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dns resolution problem with dual-wan failover

Hello everyone, I have a problem trying to setup following configuration (edge router pro, 1.9.0)

 

- I used the wizard "Load Balancing" to setup basic failover scenario:

 

eth0-192.168.1.1(lan) ---> eth6-1.1.1.2(primary-wan)

                                   ---> eth7-2.2.2.2(secondary-wan only failover)

 

- All works fine

- If I remove nat masquerade configuration that the wizard has setup for both wan interfaces, I can't ping dns address anymore from the edge router (ping google.it for example)

- I can ping however ip address (ping 8.8.8.8)

- troubleshooting using packet capture show that during dns request the edge router send  some dns query with source address 1.1.1.2 out eth7 and some dns query with source 2.2.2.2 out eth6.

- this strange behaviour cause asymmetric routing for dns flows

 

this is traffic exit eth6 (ip address 1.1.1.2)

IP 2.2.2.2.46049 > 8.8.8.8.53: 6213+ A? google.it. (27)

IP 2.2.2.2.48326 > 8.8.8.8.53: 51778+ A? ping.ubnt.com. (31)

 

this is traffic exit eth7 (ip address 2.2.2.2):

IP 1.1.1.2.35327 > 8.8.8.8.53: 15853+ A? ping.ubnt.com. (31)

IP 1.1.1.2.50428 > 8.8.8.8.53: 32648+ A? google.it. (27)

 

 

Am I missing something ?

 

Here below my simple config without masquerade:

 

set firewall all-ping enable

set firewall broadcast-ping disable

set firewall group

set firewall ipv6-receive-redirects disable

set firewall ipv6-src-route disable

set firewall ip-src-route disable

set firewall log-martians disable

set firewall modify balance rule 100 action modify

set firewall modify balance rule 100 modify lb-group G

set firewall receive-redirects disable

set firewall send-redirects enable

set firewall source-validation disable

set firewall syn-cookies enable

set interfaces ethernet eth0 address 192.168.1.1/24

set interfaces ethernet eth0 description Local

set interfaces ethernet eth0 duplex auto

set interfaces ethernet eth0 firewall in modify balance

set interfaces ethernet eth0 speed auto

set interfaces ethernet eth1 duplex auto

set interfaces ethernet eth1 speed auto

set interfaces ethernet eth2 duplex auto

set interfaces ethernet eth2 speed auto

set interfaces ethernet eth3 duplex auto

set interfaces ethernet eth3 speed auto

set interfaces ethernet eth4 duplex auto

set interfaces ethernet eth4 speed auto

set interfaces ethernet eth5 duplex auto

set interfaces ethernet eth5 speed auto

set interfaces ethernet eth6 address 1.1.1.2/24

set interfaces ethernet eth6 description WAN

set interfaces ethernet eth6 duplex auto

set interfaces ethernet eth6 speed auto

set interfaces ethernet eth7 address 2.2.2.2/24

set interfaces ethernet eth7 description 'WAN 2'

set interfaces ethernet eth7 duplex auto

set interfaces ethernet eth7 speed auto

set interfaces loopback lo

set load-balance group G interface eth6

set load-balance group G interface eth7 failover-only

set load-balance group G lb-local enable

set protocols static route 0.0.0.0/0 next-hop 1.1.1.1

set protocols static route 0.0.0.0/0 next-hop 2.2.2.1

set service gui http-port 80

set service gui https-port 443

set service gui older-ciphers enable

set service ssh port 22

set service ssh protocol-version v2

set system conntrack expect-table-size 4096

set system conntrack hash-size 4096

set system conntrack table-size 32768

set system conntrack tcp half-open-connections 512

set system conntrack tcp loose enable

set system conntrack tcp max-retrans 3

set system host-name ubnt

set system name-server 8.8.8.8

set system ntp server 0.ubnt.pool.ntp.org

set system ntp server 1.ubnt.pool.ntp.org

set system ntp server 2.ubnt.pool.ntp.org

set system ntp server 3.ubnt.pool.ntp.org

set system syslog global facility all level notice

set system syslog global facility protocols level debug

set system time-zone UTC

 

 

 

Thanks for your help!

 

 


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