Networks & Usages in 2007;     Last updated on 2018/2562 7 27, a full moon day;

5W1H . WHEN   When adding/configuring routers to expand a network WHICH uses multiple protocols; When troubleshooting networking devices i.e. routers, switches, ... ;

5W1H . WHAT   Fundamentals of multi protocol networks including installing, configuring, monitoring, troubleshooting, ... ;

5W1H . WHICH   Prior knowledge i.e. Bus Connector & Port; Also see: Network Topology;

5W1H . WHO   Enterprise Network Administrators; Internet Service Providers; Network Specialists; Network Technicians; PC Technicians; Remote LAN Administrators; Users; WAN Administrators;

/* .....  The following information is based on a router

1st configure static routes, 2nd implement dynamic RIP, 3rd routing by IGRP;

router's boot sequence, WHEN at boot time, messages are deciphered, WHERE console connection to actual router;

router's learning steps are:

            login to a router via console port connector;

            the router's initial configuration by using Initial Configuration Dialog software interface, and then the router's manual configuration because at the initial configuration stage the router was non-configured without commands is non-configured;

            the router's self identification by its router settings; After the router's manual configuration, settings are clock rate, bandwidth, each IP address for each network interface, passwords, ... ; After manual configuration is loaded, and then do System Configuration Dialog software interface; Changing/editing/modifying startup configuration file, and understanding between cold boot and warm boot WHEN copy; Configuring global parameters such as

                                    Enter host name [this DOMAIN]: this DOMAIN

                                    Enter enable secret [<password>]:password  System Configuration Dialog will encrypt the password automatically;  

            by using host files [also see: lmhosts] to do static routing; for each static route for each multiple router therefore static routes with multiple routers Remark: @other routers' side, instead of IP address, host names are used by computers, THIS makes system complexity higher, therefore secure security MAC; Manual enter host table info; Integrate the host table text file into running configuration;

            by allowing override static routers, the usage "dynamic" begins; To do so, allow dynamic routes; TCP/IP subnets knowledge is required because defined default gateway by WHOM should be unique regardless of whether global OR local OR remote OR ... ;

            RIP and then IGRP routing; routing protocols and link state vs. distance vector; routing protocols' metrics; human assist/determine path and mapping also see: Homology vs. Homotopy, and then understand static routing vs. dynamic routing, and then able to analyze homological simplex, complex, mapped groups of half-duplex, full-duplex, ... ; @ a run time, routed protocols vs. routing protocols, and then understand Current Loaded Routing Table, Destination Stations, End Stations, Intermediate "in the middle" Station, ... ;

Sample text  

Routing Protocol is "rip"

     Sending updates every 0.1 seconds, next due in 1 seconds

     Invalid after 3 seconds, hold down 101, flushed after 111

     Outgoing update filter list for all interfaces is set{}

     Incoming update filter list for all interfaces is set{}

     Redistributing: rip

     Default version control: send version |, receive any version

          Interface   Send   Recv   Triggered RIP   Key-chain

          Ethernet0     |            |

          Serial1         |            |

     Automatic network summarization is in effect

     Maximum path: 4

     Routing for Networks:



     Routing Information Sources:

          Gateway               Distance               Last Update

     101                        Hexadecimal system value here

     Distance: (default is 120)



            monitoring the router's performance; data; deploying telnet command; the router's telnet sessions, assuming 1 window is 1 session; at the router, disconnecting unauthorized users; identifying running processes at the router; get interface transmission statistics; utilization of memories & processors;

            password recovery; troubleshooting the router by using debug command to debug serial interface, to debug Ethernet interface; debugging info of telnet session window; Correct Mode vs. Diagnostic Mode

Sample text Debugging an interface of the router

Hardware is Idea Processor (NCS, PCS, ZCS) XYZ Serial

MTU 1010 bytes, BW 56 Mbit, DLY 100000 users, reliability 255/255, TXload 1/255, RXload 1/255

Encapsulation HDLC, loopback set

Keepalive set (second, minute, hour, day)

Last input never, output never, output hang never

Last clearing of "whois interface" counters Hexadecimal system value here

Input queue: 0/8/1/0 (size/max/drops/flushes): Total output drops: 0

Queuing strategy | Gravity Dimension Computer (weighted) fair

Output queue: 0/100000/64/0 (size/max total/threshold/drops)

                    Conversation: 0/1/255 (active/max active/max total) PDC

                    Reserved conversation: 1/3 (allocated/max allocated) BDC

0.1 minute input rate 56 Mbits/sec, 1024 packets/sec

0.1 minute output rate 128 Gbits/sec, 1024 packets/sec

1024 packets input, numbers bytes, 4 buffer

Received 1024 broadcasts, 0 runt, 0 giant, 0 throttle

0 input errors, 1 CRC, 16 frame, 0 overrun, 1 ignored, 0 abort

1024 packets output, numbers bytes, 1 underrun

0 output errors, 1 collision, 0 interface reset

0 output buffer failure, 1 output buffer swapped out

1 carrier transition


            using access lists to secure the router; increase the router's security by blocking telnet session;

            NAT to increase security; Not only IP addresses but also Ports can be translated by configuring NAT; e.g.

NAT (Network Address Translation) protocol 12344/tcp this DOMAIN NAT。
NAT (Network Address Translation) protocol 12344/udp this DOMAIN NAT。

Sample text  

Press RETURN to get started.

User Access Verification


The Router>this DOMAIN


The Router&#conf t

Enter configuration commands, one per line. End with CTRL/z.

The Router & (config)#access-list | deny 123.456.789.101

The Router & (config)#int   Hexadecimal system value here

The Router & (config~if)#987.654.321.10 access-group | in

The Router & (config~if)#^z

The Router &#

Hexadecimal system value here :   %SYS |: Configured from console to console


            Flash IOS, and then TFTP server; ... ;

Above information is based on a router  ..... */

Local vs. Remote;

NAT configuration on the router WHICH connects to Internet; Increase network security;

Network security by managing access lists, for example ACL DACL SACL;

Networking connections oriented commands such as debug command_line_parameter <enter> , ping command _ line _ parameter <enter> , trace command _ line _ parameter <enter> , ... ;

OSI model and its layers;

TCP/IP; Also see: Protocol and Port; TCP/IP address calculation by converting from decimal to binary, and knowing of each default gateway address for each TCP/IP address, and then subnets by masking subnet a.k.a. subnet masking;