rate limiting a connection

Hola ws00sw

You can understand traffic-shaping logic by reviewing just a few simple examples. the basics follow these simple examples: If a Router has a 128-kbps access rate, and a 64-kbps CIR, and if you want to shape the traffic to match CIR (64 kbps), the Router just has to send traffic on the link half of the time. If, over time, The Router sends traffic half of the time, at 128 kbps (because that's the only rate it can actually send traffic), the average over that time is 64 kbps. The concept is that simple!

IOS actually calculates, based on the configuration, how many bits could be sent in each interval so that the shaped rate would be met. This value is called the committed burst (Bc) for each interval. It is considered a burst, because the bits actually flow at the physical line rate. The burst is committed, because if you send this much every interval, you are still conforming to the traffic contract.

With many shaping tools, Tc = Bc/CIR.

Bc Committed burst size, measured in bits. This is the amount of traffic that can be sent over the interval Tc. Typically also defined in the traffic contract. CIR Committed information rate, in bits per second, defines the rate defined in the traffic contract.

Shaped Rate The rate, in bits per second, to which a particular configuration wants to shape the traffic. In some cases, the shaped rate is set to the same value as CIR; in others, the shaped rate is set to a larger value, with the hope of sending more traffic through the network. Be Excess burst size, in bits. This is the number of bits beyond Bc that can be sent after a period of inactivity.

Saludos, Victor Cappucio

Why must cisco be so cryptic? CIR and Bc and Tc were not meant to be bandwidth management terms. I like products like the ET/BWMGR by

BWin = 512000 BWout = 512000 BWburst = 768000 BurstDuration = 20

CIR was originally a Frame Relay term, and if you only transmitted at CIR then you were cheating yourself, because most of the time it didnt matter. The only time you had to throttle was if you got a BeCN bit from the switch. Unfortunately, the combination of bad FR switches and bad routers made it pretty messy.

I Agree

CISCO SUCKS

Look this:

interface Serial0/0 no ip address encapsulation frame-relay no fair-queue frame-relay traffic-shaping

map-class frame-relay shape-at-64 frame-relay traffic-rate 64000 64000

interface Serial0/0.1 point-to-point ip address 192.168.2.253 255.255.255.252 frame-relay class shape-all-64 frame-relay interface-dlci 101

CCOSUCKS#show traffic-shape Interface Se0/0.1 Access Target Byte Sustain Excess Interval Increment Adapt VC List Rate Limit bits/int bits/int (ms) (bytes) Active

The Sustain bits interval should be 8000.... not 64000

Cisco Programming makes nausea