Category Archives: IT Topics

TCP: MSS & MTU

Difference between MSS and MTU

If you start to study the protocols of the Internet and particular TCP/IP you may bump into MSS & MTU

MSS and MTU are almost the same, but not quite.

MTU_MSS

MSS is the Maximum Segment Size which is the largest TCP segment (layer 4, yet not including the layer 4 header) that can fit on the current physical medium.

MTU is the Maximum Transmission Unit which is the largest IP packet (layer 3, including the layer 3 header) that can be transmitted.

The MSS is used during the 3-way handshake of TCP to let each side know that maximum segment size they can transmitt in a single frame.  It’s purpose is to minimize IP fragmentation.  However, that is only each side.  Who only knows what is in the middle.  That is why each entity in between must know what its MTU size is in case fragmentation is required somewhere along the path.

For example, if you were on an ethernet segment:

Maximum frame size:       1518
less the DLC header       – 18 *
equals MTU:               1500
less IP header            – 20 **(default)
less TCP header           – 20 ***(default)
equals MSS:               1460

* DLC contains 6 bytes for destination MAC address, 6 for source, 2 for Ethertype, and 4 for CRC

** IP header is 20 bytes by default, but can be as large as 60 bytes.

*** TCP header is 20 bytes by default, but can be as large as 60 bytes.  It is much more common for the TCP header to have options and therefore be larger than the default.

2014 World’s Most Ethical Companies

Juniper, Google, Microsoft, Symantec, Dell,  & Cisco on the list

ethical-companies-WME-honorees

The World’s Most Ethical (WME) Companies designation recognizes companies that truly go beyond making statements about doing business “ethically” and translate those words into action. WME honorees not only promote ethical business standards and practices internally, they exceed legal compliance minimums and shape future industry standards by introducing best practices today.

This year’s 144 honorees represent 41 industries and include 21 first-time honorees.  In this eighth year of recognizing companies, Ethisphere is honoring the largest group of organizations based outside the U.S. – 38 organizations from 21 countries and 5 continents.

RDP /admin switch

Command line parameters for Remote Desktop Connection

2600_RDP_Admin_Login

/admin connects you to the RDP session as admin overruling all warnings. So if you get the “limit reached” connection error and can’t connect (something along that message) you can use the /admin switch to overrule it and connect anyway.

Parameter
Description

/admin

Is used for administration of a Remote Desktop Session Host server. In this version of Remote Desktop Connection, if the Remote Desktop Session Host role service is installed on the remote computer, running mstsc /admin will do the following (for the current connection only):

  • Disable Remote Desktop Services client access licensing
  • Disable time zone redirection
  • Disable RD Connection Broker redirection
  • Disable Remote Desktop Easy Print

/admin also does the following on connections to Windows Server 2008 R2 with the RD Session Host role service installed:

  • Disables Plug and Play device redirection for this connection only.
  • Changes the remote session theme to Windows Classic View (if it’s available) for this connection only.

To connect to a remote computer with the RD Session Host role service installed, follow these steps:

  1. Open the Command Prompt window by clicking the Start button Picture of the Start button. In the search box, type Command Prompt, and then, in the list of results, click Command Prompt.
  2. Type mstsc /v:server /admin.