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New Member

CBWFQ - HELP PLS - My most serious post to this forum!

my head is about to explode.

(imagine its a 1Mbps cct)

I have to do the folloiwng

Users on a that share a serial line, should have the

following restrictions


35% FTP Traffic

25% Telnet Traffic

30% Voice Traffic

So, If I am asked a question such as the above,

I should set the max-reseve-bandwidth to 90 on the interface, and configure the queing as such?

policy-map traffic

class voice

priority 300

class telnet

bandwidth 25

class ftp

bandwidth 35

now when I configure queueing and I have put the voice traffic into a strict LLQ, now my percentages change dont they?

ie, we now have only 700k to play with for CBWFQ (imagine its a 1Mbps cct) and PLEASE NOTE, that i cant seem to find a "priority percent" command for LLQ - I assume one does not exist, so you have to specify LLQ in Kbits only.

Is the 300k for voice correct, as I have calulated this as 30% of the total cct bandwidth, or should it be 30% of 900k as the max-reserved-bandwidth is set to 90.

Also, I dont now know if I should adjust my telnet and FTP percentages to 25% of 700k or 25% of 600k as is the remaining bandwidth total-bandwidth minus LLQ reserved BW or 90% of the bandwdith minum LLQ reserved BW or will this just be done automatically? and I just leave these alone?

I am just about to go jump in a lake :(

Many thx



Re: CBWFQ - HELP PLS - My most serious post to this forum!

The bandwidth you 'carve-up' should not exceed 75% of the total bandwidth available - for example if you have a 100Mb link then you can only define a policy that totals 75Mb. The LLQ is used in this calculation, so based on your requirements your policy won't work properly. The 75% rule assumes that some bandwidth is required for overhead traffic, such as routing and Layer 2 keepalives. You can change this setting on the link with the interface command 'max-reserved-bandwidth'.

I am running 12.2T on a router and the 'priority percent' command is available.


New Member

Re: CBWFQ - HELP PLS - My most serious post to this forum!

many thx indeed :)