[openib-general] RDMA connection and address translation API

[Talpey, Thomas]

At 12:56 PM 8/25/2005, Caitlin Bestler wrote:
>Generic code MUST support both IPv4 and IPv6 addresses.
>I've even seen code that actually does this.

Let me jump ahead to the root question. How will the NFS layer know
what address to resolve?

On IB mounts, it will need to resolve a hostname or numeric string to
a GID, in order to provide the address to connect. On TCP/UDP, or
iWARP mounts, it must resolve to IP address. The mount command
has little or no context to perform these lookups, since it does not
know what interface will be used to form the connection.

In exports, the server must inspect the source network of each
incoming request, in order to match against /etc/exports. If there
are wildcards in the file, a GID-specific algorithm must be applied.
Historically, /etc/exports contains hostnames and IPv4 netmasks/
addresses.

In either case, I think it is a red herring to assume that the GID
is actually an IPv6 address. They are not assigned by the sysadmin,
they are not subnetted, and they are quite foreign to many users.
IPv6 support for Linux NFS isn't even submitted yet, btw.

With an IP address service, we don't have to change a line of 
NFS code.

Tom.


>
>So supporting GIDs is not that much of an issue as long
>as no IB network IDs are assigned with a meaning that
>conflicts with any reachable IPv6 network ID. (In other
>words, assign GIDs so that they are in fact valid IPv6
>addresses. Something that was always planned to be one
>option for GIDs).
>
>
>
>> -----Original Message-----
>> From: openib-general-bounces at openib.org 
>> [mailto:openib-general-bounces at openib.org] On Behalf Of James Lentini
>> Sent: Thursday, August 25, 2005 9:48 AM
>> To: Tom Tucker
>> Cc: openib-general at openib.org
>> Subject: RE: [openib-general] RDMA connection and address 
>> translation API
>> 
>> 
>> 
>> On Wed, 24 Aug 2005, Tom Tucker wrote:
>> 
>> > > 
>> > >  - It's not just preventing connections to the wrong 
>> local address.
>> > >    NFS-RDMA wants the remote source address (ie 
>> getpeername()) so that
>> > >    it can look it up in the exports list.
>> > 
>> > Agreed. But you could also get rid of ATS by allowing GIDs to be 
>> > specified in the exports file and then treating them like
>> > IPv6 addresses for the purpose of subnet comparisons.
>> 
>> Could generic code use both GIDs and IPv4 addresses? 
>> _______________________________________________
>> openib-general mailing list
>> openib-general at openib.org
>> http://openib.org/mailman/listinfo/openib-general
>> 
>> To unsubscribe, please visit 
>> http://openib.org/mailman/listinfo/openib-general
>> 
>> 
>
>_______________________________________________
>openib-general mailing list
>openib-general at openib.org
>http://openib.org/mailman/listinfo/openib-general
>
>To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general