VoIP latency, but no packet loss

[voidedsquirrel]

Hi all,

Looking for some assistance for a particular installation which has been extremely problematic from the beginning!

The scenario:-

SIP trunks sat on a Gamma Assured 20 broadband circut - terminating on a Cisco 800 series router.

Router is connected to a ZyXEL GS1900 Gigabit Ethernet data switch which the LG IPECS telephone system and associated modules connect to.

The ONLY connectivity that our equipment has with the customer LAN is via a PC connected to the ZyXEL data switch. The second NIC on this PC sits on the customer's LAN.

Customer is experiencing delay, but no packet loss. The users of the phones are complaining about delay and talking over one-another (classic VoIP issues) but the interesting thing is packet traces are seeing nothing untoward on the phone system network. The ISP (Gamma) have provided the attached smoke ping graph which shows the spike in latency ONLY WHEN THE PHONES ARE IN USE. Broadband circuit is running at a more than suitable speed to handle 20 concurrent calls, so bandwith is not an issue.

ANY HELP WOULD BE MASSIVELY APPRECIATED!!!
Thanks in advance.

 

[VinceWhirlwind]

Those spikes aren't enough for people to be talking over each other. It has to get well over 200ms one-way for that. And your graph may well be showing return trip latency too.

Why are you routing everything through a PC? Have you tried routing it through a proper router instead and seeing what happens?