Ping Latency: Big Confusion

[Kuldeep singh]

Hello Experts,

1. What does mean of Latency Check in network ? Plz explain in simple Words...

2. How to check Latency through PING Command and how to identify result through Ping output like as

   Reply from 74.125.224.82: bytes=32 time=68ms TTL=52

   Please explain all fields like as " Bytes" and its Range, "time" and "TTL"         

3. What does mean of this command, plz explain in easy way

Ping www.cisco.com -l 3500

    I am confused with "ip packet" size, How can i check Load or Latency through change the value of  "Packet Size" ?

    I am still confused with value 3500, this value indicates which thing:   Lan/Wan 10/100/1000 Port of router  or

    ISP link bandwidth in kbps/mbps  or  else ?

4. Suppose our two location and both are connected to 4 Mbps point to point lease line pipe with router then how to check

    Latency between them . plz explain with best example so that i can understand at once.

5. What is notation of IPV4 addess:  Decimal  or Octal ?

6. How to calculate that IPV4 is 32 bits  and IPV6 is 128 Bits ? Plz explain with Mathematical Calculation 

KS

[Kuldeep singh]

Plz Help me Out

[Joseph W. Doherty · Accepted solution]

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Posting

#1 Latency is a measure of how much time.  Often a latency check on a network is done using ping, which times how much time it took another device to respond to a ping request.  I.e. you start a timer when you send the ping request and then you stop the timer when you get the ping reply.  The difference between sent time and receive time is a measure of RTT (round trip time) latency.

#2 bytes is the size of the packet sent in the ping request, time is the difference between when the request was made and the reply (i.e. how long did it take), TTL is time to live (a counter that gets decremented across every L3 hop - when it hits zero packet is dropped - if you knew what it started with, it would indicate number of L3 hops)

#3 part of latency is how long it takes to serialize the packet (bigger packets take longer to transmit and receive, because they are bigger - if you have ever copied files on a computer - bigger files take longer to copy, right?)

#4 starting from device on one side of the p2p link, ping the other side's IP - ms provides latency - normal pings may not be highly accurate (for multiple reasons)

#5 IPv4 is normally shown as dotted decimal values for its 4 octets.

e.g. 192.168.5.53 = 11000000 10101000 00000101 00110101

#6 unclear what you want to calculate - an IPv4 address is 32 bits, an IPv6 address is 128 bits - this question would be similar to how to calulate an eight bit byte - again, calculate how?

[blau grana · Accepted solution]

Hello,

192.168.100.200

IPv4 address is composed of 4 octets, each octet is represented by number from range [0 - 255 in decimal] or [00000000 - 11111111 in binary]. As you can see in binary you have to use 8 digits, each digit is one bit.

So each octet is represented with 8 bits, there is 4 octets => 8 x 4 = 32 bits.

Same logic is used with IPv6 address.

2001:0db8:85a3:0000:0000:8a2e:0370:7334

There is 8 fields. Each field is composed of 4 characters and each chareacter is represented by 4 bits.

1 character range - 0 - F [0000 - 1111 in binary]

8 x 4 x 4 = 128 bits.

Best Regards

Please rate all helpful posts and close solved questions

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

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In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

#3, It is unclear to me, how can we check load through change "ip packet" value in bytes without sending any data over Link physically? Please explain with simple example ?

No, that's correct, you do send data over the link physically.

Let's say your physical link offers 1 Mbps. So sending 64 bytes takes:  64 bytes * 8 bits/byte / 1,000,000 bps = .512 ms.  While sending 1500 bytes takes: 1,500 bytes * 8 bits/byte / 1,000,000 = 12 ms.  If two way ping, double the values.

If we worked the above in reverse, i.e. ping'ed both 64 and 1500, took the delta between the two, assumed the extra latency was due to just bandwidth, we could have found 1 Mbps would account for the extra latency between the ping sizes.

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

I'm still not 100% sure what you're looking to calculate.  IPv4 is 32 bits, because that's what it was designed to be and IPv6 is 128 bits as that's what it was designed to be.  Perhaps Blau is on the right track in his post showing how we represent IPv4 and IPv6 addresses.

Blau nicely describes IPv4.  The 32 bit address is broken into 4 8 bit components, each of their binary values are converted to decimal, and we use periods to separate them.  Each decimal number suppresses leading zeros.

As IPv6 is 4 times larger, its 128 bit address is broken into 8 16 bit components, each of their binary values are converted to hexadecimal, and we use colons between them.  As these addresses are so large, you can suppress leading zeros, and if you have multiple components, back-to-back, that are zero you can also suppress the zero and excess colons, but you can only do this once.

e.g.

0012:0abc:0000:0000:0000:fe09:0000:0001

may be shown as:

12:abc:0:0:0:fe09:0:1

or

12:abc::fe09:0:1

or

0000:0000:0000:0000:0000:0000:0000:0001

may be shown as:

::1