Summary

Nomad dynamically analyzes the overall WAN traffic to ensure that it only uses a percentage of the total. It uses dynamic block sizes to allow it to take full speed advantage of high-bandwidth links while retaining its low impact on low-bandwidth links. It is also aware of mobile devices and knows the difference between wireless and wired connections and is able to select the most efficient available connection to use.

On this page

Overall bandwidth usage throttling

Nomad respects business data on the network – it detects the true end-to-end available bandwidth and monitors this throughout the duration of the download. This is calculated using a sophisticated algorithm that looks beyond the receiving capabilities of each machine's network card. If bandwidth is available, the transfer speeds up; if it becomes restricted, the transfer slows down. As a result, overall WAN availability is maximized and the impact on the critical link between the branch networks and the central network is minimized.

To avoid placing a burden on office wireless bandwidth and to use the most efficient transfer system possible, Nomad can be configured to switch from a wireless to a wired network connection automatically when one becomes available.

Bandwidth throttling

Maximizing download speed for high-bandwidth links using Dynamic Block Sizes

Nomad version 6.3 introduces a new mechanism to speed up downloads for high-bandwidth links. Nomad was originally designed to run over low-bandwidth links and to minimize impact on bandwidth usage. To ensure this Nomad used a fixed block size of 32KB to avoid congestion on the link. However with today's high-bandwidth links, running with a far higher capacity than was previously thought imaginable, a fixed block size severely restricts copying efficiency.

To solve the high-bandwidth efficiency issue while still retaining minimal impact on low-bandwidth links, Nomad 6.3 introduces a mechanism called Dynamic Block Size (DBS). Using DBS, Nomad is able to automatically decide the appropriate block size for a given link bandwidth and also adjust it as needed during the download if the link conditions change. As a result, Nomad is far more efficient and faster on all types of connection bandwidths while retaining its minimal impact on other link traffic.

To make DBS perform at its highest level, in Nomad 6.3 the default value of BlockSize registry setting has been changed from 32KB (0x8000) to 128KB (0x20000).

The Nomad 6.3 installer will automatically set this to 128KB for both fresh installs and upgrades from previous versions. The only exceptions to this are:

  • It will use the specified value if the BLOCKSIZE property is used in the installation command line or in a MST transform, when doing a fresh install or upgrade
  • It will retain the previous value of BlockSize if it was set to anything other than 32KB (the older default), when doing an upgrade

Managing stable LAN connections

Nomad provides extra stability by managing a machine's network connections as they move between a wireless and a wired LAN. Often, once an SMB or HTTP session is running on a wireless connection, it will remain on it even when a wired LAN becomes available. Nomad will drop a wireless connection in favor of a wired LAN connection if one is available.

If a Nomad master was initiated when a machine was on a wireless connection and a wired connection subsequently became available, Nomad disables the wireless adapter for a long enough period to enable a switchover to the wired connection. As a result of this, the IP address and the share path will change and error messages will appear in the logs until the connection is re-established to the master and the new share location.

This feature is turned off by default so as not to disrupt other applications which might be using the existing wireless connection.

To enable this feature, update the NormadBranch WLanBlipSecs registry value to 20 seconds or more. By default, it is 0.

WLanBlipSecs REG_DWORD 20

You can also control which service set identifier (SSID) Nomad connects to by managing a list. To do this, update the NomadBranch WLanProfileList registry value with a comma-delimited list of SSIDs or use the wildcard (*) character for any SSID. For example:

WLanProfileList REG_SZ WIFIGAP,GUEST
WLanProfileList REG_SZ *

WanBlipSecs registry value

Setting intra-day work rates

Nomad allows hourly variable work rates to be set throughout the day enabling organizations to use different maximum percentage of available bandwidth during the working day and in the evenings. Intra-day work rates are set on the client using the MaxWorkRates registry value. If the intra-day work rate is less than that defined on the command-line, it will override the command-line value. If the intra-day work rate is higher than that defined on command-line, the command-line value is used in preference.

Work rates only applies to transfers from a DP not to P2P transfers within a LAN, hence, it does not apply to SSD downloads.

On Configuration Manager 2012 machines, the registry value is located in

HKLM\Software\1E\NomadBranch\MaxWorkRates

Work rate override arguments

The intra-day work rates can be overridden using the -- wro and -- wr Nomad command-line arguments.

  • If these two arguments are combined, the value for the -- wr switch is used in preference to the intra-day work rate set in the registry
  • If using intra-day work rates and the -- wr argument only, the lower of the two values is used

MaxWorkRates value can be set from 1-100.

Inhibiting subnets and sites

You can define subnets and AD sites where machines will download from the DP (these machines will not relay download status messages) and not participate in Nomad elections. This feature only supports IPv4 subnets and is useful for sites that have:

  • a local DP
  • a VPN without isolation. Typically, VPN solutions isolate each client using single-node subnets (i.e. each client is in its own subnet with a 32-bit subnet mask) to prevent broadcast traffic between VPN clients that are typically geographically dispersed and not on the same local network. If the VPN solution is not configured in this manner and clients get an IP address with a subnet mask less than 32 bits, broadcasts can be exchanged between the VPN clients enabling Nomad to elect a master that is not on the same local network.

The Nomad additional setting ++pr will not override the download priority.

The Nomad NomadInhibitedSubnets or NomadInhibitedADSites registry values can be set with a comma separated list of sites or subnets in which Nomad functionality should be inhibited. If the client machine exists in either an inhibited subnet or an inhibited site, peer functionality is disabled, the agent will not participate in elections and will download from the DP.

Inhibit files and formats

You can append the inhibited subnet and AD site lists with content from text files to make it easier to manage if there are many sites and subnets to be defined. Inhibited sites or subnets are defined in text files with a .inh extension and must reside in the %INSTALLDIR%\Inhibits directory.

Each file should contain a list of the inhibited subnets in a classless inter-domain routing (CIDR) format, or a list of inhibited AD sites. Each site or subnet must be on a separate line or be separated by commas. For example, the following defines two subnets and one AD site to be inhibited:

192.168.0.0/24, 192.168.1.0/24
ACMEDOM1

When the Nomad service starts or is reset, any .inh files in the Nomad %INSTALLDIR%\Inhibits directory are read in. Both the registry values and the contents of these files are used together to determine the list of inhibited subnets and sites.

A service reset occurs when the Nomad registry is updated or there is a change of subnet. So, if a laptop moves to another subnet half way through a download, the Nomad service will reset and check the current subnet against its list of inhibited subnets. If the check determines that the new subnet is an inhibited subnet, Nomad’s peer-to-peer functionality is disabled – the service stops downloading from the peer and will instead download from the local DP.