Listening on Multiple IPs
Hi,
My Xymon server has 3 IP addresses that I want to spread out my incoming status messages on. I did not use the --listen so that xymond would come up to use 0.0.0.0:1984 and netstat shows it listening on 0.0.0.0:1984, but when I look at the network traffic 99.9% of it is on eth0.
My client servers are using the dns entry of the Xymon server and dns has all 3 IP addresses of the Xymon server associated correctly.
Any suggestions of what I may be doing wrong on the client or server?
Christopher Ahrens Macy's Systems & Technology Off: (440) 233-7162 x3122 chris.ahrens at macys.com
I think you want to bond your Ethernet interfaces, nothing to do with Xymon (beyond listening to the correct addresses).
Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373
On Thu, Nov 3, 2011 at 2:23 PM, Chris Ahrens <chris.ahrens at macys.com> wrote:
Hi,
My Xymon server has 3 IP addresses that I want to spread out my incoming status messages on. I did not use the --listen so that xymond would come up to use 0.0.0.0:1984 and netstat shows it listening on 0.0.0.0:1984, but when I look at the network traffic 99.9% of it is on eth0.
My client servers are using the dns entry of the Xymon server and dns has all 3 IP addresses of the Xymon server associated correctly.
Any suggestions of what I may be doing wrong on the client or server?
Christopher Ahrens Macy's Systems & Technology Off: (440) 233-7162 x3122 chris.ahrens at macys.com
Xymon mailing list Xymon at xymon.com http://lists.xymon.com/mailman/listinfo/xymon
On Thu, November 3, 2011 14:23, Chris Ahrens wrote:
Hi,
My Xymon server has 3 IP addresses that I want to spread out my incoming status messages on. I did not use the --listen so that xymond would come up to use 0.0.0.0:1984 and netstat shows it listening on 0.0.0.0:1984, but when I look at the network traffic 99.9% of it is on eth0.
My client servers are using the dns entry of the Xymon server and dns has all 3 IP addresses of the Xymon server associated correctly.
Any suggestions of what I may be doing wrong on the client or server?
DNS will return all 3 IPs on a query, and it's left to the client side which to use. Most often the first one is used. "Round robin" DNS servers will alternate the order of the 3, but that still leaves a lot of room for locking in on a single address by multiple clients. You could set up different names for the IPs and bind groups of Xymon clients to each to spread out the load, I think.
On 11/03/2011 03:57 PM, Xymon User in Richmond wrote:
DNS will return all 3 IPs on a query, and it's left to the client side which to use. Most often the first one is used. "Round robin" DNS servers will alternate the order of the 3, but that still leaves a lot of room for locking in on a single address by multiple clients. You could set up different names for the IPs and bind groups of Xymon clients to each to spread out the load, I think.
This will also depend on whether the xymon client resolves the ip once at startup or on each data send. If it's once at startup, then whatever ip it is given (even from a round-robin dns server) will persist until it is restarted. I'll leave it to those who have examined this behavior and xymon client internals to say which is the case.
Darrik
-- Darrik Mazey DarmaSoft, LLC. 1627 Marigold Avenue Akron, Ohio 44301-2627 tele: 330.238.1333 darrik at darmasoft.com http://www.darmasoft.com/
To obtain my public key, send an email to darrik at publickey.darmasoft.com.
On Thu, Nov 3, 2011 at 6:44 PM, Darrik Mazey <darrik.lists at darmasoft.com>wrote:
On 11/03/2011 03:57 PM, Xymon User in Richmond wrote:
DNS will return all 3 IPs on a query, and it's left to the client side which to use. Most often the first one is used. "Round robin" DNS servers will alternate the order of the 3, but that still leaves a lot of room for locking in on a single address by multiple clients. You could set up different names for the IPs and bind groups of Xymon clients to each to spread out the load, I think.
This will also depend on whether the xymon client resolves the ip once at startup or on each data send. If it's once at startup, then whatever ip it is given (even from a round-robin dns server) will persist until it is restarted. I'll leave it to those who have examined this behavior and xymon client internals to say which is the case.
If I recall past conversations correctly, xymon goes out to resolve hostnames every time. However, the actual behaviour depends on the host system - if the host is running a name server cache daemon (e.g. nscd), then xymon will be handed whatever is cached until that expires, then it'll get a fresh copy from the real DNS.
You can override the name lookup for any given hostname by putting "testip" on it's line in server/etc/hosts.cfg:
1.2.3.4 xxx.thingy.com # testipRalph Mitchell
On 03-11-2011 19:23, Chris Ahrens wrote:
My Xymon server has 3 IP addresses that I want to spread out my incoming status messages on. I did not use the --listen so that xymond would come up to use 0.0.0.0:1984 and netstat shows it listening on 0.0.0.0:1984, but when I look at the network traffic 99.9% of it is on eth0.
My client servers are using the dns entry of the Xymon server and dns has all 3 IP addresses of the Xymon server associated correctly.
I suppose all three IP's are on the same IP-network ? How this is handled is highly OS dependant. I mostly have Linux experience, and there the IP's are not really associated with specific network interfaces - they are bound to the system as a whole. So even if you have an IP configured on one network interface, the traffic may just as well be received and transmitted over another interface, as long as they are all on the same IP network.
And that goes for ARP requests too, so you can easily end up with most of the traffic being handled by one interface.
As Josh wrote, the solution is to use Ethernet bonding - i.e. instead of 3 100 Mbit interfaces each with their own IP, you have one 300 Mbit interface with a single IP.
Regards, Henrik
participants (6)
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chris.ahrens＠macys.com
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darrik.lists＠darmasoft.com
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henrik＠hswn.dk
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hobbit＠epperson.homelinux.net
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josh＠imaginenetworksllc.com
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ralphmitchell＠gmail.com