[CentOS] VLAN tagging problems

Robin Mordasiewicz
Fri, 28 Oct 2005 14:48:05 -0000

We are using Centos behind an F5 Bigip load balancer.
The linux box is using bonding and tagged VLAN's

Everything works fine except that when traffic is forwarded from the BigIP
to the linux box on the VLAN where the web server is running the linux box
returns the traffic on the wrong VLAN, It returns traffic on the lowest
ordered VLAN.

ie. here is a tcpdump on my load balancer showing traffic being sent on
VLAN 911 to the linux box, but the linux box returns traffic on VLAN 902.
The linux box is returning traffic on the same VLAN as its configured
default gateway. If I change the default gateway to be on the VLAN 911
then everytyhing works.

Any ideas ?

07:38:15.480141 802.1Q vlan#911 P0 10.90.11.244.http > 10.90.11.1.47970: .
ack 9 win 1098 (DF)
07:38:15.691074 802.1Q vlan#911 P0 10.10.0.27.34023 > 10.90.11.244.http: S
2715145345:2715145345(0) win 4380 <mss 1460,nop,wscale 0,nop,nop,timestamp
72820060 0,sackOK,eol> (DF)
07:38:15.691074 802.1Q vlan#902 P0 10.90.11.244.http > 10.10.0.27.34023: S
514059651:514059651(0) ack 2715145346 win 5808 <mss 1464,sackOK,timestamp
51754641 72820060,nop,wscale 2> (DF)
07:38:18.630101 802.1Q vlan#902 P0 10.90.11.244.http > 10.10.0.27.34023: S
514059651:514059651(0) ack 2715145346 win 5808 <mss 1464,sackOK,timestamp
51757641 72820060,nop,wscale 2> (DF)
07:38:18.630101 802.1Q vlan#911 P0 10.10.0.27.34023 > 10.90.11.244.http: S
2715145345:2715145345(0) win 4380 <mss 1460,nop,wscale 0,nop,nop,timestamp
72823060 0,sackOK,eol> (DF)
07:38:18.630101 802.1Q vlan#902 P0 10.90.11.244.http > 10.10.0.27.34023: S
514059651:514059651(0) ack 2715145346 win 5808 <mss 1464,sackOK,timestamp
51757642 72820060,nop,wscale 2> (DF)
07:38:20.520099 802.1Q vlan#911 P0 10.90.11.1.48003 > 10.90.11.244.http: S
1650014488:1650014488(0) win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 0>
(DF)