From mboxrd@z Thu Jan  1 00:00:00 1970
From: =?iso-8859-15?q?Ra=FAl_Alexis_Betancort_Santana?= <rabs@dimension-virtual.com>
Date: Thu, 12 Feb 2004 09:53:08 +0000
Subject: [LARTC] Multipath problems
Message-Id: <200402120953.08772.rabs@dimension-virtual.com>
List-Id: <lartc.vger.kernel.org>
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To: lartc@vger.kernel.org


Hi all, I'm getting lot of problems with a multihomed linux router.

I have 3 lines conected to my Linux Box, with 2.6.1 kernel with DgD patches=
,=20
and I have setup it that it does load balancing between the 3 lines, but I =

have a problem with sending specific traffic (mail one) throught only one o=
f=20
the lines. let me put my config bellow ..

------- Multiroute.sh ---------
#!/bin/bash

# CONFIGURATION
IP=3D/sbin/ip
PING=3D/bin/ping

#--------------- LINK PART -----------------
# EXTIFn - interface name
# EXTIPn - outgoing IP
# EXTMn  - netmask length (bits)
# EXTGWn - outgoing gateway
#-------------------------------------------

# LINK 1 ADSL ISP1
EXTIF1=3Deth1
EXTIP1=AAa.bbb.ccc.ddd
EXTM10
EXTGW1=AAa.bbb.ccc.eee

# LINK 2 ADSL ISP2
EXTIF2=3Deth1
EXTIP2=BBb.ccc.ddd.eee
EXTM2&
EXTGW2=BBb.ccc.ddd.fff

# LINK 3 Cable ISP3
EXTIF3=3Deth1
EXTIP3=CCc.ddd.eee.fff
EXTM30
EXTGW3=CCc.ddd.eee.ggg

#ROUTING PART
# removing old rules and routes

echo "removing old rules"
${IP} rule del prio 50 table main
${IP} rule del prio 201 from ${EXTIP1}/${EXTM1} table 201
${IP} rule del prio 202 from ${EXTIP2}/${EXTM2} table 202
${IP} rule del prio 203 from ${EXTIP3}/${EXTM3} table 203
${IP} rule del prio 221 table 221
echo "flushing tables"
${IP} route flush table 201
${IP} route flush table 202
${IP} route flush table 203
${IP} route flush table 221
echo "removing tables"
${IP} route del table 201
${IP} route del table 202
${IP} route del table 203
${IP} route del table 221

# setting new rules
echo "Setting new routing rules"

# main table w/o default gateway here
${IP} rule add prio 50 table main
${IP} route del default table main

# identified routes here
${IP} rule add prio 201 from ${EXTIP1}/${EXTM1} table 201
${IP} rule add prio 202 from ${EXTIP2}/${EXTM2} table 202
${IP} rule add prio 203 from ${EXTIP3}/${EXTM3} table 203

${IP} route add default via ${EXTGW1} dev ${EXTIF1} src ${EXTIP1} proto sta=
tic=20
table 201
${IP} route append prohibit default table 201 metric 1 proto static

${IP} route add default via ${EXTGW2} dev ${EXTIF2} src ${EXTIP2} proto sta=
tic=20
table 202
${IP} route append prohibit default table 202 metric 1 proto static

${IP} route add default via ${EXTGW3} dev ${EXTIF3} src ${EXTIP3} proto sta=
tic=20
table 203
${IP} route append prohibit default table 203 metric 1 proto static

# mutipath
${IP} rule add prio 221 table 221

${IP} route add default table 221 proto static \
        nexthop via ${EXTGW3} dev ${EXTIF3} weight 1\
        nexthop via ${EXTGW2} dev ${EXTIF2} weight 100\
        nexthop via ${EXTGW1} dev ${EXTIF1} weight 200

# Multipath for email traffic.
${IP} route add default table mail.traffic proto static \
        nexthop via ${EXTGW1} dev ${EXTIF1} weight 1 \
        nexthop via ${EXTGW2} dev ${EXTIF2} weight 250\
        nexthop via ${EXTGW3} dev ${EXTIF3} weight 100
${IP} rule add prio 230 fwmark 0x02 table mail.traffic

${IP} route flush cache

--------- Multiroute.sh ------------

Then I mark the pakets coming from the lan and going to internet mail=20
servers ...

iptables -A PREROUTING -t mangle -s ${LAN}/${LAN_MASK} -d !
${DMZ1}/${DMZ1_MASK} -p tcp --dport 25 -j MARK --set-mark 0x02
iptables -A PREROUTING -t mangle -s ${LAN}/${LAN_MASK} -d !
${DMZ1}/${DMZ1_MASK} -p tcp --dport 110 -j MARK --set-mark 0x02

The idea is that mail traffic going to internet try to go out allways by IS=
P1=20
but if it fails (that is why the weight are so diferents) by ISP2 and if th=
at=20
one fails too try to go out by ISP3, but in the real scenario mail traffic =
is=20
going out by a radom provider :( ... for the rest of traffic priorities=20
should be reversed ... first ISP3,then ISP2 and finaly ISP1 and that part i=
s=20
running more or least ... sometimes one conection goes out by ISP2 but that=
's=20
not a big problem ..

I'm doing something wrong ?, why my mail.traffic table is not working as it=
 is=20
supposed to

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