Performance

DSCP / QoS Converter

Translate a QoS marking between DSCP (EF, AFxy, CSx), the ToS/DS byte in hex and binary, IP Precedence and 802.1p CoS, with the meaning of each class (PHB). Type a number 0–63, a name or the byte 0–255. Everything in your browser.

redzilla.cl — dscp

DSCP —

Name —

ToS/DS —

CoS —

DSCP

—

ToS/DS byte

—

DSCP × 4 · bits 7–2

IP Precedence · CoS

—

DSCP ÷ 8 (top 3 bits)

Class meaning (PHB)

—

DS / ToS byte breakdown

Bits	Field	Value

DSCP bits (7–2) ECN bits (1–0, here 0)

Common QoS markings

Name	DSCP	ToS hex	Prec.	CoS

How it is calculated · DSCP, ToS, IP Precedence and CoS

1. The DSCP is the top 6 bits of the differentiated services (DS) byte, formerly the ToS field. It ranges from 0 to 63.

2. The full byte is ToS = DSCP × 4 (DSCP << 2): the DSCP occupies bits 7–2 and the low 2 bits (1–0) are ECN, here set to 0.

3. The IP Precedence and the suggested 802.1p CoS are the top 3 bits: DSCP ÷ 8 (DSCP >> 3), from 0 to 7.

4. Names: CSx = x·8, AFxy = 8·x + 2·y (class x, drop precedence y) and EF = 46 for low-latency voice.

Runs locally in your browser · no sign-up · nothing leaves your browser.

How it works

The converter translates a QoS marking across all its representations: DSCP (0-63, the top 6 bits of the differentiated services byte defined in RFC 2474), its standard name (default, CS0 to CS7, AF11 to AF43, EF), the full ToS/DS byte in decimal, hex and binary, the legacy IP Precedence and the suggested 802.1p CoS for the Ethernet frame. It auto-detects the input format: name, number or hex (0x…).

The conversions follow the DiffServ specification: ToS byte = DSCP × 4 (DSCP sits in bits 7-2; bits 1-0 are ECN), IP Precedence = CoS = DSCP ÷ 8 (the top 3 bits), CSx = x × 8, AFxy = 8x + 2y (RFC 2597) and EF = 46 (RFC 3246). It also describes the PHB (per-hop behavior) of each class: how that traffic is treated in the queues of a router or switch.

Example: decoding the EF voice marking

Type EF (or 46): it is the standard DSCP for real-time voice, Expedited Forwarding (RFC 3246).
ToS/DS byte: 46 × 4 = 184 = 0xB8, the value you will see in Wireshark captures or legacy configurations.
IP Precedence and CoS: 46 ÷ 8 = 5, so on the VLAN the traffic should be marked with 802.1p CoS 5.

Frequently asked questions

Which DSCP is used for voice, video and signaling?

The common convention (based on RFC 4594) is EF (46) for the RTP audio of voice calls, AF41 (34) for video conferencing and CS3 (24) for SIP/SCCP signaling. CS6 and CS7 are reserved for network control protocols such as OSPF or BGP, and CS1 (8) for low-priority (scavenger) traffic.

What is the difference between DSCP and 802.1p CoS?

DSCP travels in the IP header (layer 3) and survives end to end as long as nobody rewrites it; 802.1p CoS is 3 bits in the VLAN tag (layer 2) that only exist inside tagged frames and are lost when crossing an untagged link. Since CoS has 8 values and DSCP 64, the typical mapping uses the top 3 bits: CoS = DSCP ÷ 8.

What do the two digits of AF31 or AF41 mean?

The first digit is the Assured Forwarding class (1 to 4), which selects the queue; the second is the drop precedence (1 low, 2 medium, 3 high): under congestion, packets with the higher number are dropped first. The numeric value comes from 8x + 2y: AF31 = 8×3 + 2×1 = 26 and AF41 = 34.

Why does Wireshark show 0xB8 when my DSCP is 46?

Because many tools display the full DS byte, not just the DSCP: the DSCP occupies the top 6 bits, so the byte equals DSCP × 4 plus the 2 ECN bits. 46 × 4 = 184 = 0xB8 with ECN at zero. The reverse conversion is dividing the byte by 4. The converter runs entirely in your browser and sends no data.

Was this tool useful?

Disclaimer

We take great care to keep every tool accurate and review it thoroughly; even so, we can't guarantee it is free of errors or take responsibility for how the results are used. We recommend double-checking anything critical.

Found an error? Let us know →