An IP protocol number is an 8-bit value in an IPv4 packet’s Protocol field that identifies the next-level protocol carried after the IP header. For example, 6 identifies TCP and 17 identifies UDP. IPv6 uses the corresponding 8-bit field called Next Header.
What an IP protocol number means
The number tells a receiving system how to interpret what follows the IP header. It is a protocol selector—not an IP address, an IP version, an Ethernet type, or a TCP/UDP port. IANA maintains the official Protocol Numbers registry, which lists assigned values and references.
As an Amazon Associate I earn from qualifying purchases.
In IPv4, the selector is in the Protocol field. IANA describes it as an 8-bit field identifying the next-level protocol; the registry note was last updated March 9, 2026. An 8-bit field has 256 possible bit patterns, calculated as 28.
Common IP protocol number examples
| Number | Protocol |
|---|---|
| 1 | ICMP |
| 6 | TCP |
| 17 | UDP |
These values are assigned in IANA’s Protocol Numbers registry. Check that registry for the current assignment and its references if you need to interpret another number.
#1 Best Overall
- Dual band router upgrades to 1200 Mbps high speed internet (300mbps for 2.4GHz plus 900Mbps for 5GHz), reducing buffering and ideal for 4K stream
- Full Gigabit Ports - Gigabit Router with 4 Gigabit LAN ports, ideal for any internet plan and allow you to directly connect your wired devices
- Boosted Coverage - Four external antennas equipped with Beamforming technology extend and concentrate the Wi-Fi signals
- MU-MIMO technology - (5GHz band) allows high speeds for multiple devices simultaneously
- Access Point Mode - Supports AP Mode to transform your wired connection into wireless network, an ideal wireless router for home
How IPv6 uses the selector
IPv6 calls the corresponding 8-bit selector the Next Header field. RFC 8200 defines it as identifying the type of header immediately following the IPv6 header. It uses the same IANA number space as IPv4’s Protocol field.
IPv6 extension headers can appear between the base IPv6 header and an upper-layer header. Each extension header has its own Next Header value, so the values form a chain: each one identifies what header comes next. The base header’s value therefore may identify an extension header rather than TCP, UDP, or another upper-layer protocol directly.
Rank #2
- 【Five Gigabit Ports】1 Gigabit WAN Port plus 2 Gigabit WAN/LAN Ports plus 2 Gigabit LAN Port. Up to 3 WAN ports optimize bandwidth usage through one device.
- 【One USB WAN Port】Mobile broadband via 4G/3G modem is supported for WAN backup by connecting to the USB port. For complete list of compatible 4G/3G modems, please visit TP-Link website.
- 【Abundant Security Features】Advanced firewall policies, DoS defense, IP/MAC/URL filtering, speed test and more security functions protect your network and data.
- 【Highly Secure VPN】Supports up to 20× LAN-to-LAN IPsec, 16× OpenVPN, 16× L2TP, and 16× PPTP VPN connections.
- Security - SPI Firewall, VPN Pass through, FTP/H.323/PPTP/SIP/IPsec ALG, DoS Defence, Ping of Death and Local Management. Standards and Protocols IEEE 802.3, 802.3u, 802.3ab, IEEE 802.3x, IEEE 802.1q
| IP version | Field name | Width | What it identifies |
|---|---|---|---|
| IPv4 | Protocol | 8 bits | The next-level protocol after the IPv4 header |
| IPv6 | Next Header | 8 bits | The next header; extension headers can chain to later headers |
Protocol number versus IP version number
These fields answer different questions. The protocol number identifies what comes next in the packet; the IP version number identifies which IP format is in use. The version field is 4 bits: 4 means IPv4 and 6 means IPv6. IANA’s IP Version Numbers registry was last updated January 28, 2021.
Protocol number versus port number
A protocol number is in the IP header and identifies the next-level protocol, such as TCP or UDP. A port number is used by TCP or UDP to identify an application endpoint within that transport protocol. For instance, 17 identifies UDP at the IP layer; it is not a UDP port.
Rank #3
- Dual-band Wi-Fi with 5 GHz speeds up to 867 Mbps and 2.4 GHz speeds up to 300 Mbps, delivering 1200 Mbps of total bandwidth¹. Dual-band routers do not support 6 GHz. Performance varies by conditions, distance to devices, and obstacles such as walls.
- Covers up to 1,000 sq. ft. with four external antennas for stable wireless connections and optimal coverage.
- Supports IGMP Proxy/Snooping, Bridge and Tag VLAN to optimize IPTV streaming
- Access Point Mode - Supports AP Mode to transform your wired connection into wireless network, an ideal wireless router for home
- Advanced Security with WPA3 - The latest Wi-Fi security protocol, WPA3, brings new capabilities to improve cybersecurity in personal networks
Where to verify an assignment
Use IANA’s Protocol Numbers registry for current numeric assignments and references. For the IPv6 Next Header field’s definition and extension-header behavior, see RFC 8200, Section 3 (published July 2017).
Quick Recap
Best Value
- Next-Gen Gigabit Wi-Fi 6 Speeds: 2402 Mbps on 5 GHz and 574 Mbps on 2.4 GHz bands ensure smoother streaming and faster downloads; support VPN server and VPN client¹
- A More Responsive Experience: Enjoy smooth gaming, video streaming, and live feeds simultaneously. OFDMA makes your Wi-Fi stronger by allowing multiple clients to share one band at the same time, cutting latency and jitter.²
- Expanded Wi-Fi Coverage: 4 high-gain external antennas and Beamforming technology combine to extend strong, reliable, Wi-Fi throughout your home.
- Improved Battery Life: Target Wake Time helps your devices to communicate efficiently while consuming less power.
- Improved Cooling Design: No heat ups, no throttles. A larger heat sink and redefined case design cools the WiFi 6 system and enables your network to stay at top speeds in more versatile environments.
Rank #4
- DUAL-BAND WIFI 6 ROUTER: Wi-Fi 6(802.11ax) technology achieves faster speeds, greater capacity and reduced network congestion compared to the previous gen. All WiFi routers require a separate modem. Dual-Band WiFi routers do not support the 6 GHz band.
- AX1800: Enjoy smoother and more stable streaming, gaming, downloading with 1.8 Gbps total bandwidth (up to 1200 Mbps on 5 GHz and up to 574 Mbps on 2.4 GHz). Performance varies by conditions, distance to devices, and obstacles such as walls.
- CONNECT MORE DEVICES: Wi-Fi 6 technology communicates more data to more devices simultaneously using revolutionary OFDMA technology
- EXTENSIVE COVERAGE: Achieve the strong, reliable WiFi coverage with Archer AX1800 as it focuses signal strength to your devices far away using Beamforming technology, 4 high-gain antennas and an advanced front-end module (FEM) chipset
- OUR CYBERSECURITY COMMITMENT: TP-Link is a signatory of the U.S. Cybersecurity and Infrastructure Security Agency’s (CISA) Secure-by-Design pledge. This device is designed, built, and maintained, with advanced security as a core requirement.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
