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20 second delay with private ip address [message #38633]

Sat, 09 January 2010 17:09

walter7788
Messages: 7
Registered: January 2010

Junior Member

Hi,
I run into a strange problem which I call "20 second delay" problem. I found that this huge delay is caused by the private ip of the 've database'. Well, I got a pc with 3 VEs:

ve reverse proxy (82.xx.xx.xx public ip)
|
ve webserver (192.168.90.20 private ip)
|
ve database (192.168.90.30 private ip)

The 've reverse proxy' talks to the 've webserver' and this talks to the 've database'. Basically everything works BUT a reply from the database takes ca. 20 seconds! When I change the 've database' ip from private ip to a public ip then everything works very fast, no delay. Though, I do not want the database to have a public ip.

I know that the information I provide is pretty vague. Please, could anyone point me into the right direction? Do I have to deal with 'routing' or something?

When I enter the 've webserver' and there do a 'ping 192.168.90.30' to the 've database' I get:

[root@webserver]# ping 192.168.90.30
PING 192.168.90.30 (192.168.90.30) 56(84) bytes of data.
From 82.xx.xx.xx: icmp_seq=1 Redirect Host(New nexthop: 192.168.90.30)
64 bytes from 192.168.90.30: icmp_seq=1 ttl=64 time=0.056 ms
From 82.xx.xx.xx: icmp_seq=2 Redirect Host(New nexthop: 192.168.90.30)
64 bytes from 192.168.90.30: icmp_seq=2 ttl=64 time=0.048 ms
From 82.xx.xx.xx: icmp_seq=3 Redirect Host(New nexthop: 192.168.90.30)
64 bytes from 192.168.90.30: icmp_seq=3 ttl=64 time=0.030 ms
64 bytes from 192.168.90.30: icmp_seq=4 ttl=64 time=0.025 ms
...

List looks similar when I enter 've database' and send ping to 've webserver'. So ping tests 've webserver' <-> 've database' in both directions work very fast (but the "Redirect Host(New nexthop" text makes me wonder).

Thanks for any help and pointers.

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Re: 20 second delay with private ip address [message #38635 is a reply to message #38633]

Sun, 10 January 2010 02:53

walter7788
Messages: 7
Registered: January 2010

Junior Member

Latest news from my I-can't-get-it-to-work project.

Short story: Is 'VETH' the way to go? http://wiki.openvz.org/Veth

Long story: Spend 6 hours more for searching, reading and much testing but no success. What I noticed (and already mentioned in my first post) was, that using a public IP worked and using a privat IP failed (but I need to use a privat IP). What I did until now was simply creating 3 VEs on my server and set it up as

've reverse proxy' <-> 've webserver' <-> 've database'

To 've webserver' and 've database' I assigned private IPs (192.168.x.x) but this VE <-> VE communication doesn't work properly (= 20 second response delay). Am I trying something that is technically impossible? This networking stuff is a pretty difficult matter and I'm just a beginner. It feels like walking through a heavy fog, not knowhing where to go and not seeing anything.

Is this what I'm going to build a so-called 'virtual lan' or VLAN? Do I need to utilize 'VETH' in order to build my 'virtual lan'? Thanks for any input.

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Re: 20 second delay with private ip address [message #38638 is a reply to message #38635]

Sun, 10 January 2010 18:45

nuno
Messages: 43
Registered: January 2010

Member

That looks like a DNS timeout. Remove the reverse lookups from your applications or add the hosts to /etc/hosts in all 3 VEs.

Regards,

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Re: 20 second delay with private ip address [message #38640 is a reply to message #38638]

Sun, 10 January 2010 21:29

walter7788
Messages: 7
Registered: January 2010

Junior Member

nuno, thanks for your reply. I also was thinking of something like a timeout, tried much but no luck. Guess I did it wrong because I'm a beginner. Well, today I can report some success Wink

I configured my

've database' as 'SNAT' (for anyone who is interested please see "How to provide access for container to Internet" here: http://wiki.openvz.org/NAT ) I could access the Internet but my delay problem still existed. So I removed 'SNAT' and configured my

've database' as 'VETH' (see "Adding veth to a CT" here: http://wiki.openvz.org/Veth ). My delay problem still existed so I added 'SNAT' again.

So in total I ended up with applying 'SNAT' + 'VETH' to my 've database' and voila, then it worked. No more delay Wink

While I got it to work I'm still absolutely clueless regarding networking and questions remain: While 'SNAT'+'VETH' works for me I wonder if this is the right way to do it? Thanks to anyone for input.

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