From: Daniel Browne <dbrowne@(email surpressed)>
Subject: Jumbo Frames and Older Machines
   Date: Wed, 08 Sep 2010 22:14:30 -0400

We're in the midst of some network upgrades and are having some difficulties
transitioning to using ethernet Jumbo frames. Several of our older
machines (PowerMac G5's) do not have hardware support for Jumbo frames.
The switch they are connected to allows me to configure frame mtu size
on a per-port basis, but this is not preventing packet drops enough
to allow Rush to work properly. Jobs are taking inordinately long
(which may be due to NFS packet loss caused by jumbo frames) and
I cannot push updated hosts list files to these machines.

If anyone can suggest a solution I'm open to it, though we overall are
having enough issues that we may need to abandon Jumbo frames altogether
until such time as the older equipment is decommissioned.

Thanks,

-Dan

	Up the MTU using ifconfig(1) to match the other boxes if you can.
	I believe mismatched MTUs affects UDP packet assembly.

Daniel Browne wrote:
> We're in the midst of some network upgrades and are having some difficulties
> transitioning to using ethernet Jumbo frames. Several of our older machines
> (PowerMac G5's) do not have hardware support for Jumbo frames. The switch
> they are connected to allows me to configure frame mtu size on a per-port
> basis, but this is not preventing packet drops enough to allow Rush to work
> properly. Jobs are taking inordinately long (which may be due to NFS packet
> loss caused by jumbo frames) and I cannot push updated hosts list files
> to these machines.
> 
> If anyone can suggest a solution I'm open to it, though we overall are having
> enough issues that we may need to abandon Jumbo frames altogether until
> such time as the older equipment is decommissioned.

-- 
Greg Ercolano, erco@(email surpressed)
Seriss Corporation
Rush Render Queue, http://seriss.com/rush/
Tel: (Tel# suppressed)ext.23
Fax: (Tel# suppressed)
Cel: (Tel# suppressed)

The system rejects any mtu larger than 1518. We've had lots of other issues
with it as well, so we've basically got no choice but to change back to 
standard.


On Sep 8, 2010, at 7:17 PM, Greg Ercolano wrote:

[posted to rush.general]

	Up the MTU using ifconfig(1) to match the other boxes if you can.
	I believe mismatched MTUs affects UDP packet assembly.

Daniel Browne wrote:
> We're in the midst of some network upgrades and are having some difficulties
> transitioning to using ethernet Jumbo frames. Several of our older machines
> (PowerMac G5's) do not have hardware support for Jumbo frames. The switch
> they are connected to allows me to configure frame mtu size on a per-port
> basis, but this is not preventing packet drops enough to allow Rush to work
> properly. Jobs are taking inordinately long (which may be due to NFS packet
> loss caused by jumbo frames) and I cannot push updated hosts list files
> to these machines.
> 
> If anyone can suggest a solution I'm open to it, though we overall are having
> enough issues that we may need to abandon Jumbo frames altogether until
> such time as the older equipment is decommissioned.
>
> If anyone can suggest a solution I'm open to it, though we overall are having
> enough issues that we may need to abandon Jumbo frames altogether until
> such time as the older equipment is decommissioned.

-- 
Greg Ercolano, erco@(email surpressed)
Seriss Corporation
Rush Render Queue, http://seriss.com/rush/
Tel: (Tel# suppressed)ext.23
Fax: (Tel# suppressed)
Cel: (Tel# suppressed)

For NFS mounts you can use the 'tcp' option.  tcp figures out what the maximum
packet size it can use on a connection.  tcp sends larger and larger ICMP
packets with the 'do not fragment' flag until one comes back with an error.

http://en.wikipedia.org/wiki/Path_MTU_discovery

Unfortunatly udp can not determine what the maximum packet size it can use.
Rush uses udp in several places.  The only way to fix the udp problem is to
lower all you hosts MTU to the smallest of all the machines, in your case
1518.  There is really no way for rush to work around this as it is a problem
with mismatched MTUs and udp.

Daniel Browne wrote:
> [posted to rush.general]
> 
> The system rejects any mtu larger than 1518. We've had lots of other issues=
>  with it as well, so we've basically got no choice but to change back to st=
> andard.
> 
> 
> On Sep 8, 2010, at 7:17 PM, Greg Ercolano wrote:
> 
> [posted to rush.general]
> 
> 	Up the MTU using ifconfig(1) to match the other boxes if you can.
> 	I believe mismatched MTUs affects UDP packet assembly.
> 
> Daniel Browne wrote:
> > We're in the midst of some network upgrades and are having some difficulties
> > transitioning to using ethernet Jumbo frames. Several of our older machines
> > (PowerMac G5's) do not have hardware support for Jumbo frames. The switch
> > they are connected to allows me to configure frame mtu size on a per-port
> > basis, but this is not preventing packet drops enough to allow Rush to work
> > properly. Jobs are taking inordinately long (which may be due to NFS packet
> > loss caused by jumbo frames) and I cannot push updated hosts list files
> > to these machines.
> > 
> > If anyone can suggest a solution I'm open to it, though we overall are having
> > enough issues that we may need to abandon Jumbo frames altogether until
> > such time as the older equipment is decommissioned.
> >
> > If anyone can suggest a solution I'm open to it, though we overall are having
> > enough issues that we may need to abandon Jumbo frames altogether until
> > such time as the older equipment is decommissioned.
> 
> -- 
> Greg Ercolano, erco@(email surpressed)
> Seriss Corporation
> Rush Render Queue, http://seriss.com/rush/
> Tel: +1 626-576-0010 ext.23
> Fax: +1 626-576-0020
> Cel: +1 310-266-8906

Late on this but if you can vlan off your network for these older machines
that can work. What type of servers do you have?
If your servers have multiple gige ports on it.. you could dedicate 1 port
to feed the older machines on a separate vlan. Otherwise all machines on 
your network need to have jumboframe support or your SOL. I am assuming these
MACs are not part of some AD windows network setup.. otherwise you will
need to do the same for 1 port in an AD server for it to authenticate..


-S

-----Original Message-----
From: Daniel Browne [mailto:dbrowne@(email surpressed)]
Sent: Wednesday, September 08, 2010 7:24 PM
To: void@(email surpressed)
Subject: Re: Jumbo Frames and Older Machines

[posted to rush.general]

The system rejects any mtu larger than 1518. We've had lots of other issues
with it as well, so we've basically got no choice but to change back to 
standard.


On Sep 8, 2010, at 7:17 PM, Greg Ercolano wrote:

[posted to rush.general]

        Up the MTU using ifconfig(1) to match the other boxes if you can.
        I believe mismatched MTUs affects UDP packet assembly.

Daniel Browne wrote:
> We're in the midst of some network upgrades and are having some difficulties
> transitioning to using ethernet Jumbo frames. Several of our older
> machines (PowerMac G5's) do not have hardware support for Jumbo frames. 
> The switch they are connected to allows me to configure frame mtu size 
> on a per-port basis, but this is not preventing packet drops enough
> to allow Rush to work properly. Jobs are taking inordinately long 
> (which may be due to NFS packet loss caused by jumbo frames) and 
> I cannot push updated hosts list files to these machines.
>
> If anyone can suggest a solution I'm open to it, though we overall are
> having enough issues that we may need to abandon Jumbo frames altogether
> until such time as the older equipment is decommissioned.

-- 
Greg Ercolano, erco@(email surpressed)
Seriss Corporation
Rush Render Queue, http://seriss.com/rush/
Tel: (Tel# suppressed)ext.23
Fax: (Tel# suppressed)
Cel: (Tel# suppressed)

Our LAN is pooled into a single subnet; we don't have need of a more rigoro=
us network topology, let alone vlans. The machines which are at issue are o=
ld PowerMac G5's.


On Sep 21, 2010, at 10:30 AM, Saker Klippsten wrote:

[posted to rush.general]

Late on this but if you can vlan off your network for these older machines
that can work. What type of servers do you have?
If your servers have multiple gige ports on it.. you could dedicate 1 port
to feed the older machines on a separate vlan. Otherwise all machines on 
your network need to have jumboframe support or your SOL. I am assuming these
MACs are not part of some AD windows network setup.. otherwise you will need
to do the same for 1 port in an AD server for it to authenticate..


-S

-----Original Message-----
From: Daniel Browne [mailto:dbrowne@(email surpressed)]
Sent: Wednesday, September 08, 2010 7:24 PM
To: void@(email surpressed)
Subject: Re: Jumbo Frames and Older Machines

[posted to rush.general]

The system rejects any mtu larger than 1518. We've had lots of other issues
with it as well, so we've basically got no choice but to change back to 
standard.


On Sep 8, 2010, at 7:17 PM, Greg Ercolano wrote:

[posted to rush.general]

       Up the MTU using ifconfig(1) to match the other boxes if you can.
       I believe mismatched MTUs affects UDP packet assembly.

Daniel Browne wrote:
> We're in the midst of some network upgrades and are having some difficulties
> transitioning to using ethernet Jumbo frames. Several of our older
> machines (PowerMac G5's) do not have hardware support for Jumbo frames. 
> The switch they are connected to allows me to configure frame mtu size 
> on a per-port basis, but this is not preventing packet drops enough
> to allow Rush to work properly. Jobs are taking inordinately long 
> (which may be due to NFS packet loss caused by jumbo frames) and 
> I cannot push updated hosts list files to these machines.
>
> If anyone can suggest a solution I'm open to it, though we overall are
> having enough issues that we may need to abandon Jumbo frames altogether
> until such time as the older equipment is decommissioned.

-- 
Greg Ercolano, erco@(email surpressed)
Seriss Corporation
Rush Render Queue, http://seriss.com/rush/
Tel: (Tel# suppressed)ext.23
Fax: (Tel# suppressed)
Cel: (Tel# suppressed)