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From Igor Cicimov <ig...@encompasscorporation.com>
Subject Re: How to load balance across hierarchical Proxies
Date Tue, 14 Nov 2017 23:20:15 GMT
Hi,

I guess that very much depends on your DNS setup. For example if your ATS
domain name is same as the domain name hosted by the origin servers then
when ATS tries DNS resolution it will get it's own IP. I'm sure this does
not sound very clear so recommend looking at the *splitdns.config* file and
it's documentation for details.

On Wed, Nov 15, 2017 at 3:02 AM, Velusamy, Gandhimathi <
gvelusam@central.uh.edu> wrote:

> Hi,
> I noticed that there is problem with DNS resolution.
> When I send http request  directly from the node on which the traffic
> server is installed  to the origin server, I am able to receive response
> from the server. That seems the DNS is working. But When I use Traffic
> server, It is giving 502 server not found error. When I debugged with “dns”
> option, it is returns response code 3.
> Does Traffic server need any special DNS mapping.
>
> I first tried with only one level of proxying but unable to do when I use
> hostnames in the remap config.
> It resolves the hostname for traffic server node but the dns resolving
> does not happens for origin servers. WhenI use IP addresses for origin
> servers, the loadbalancer is working. But I need hostnames to be used for
> origin servers in the remap.config when I go hierarchical proxying.
>
> Any pointers on where to look to solve this issue will be appreciated.
>
> Thanks
> Gandhimathi
>
>
> gvelus01@clb:/usr/local$ sudo bin/traffic_server -T "dns"
> traffic_server: using root directory '/usr/local'
> [Nov 14 10:30:56.876] Server {0x7f41b7666780} DEBUG: <DNS.cc
> <http://dns.cc>:1604 (ink_dns_init)> (dns) ink_dns_init: called with
> init_called = 0
> [Nov 14 10:30:56.879] Server {0x7f41b7666780} DEBUG: <DNS.cc
> <http://dns.cc>:247 (dns_init)> (dns) localhost=clb
> [Nov 14 10:30:56.879] Server {0x7f41b7666780} DEBUG: <DNS.cc
> <http://dns.cc>:248 (dns_init)> (dns) Round-robin nameservers = 1
> [Nov 14 10:30:56.888] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:482 (startEvent)> (dns) DNSHandler::startEvent: on thread
> 0
> [Nov 14 10:30:56.888] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:427 (open_con)> (dns) open_con: opening connection
> 10.103.0.1:53
> [Nov 14 10:30:56.888] Server {0x7f41b3c7d700} DEBUG: <DNSConnection.cc
> <http://dnsconnection.cc>:143 (connect)> (dns) random port = 0.0.0.0:52329
> [Nov 14 10:30:56.888] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:455 (open_con)> (dns) opening connection 10.103.0.1:53
> SUCCEEDED for 0
> [Nov 14 10:30:56.888] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:504 (startEvent)> (dns_pas) opened connection to
> 10.103.0.1:53, n_con = 1
> [Nov 14 10:31:11.913] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:1091 (getby)> (dns) received query cs2 type = 1, timeout
> = 0
> [Nov 14 10:31:11.913] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:1057 (mainEvent)> (dns) enqueing query cs2
> [Nov 14 10:31:11.913] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:1063 (mainEvent)> (dns) adding first to collapsing queue
> [Nov 14 10:31:11.913] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:978 (write_dns_event)> (dns) send query (qtype=1) for cs2
> to fd 21
> [Nov 14 10:31:11.913] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:1010 (write_dns_event)> (dns) sent qname = cs2, id =
> 22417, nameserver = 0
> [Nov 14 10:31:11.913] Server {0x7f41b3c7d700} DEBUG: <P_DNSProcessor.h:239
> (sent_one)> (dns) sent_one: failover_number for resolver 0 is 1
> [Nov 14 10:31:11.914] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:759 (recv_dns)> (dns) received packet size = 21
> [Nov 14 10:31:11.914] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:761 (recv_dns)> (dns) round-robin: nameserver 0 DNS
> response code = 0
> [Nov 14 10:31:11.914] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:1306 (dns_process)> (dns) received rcode = 3
> [Nov 14 10:31:11.914] Server {0x7f41b3c7d700} DEBUG: <DNS.cc
> <http://dns.cc>:1328 (dns_process)> (dns) DNS error 3 for [cs2]
>
>
>
> On Nov 13, 2017, at 6:16 PM, Velusamy, Gandhimathi <
> gvelusam@Central.UH.EDU <gvelusam@central.uh.edu>> wrote:
>
> Hi,
>
> I am trying to distribute the load balancing between servers connected
> with three proxies.
>
> In my setup, I have three proxy servers and each of them have two origin
> servers and one client.
> I would like to balance the load across servers connected with other
> proxies when the rate of incoming requests are more.
> To begin, I started with round robin policy.
> First I tried to add the proxy2 and proxy 2 as one of the origin servers
> in remap config as below:
>
> map http://UHLB <http://uhlb/> http://UHLB <http://uhlb/>
> @plugin=balancer.so @pparam=--policy=roundrobin @pparam=192.168.20.2
> @pparam=192.168.30.2 @pparam=192.168.40.2 @pparam=192.168.50.2
> The last two IP addresses are proxy 2 and proxy3.
> But It did not work.
> I read about parent proxying. But in my case, I want to load balance. May
> I please know to configure to achieve load balancing across hierarchical
> proxies.
>
> Thanks
> Gandhimathi
>
> <PastedGraphic-1.tiff>
>
>
>


-- 
Igor Cicimov | DevOps


p. +61 (0) 433 078 728
e. igorc@encompasscorporation.com <http://encompasscorporation.com/>
w*.* www.encompasscorporation.com
a. Level 4, 65 York Street, Sydney 2000

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