[c-nsp] policer in case of burstable IP transit service

[Aaron]

Hi Martin, I provide cell backhaul for a cell phone carrier in my
area....they pay for 50 mbps.  They have a gige connection to my
switch/router (asr901).  My testing showed that small frame sizes (64 byte)
would result in needing a traffic contract of 70 or 75 mbps for them to see
the 50 mbps data rate they wanted.....however, I recall that frames of 1500
(or maybe it was ~9000) bytes allowed them less overhead and I could
contract at ~50 mbps....so I went ahead with the 75 mbps to ensure a good
experience for them regardless of pdu size.... also, when I created the
policers, I saw that IOS created an automatic committed burst (bc)...i'm not
sure how it did that but it did.  I left that in place as I believe it
causes the policer to be not-so-strict and allow for some bursting...again,
a better experience for them is what I was hoping for.

Not sure if this is the answer you were looking for but thought I'd share.

Aaron

901#sh run in g0/5 | in policy
 service-policy input pm

901#sh policy-map
  Policy Map pm
    Class class-default
     police cir 75000000 bc 2343750
       conform-action transmit
       exceed-action drop

901#sh policy-map int g0/5
 GigabitEthernet0/5

  Service-policy input: pm

    Class-map: class-default (match-any)
      0 packets, 57939250 bytes
      30 second offered rate 1000 bps, drop rate 0000 bps
      Match: any
      police:
          cir 75000000 bps, bc 2343750 bytes
        conformed Packet count - n/a, 57939250 bytes; actions:
          transmit
        exceeded Packet count - n/a, 0 bytes; actions:
          drop
        conformed 1000 bps, exceeded 0000 bps
901#


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Martin T
Sent: Sunday, September 02, 2012 10:06 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] policer in case of burstable IP transit service

Hello,

in case of IP transit service, is it common to use shaper/policer? For
example customer commits to 100Mbps IP transit with burst(billed using the
95th percentile calculation). In such case ISP has to provide at least GigE
port. Is it common to use policer with 200-400Mbps value?
Or is it more common to allow customer to burst up to port-speed? Both seem
to have their advantages and disadvantages to ISP. More traffic consumed by
customer means more profit to ISP. On the other hand ISP needs to commit
more bandwidth with their upstream provider. In addition, such policer would
provide some sort of protection and help to avoid very high IP transit bill
for customer in case of DDoS attacks.


regards,
martin
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