RE: Which one should I pick ?

From: asadovnikov (asadovnikov@comcast.net)
Date: Wed Oct 08 2003 - 21:04:54 GMT-3


Thank you for the correction. I believe you are right. Some time my brains
do not function right in the middle of the night, I gotta quit sending notes
that that late. Stand corrected.

Best regards,
Alexei

-----Original Message-----
From: Mike Williams [mailto:ccie2be@swbell.net]
Sent: Wednesday, October 08, 2003 6:16 PM
To: 'asadovnikov'; 'Hunt Lee'; ccielab@groupstudy.com
Subject: RE: Which one should I pick ?

Not neccesarily true... If you use GTS on an interface, then (AFAIK) it
will only kick in when there is congestion, but if you apply shaping using a
policy map (i.e. class-based shaping), the shaping "creates a false
congestion" whenever the that traffic class exceeds the values you use on
the shaping command (this was told to me by a group of Cisco
SE's) and then actively shapes the traffic. I configured the policy to
shape certain traffic down to 8Kbps, and it works like a charm regardless of
whether the interface was congested or not. Furthermore, my testing was
also done on an ethernet interface, and this was a 3600 router (not really
"high-end"). In my testing, we were trying to limit the bandwidth used by a
VPN tunnel. Since we knew the IP address of each endpoint, I just made an
access-list, made a class that matched that ACL, then made a policy that
only affected that class. Since you can only shape on traffic going out of
an interface, I had to apply this shaping to the FastEthernet interface
(instead of the ATM interface). Like I said, it worked like a charm, and I
could see that it was actively shaping the traffic down to 8Kbps, as well as
how many packets were delayed, dropped, etc...

Mike W.

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
asadovnikov
Sent: Wednesday, October 08, 2003 5:51 AM
To: 'Hunt Lee'; ccielab@groupstudy.com
Subject: RE: Which one should I pick ?

The way you put the question makes policing the only choice. Either a
police statement as you specified, or older CAR will do. Shaping only kicks
in during congestion periods and is not in effect unless a congestion is
present.

Further I do not believe shaping is supported on Ethernet (some higher end
boxes to have additional QOS implemented in hardware).

Best regards,
Alexei

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Hunt
Lee
Sent: Tuesday, October 07, 2003 10:06 PM
To: ccielab@groupstudy.com
Subject: Which one should I pick ?

If I have a question:

Configure CBWFQ on R1's Ethernet interface such that it allocates min
bandwidth of 3mbps for VLANA. VLANA traffic should limit to 5mbps and
cannot utilize more physical bandwidth during non-congestion period.

Should I use:

policy-map cbwfq
 class VLAND
   bandwidth 3000
   shape peak 5000000

OR

policy-map cbwfq
 class VLAND
   bandwidth 3000
   police 5000000 937500 1875000 conform-action transmit exceed-action drop
violate-action drop

And if you could give me reasoning on why you pick that one, it would be
greatly appreciated.

Thank you so much in advance,
H.

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