Hi all,
I've a multigateway router doing load balancing. I've detected that a low % of
packets are going out through the wrong interface.
To test this I've deployed the following scenario:
routerA 10.10.1.251 <=> eth1 10.10.1.1/24
router eth3 192.168.1.1/24 <=> client
routerB 10.10.2.251 <=> eth2 10.10.2.1/24
On the client I've a perl script doing wgets to different urls and on both
routers I've tcpdump looking for wrong packets:
routerA:~# tcpdump -i eth1 -n src 10.10.2.1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
16:28:33.540895 IP 10.10.2.1.38572 > 192.168.100.254.53: S
3734774276:3734774276(0) win 5840 <mss 1460,sackOK,timestamp 24681764
0,nop,wscale 1>
16:28:57.541067 IP 10.10.2.1.38572 > 192.168.100.254.53: S
3734774276:3734774276(0) win 5840 <mss 1460,sackOK,timestamp 24687764
0,nop,wscale 1>
16:29:45.542669 IP 10.10.2.1.38572 > 192.168.100.254.53: S
3734774276:3734774276(0) win 5840 <mss 1460,sackOK,timestamp 24699764
0,nop,wscale 1>
routerB:~# tcpdump -i eth1 -n src 10.10.1.1
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 96 bytes
16:38:25.020443 IP 10.10.1.1.44962 > 80.247.32.136.82: S
3427612315:3427612315(0) win 5840 <mss 1460,sackOK,timestamp 24832042
0,nop,wscale 1>
16:38:41.059188 IP 10.10.1.1.50276 > 212.175.239.74.90: S
133519430:133519430(0) win 5840 <mss 1460,sackOK,timestamp 24836052
0,nop,wscale 1>
16:39:29.056531 IP 10.10.1.1.50276 > 212.175.239.74.90: S
133519430:133519430(0) win 5840 <mss 1460,sackOK,timestamp 24848052
0,nop,wscale 1>
16:48:44.961472 IP 10.10.1.1.35885 > 12.19.68.8.8008: S 250197835:250197835(0)
win 5840 <mss 1460,sackOK,timestamp 24987036 0,nop,wscale 1>
The load balacing router is hardy 2.6.24 with the following setup:
# ip rule ls
0: from all lookup local
32761: from all lookup main
32762: from 10.10.1.1 lookup 2
32763: from all fwmark 0x2 lookup 2
32764: from 10.10.2.1 lookup 1
32765: from all fwmark 0x1 lookup 1
32766: from all lookup main
32767: from all lookup default
# ip route ls table main
10.6.7.0/24 dev eth0 proto kernel scope link src 10.6.7.12
10.10.2.0/24 dev eth2 proto kernel scope link src 10.10.2.1
192.168.1.0/24 dev eth3 proto kernel scope link src 192.168.1.1
10.10.1.0/24 dev eth1 proto kernel scope link src 10.10.1.1
# ip route ls table 1
default via 10.10.2.251 dev eth2
# ip route ls table 2
default via 10.10.1.251 dev eth1
# ip route ls table default
default
nexthop via 10.10.2.251 dev eth2 weight 1
nexthop via 10.10.1.251 dev eth1 weight 1
iptables rules just have MASQUERADING, but I've tried dropping invalid
packets, SNAT, etc with the same results. Nothing on mangle but if I setup
rules for policy routing using marks I also can observer same behavior.
Do you know how could I debug this issue or what could be wrong ? Clients can
browse when packets of their conections go out using the wrong iface.
Thanks in advance!
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