[LARTC] Bad performance using source routing

[Henrik Johansson - GlobeCom <hj@globecom.se>]

Hi,

I have a performance problem when using source routing, following the
instructions in the Adv Linux Routing HOW-TO. I have a box with 3 NICs,
all connected to 3 different ip networks. The box look like this:

733MHz P3 CPU
256MB RAM
Mandrake Linux 9.0
3 3C905B NIC
                         _________
      1.2.3.93/29 ETH2 -|         |- ETH0 2.2.3.44/26
                         ---------
                             |
                           ETH 1
                        10.7.7.3/24

ETH2 gw 1.2.3.89
ETH1 is a "point-to-point" link to an NFS-server
ETH0 gw 2.2.3.6/26

I want traffic comming in on ETH2 and ETH0 to be routed back via their
respective default gw. This is not a problem, routing wise, it works just
as it should, but the problem is that when uploading to the box, it is
realllly slow. If I try and FTP to it, I get between 7-10MB/s download,
but only around 1-2MB/s upload. This is if I use source routing. As a
small problem fix, I use the following script, only applying source
routing to ETH2, and letting the "normal def gw"-rule apply for ETH0, that
way up- and download to ETH0 is basically 100Mbit.

The script I run is this:

# add instructions for eth2
/sbin/ip route add 1.2.3.88/29 dev eth2 src 1.2.3.93 table nic3
/sbin/ip route add default via 1.2.3.89 table nic3
/sbin/ip rule add from 1.2.3.93 table nic3
/sbin/ip route flush cache

I also had a similar script for ETH0, but as I said, the performance was
really bad. At least now, performace for ETH0 is okey both upstream and
downstream.

Anyone know where I should start looking?

Regards

Henrik Johansson
GlobeCom Network


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