From: Fabrice Bobes (study@6colabs.com)
Date: Fri Mar 28 2003 - 03:04:42 GMT-3
Scott,
Actually if I quote the link you are referencing to, it says:
"The bandwidth that a custom queue will receive is given by the
following formula:
(queue byte count / total byte count of all queues) * bandwidth capacity
of the interface
where bandwidth capacity is equal to the interface bandwidth minus the
bandwidth for priority queues. "
It doesn't say bandwidth of the link but bandwidth minus priority queues
(system queues). The traffic generated by the priority queues must be
minimal though.
Finally, the only thing you are quite sure to assign to a queue is its
weight in regards to the other queues. For example, queue #1 get 4 times
more bandwidth than queue #2.
When you convert from CQ to CBWFQ and take into account that 75% of the
bandwidth is allocable to the classes, you keep the relative weight of
each queue. I think it's what matters but I may be wrong of course.
In your initial formula that converts CB towards CBWFQ, you are not
taking into account additional traffic like let's say keepalives but you
are still distributing 100% of the traffic between classes. I believe
it's a problem.
I hope I am not adding too much confusion here :-)
Thanks,
Fabrice
-----Original Message-----
From: Scott M. Livingston [mailto:scottl@sprinthosting.net]
Sent: Thursday, March 27, 2003 8:52 PM
To: 'Fabrice Bobes'; 'Abdul Waheed Ghaffar'; ccielab@groupstudy.com
Subject: RE: QOS
Fabrice,
I am still debating between the two formulas tonight.
What do you think about this? Referencing CQ; I am sure you know the
formula in how to calculate BW distribution in bytes for queues based on
packet size of protocol.... If that was wordy and confusing here is a
url that illustrates;
http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121cgcr/
qos_c/qcprt2/qcdconmg.htm#1001366
So then, when we use this Cisco formula to determine bytes for each
queue we are not referencing the 25% default BW for system traffic. We
are configuring for 100% of the link, but in reality the router will
only allow us 75% of the interface; much in the same way my original
formula was doing when converting from CQ to CBWFQ?
What I mean is the following - when we are just configuring CQ and
determining the byte size of each queue based off protocol packet size
we are aware there is that implicit 25% default queue that does not come
into play w/ our formula. Also, when we convert our CQ bytes to a CBWFQ
bandwidth my original formula does not take into account that same 25%
"system queue" (ya nobody calls it that, but I am just trying to make a
point).
So, by not referencing 75% anywhere in our equation we are basically
comparing apples to apples when converting the byte count (BW) in CQ to
bandwidth in CBWFQ? Does that make sense? Am I missing something?
I probably didn't do a very good job explaining that so let me know if I
was too confusing.
Thanks,
scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott M. Livingston
Sent: Thursday, March 27, 2003 4:20 PM
To: 'Fabrice Bobes'; 'Abdul Waheed Ghaffar'; ccielab@groupstudy.com
Subject: RE: QOS
MMMMMM. You diggin' deep on this one. I understand what you are
explaining now; I forgot about that system queue. HMMMM I will have to
look at this a little harder, but your argument sounds pretty good to me
right now.
Any contention from anyone or does everyone see it like Fabrice does?
Thanks Fabrice!
scott
-----Original Message-----
From: Fabrice Bobes [mailto:study@6colabs.com]
Sent: Thursday, March 27, 2003 4:07 PM
To: 'Scott M. Livingston'; 'Abdul Waheed Ghaffar';
ccielab@groupstudy.com
Subject: RE: QOS
Well, you are still assigning the same percentage of bandwidth
relatively to the max allocable bandwidth (75%). Not sure it's very
clear.
Also, with CQ, there is this queue #0 (system queue) that you don't
configure. Queue #0 borrows the bandwidth that it needs. When we say
that queue #1 in CQ takes 9% of the total bandwidth, it's not completely
true. It takes 9% of the bandwidth that we can assign to the 16
configurable queues. The queue 0 shouldn't take 25% of the bandwidth but
like CBWFQ, there is this idea of a max bandwidth that you allocate to
the queues and it's inferior to 100% of the bandwidth of the link.
Fabrice
-----Original Message-----
From: Scott M. Livingston [mailto:scottl@sprinthosting.net]
Sent: Thursday, March 27, 2003 1:37 PM
To: 'Fabrice Bobes'; 'Abdul Waheed Ghaffar'; ccielab@groupstudy.com
Subject: RE: QOS
Hmmmm? Interesting thinking on your part.
If you do it that way though you really wouldn't be allocating the same
amount of BW that the CQ was allocating to that traffic right? Am I
missing something here?
Scott
-----Original Message-----
From: Fabrice Bobes [mailto:study@6colabs.com]
Sent: Thursday, March 27, 2003 3:21 PM
To: 'Scott M. Livingston'; 'Abdul Waheed Ghaffar';
ccielab@groupstudy.com
Subject: RE: QOS
Hi Scott,
If I may, I wouldn't allocate 100% of the bandwidth to the classes and
would keep the default to 75 %. If you want to assign more than 75% to
the classes, that's fine but not up to 100%.
In other words, I'd rather use this formula for queue #1:
128 kbps * (1000/11500) * 0.75 = 8 (bandwidth 8)
In percentage, this gives us:
(1000/11500) * 0.75 = 6.5 (bandwidth percent 6)
May be I am missing something here so any input?
Fabrice
http://www.6colabs.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Scott M. Livingston
Sent: Monday, March 24, 2003 8:01 PM
To: 'Abdul Waheed Ghaffar'; ccielab@groupstudy.com
Subject: RE: QOS
Here is my attempt. For these scenarios if I can spot the bandwidth
percent real quick then I just use the 'bandwidth percent' command. In
my own freakish way of thinking I can convert it quicker using the
formula below. Tell me what you all think and please let me know if I
messed up somewhere.
BW of Link in kbps * (byte count / total byte count) = BW
For example:
Queue #1
---------
128 kbps * (1000 / 11500) = 11
!
class-map match-all TELNET
match protocol telnet
class-map match-all DLSW
match protocol dlsw
class-map match-all FTP
match protocol ftp
class-map match-all DNS
match protocol dns
!
policy-map MORE-FUN
class TELNET
bandwidth 11
queue-limit 100
class DNS
bandwidth 16
queue-limit 100
class FTP
bandwidth 33
queue-limit 20
class DLSW
bandwidth 55
queue-limit 20
class class-default
bandwidth 11
queue-limit 20
!
thank you,
scott
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Abdul Waheed Ghaffar
Sent: Monday, March 24, 2003 7:04 AM
To: ccielab@groupstudy.com
Subject: QOS
Hi group,
I need to convert following CQ into CBWFQ
# queue-list 1 protocol tcp 1 telnet byte-count 1000 limit 100
# queue-list 1 protocol udp 2 domain limit 100
# queue-list 1 protocol tcp 3 ftp byte-count 3000
# queue-list 1 protocol dlsw 4 byte-count 5000
# queue-list 1 default 16 byte-count 1000
# interface serial 0/1
# custom-queue-list 1
can any body giude me...the serial interface is frame-relay encapsulated
...will i map the service on physical interface or under class-map
frame-relay?
thanks in advance
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