Pirana problem with MTU fragmentation

[Khapare Joshi]

Hello all,

I am running pulse on virtual machine for webserver, it seems working
well, but there is one problem with networking I think. It seems there
is a problem with lvs server is not fragmenting larger than 1500
packets size. I did the quick tcpdump and I get following info.

my problem is when user is uploading files it takes for ever and never
completes. I am thinking lvs (pulse) is not not fragmenting the larger
packet size than 1500 hence it never goes to backend server.

16:25:22.543563 00:1f:6d:cf:4e:49 > 52:54:00:b5:30:3c, ethertype IPv4
(0x0800), length 2974: 10.128.1.5.60715 > 10.192.6.1.https: Flags [.],
seq 7705:10625, ack 146, win 16388, length 2920
16:25:22.543590 52:54:00:b5:30:3c > 00:1f:6d:cf:4e:49, ethertype IPv4
(0x0800), length 590: 10.192.6.1 > 10.128.1.5: ICMP 130.208.165.177
unreachable - need to frag (mtu 1500), length 556

I tested following:

1. IP forward is enabled.
2. lro,gro are off on eth0
ethtool -k eth0
Offload parameters for eth0:
rx-checksumming: on
tx-checksumming: on
scatter-gather: on
tcp-segmentation-offload: on
udp-fragmentation-offload: on
generic-segmentation-offload: on
generic-receive-offload: off
large-receive-offload: off
3. IPVS version is v1.2.1
4. Backend server has arptables and set to mangaled to right interface
5. Firewall is allowed on both lvs and backend server.
6. http and https are open for all.

Any help in this would be great.

K
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