Queuing Models in NS2

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M/M/1 is a system with poisson arrival time, servicing exponentially and a queue of unlimited capacity and type of FIFO Queue. This is the simplest queuing system.  NS2 supports various distributions like pareto, exponential, constant, unifrom, etc to handle the network dynamics and metrics. So it is very easy to test the given network link to monitor a given queue using any of these queuing models. The listing 3 and 4 are monitoring the link when DropTail queue is used with a capacity of finite and infinite. Listing 13.3 uses infinite capacity and Listing 13.4 uses Finite capacity The output screen shot is shown below the scripts for further understanding
Listing 3 – M/M/1 Queuing Model #new Simulator creation set ns [new Simulator] #trace file creation for capturing the UDP data set tf [open out.tr w] $ns trace-all $tf
#setting the exponential distribution param set lambda 30.0 set mu     33.0
#creation of nodes set n1 [$ns node] set n2 [$ns node] #The queue limit is 1Lakh as the capacity is infin…

Top 10 Networking Commands in Linux

There are many network commands linux supports but there are only a few commands that explore the major things in a network. There are 10 such networking commands in Linux to explore the routing, packets, etc.
if you want to know about the commands use "man commandname" (without Quotes)
Command 1:
# ifconfig
you may use the options to configure ifconfig -v (for showing the verbose mode)
command to configure the given network interface (wlan0, eth0, etc)
Command 2 :
# ping 172.16.1.10

To send ICMP, Echo request to hosts

Here is the output
PING 172.16.1.10 (172.16.1.10) 56(84) bytes of data.
64 bytes from 172.16.1.10: icmp_req=1 ttl=128 time=0.735 ms
64 bytes from 172.16.1.10: icmp_req=2 ttl=128 time=0.871 ms

--- 172.16.1.10 ping statistics ---

2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.735/0.803/0.871/0.068 ms
Command 3: 
traceroute domainname or IP Address
print the route packets trace to network host
Ex: 
traceroute www.vit.ac.in
See the image below for output
Command 4: 
route -n
 show / manipulate the IP routing table
it displays the kernel routing table with the default address and next hop address as given below
Output:
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         172.16.0.10     0.0.0.0         UG    0      0        0 wlan0
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlan0
172.16.0.0      0.0.0.0         255.255.192.0   U     9      0        0 wlan0
172.16.29.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet8
172.16.33.0     0.0.0.0         255.255.255.0   U     0      0        0 vmnet1
Command 5: 
# nslookup domainname
it querys Internet name servers interactively
Command 6: 
telnet ipaddress
user interface to the TELNET protocol
it uses to connect to other machines using the TELNET protocol
Command 7: 
ssh ipaddress
OpenSSH SSH client (remote login program)
the usage is
ssh username@ipaddress
you need to enter the password of the user
Ex: ssh pradeepkumar@172.16.49.132
if you want to use it with graphical interface, "ssh -X pradeepkumar@172.16.49.132"
Command 8: 
host ipaddress or domainname (DNS lookup utility)
Here is the output for the following 
host nsnam.com
Command 9: 
dig ipaddress mx   (DNS lookup utility (domain information groper))
dig nsnam.com mx (mx for mail exchange)
Command 10: 
netstat -a
Print network connections, routing tables, interface statistics, masquerade connections, and multicast memberships

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