Peers unreachable and reachable again frequently

The peers and Trunk SIP change the status unreachable and reachable again frequently.
I believe that i have a network trouble.

The network topology has 3 HP Switch connected directly to a Draytek, and the Asterisk and phones are connected to the Switches

Asterisk log show for each SIP peer:

[May 23 16:55:46] WARNING[3796] chan_sip.c: sip_xmit of 0x7fd01c0129c0 (len 608) to returned -2: Network is unreachable
[May 23 16:55:46] ERROR[3796] chan_sip.c: Serious Network Trouble; __sip_xmit returns error for pkt data
[May 23 16:55:46] WARNING[3796] acl.c: Cannot connect

Asterisk 13.11.2
CentOS Linux release 7.3.1611 (Core)

I appreciate your help.

That’s not an Asterisk problem. As you say, you have network trouble.

One common cause of this is having two machines trying to claim the same IP address (neither of them the Asterisk machine.)

@david551 is correct. Look outside of Asterisk and confirm that the network connection itself is fine. The problem in Asterisk is a symptom, not the problem.

OK, i wanted to another opinion or point view for continue checking the network.

i have been checking the network, when i solve it, i tell you what is the problem.


In this moment i solved my network trouble.
I had 3 HP switches with old firmware, when i upgrade the firmware the asterisk began to work good.


Hi Friends,

I identified the real trouble time after. It problem was caused by the ISP Provider’s DNS.
I used another DNS server and finally the system could worked correctly.

Please, somebody knows about the function of DNS in Asterisk?

I need to understand this, if you have documentation please share me. thank you.