VPNs and Voice SBCs on epmp TDMA (75/25% Spilit) networks

Hello I was wondering is there any performance tips / VPNs / VIOP Codecs that are known to work well over the ePMP TDMA networks,

we have great performance using ePMP with a 75% 25 % split using DHCP / IPOE to the client unit,

however if the customers use SBCs (for VOIP ) and certain types of Security VPN they see
poor voice quality inside the SBC tunnel
poor download performance inside the VPN … zScaler being an example of a problematic VPN…
any tips or tricks (Codes / VPN protocols that work better with ePMP) would be very much appreciated

Hello and welcome to the forum! We have quite a few ePMP sites (e1k and e3k) all using a 75/25 TDD split and I can’t remember any complaints from users about poor VoIP or VPN performance. We set the MTU on both the AP’s and clients to the max of 1700, and enable QoS on the AP and client side with traffic and VoIP priority. We also enable the NAT Helper For SIP on the SM. We typically use firmware 4.6.2 for clients and AP’s.

Can you give us any additional information on your setup? Are these e1k or e3k radios? What firmware revision are you using? Are you using NAT or bridge mode on the SM’s?

We also use voip over ePMP3k for clients and have lots of vpn, etc.

I’d start by doing something like a ping plotter from the client site to their destination or from your edge down to their SM and monitor the hops for a while.

The MOS will be an indicator of performance issues as well as the standard of jitter and latency.

We run a 50/50 network but ratio should have nothing to do with vpn or voip issues. The factors that come to play is network mtu and pps rates. MTU on your network needs to be big enough to handle full sized packets. So at a minimum it needs to be 1536 across all devices from the SM to the AP, tower switch and router, backhauls and core switches and routers. It will not hurt to have your network MTU set to the max of 1700 as this provides capacity and capability to your network.

Pps rates of some codecs are such that you can be hitting a cpu wall on the SM. G.711 and g.712 are normal voip codecs that use larger packets with less compression. Once you get into the g729 and higher compression codecs, you get a lot of tiny packets that makes the call less vulnerable to loss.

Vpn issues are almost always mtu or head end issues.

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