kernel pppoe performance problems

classic Classic list List threaded Threaded
3 messages Options
Reply | Threaded
Open this post in threaded view
|

kernel pppoe performance problems

Matt S-3
Hello All,

I want to try to use pppoe with kernel ppp in an attempt to improve
performance.  So, I have a pppoe0 device configured and connection
established properly.  The box that runs kernel pppoe is obviously my
gateway machine.  If I am on the gateway machine, performance is decent.  If
I am on one of my other boxes, performance really drops to the point of
dialup.  I made certain to rm -f /etc/mygate as one wiki suggested but it
had no effect.  If I use userland pppoe, I don't have this problem so I
think that both my NIC cards are okay.  The nic card connected to my DSL
modem is bge0 and the nic for my home network is em0.  My home network is
10.40.60.0/24.  I know I have NAT correctly configured because I can ping
google.com from one of the other boxes.  Do you have any hints as to how I
can troubleshoot this further?  Below is my configuration for the
hostname.pppoe0 :

inet 0.0.0.0 255.255.255.255 NONE pppoedev bge0 authproto pap authname
"<myauthname>" authkey "<myauthkey>" up
dest 0.0.0.1
!/sbin/route add default 0.0.0.1


Thank you,
Matt

Reply | Threaded
Open this post in threaded view
|

Re: kernel pppoe performance problems

Matt S-3
Hi.  I don't see that option available for kernel pppoe.  I see it for a
userland version.  man 4 pppoe shows the same as man 8 pppoe.



On Jul 14, 2010, at 1:25 PM, Mitja MuE>eniD
 <[hidden email]> wrote:

> Sounds like you didn't clamp the MSS, see man 4 pppoe towards the end. It's
> not a performance problem, but a misconfiguration one.
>
>> -----Original Message-----
>> From: [hidden email] [mailto:[hidden email]] On Behalf Of
> Matt
>> S
>> Sent: Wednesday, July 14, 2010 10:16 PM
>> To: [hidden email]
>> Subject: kernel pppoe performance problems
>>
>> Hello All,
>>
>> I want to try to use pppoe with kernel ppp in an attempt to improve
>> performance.  So, I have a pppoe0 device configured and connection
>> established properly.  The box that runs kernel pppoe is obviously my
>> gateway machine.  If I am on the gateway machine, performance is decent.
> If
>> I am on one of my other boxes, performance really drops to the point of
>> dialup.  I made certain to rm -f /etc/mygate as one wiki suggested but it
>> had no effect.  If I use userland pppoe, I don't have this problem so I
>> think that both my NIC cards are okay.  The nic card connected to my DSL
>> modem is bge0 and the nic for my home network is em0.  My home network is
>> 10.40.60.0/24.  I know I have NAT correctly configured because I can ping
>> google.com from one of the other boxes.  Do you have any hints as to how I
>> can troubleshoot this further?  Below is my configuration for the
>> hostname.pppoe0 :
>>
>> inet 0.0.0.0 255.255.255.255 NONE pppoedev bge0 authproto pap authname
>> "<myauthname>" authkey "<myauthkey>" up
>> dest 0.0.0.1
>> !/sbin/route add default 0.0.0.1
>>
>>
>> Thank you,
>> Matt

Reply | Threaded
Open this post in threaded view
|

Re: kernel pppoe performance problems

Mitja Muženič
First of all, do not reply to mails sent in private on a public list, it's
impolite and will expose my email address to more spam.

Second, man 4 pppoe says:

MTU/MSS ISSUES
     Problems can arise on machines with private IPs connecting to the Inter-
     net via a machine running both Network Address Translation (NAT) and
     pppoe.  Standard Ethernet uses a Maximum Transmission Unit (MTU) of 1500
     bytes, whereas PPPoE mechanisms need a further 8 bytes of overhead.
This
     leaves a maximum MTU of 1492.  pppoe sets the MTU on its interface to
     1492 as a matter of course.  However, machines connecting on a private
     LAN will still have their MTUs set to 1500, causing conflict.

     While pppoe(8) has an internal option, ``mssfixup'', which is enabled by
     default and takes care of this, pppoe users have to rely on other meth-
     ods.  Using a packet filter, the Maximum Segment Size (MSS) can be set
     (clamped) to the required value.  The following rule in pf.conf(5) would
     set the MSS to 1440:

           match on pppoe0 scrub (max-mss 1440)

     Although in theory the maximum MSS over a PPPoE interface is 1452 bytes,
     1440 appears to be a safer bet.  Note that setting the MSS this way can
     have undesirable effects, such as interfering with the OS detection fea-
     tures of pf(4).

which is definitely not "the same as man 8 pppoe".


> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of
Matt

> Schwartz
> Sent: Wednesday, July 14, 2010 10:42 PM
> To: [hidden email]
> Subject: Re: kernel pppoe performance problems
>
> Hi.  I don't see that option available for kernel pppoe.  I see it for a
> userland version.  man 4 pppoe shows the same as man 8 pppoe.
>
>
>
> On Jul 14, 2010, at 1:25 PM, Mitja MuE>eniD
>  <[hidden email]> wrote:
>
> > Sounds like you didn't clamp the MSS, see man 4 pppoe towards the end.
It's
> > not a performance problem, but a misconfiguration one.
> >
> >> -----Original Message-----
> >> From: [hidden email] [mailto:[hidden email]] On Behalf
Of

> > Matt
> >> S
> >> Sent: Wednesday, July 14, 2010 10:16 PM
> >> To: [hidden email]
> >> Subject: kernel pppoe performance problems
> >>
> >> Hello All,
> >>
> >> I want to try to use pppoe with kernel ppp in an attempt to improve
> >> performance.  So, I have a pppoe0 device configured and connection
> >> established properly.  The box that runs kernel pppoe is obviously my
> >> gateway machine.  If I am on the gateway machine, performance is decent.
> > If
> >> I am on one of my other boxes, performance really drops to the point of
> >> dialup.  I made certain to rm -f /etc/mygate as one wiki suggested but
it
> >> had no effect.  If I use userland pppoe, I don't have this problem so I
> >> think that both my NIC cards are okay.  The nic card connected to my DSL
> >> modem is bge0 and the nic for my home network is em0.  My home network
is
> >> 10.40.60.0/24.  I know I have NAT correctly configured because I can
ping
> >> google.com from one of the other boxes.  Do you have any hints as to how
I

> >> can troubleshoot this further?  Below is my configuration for the
> >> hostname.pppoe0 :
> >>
> >> inet 0.0.0.0 255.255.255.255 NONE pppoedev bge0 authproto pap authname
> >> "<myauthname>" authkey "<myauthkey>" up
> >> dest 0.0.0.1
> >> !/sbin/route add default 0.0.0.1
> >>
> >>
> >> Thank you,
> >> Matt