Andrew Steele

Router Jargon

This page looks at some of the more obscurely-named items often found in routers. Please note that some of the names used are vendor specific, and that names differ between manufacturers and even models of router.

LAN

IGMP Snooping

IGMP (Internet Group Management Protocol) Snooping allows the router to listen in on IGMP conversations between hosts and routers, and maintain a map of multicase transmissions. Any links which do not require multicast can be omitted, therefore saving bandwidth on those links.

Wireless

Disable WMM Advertise

WMM are Wireless Multimedia Extensions which provides Quality of Service and traffic prioritisation. This is typically required to achieve higher bit rates on wireless connections, so is usually enabled though it can be disabled for compatibility reasons.

Wireless Multicast Forwarding

Protected Management Frames

Protected Management Frames provides protection for action frames and prevent eavesdropping and forging.

OBSS Coexistence

Allows the 5GHz wireless mode to automatically change the channel width between 40MHz and 20MHz. This prevents interference from other nearby access points. When it is disabled, the router uses the manually set channel width.

Turbo QAM

Requiring support on both devices, Turbo QAM allows the bandwidth between the router and communicating device to be increased.

Regulatory Mode

Often turned off by default, the usual settings are 802.11d (also known as World Mode) or 802.11h. The idea is prevent interference with satellites and radar using the same 5GHz frequency band.

802.11n/EWC

802.11n/EWC (Enhanced Wireless Core)

Control Sideband

Allows the extension channel to be set as the upper or lower sideband.

RIFS Advertisement

An 802.11n feature, RIFS Advertisement improved performance by reducing the amount of time between Orthogonal frequency-division multiplexing (OFDM) transmissions.

RX Chain Power Save

If enabled, the access point will save power by turning off one of the receive chains if the Quiet Time and PPS threshold values are reached.

XPress™ Technology

XPress™ Technology is a Broadcom standard which repackages data to reduce the number of control packets, and allow an increase in the amount of data which is sent at any given time.

Broadband

Modulation

The following modulation types are available on most routers:

Each of the different modulation types support different connection types and speeds, and use varying methods to attain the best speed and stability balance. Some modulation types work better than others for different lines, and may achieve varying download and upload speeds.

Profile

The following profile values are usually available:

The profile type is defined by the DSLAM.

US0

PhyR

PhyR (also known as Physical Retransmission) can usually be independently enabled for the upstream and downstream DSL connection. It is a Broadcom specific feature, which is only useful if the endpoint is also Broadcom, and intends to make the connection more resilient to errors.

Bitswap

Bitswap attempts to make the line connection more reliable by swapping out noisy frequencies with others that have less interference. In most cases, enabling it has no negative effect and can reduce errors, particularly on long lines.

SRA

SRA (Seamless Rate Adaption) if supported by the DSLAM, allows for the broadband speed to be changed on-the-fly, rather than having to drop the connection and re-establish. This is useful for lines which have fluctuating signal-to-noise ratios, and allows the speed to be adjusted up or down based on the current signal-to-noise ratio.

Power Management

Energy Efficient Ethernet

Energy Efficient Ethernet (sometimes known as EEE or Green Ethernet) are enhancements which reduce the power consumption of Ethernet connections during low data activity.