Saturday, July 13, 2013

JUNOS Security Configuration Guide


Friday, July 12, 2013

The Network Layer

IP Routing Tutorial

An Introduction to BGP Flow Spec

I have given this presentation a few times in the last year and was asked to make this available for public consumption. Essentially, this is a brief overview of RFC 5575, entitled “Dissemination of Flow Specification Rules”, written by Danny McPherson, Jared Mauch, and others. This standard had somewhat of a rocky beginning as there was limited vendor support, but as of recently it appears to have picked up quite a bit of steam with Cisco announcing support for the protocol in the very near future. The benefit of BGP Flow Spec is that it allows BGP speakers to use a new BGP NLRI defining flow filter information which can then be advertised to upsteam neighbors via BGP. The primary and immediate motivation of this protocol is to provide intra and inter provider distribution of traffic filtering rules to filter DoS and DDoS attacks, however it can be used for a wide variety of applications in which filtering information must be dynamically distributed throughout a network. I will probably make additional modifications to these slides as the protocol gains more significant foothold throughout the vendor community and as Service Providers gain more practical deployment experience. As with my other presentations, I will eventually add a voice-over to turn this into a slide-cast.

JNCIE Tips for Field ..

Today we'll start with a series of articles covering tips and techniques that might be utilized by JNCIE candidates, whether pursuing the JNCIE-SP, JNCIE-ENT, or even the JNCIE-SEC.  The tips and techniques I will be covering might prove to be useful during a lab attempt but could also be used in real-world scenarios to save time and minimize configuration burden in addition to eliminating mistakes that might otherwise be made.  I want everyone to understand that what I am about to write is simply a technique.  I am not divulging any materials or topics which are covered under NDA.
NOTE: For full disclosure, I must reveal that I am an employee of Juniper Networks in their Education Services department.  As such, I take the responsibility of protecting the content and integrity of the exam as well as the certification credentials very seriously.  I would never reveal anything which would allow a candidate to have in-depth knowledge of any specific topics or questions that may appear on the exam.  Not only that, I worked REALLY, REALLY hard to achieve my JNCIE certifications, and I believe everyone else should too! It's certainly more rewarding that way too don't you think?!
So without further delay, let's take a look at today's technique.
It is well known that sumarization is a key aspect of any type of practical exam involving routing of some sort.  Those who have ever taken a CCIE Routing & Switching or CCIE Service Provider exam can attest, summarization is one thing every expert level candidate needs to master.  It is no different with Juniper.  In fact, Juniper's certification web page clearly lists as one of the JNCIE-ENT exam objectives the requrement to "Filter/summarize specific routes". 
What I will show you next is a technique which I find quite handy when attempting to determine the best summary for a given route, and you can do so without having to resort to pen and paper and figuring it out the old fashioned way, i.e. looking at prefixes in binary. This technique, rather, allows you to use the power of Junos to your advantage to perform these tasks.  What I will reveal will also show you a fundamental difference between IOS and Junos and highlights why I believe Junos to be a more flexible, powerful, and superior network operating system.  You simply can't do what I am about to do on a Cisco platform running IOS.
So let's start off by looking at a diagram.  Let's say we have a network that has several OSPF areas, and we must summarize some information for each respective area towards the backbone without encompassing routing information that might exist outside of that area.
ospf-summarization-example
Here we can see we have a backbone area, consisting of two routers, P1 and P2.  P1 is acting as an ABR for Area 1 and is connected to both R1 and R2. P2 is acting as an ABR for Area 2 and is connected to R3.  As you can see from the diagram, I have configured more than a single set of IP addresses on many of the physical interfaces as well as the loopbacks.  This way I can represent many more networks and therefore create multiple Network LSAs for purposes of summarization.
So let's assume that we need to create the largest aggregate possible for a particular area and advertise only that aggregate towards the core without encompassing any routes which might be outside the area from which the summary describes.  Now normally, one would take a look at the diagram, get out a pen and paper, and start a lengthy exercise of supernetting based on binary addresses.  This can take several minutes or more and is valuable time that could certainly be used on wide variety of other more important tasks like setting up MPLS LSPs or troubleshooting that Layer 2 VPN connectivity.  So let's take a look at a simple trick that actually takes advantage of Junos to determine what the summary should be.
What we are going to do is take advantage of a feaure inside Junos which automatically shows us a range of prefixes which match a given CIDR block.  The Junos operating system has built-in route matching functionality which allows us to specify a given CIDR block and returns all routes with a mask length equal to or greater than that which is specified.  So by applying this principle, what we want to do is look at the diagram for a particular area, choose the lowest IP within that area as our base, and then apply a subnet mask to it which attempts to encompass that route as well as others. 
For example, looking at this diagram, we see that the lowest IP address being used in Area 1 is the 168.10.32.1 address assigned to R1's loopback.  So let's start by using this as our base for our summary, and then simply apply a subnet mask to it which we think might encompass additional routes:
sfouant@p1# run show route 168.10.32.0/22   
inet.0: 28 destinations, 28 routes (28 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
168.10.32.1/32     *[OSPF/10] 8w4d 19:04:48, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.2/32     *[OSPF/10] 8w4d 19:04:48, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.3/32     *[OSPF/10] 8w4d 19:04:43, metric 1
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
168.10.32.4/32     *[OSPF/10] 8w4d 19:04:43, metric 1
                    > to 168.10.48.10 via ge-0/0/1.0
                      to 168.10.60.10 via ge-0/0/1.0

Note: We can do this on any router within Area 1 since the Link-State Database is the same on all devices, but I prefer to perform the work on the ABR since this is where I will be performing the aggregation.  Also, the ABR may have other local and/or direct routes (or perhaps routes from other protocol sources) so we want to see things from the perspective of the ABR.
What we see here is that we have just now determined the summary route which in fact encompasses all the loopback addresses on both R1 as well as R2, but we need to keep going because this doesn't incorporate the Gigabit Ethernet links between all the devices:
sfouant@p1# run show route 168.10.32.0/21   
inet.0: 28 destinations, 28 routes (28 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
168.10.32.1/32     *[OSPF/10] 8w4d 19:04:50, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.2/32     *[OSPF/10] 8w4d 19:04:50, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.3/32     *[OSPF/10] 8w4d 19:04:45, metric 1
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
168.10.32.4/32     *[OSPF/10] 8w4d 19:04:45, metric 1
                    > to 168.10.48.10 via ge-0/0/1.0
                      to 168.10.60.10 via ge-0/0/1.0

Not quite. Let's keep trying:
sfouant@p1# run show route 168.10.32.0/20   
inet.0: 28 destinations, 28 routes (28 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
168.10.32.1/32     *[OSPF/10] 8w4d 19:04:55, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.2/32     *[OSPF/10] 8w4d 19:04:55, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.3/32     *[OSPF/10] 8w4d 19:04:50, metric 1
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
168.10.32.4/32     *[OSPF/10] 8w4d 19:04:50, metric 1
                    > to 168.10.48.10 via ge-0/0/1.0
                      to 168.10.60.10 via ge-0/0/1.0

Nope, still not there yet. Let's try again:
sfouant@p1# run show route 168.10.32.0/19   
inet.0: 28 destinations, 28 routes (28 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
168.10.32.1/32     *[OSPF/10] 8w4d 19:04:58, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.2/32     *[OSPF/10] 8w4d 19:04:58, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.3/32     *[OSPF/10] 8w4d 19:04:53, metric 1
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
168.10.32.4/32     *[OSPF/10] 8w4d 19:04:53, metric 1
                    > to 168.10.48.10 via ge-0/0/1.0
                      to 168.10.60.10 via ge-0/0/1.0
168.10.48.4/30     *[OSPF/10] 00:36:26, metric 2
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
                      to 168.10.60.2 via ge-0/0/0.0
168.10.48.8/30     *[Direct/0] 8w4d 19:36:13
                    > via ge-0/0/1.0
168.10.48.9/32     *[Local/0] 8w4d 19:36:13
                      Local via ge-0/0/1.0
168.10.60.0/30     *[Direct/0] 8w4d 19:51:31
                    > via ge-0/0/0.0
168.10.60.1/32     *[Local/0] 8w4d 19:51:31
                      Local via ge-0/0/0.0
168.10.60.4/30     *[OSPF/10] 00:36:26, metric 2
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
                      to 168.10.60.2 via ge-0/0/0.0
168.10.60.8/30     *[Direct/0] 8w4d 19:36:13
                    > via ge-0/0/1.0
168.10.60.9/32     *[Local/0] 8w4d 19:36:13
                      Local via ge-0/0/1.0

Ok, this looks more like it.  Here we can see we have all the Gigabit Ethernet links connecting all devices, as well as the loopback addresses.  This might be a suitable summary.  Let's keep going to see what happens:
sfouant@p1# run show route 168.10.32.0/18   
inet.0: 28 destinations, 28 routes (28 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
168.10.0.1/32      *[Direct/0] 8w4d 19:51:37
                    > via lo0.0
168.10.0.2/32      *[Direct/0] 8w4d 19:36:19
                    > via lo0.0
168.10.0.3/32      *[OSPF/10] 00:28:41, metric 1
                    > to 168.10.18.2 via fe-0/0/2.0
                      to 168.10.26.2 via fe-0/0/2.0
168.10.0.4/32      *[OSPF/10] 00:28:41, metric 1
                    > to 168.10.18.2 via fe-0/0/2.0
                      to 168.10.26.2 via fe-0/0/2.0
168.10.18.0/30     *[Direct/0] 8w4d 19:05:28
                    > via fe-0/0/2.0
168.10.18.1/32     *[Local/0] 8w4d 19:05:28
                      Local via fe-0/0/2.0
168.10.26.0/30     *[Direct/0] 8w4d 19:05:28
                    > via fe-0/0/2.0
168.10.26.1/32     *[Local/0] 8w4d 19:05:28
                      Local via fe-0/0/2.0
168.10.32.1/32     *[OSPF/10] 8w4d 19:05:04, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.2/32     *[OSPF/10] 8w4d 19:05:04, metric 1
                    > to 168.10.60.2 via ge-0/0/0.0
168.10.32.3/32     *[OSPF/10] 8w4d 19:04:59, metric 1
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
168.10.32.4/32     *[OSPF/10] 8w4d 19:04:59, metric 1
                    > to 168.10.48.10 via ge-0/0/1.0
                      to 168.10.60.10 via ge-0/0/1.0
168.10.48.4/30     *[OSPF/10] 00:36:32, metric 2
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
                      to 168.10.60.2 via ge-0/0/0.0
168.10.48.8/30     *[Direct/0] 8w4d 19:36:19
                    > via ge-0/0/1.0
168.10.48.9/32     *[Local/0] 8w4d 19:36:19
                      Local via ge-0/0/1.0
168.10.60.0/30     *[Direct/0] 8w4d 19:51:37
                    > via ge-0/0/0.0
168.10.60.1/32     *[Local/0] 8w4d 19:51:37
                      Local via ge-0/0/0.0
168.10.60.4/30     *[OSPF/10] 00:36:32, metric 2
                      to 168.10.48.10 via ge-0/0/1.0
                    > to 168.10.60.10 via ge-0/0/1.0
                      to 168.10.60.2 via ge-0/0/0.0
168.10.60.8/30     *[Direct/0] 8w4d 19:36:19
                    > via ge-0/0/1.0
168.10.60.9/32     *[Local/0] 8w4d 19:36:19
                      Local via ge-0/0/1.0

Clearly from this command, we can see we have now gone beyond what might be considered a suitable summary because we are now encompassing routes that exist within the backbone Area 0.  So it should be clear from this simple set of commands that the 168.10.32.0/19 would be a suitable address to use for our summary.
We could easily apply a similar example to Area 2 to quickly determine what the best summary would be.  We see from looking at the diagram the lowest IP within Area 2 is the 168.10.96.1 loopback address applied to R3.  When we use that as our base and go through the steps above, we can find our summary:
sfouant@p2# run show route 168.10.96.0/19   
inet.0: 27 destinations, 27 routes (27 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
168.10.96.1/32     *[OSPF/10] 01:00:57, metric 1
                      to 168.10.112.2 via fe-0/0/3.0
                    > to 168.10.118.2 via fe-0/0/3.0
168.10.96.2/32     *[OSPF/10] 01:00:57, metric 1
                    > to 168.10.112.2 via fe-0/0/3.0
                      to 168.10.118.2 via fe-0/0/3.0
168.10.112.0/30    *[Direct/0] 01:13:48
                    > via fe-0/0/3.0
168.10.112.1/32    *[Local/0] 01:13:48
                      Local via fe-0/0/3.0
168.10.118.0/30    *[Direct/0] 01:13:48
                    > via fe-0/0/3.0
168.10.118.1/32    *[Local/0] 01:13:48
                      Local via fe-0/0/3.0

And there you have it! As you can see it's really quite simple and if you haven't stumbled upon this already you may be saying to yourself, "Why didn't I think of that before?".  I hear from many candidates that they spend considerable time the old fashioned way to determine summaries and I always ask myself why.  As you can see, there is an easier way!
Clearly the benefit to using a technique such as the above is to easily find the routes that best summarize a bunch of more specific routes.  The utility of such an approach, while very useful during a practical exam, might be considerably lessened in the real-world where it is likely that hierarchy has already been built into the network and you have network diagrams at your disposal.  On the other hand, there may be situations where you inherit a network that was developed with hierarchy in mind, however summarization was never employed, or it was employed improperly.  In such cases, the above technique can be a real time saver, allowing you to spend less time doing binary math and more time doing the fun stuff - like troubleshooting why that MPLS LSP isn't getting established!
Stay tuned for additional articles covering time saving tips and techniques which can be used during your next lab attempt!  Good luck, and may the force be with you!                

Wednesday, July 10, 2013

Ramadan kareem

ssalamualikum Dear Brother in Islam,
 

 
Wish u happy Ramadan kareem
 
 
 
 
It is the month when the devils are chained,
The gates of hell are closed & those of Paradise are opened,
It is the month the holy Prophet used to Pray to witness,
It is The Blessed Month Of Ramadhan.
May Allah shower his blessings &
 Grant You forgiveness in this holy month.
Fasting is our sacrifice it is the life of our soul let us sacrifice all our body since the soul has arrived as guest.
 
Happy Ramadan & Plzzzzz do remember in Dua.
 
Pls. find Attached....
 
 
Ramadan Dua: DAY 1
cid:2.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day make my fasts the fasts of those who fast (sincerely), and my standing up in prayer of those who stand up in prayer (obediently), awaken me in it from the sleep of the heedless, and forgive me my sins , O God of the worlds, and forgive me, O one who forgives the sinners.
 
Ramadan Dua: DAY 2
cid:3.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, take me closer towards Your pleasure, keep me away from Your anger and punishment, grant me the opportunity to recite Your verses (of the Qur'an), by Your mercy, O the most Merciful.
 
Ramadan Dua: DAY 3
cid:4.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, grant me wisdom and awareness, keep me away from foolishness and pretension, grant me a share in every blessing You send down, by You generosity, O the most Generous.
 
Ramadan Dua: DAY 4
cid:5.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, strengthen me in carrying out Your commands, let me taste the sweetness of Your remembrance, grant me, through Your graciousness, that I give thanks to You. Protect me, with Your protection and cover, O the most discerning of those who see.
 
Ramadan Dua: DAY 5
cid:6.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, place me among those who seek forgiveness. Place me among Your righteous and obedient servants, and place me among Your close friends, by Your kindness, O the most Merciful.
 
Ramadan Dua: DAY 6
cid:7.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, do not let me abase myself by incurring Your disobedience, and do not strike me with the whip of Your punishment, keep me away from the causes of Your anger, by and Your power, O the ultimate wish of those who desire.
 
Ramadan Dua: DAY 7
 
ALLAH, on this day, help me with its fasts and prayers, and keep me away from mistakes and sins of the day, grant me that I remember You continuously through the day, by Your assistance, O the Guide of those who stray.
 
Ramadan Dua: DAY 8
 
ALLAH, on this day, let me have mercy on the orphans, and feed [the hungry], and spread peace, and keep company with the noble-minded, O the shelter of the hopeful.
 
Ramadan Dua: DAY 9
 
ALLAH, on this day, grant me a share from Your mercy which is wide, guide me towards Your shining proofs, lead me to Your all encompassing pleasure, by Your love, O the hope of the desirous.
 
Ramadan Dua: DAY 10
cid:8.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, make me, among those who rely on You, from those who You consider successful, and place me among those who are near to you, by Your favor, O goal of the seekers.
 
Ramadan Dua: DAY 11
cid:9.4192935954@web192704.mail.sg3.yahoo.com
ALLAH, on this day, make me love goodness, and dislike corruption and disobedience, bar me from anger and the fire [of Hell], by Your help, O the helper of those who seek help
 
Ramadan Dua: DAY 12
 
ALLAH, on this day, beautify me with covering and chastity, cover me with the clothes of contentment and chastity, let me adhere to justice and fairness, and keep me safe from all that I fear, by Your protection, O the protector of the frightened.
 
Ramadan Dua: DAY 13
cid:10.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, purify me from un-cleanliness and dirt, make me patient over events that are decreed, grant me the ability to be pious, and keep company with the good, by Your help, O the beloved of the destitute.
 
Ramadan Dua: DAY 14
cid:11.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, do not condemn me for slips, make me decrease mistakes and errors, do not make me a target for afflictions and troubles, by Your honor, O the honor of the Muslims.
 
Ramadan Dua: DAY 15
 
cid:12.4192935955@web192704.mail.sg3.yahoo.com
 
 
 
 
Ramadan Dua: DAY 16
cid:13.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, grant me compatibility with the good, keep me away from patching up with the evil, lead me in it, by Your mercy, to the permanent abode, by Your God ship, O the God of the worlds.
 
 
Ramadan Dua: DAY 17
 
ALLAH, on this day, guide me towards righteous actions, fulfill my needs and hopes, O One who does not need explanations nor questions, O One who knows what is in the chests of the (people of the) world. Bless Muhammad and his family, the Pure.
 
 
Ramadan Dua: DAY 18
 
ALLAH, on this day, make me love goodness, and dislike corruption and disobedience, bar me from anger and the fire [of Hell], by Your help, O the helper of those who seek help.
 
 
Ramadan Dua: DAY 19
cid:14.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, multiply for me its blessings, and ease my path towards its bounties, do not deprive me of the acceptance of its good deeds, O the Guide towards the clear truth.
 
 
Ramadan Dua: DAY 20
cid:15.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, open for me the doors of the heavens, and lock the doors of Hell from me, help me to recite the Qur'an, O the One who sends down tranquility into the hearts of believers.
   
Ramadan Dua: DAY 21
cid:16.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, show me the way to win Your pleasure, do not let Shaytan have a means over me, make Paradise an abode and a resting place for me, O the One who fulfills the requests of the needy.
 
Ramadan Dua: DAY 22
cid:17.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, open for me the doors of Your Grace, send down on me its blessings, help me towards the causes of Your mercy, and give me a place in the comforts of Paradise, O the one who answers the call of the distressed.
 
Ramadan Dua: DAY 23
cid:18.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, wash away my sins, purify me from all flaws, examine my heart with (for) the piety of the hearts, O One who overlooks the shortcomings of the sinners.
 
Ramadan Dua: DAY 24
cid:19.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, I ask You for what pleases You, and I seek refuge in You from what displeases You, I ask You to grant me the opportunity to obey You and not disobey You, O One who is generous with those who ask
 
Ramadan Dua: DAY 25
 
ALLAH, on this day, make me among those who love Your friends, and hate Your enemies, following the way of Your last Prophet, O the Guardian of the hearts of the Prophets.
 
Ramadan Dua: DAY 26
 
ALLAH, on this day, make my efforts worthy of appreciation, and my sins forgiven, my deeds accepted, my flaws concealed, O the best of those who hear..
 
Ramadan Dua: DAY 27
 
ALLAH, on this day, bestow on me the blessings of Laylatul Qadr, change my affairs from (being) difficult to (being) easy, accept my apologies, and decrease for me [my] sins and burdens, O the Compassionate with His righteous servants.
 
Ramadan Dua: DAY 28
cid:20.4192935955@web192704.mail.sg3.yahoo.com
ALLAH, on this day, grant me a share in its nawafil (recommended prayers), honor me by attending to my problems, make closer the means to approach You, from all the means, O One who is not preoccupied by the requests of the beseechers.
 
Ramadan Dua: DAY 29
cid:21.4192935955@web192704.mail.sg3.yahoo.com
O ALLAH, on this day, cover me with Your mercy, grant me in it success and protection, purify my heart from the darkness of false accusations, O the Merciful to His believing servants.
 
Ramadan Dua: DAY 30
cid:22.4192935955@web192704.mail.sg3.yahoo.com
O ALLAH, on this day, make my fasts worthy of appreciation and acceptance, according to what pleases You, and pleases the Messenger, the branches being strengthened by the roots, for the sake of our leader, Muhammad, and his purified family. Praise be to ALLAH, the Lord of the worlds.
 

Tuesday, July 9, 2013

Life of Packet

Packet

A packet is the unit of data that is routed between an origin and a destination on the Internet or any other packet-switched network. When any file (e-mail message, HTML file, Graphics Interchange Format file, Uniform Resource Locator request, and so forth) is sent from one place to another on the Internet, the Transmission Control Protocol (TCP) layer ofTCP/IP divides the file into "chunks" of an efficient size for routing. Each of these packets is separately numbered and includes the Internet address of the destination. The individual packets for a given file may travel different routes through the Internet. When they have all arrived, they are reassembled into the original file (by the TCP layer at the receiving end).
A packet-switching scheme is an efficient way to handle transmissions on a connection less network such as the Internet. An alternative scheme, circuit-switched, is used for networks allocated for voice connections. In circuit-switching, lines in the network are shared among many users as with packet-switching, but each connection requires the dedication of a particular path for the duration of the connection.
"Packet" and "datagram" are similar in meaning. A protocol similar to TCP, the User Datagram Protocol(UDP) uses the term datagram.
RELATED GLOSSARY TERMS: RS-232C,