-to-end packet-queuing delays.
Voice traffic need a high grade of service (GoS).
GoS refers to the fraction of calls that are successfully completed in a timely manner.
A network must have high availability to meet the GoS requirement.
- Document applications with inflexible requirements for constant bandwidth, delay, delay variation, accuracy, and throughput.
- Document applications that just expect a best effort network transmission.