Multi-Tech Systems MVPFXS-24, MVPFXS-8, MVPFXS-16 manual Bits =, Type of Service or TOS field

MultiVOIP FXS User Guide Technical Configuration

The IP Datagram with Header, Its Type-of-Service field, & DiffServ

bits =>

0	4	8	16		19	24		31
VERS	HLEN	TYPE OF				TOTAL LENGTH
		SERVICE
	IDENTIFICATION			FLAGS		FRAGMENT OFFSET
TIME TO LIVE		PROTOCOL				HEADER CHECKSUM
		SOURCE IP		ADDRESS
		DESTINATION IP ADDRESS
		IP OPTIONS (if any)					PADDING …
							end of header
			DATA
			…

The TOS field consists of eight bits, of which only the first six are used. These six bits are called the “Differentiated Service Codepoint” or DSCP bits.

The Type of Service or “TOS” field

0	1	2	3	4
	PRECEDENCE		D	T

5

R

67 unused

three precedence have eight values, 0-7, ranging from “normal” precedence (value of 0) to “network control” (value of 7). When set, the D bit requests low delay, the T bit requests high throughput, and the R bit requests high reliability.

Routers that support DiffServ can examine the six DSCP bits and prioritize the packet based on the DSCP value. The DiffServ Parameters fields in the MultiVOIP IP Parameters screen allow you to configure the DSCP bits to values supported by the router. Specifically, the Voip Media PHB field relates to the prioritizing of audio packets (RTP and RTCP packets) and the Call Control PHB field relates to the prioritzing of non-audio packets (packets concerning call set-up and tear-down, gatekeeper registration, etc.).

The MultiVOIP Call Control PHB parameter defaults to 34 decimal (22 hex; 100010 binary – consider vis-à-vis TOS field above) for Assured Forwarding behavior. The MultiVOIP Voip Media PHB parameter defaults to the value 46 decimal (2E hex; 101110 binary – consider vis-à-vis TOS field above). To disable DiffServ, configure both fields to 0 decimal.

IP Parameter Definitions (cont’d)

Field Name	Values	Description
DNS Parameter fields
Enable DNS	Y/N	Enables Domain Name Space/System function where computer
	Default = disabled	names are resolved using a worldwide distributed database.
DNS Server IP	4-places, 0-255.	IP address of specific DNS server to be used to resolve Internet
Address		computer names.
FTP Parameter fields
FTP Server	Y/N	MultiVOIP unit has an FTP Server function so that firmware and
Enable	Default = enabled	other important operating software files can be transferred to the
	See “FTP Server	voip via the network.
	File Transfers” in
	Operation &
	Maintenance
	chapter.

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