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RE: port unreachable

To: "LinuxVirtualServer.org users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: RE: port unreachable
From: "Dennis Kruyt" <d.kruyt@xxxxx>
Date: Mon, 8 Mar 2004 14:05:57 +0100
I think it has something  todo with scheduler sh, I see that you use
also sh. I have changed from sh to rr a week ago and now I have no
problems any more.

Mmm, a litte bug in source hashing???

Regards, Dennis


-----Original Message-----
From: Martijn Grendelman [mailto:martijn@xxxxxxxxxxxxxx] 
Sent: maandag 8 maart 2004 12:56
To: lvs-users@xxxxxxxxxxxxxxxxxxxxxx
Subject: Re: port unreachable


Hi,

> I have the following problem, I have a loadbalancer to loadbalance 
> https/http, pop and smtp request. Al are working fine except for 
> https. I get some times a connection refused. If I look with tcpdump I

> get a "tcp port https unreachable". But the real servers are ok, I 
> test them also directly no problem with that. But via the loadbalancer

> I get sometimes the port unreachable problem. At that time both the 
> realservers are in the loadbalancer.

I've got the same problem, but also with http. I use LVS-DR with one of
the real servers on the director:

IP Virtual Server version 1.0.10 (size=4096)
Prot LocalAddress:Port Scheduler Flags
  -> RemoteAddress:Port           Forward Weight ActiveConn InActConn
TCP  212.204.230.98:80 sh
  -> 212.204.230.91:80            Route   1      3          0
  -> 212.204.230.96:80            Local   1      0          0

Both real servers work fine, and most of the time, the virtual server
also works. However sometimes, clients get "connection refused". After a
few minutes, everything's fine again.

A tcpdump on the client shows "bad tcp cksum". Unfortunately I don't
know what that means.

11:02:06.112745 IP (tos 0x0, ttl  64, id 35405, offset 0, flags [DF],
length: 60) 10.60.0.20.50259 > 212.204.230.98.http: S [bad tcp cksum
c5ad (->95f7)!] 4101824739:4101824739(0) win 65535 <mss 1460,nop,wscale
0,nop,nop,timestamp 918167251 0>

The load balancer returns ICMP port unreachable messages to the client:

12:32:55.431896 212.204.230.98 > hq.appoint.nl: icmp: 212.204.230.98 tcp
port www unreachable for hq.appoint.nl.52752 > 212.204.230.98.www: S
2831096624:2831096624(0) win 65535 <mss 1460,nop,wscale
0,nop,nop,timestamp[|tcp]> (DF) (ttl 58, id 20064, len 60) [tos 0xc0]
(ttl 64, id 23682, len 88)

I hope someone can help. At this point, I don't consider the LVS ready
for production :-(

Best regards,
Martijn.

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