tcp-udp

TCP/UDP Load Balancing Example

In this example we deploy the NGINX OpenShift Router, a DNS server and then configure both TCP and UDP load balancing for the DNS server using routes.

Prerequisites

• We use dig for testing. Make sure it is installed on your machine.
• Make sure to open port 5353 in the firewall for both TCP and UDP traffic on the node where the Router is running:

  $ sudo iptables -I OS_FIREWALL_ALLOW -p tcp --dport 5353 -j ACCEPT
  $ sudo iptables -I OS_FIREWALL_ALLOW -p udp --dport 5353 -j ACCEPT
  

1. Deploy the NGINX Router

1. Follow the installation instructions for NGINX or NGINX Plus.

2. Save the public IP address of the node where the Router is running into a shell variable:

   $ export ROUTER_IP=xxx.xxx.xxx.xxx
   

3. Save port 5353 of the Router into a shell variable:

   $ export ROUTER_5353_PORT=5353
   

2. Deploy the DNS Server

We deploy two replicas of CoreDNS, configured to forward DNS queries to 8.8.8.8.

Deploy the DNS server:

$ kubectl apply -f dns.yaml

3. Create the Routes

$ oc create -f dns-udp-route.yaml
$ oc create -f dns-tcp-route.yaml

3. Test the DNS Server

To test that the configured TCP/UDP load balancing works, we resolve the name openshift.io using our DNS server available through the Router:

1. Resolve openshift.io through UDP:

   $ dig @$ROUTER_IP -p $ROUTER_5353_PORT openshift.io
   
   ; <<>> DiG 9.10.6 <<>> @192.168.99.100 -p 5353 openshift.io
   ; (1 server found)
   ;; global options: +cmd
   ;; Got answer:
   ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 34229
   ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
   
   ;; OPT PSEUDOSECTION:
   ; EDNS: version: 0, flags:; udp: 512
   ;; QUESTION SECTION:
   ;openshift.io.			IN	A
   
   ;; ANSWER SECTION:
   openshift.io.		6	IN	A	52.44.3.11
   openshift.io.		6	IN	A	52.71.98.175
   
   ;; Query time: 47 msec
   ;; SERVER: 192.168.99.100#5353(192.168.99.100)
   ;; WHEN: Fri Aug 17 12:21:42 PDT 2018
   ;; MSG SIZE  rcvd: 97
   

2. Resolve openshift.io through TCP:

   $ dig @$ROUTER_IP -p $ROUTER_5353_PORT openshift.io +tcp
   
   ; <<>> DiG 9.10.6 <<>> @192.168.99.100 -p 5353 openshift.io +tcp
   ; (1 server found)
   ;; global options: +cmd
   ;; Got answer:
   ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 24550
   ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1
   
   ;; OPT PSEUDOSECTION:
   ; EDNS: version: 0, flags:; udp: 512
   ;; QUESTION SECTION:
   ;openshift.io.			IN	A
   
   ;; ANSWER SECTION:
   openshift.io.		7	IN	A	52.44.3.11
   openshift.io.		7	IN	A	52.71.98.175
   
   ;; Query time: 62 msec
   ;; SERVER: 192.168.99.100#5353(192.168.99.100)
   ;; WHEN: Fri Aug 17 12:22:12 PDT 2018
   ;; MSG SIZE  rcvd: 97