Summary:ASTERISK-26005: res_pjsip: Multiple SIP messages are combined into 1 TCP packet
Reporter:Ross Beer (rossbeer)Labels:
Date Opened:2016-05-09 10:22:37Date Closed:2016-05-17 05:24:22
Versions:13.8.2 13.9.0 Frequency of
Environment:CentOS 7Attachments:
Description:When using chan_pjsip with TCP transport multiple packets are concatenated into one TCP packet causing the packet to exceed the MTU size.

Setting the standard kernel options has no effect:

net.ipv4.ip_no_pmtu_disc = 1
net.ipv4.tcp_low_latency = 1
net.ipv4.tcp_autocorking = 0

The above options should stop the kernel concatenating the packets, however this is still occurring.

This causes an issue for a lot of handsets, this is most noticeable on handsets that have multiple BLF keys. For example Snom D715 or Cisco SAP504G + Sidecarts. This causes the phones to misbehave and to be come unusable. Switching to UDP or TLS resolves the issue and the phones function correctly.
Comments:By: Asterisk Team (asteriskteam) 2016-05-09 10:22:38.195-0500

Thanks for creating a report! The issue has entered the triage process. That means the issue will wait in this status until a Bug Marshal has an opportunity to review the issue. Once the issue has been reviewed you will receive comments regarding the next steps towards resolution.

A good first step is for you to review the [Asterisk Issue Guidelines|https://wiki.asterisk.org/wiki/display/AST/Asterisk+Issue+Guidelines] if you haven't already. The guidelines detail what is expected from an Asterisk issue report.

Then, if you are submitting a patch, please review the [Patch Contribution Process|https://wiki.asterisk.org/wiki/display/AST/Patch+Contribution+Process].

By: George Joseph (gjoseph) 2016-05-15 19:10:36.325-0500

Ross can you test review 2389?  It ias the TCP_NODELAY flag set on tcp transports.

By: Ross Beer (rossbeer) 2016-05-17 05:18:57.143-0500

This appears to have resolved the TCP issue and phones with BLF now register and show presence correctly.