DSCP / ToS / ECN Decoder

The IPv4 ToS / IPv6 Traffic Class byte carries 6 bits of DSCP (Differentiated Services Code Point, RFC 2474) and 2 bits of ECN (Explicit Congestion Notification, RFC 3168). Click any bit, paste a hex byte, or pick a class — the tool shows the per-hop behavior, the legacy IP-Precedence/ToS mapping, and the kernel-tools commands to set the value.

Bit editor

Class lookup

bits 7–2DSCP · bits 1–0ECN · Click a bit to flip it.

ToS byte (hex)

ToS byte (decimal)

DSCP (0–63)

ECN

DSCP class

Expedited

PHB

5 (Critical)

IPv4 precedence

Not-ECT

ECN state

10111000

Binary

0xB8 / 184

Hex / decimal

EF (Expedited Forwarding)

Used for low-latency, low-jitter traffic like voice over IP. Receives priority queueing at routers.

Apply this on Linux

Class	DSCP	Hex (ToS)	Binary	Typical use

Legacy ToS field (RFC 791 / RFC 1349)

Before DiffServ, the same byte held 3 bits of IP Precedence plus single-bit Delay / Throughput / Reliability flags. Most modern stacks ignore these but some legacy routers still honor them — the table below shows how today's DSCP value would have been interpreted.

Precedence

D (low delay)

T (high throughput)

R (high reliability)