iSNS, Internet Storage Name Service

Description Glossary RFCs Publications Obsolete RFCs


Protocol suite: TCP/IP.
Protocol type:Application layer protocol.
Port:3205 (TCP, UDP).
MIME subtype:
Working groups: ips, IP Storage.

The iSNS protocol is designed to facilitate the automated discovery, management, and configuration of iSCSI and Fibre Channel devices on a TCP/IP network. iSNS provides intelligent storage discovery and management services comparable to those found in Fibre Channel networks, allowing a commodity IP network to function in a similar capacity as a storage area network. iSNS also facilitates a seamless integration of IP and Fibre Channel networks, due to its ability to emulate Fibre Channel fabric services, and manage both iSCSI and Fibre Channel devices. iSNS thereby provides value in any storage network comprised of iSCSI devices, Fibre Channel devices, or any combination thereof.

MAC header IP header TCP | UDP header iSNS header Data :::

iSNS header:

0001020304050607 0809101112131415 1617181920212223 2425262728293031
Version Function ID
Length Flags
Transaction ID Sequence ID
Data :::

Version. 16 bits.
iSNS version number.

Function ID. 16 bits.
Defines the type of iSNS message and the operation to be executed. Values with the leading bit cleared indicate query, registration, and notification messages. Values with the leading bit set indicate response messages.

Length. 16 bits.
Specifies the size of the payload in bytes. The message contains TLV attributes for the operation. Additionally, response messages contain a success/failure code. The data in this field MUST be 4-byte aligned.

Flags. 16 bits.

0001020304050607 0809101112131415

C, iSNS client. 1 bit.
If set, the sender is the iSNS client.

S, iSNS server. 1 bit.
If set, the sender is the iSNS server.

A, Authentication block. 1 bit.
If set, the authentication block is present.

R, Replace flag. 1 bit.

L, Last PDU. 1 bit.

F, First PDU. 1 bit.

Transaction ID. 16 bits.
This field MUST be set to a unique value for each concurrently outstanding request message. Replies MUST use the same Transaction ID value as the associated iSNS request message. If a message is retransmitted, the original Transaction ID value MUST be used. All PDUs comprising an iSNSP message must have the same Transaction ID value.

Sequence ID. 16 bits.
This field has a unique value for each PDU within a single transaction. The Sequence ID value of the first PDU transmitted in a given iSNS message MUST be zero, and each Sequence ID value in each PDU MUST be numbered sequentially in the order in which the PDUs are transmitted.

Data. Variable length.



[RFC 3723] Securing Block Storage Protocols over IP.

[RFC 4171] Internet Storage Name Service (iSNS).


Obsolete RFCs:

Description Glossary RFCs Publications Obsolete RFCs