Performace problems with NAT

Performace problems with NAT

[Berndt Sevcik]

I am using a combination of source based routing with iproute2 and nat
(iptables 1.2.6a-5). The problem I cant use the full performance of our
line. We have a 10MBit line and i can only use about 2MBit, and not a
fault of our ISP.


Here is my config:
 
Regards 
Berndt
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Re: Performace problems with NAT

[Antony Stone]

On Friday 25 October 2002 2:56 pm, Berndt Sevcik wrote:

> I am using a combination of source based routing with iproute2 and nat
> (iptables 1.2.6a-5). The problem I cant use the full performance of our
> line. We have a 10MBit line and i can only use about 2MBit, and not a
> fault of our ISP.

Okay, knowing that your line is 10Mbit adds some more information.

1. How do you know the problem is not with your ISP ?   Can you download at 
10Mbit under any circumstances ?

2. What makes you think is it NAT which is causing the performance problem ?  
Does the problem go away if you do not use NAT ?

3. How busy is your box (what load average does uptime show) ?

4. Are you getting any kernellogging messages about conntrack table full etc ?

5. What speed CPU / how much memory is in the netfilter machine ?

Antony.

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Re: Performace problems with NAT

[Antony Stone]

On Friday 25 October 2002 4:38 pm, Berndt Sevcik wrote:

> Thanks for the answer!
>
> We use two Internet Connections. So we need to splitt our Source
> addresses over these. All our official addresses are sent via the slower
> one and all private addresses and proxies are transmitted via the fast
> line (neede NAT).
>
> Another interessting fact ist that ping times are exptremely good. We
> have about 2ms between each Hop in the Chello Nertwork, better than
> ever.
>
> We need source based routing, because we have to default gateways, one
> for each internet connection.

Okay, I understand.

> Here our full configuration:
>
> route add -net ..... (local nets)
> route add default gw 193.170.9.1 (first ISP)
>
> ip rule add from 10.0.0.0/8 table chello1
> ip route add feault via 192.168.158.101 table chello1 (second ISP)
> ip rule add from 193.170.8.133 table chello1
> ip rule add from 193.170.8.134 table chello1
> ip route flush cash

Ah.   A little more than you posted last time :-)   However I still don't see 
a reason for only 20% usage of a 10Mbit connection.

How do you know the problem is not with your ISP ?   Can you download
at 10Mbit under any circumstances ?

What makes you think is it NAT which is causing the performance
problem ? Does the problem go away if you do not use NAT ?

How busy is your box (what load average does uptime show) ?

Are you getting any kernellogging messages about conntrack table full
etc ?

What speed CPU / how much memory is in the netfilter machine ?

Antony.

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