Along with the processes that are
described above, there are software tools that are available for the
network administrator to use to solve network connectivity problems.
These tools can help in Local Area Network troubleshooting, but are
especially helpful in a Wide Area Network troubleshooting situation.
We will look at the commands that are
available to a network administrator in most client software packages.
These commands include the Ping, Tracert
(Traceroute), Telnet, Netstat, ARP, and
IPconfig
(WinIPcfg). 
Ping
Sends ICMP echo packets to verify connections to a remote host. The
following output will display if the ping is successful. The output
shows the number of packets responded to and the return time of the
echo. 
Ping [-t] [-a] [-n count] [-l length]
[-f] [-i ttl] [-r count] destination
-t |
ping until
interrupted |
-a |
resolves host name
and ping address |
-n |
resolves host name
and ping address |
-l |
length - send
specified size echo packets |
-f |
DO NOT FRAGMENT
command sent to gateways |
-i |
ttl sets the TTL
field |
-r |
count records the
route of the outgoing and returning packets |
destination |
specifies the remote
host to ping, by domain name or by IP address |
Tracert (Traceroute)
This utility shows the route a packet took to reach its destination.
The following output shows the trace command. 
Tracert [-d] [-h maximum_hops] [-j
host-list] [-w timeout] target_name
-d |
specifies IP addresses
shouldn't be resolved to host names |
-h |
max_hops Maximum
number of hops searched |
-j |
host-list specifies
the loose source route |
-w |
timeout waits the
number of milliseconds specified for each reply |
Telnet
This is a terminal emulation program that will allow you to run
interactive commands on the telnet server. Until a connection is
established, no data will pass and if the connection should break
telnet will inform you. Good for testing login configuration
parameters to a remote host.
Telnet [destination (IP
or DNS name)]
Netstat Displays protocol statistics
and current TCP/IP network connections. 
Netstat [-a] [-e] [-n] [-s] [-p
proto] [-r] [interval]
-a |
Displays all
connections and listening ports. (Server-side connections are
normally not shown). |
-e |
Displays Ethernet
statistics. This may be combined with the -s option. |
-n |
Displays addresses and
port numbers in numerical form. |
-p proto |
Shows connections for
the protocol specified by proto; proto may be tcp or udp. If
used with the -s option to display per-protocol statistics,
proto may be tcp, udp, or ip. |
-r |
Displays the contents
of the routing table. |
-s |
Displays per-protocol
statistics. By default, statistics are shown for TCP, UDP and
IP; the -p option may be used to specify a subset of the
default. |
interval |
Redisplays
selected statistics, pausing interval seconds between each
display. Press CTRL+C to stop redisplaying statistics. If
omitted, Netstat will print the current configuration
information once. |
ARP
Used to gather hardware addresses of local hosts and the default
gateway, you can view the ARP cache and check for invalid or
duplicate entries 
arp -a [inet_addr] [-N [if_addr]]
arp -d inet_addr [if_addr]
arp -s inet_addr ether_addr [if_addr]
-a or -g |
Displays the current
contents of the arp cache |
-d |
Deletes the entry
specified by inet_addr |
-s |
Adds a static entry to
the cache |
-N |
Displays the arp
entries for the specified physical address |
inet_addr |
IP address, in dotted
decimal format |
if_addr |
IP address whose cache
should be modified |
ether_addr |
The MAC address in hex
separated by hyphens |
IPconfig
(Windows NT)/WinIPcfg
(Windows 95-98) These Windows utilities display IP-addressing
information for the local network adapter(s) or a specified NIC. 
IPconfig
[/all | /renew [adapter] |
/release [adapter]]
/all |
all information about
adapter(s) |
/renew |
renew DHCP lease
information for all local adapters if none is named |
/release |
release DHCP lease
information disabling TCP/IP on this adapter |
These are the tools that will allow a
network administrator to remotely monitor and control the network. It
is important to implement the proper security when using SNMP and RMON
so that the network is not violated.
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Lab
Activity |
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This lab focuses
"out-of-band" router management using the
AUX port on the
router and a
modem.
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