[j-nsp] JUNIPER POLICER and CoS Shaping Rate

[Andrew Jones]

I personally use the following guide,
http://www.juniper.net/techpubs/en_US/junos11.2/topics/reference/general/policer-guidelines-burst-size-calculating.html
except
with mutiples of 8ms (makes it easier on the maths).

For example, if you've got a 20mbit shaper applied to the interface than
the burst rate for all of your policers will be 20kbytes, this will allow
for a full shaped rate burst for 8ms. Can tweak to 16ms, 32ms, etc if
required.
On Thu, Oct 4, 2012 at 12:54 PM, GIULIANO (WZTECH)
<giuliano at wztech.com.br>wrote:

> People,
>
> Some topics where questioned today about how to limit traffic for vlan
> subscribers using MX5 routers.
>
> The main question is related to system architecture related to the main
> gear (internal machine) to control and limiting packets.
>
> Using policers (input or output) or shaping-rate we have quite the same
> result: miscalculating or error.
>
> If we create a rule like the following:
>
>
> set class-of-service interfaces ge-0/0/1 unit 530 shaping-rate 20m
>
>
> The output traffic rates 19.2~ Mbps only (using MRTG and SNMP statistics
> and graphics).
>
> We ever needs to allocate more bandwidth for the subscriber like.
>
> set class-of-service interfaces ge-0/0/1 unit 530 shaping-rate 22m
>
> To get the correct result ...
>
> Using policers generate almost the same result for output traffic.
>
> Is this because of system architecture or this is a graphic's mistake ?
>
> The burst size limit influence this result ? It must be calculated using
> what kind of parameter ?
>
> For example (same physical interface, same MTU, etc):
>
> Interface ge-0/0/0 unit 10 - VLAN 10 - 30 Mbps What is the correct burst ?
>
> Interface ge-0/0/0 unit 20 - VLAN 20 - 50 Mbps What is the correct burst ?
>
> Interface ge-0/0/0 unit 30 - VLAN 30 - 150 Mbps What is the correct burst ?
>
> Interface ge-0/0/0 unit 30 - VLAN 30 - 4 Mbps What is the correct burst ?
>
> Does anyone has solved this problems ?
>
> Is it possible to get a correct parameter and points to a correct limit
> for the contracted bandwidth ?
>
> Thanks a lot,
>
> Giuliano
>
>
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