Transport

The Transport layer does the following: Responsible for end-
to-end integrity of data transmission. Handles multiplexing 
upper-layer application, session establishment and tear 
down of virtual circuits. Hides details of network 
dependent info from the higher layers by providing 
transparent data transfer. The 'windows' works at this 
level to control how much information is transferred before 
an acknowledgement is required.

Presentation

session

networklayer

session

All of the above are logged when IP access list logging is 
enabled.

destination address

Source IP address n access list number

180 seconds

Cisco Discovery Protocol is a proprietary protocol to allow 
you to access configuration information on other routers 
and switches with a single command. It uses SNAP at the 
Data-Link Layer. By default CDP sends out a broadcast every 
60 seconds and it holds this information for 180 seconds. 
CDP is enabled by default.

60 seconds

180 seconds

60 seconds

60 secs is the cdp timer & holddown timer is three times 
than the timer it will be 180 secs.

cdp hold ime is three time the cdp timer then it must be 
180 second

180

180

By default CDP hold time is 180 sec.

 Router_2#sho cdp
   Global CDP information:
           Sending CDP packets every 60 seconds
           Sending a holdtime value of 180 seconds 


But you can also set CDP timer and holdtime values.

Router_2#conf t
   Enter configuration commands, one per line.  End with 
CNTL/Z.
   Router_2(config)#cdp timer 90
   Router_2(config)#cdp holdtime 360

90 seconds

TCP and UDP operate at the Transport layer.

UDP
TCP

TCP
UDP

TCP
UDP

UDP and TCP

yes Transport Layer use TCP and UDP User Datagram Protocol 
for virtual circute TCP is a connection orented where UDP 
is connection less protocol TCP uses a Ack packet after 
sending the data or information to the remote host but UDP 
dosn't use any Ack packet .

TCP--Sequenced,Reliable,Connection-oriented,Virtual 
circuit,Acknowledgments,Windowing and uses flow control.

UDP--Unsequenced,Unreliable,Connectionless,Low overhead,No 
acknowledgment,No windowing or flow control.


so right now you are abel to explain both Protocol ...ok!

TCP & UDP are used in transport layer.
TCP is connection oriented protocol and UDP is
connectionless protocol.

Tcp
Udp

TCP and UDP will work at Transport Layer.

ARP  - its address resolution protocol.
UDP  - Helps in packet transfering
ICMP - Sending echo packets 
RARP - NIC to ip 
TCP  - Helps in transport the packets 
Bootp- Helps in DHCP resolutions .

Now its very clear TCP and UDP are in Transport layer catagory 

Regards,
Pradeep.

TCP, UDP

tcp
udp

TCP.AND UDP.AT WORK ON TRANSPORT LAYER.

It facilitates systematic troubleshooting
It allows changes in one layer to occur without changing 
other layers
It clarifies what general function is to be done rather 
than how to do it

It clarifies what general function is to be done rather 
than how to do it

 It allows changes to occur in all layers when changing 
one protocol
It facilitates systematic troubleshooting

Application

The Application layer performs the following: Synchronizing 
sending and receiving applications. Program-to program 
communication. Identify and establish the availability of 
the intended communication partner, and determine if 
sufficient resources exist for the communication. Popular 
application protocols include WWW, SMTP, EDI, FTP, Telnet, 
and SNMP

Session

transport layer

tcp- connection oriented
udp- connection less

RAID-1: This type is also known as disk mirroring and 
consists of at least two drives that duplicate the storage 
of data. There is no striping. Read performance is improved 
since either disk can be read at the same time. Write 
performance is the same as for single disk storage. RAID-1 
provides the best performance and the best fault-tolerance 
in a multi-user system.

Raid 1 used for mirroring .

Minimum 2 disk required in order to configure the Raid 1. 

Its one of the best solution for the fault tolerance of the
failed disks.

You can remove the failed disk and add a fresh disk which
will synchronize automatically.

RAID 1 specially for mirroring the disk in order to avoid
the   downtime bcoz of failure of HARD DISK.

Regards,
Pradeep

This type is also known as disk mirroring and consists of 
at least two drives that duplicate the storage of data. 
There is no striping. Read performance is improved since 
either disk can be read at the same time. Write performance 
is the same as for single disk storage. RAID-1 provides the 
best performance and the best fault-tolerance in a multi-
user system.

Conguring a master NIS server: Follow the following steps
to set up a server on the second
physical machine:
1. Set up the NIS domain name with the domainname command.
Use groupi.cs498hou.uiuc.edu
as the NIS domain name for the ith group.
1
domainname groupi.cs498hou.uiuc.edu
2. Determine what les you would like to share via NIS by
editing /var/yp/Makele. Search
for the following block of lines in the makele
GROUP = $(YPPWDDIR)/group
PASSWD = $(YPPWDDIR)/passwd
etc ...
This tells NIS where your database les are located (note
that $(YPPWDDIR) is set
to /etc at the top of the makele). You need to edit the
block of lines properly. Scroll
down the makele until the following block is reached:
all: passwd group hosts rpc services netid protocols mail \
# netgrp shadow publickey networks ethers bootparams printcap \
# amd.home auto.master auto.home auto.local passwd.adjunct \
# timezone locale netmasks
This line species which maps will be made available via
NIS. You need to edit this
block of lines in order to specify which les you would like
to distribute. The only les
you need to distribute for your network are ypservers,
passwd, group, hosts, rpc, services,
netid, and protocols.
3. Initialize the NIS database with
/usr/lib/yp/ypinit -m
Do not add any slave server, as our network is really small
and a master server is
sucient. (The hosts that you add are put to the le
/var/yp/ypservers.)
4. To start the NIS server automatically at boot time, use
the commands /sbin/chkcong
--------------------------------------
Conguring an NIS client: As compared to conguring an NIS
server, NIS clients are much
easier to set up. You need to modify the following three les.
1. Edit the le /etc/yp.conf, e.g., for the rst group,
the le should be like
# /etc/yp.conf - ypbind configuration file
# Valid entries are
#
domain group1.cs498hou.uiuc.edu server m2.cs498hou.uiuc.edu

# Use server HOSTNAME for the domain NISDOMAIN.
#
#domain NISDOMAIN broadcast
# Use broadcast on the local net for domain NISDOMAIN
#
#ypserver HOSTNAME
# Use server HOSTNAME for the local domain. The
# IP-address of server must be listed in /etc/hosts.
#
2. Edit the /etc/syscong/network le to set the NIS domain
name at boot time.
NISDOMAIN=group1.cs498hou.uiuc.edu
3. Edit the /etc/nsswitch.conf le. Search for the block of
lines
passwd: files nisplus nis
shadow: files nisplus nis
group: files nisplus nis
hosts: files nisplus nis dns
services: nisplus [NOTFOUND=return] files
etc...
The order placed in the le determines the search order used
by the system, e.g., the host-
names are rst searched for in the /etc/hosts les, then via
NIS in the map hosts.byname,
and nally by DNS via the DNS server specied in
/etc/resolv.conf.
4. Now all the les are in place, set up the client daemon
to automatically start at boot time
by creating a symbolic link from /etc/rc.d/rc.3/S60ypbind to
/etc/rc.d/init.d/ypbind.

Subnet of class C Network is 255.255.255.0

For class c Network default Subnet mask is 255.255.255.0 
but make sure while putting a question its subnet or subnet 
mask.

every Address has 24 bit if u r talking about CLASS C Ip 
address so it will be --255.255.255.0
There are 18 bit for network address and 8 bit for host 
address.

CLASS A -8 bit for network and 24 bit for host.
CLASS B -16 bit for network and 16 bit for host.
CLASS C -24 bit for network and 8 bit for host.

for class C subnetmask 255.255.255.0

writenow we are using IPv4 in that ips every address 32bits
if u r taking class c the subnetmask is 255.255.255.0    
       and the wildcordmask is  0.0.0.255 in that ip 32bits
24bits for networkbits and remaining 8bits are hostbits


class A - 8bits for network bits 24 bits for host bits
class B - 16bits for network bits 16 bits for hostbits
class C - 24bits for network bits 8bits for hostbits

Its Very simple 

As you in the 32 bit address class . 24 bit comes in C class
hence 

8 8 8 8 byes 

255 255 255 0 defines C class subnet.

Regards,
Pradeep

255.255.255.0 subnet for class C network

The Subnet will be 255.255.255.0 for class C network

Short for virtual LAN, a network of computers that behave 
as if they are connected to the same wire even though they 
may actually be physically located on different segments of 
a LAN. VLANs are configured through software rather than 
hardware, which makes them extremely flexible. One of the 
biggest advantages of VLANs is that when a computer is 
physically moved to another location, it can stay on the 
same VLAN without any hardware reconfiguration.

Sunilbaglur's answer is right...but this is a software
implementation... there is also a hardware implementation on
switches.... and since Cisco is asking about it this might
be the right answer

VLAN on switches is a feature that allows u to use a single
switch to logically divide their ports so that we can have
different networks on them...

for example if a switch has 32 ports then we can logically
separate 8 ports for network A (or LAN A)
         8 ports for network B (or LAN B)
         8 ports for network C (or LAN C)
         8 ports for network D (or LAN D)

Since switches by default breakup collision domains, VLAN is
a way for them to act like routers by breaking up the
broadcast domain too...

VLAN virtual local area network

Vlan is logical grouping of n/w users & resources that is 
connected administratively to  a defined port on a switch.

benefits of Vlan:
1)Provides n/w security
2)Provides Broadcast control.
3)Effiocient usage of bandwidth
4)Phsically you can move the host to any location,it will 
remain in same vlan.

before understand vlan, we must have to understand of the 
defination of lan..
{ lan include the all devices in the same broadcast domain}

broadcast domain include the set of lan-connected devices, 
when any of the devices send a broadcast frame all the 
other devices get a copy of the frame, so think of a lan 
and a broadcast basically the same thing.

without vlan, switch consider all its interfaces to be in 
the same broadcast domain, in other words all connected 
devices are in the same lan.

With vlan, a switch can put some interfaces into one 
broadcast domain and some into another creating multiple 
broadcast domain. these individual broadcast domain created 
by switch are called Vlan.....

Vlan - Virtual Local Area Network

the vlan can group serveral broadcast domains into multiful 
logical subnets.

u can accomplish network additions moves and changes by 
configurung a port into the appropriate VLAN. 

Vlans can enhance network security.  Vlans increase the 
number of broascast domains while decreasing thir size. 

two types vlan 1. static vlan 2. dynamic vlan.

L-2 devices worked on mac address & L-3 devices worked on ip
address.
L-2 device more fast than the L-3 device.

L2 devices( switches) work on mac add & LLC that prepares
frames for bit formation
and 
L3 devices work on ip add that is routers.......which
perform routing decisions and logical addressing

L2 devices( switches) work on mac add & LLC that prepares
frames for bit formation and switch understand only mac 
address.
and 
L3 devices work on ip add that is (routers).......which
perform routing decisions and logical addressing. router 
understand only ip address.

terminal access controller access control system
remote access dial in user service
security enabled by aaa
authentication, authorization, accounting
provides a means of validation of users gaining access to a 
router 
accounting not used with radius.

Terminal Access Controller Access-Control System (TACACS) is
a remote authentication protocol that is used to communicate
with an authentication server commonly used in UNIX
networks. TACACS allows a remote access server to
communicate with an authentication server in order to
determine if the user has access to the network.

But RADIUS is also remote authentication protocol which is
used in WINDOWS, and working between RAS (Remote access
server) and IAS (Internet Authentication Server).

TACACS : Terminal Access Control Access control Server

TACACS Vs Radius

1) TACACS is an implementation of CISCO [proprietory]
   Radius in non proprietory

2) AAA [Authentication,Authorization,Accounting] can be 
handled separately in TACACS
  Radius does Authentication+Authorization in a single step 
& can perform Accounting separately.

3) TACACS uses TCP [Forgot the port numbers]
   Radius uses UDP

These 3 major differences are expected at the least ! i 
hope so !