Cisco Support Community
Community Member

Acceptable % of BECN, FECN and Dropped Packets


We have a Frame Relay PVC , which is being used with Traffic Shaping to limit Traffic within our CIR Limit.

However still we receive some FECN, BECN notifications from the Provider's Frame Switch and dropped packets counter also increments occasionally.

Ideally i think that if we are within our CIR, we shouldn't be getting any BECN\FECN etc ?

However is there an acceptable percentage of BECN\FECN that i can compromise on ?

We actually use this PVC for Voice (however it is still considered a DATA PVC in provider's network) and that is why i have configured it to not to go above our CIR, so there are no packets eligible to be dropped.


Re: Acceptable % of BECN, FECN and Dropped Packets

Please paste your configs for Traffic shaping. Settings of Traffic Shaping parameters, while using Voice have to be set correctly to avoid drop of packets.

Community Member

Re: Acceptable % of BECN, FECN and Dropped Packets

dial-peer voice 2000 vofr

destination-pattern 2...


no vad

session target Serial0/0 103

interface Serial0/0

bandwidth 256

ip unnumbered Ethernet0/0

encapsulation frame-relay

no ip mroute-cache

frame-relay traffic-shaping

interface Serial0/0.3 point-to-point

description VOICE LINK

bandwidth 48

ip address x.x.x.x x.x.x.x

no ip mroute-cache

frame-relay interface-dlci 103 IETF

class voice

vofr cisco

frame-relay ip rtp header-compression

map-class frame-relay voice

no frame-relay adaptive-shaping

frame-relay cir 32000

frame-relay bc 320

frame-relay be 0

frame-relay mincir 32000

frame-relay fair-queue

frame-relay voice bandwidth 30000

frame-relay fragment 320

Re: Acceptable % of BECN, FECN and Dropped Packets

Looking at the configs, they do look fine.

Be = 0, Bc = cir/100 for voice, cir = mincir.

Since you are using VOFR, there is no need for Frame-relay ip rtp header compression command, as Voice is sent as Framerelay frames, and not as IP packets.

RTP header compresion could have been used, if you were using VOIP over framrelay.

Check to see in your "show frame-relay pvc" and see if your Frame-relay traffic shaping is shown as ACTIVE or INACTIVE. Traffic shaping will be active, only when your router is subscribing over the CIR.

CreatePlease to create content