[openib-general] [RFCv2] InfiniBand EndPort Liveness and Responsiveness

[Hal Rosenstock]

Hi,

Here is version 2 of a writeup on proposed IB endport liveness and
responsiveness. This "grew" out of discussions on ibping on this list
some time ago and is updated based on comments from James. Thanks again
in advance for any comments on this.

-- Hal

InfiniBand EndPort Liveness and Responsiveness

Motivation

  While there exist methods to obtain some degree of the liveness and
  responsiveness of an InfiniBand end port using existing mechanisms
  (e.g. SM Get attribute), these rely on a lack of protection as well
  as not allowing sufficient flexibility. In addition, less of the 
  end port stack may be exercised.

  IBA supports general service (GS) vendor classes. There are 2 ranges
  of these: the first range does not support RMPP whereas the second
  range does. OpenIB has a vendor OUI of 0x001405. A vendor class of 
  0x34 (in vendor class 2 range) would be utilized for this. The class
  version in the MAD header indicates the version of this. Currently,
  this is version 1.

Packet Format
  (Refer to IBA 1.2 p. 1006 for vendor class 2 MAD format)

  Bytes 40-255 are defined as vendor data as follows:

In MAD if not RMPP'd, or in first MAD if RMPP'd:
  Byte 40: Type (1 byte)
    1 - Echo request
    2 - Echo response
    3 - LID/GUID information request
    4 - LID/GUID information response
  
  Byte 41-43: Reserved

  Byte 44-45: Identifier
  Byte 46-47: Sequence Number

  Byte 48-255: Data for Type 

In subsequent (non first) RMPP MADs:
  Byte 40-255: Continued Data for Type


Echo

The data received in the echo request message must be returned
in the echo reply message.

The identifier and sequence number may be used by the echo sender to aid
in matching the replies with the echo requests. For example, the
identifier might be used like a port in TCP or UDP to identify a
session, and the sequence number might be incremented on each echo
request sent. The echoer returns these same values in the echo reply.

can be RMPP'd or not

In MAD if not RMPP'd, or in first MAD if RMPP'd:
Byte 48-255: Echo data

Identifier. 16 bits.
This field is used to help match echo requests to the associated reply.
It may be set to zero.

Sequence number. 16 bits.
This field is used to help match echo requests to the associated reply.
It may be zero.

Echo Data. Variable length.
Implementation specific data.


LID/GUID information

Obtain the LID and port GUID of the requested port.

can be RMPP'd or not

In MAD if not RMPP'd, or in first MAD if RMPP'd:
Byte 48-49: LID
Byte 50-57: Port GUID