Restricting BW for FTP & Filesharing

[sridhar ch]

I have a 40 Mb MPLS link with 20Mb gold car for 1000 users. These days my users started downloading MB's of data from my head office. i have recently modified the existing QOS policy to restrict FTP & Filesharing to 7Mb. still i could see when someone is downloading 300-400Mb, circuit is getting choked and resulting in packet loss. let me know if the below QOS conf holds good, else pls suggest.

i dont want the users to use the available BW if it exceeds 7Mb.

 Policy Map BW
    Class L3-to-L2_VOIP-Cntrl
      priority 128 (kbps)
    Class L3-to-L2_VoIP-RTP
      priority 20480 (kbps)
    Class filecopy
      priority 7168 (kbps)
    Class class-default
      fair-queue

 Class Map match-all L3-to-L2_VOIP-Cntrl (id 3)
   Match ip  dscp af31 (26)
   Match ip  dscp cs3 (24)

 Class Map match-all L3-to-L2_VoIP-RTP (id 1)
   Match ip  dscp ef (46)

 Class Map match-any filecopy (id 7)

   Match protocol netbios
   Match protocol ftp

Thanks,

Sridhar

[Joseph W. Doherty]

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Posting

40 MPLS link, eh?  And the interface hand-off has how much bandwidth?  If it's more than your 40 MPLS, you often need to shape (also as I don't believe most shapers account for L2 overhead, shape about 15% slower).

Ah, I wouldn't recommend using a LLQ class for bulk traffic.  Would recommend a non-LLQ class with an explicit policer or shaper (I generally recommend shaping, over policing, when its available).

You might find, if you shape for your bandwidth, your existing FQ in class-default might preclude the need for a special class for your FTP/NetBIOS traffic.

If that's not sufficient, then you can define a class for it, like you've done, but just provide it a minimum bandwidth guarantee.  For bulk classes, I've often used 1%.  Even with 1%, such traffic can still use all available bandwidth, but it "moves aside" for other traffic.  (My thinking is, I'm paying for the bandwidth, use it if I can, but don't let bulk stuff be adverse to non-bulk traffic.)