# Frame Relay BE excess burst size

Discussion in 'Cisco' started by Chris T., May 4, 2005.

1. ### Chris T.Guest

How do I calculate the excess bust size ( BE ) for frame relay?
I am not sure what to set BE to, I have looked around on the internet and do
not see a recommended setting or a way to calculate it.

I know how to calculate BC:
BC = TC x CIR
12,800 = .02 x 640,000

Thank You,

Chris

Chris T., May 4, 2005

2. ### JonathanGuest

Speed of link - CIR = Total Be

Speed of link * Tc = Burst Size

Burst Size is the total amount of data you can send in Tc

Jonathan

Jonathan, May 5, 2005

3. ### apikou

Joined:
Sep 30, 2010
Messages:
1
0
I will give an example how to calculate FR BE, BC etc and traffic-shaping methodologies.

Scenario: DS3 (45Mpbs port), provisioned though for 15Mbps traffic in DLCI, throttle down to 10Mbps in an event
of congestion with an interval of Tc=50 ms, with traffic shapping. Work out values for FR traffic-Shaping (2 mthds):

cir=15000000, mincir=10000000, bc=CIR*Tc=750000, be+bc=max port bandwidth in one Tc which is 45Mbps (but in 50ms).
Hence, 45Mbps in 1 Sec or 2250000bps in 50 ms. So, Be=Max-Bc or 2250000-750000=1500000.

a) method

map-class frame-relay FR_SHAPE
frame-relay cir 15000000
frame-relay bc 750000
frame-relay be 1500000
frame-relay mincir 10000000

interface Serial2/0
encapsulation frame-relay
no keepalive
no fair-queue
frame-relay class FR_SHAPE
frame-relay traffic-shaping

b) method

policy-map FRTS
class class-default
shape average 15000000 750000 1500000

interface Serial2/0
bandwidth 45000
frame-relay interface-dlci 101
service-policy out FRTS

apikou, Sep 30, 2010