QOS-Output interpretation

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Jul 9th, 2007
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Hi


We ahve a 15 MB internet connection used for internet as well as for VPN users. I want to reserve 5 MB for the VPN concentrator so that our site to site VPN / VPN clients get atleast 5 MB.


I have configured a class map statement to match ipsec and PPTP (we have some windows clients). On the policy map, I have defined the class and assigned bandwidth 5000 statement.


I applied the service polciy statement on the serial interface. I have attached the output of my sh interface ser1/0 and sh policy-map int ser1/0.


#sh int ser1/0

Serial1/0 is up, line protocol is up

Hardware is DSXPNM Serial

Internet address is x.x.x.x/30

MTU 4470 bytes, BW 15338 Kbit, DLY 200 usec,

reliability 255/255, txload 140/255, rxload 247/255

Encapsulation PPP, LCP Open

Listen: CDPCP

Open: IPCP, crc 16, loopback not set

Keepalive set (10 sec)

Last input 00:00:00, output 00:00:08, output hang never

Last clearing of "show interface" counters 00:17:57

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1385

Queueing strategy: Class-based queueing

Output queue: 0/1000/64/1385 (size/max total/threshold/drops)

Conversations 0/66/256 (active/max active/max total)

Reserved Conversations 1/1 (allocated/max allocated)

Available Bandwidth 6503 kilobits/sec

5 minute input rate 14881000 bits/sec, 2668 packets/sec

5 minute output rate 8474000 bits/sec, 2265 packets/sec

2879169 packets input, 1965574028 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

2482980 packets output, 1178489110 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DSU mode 0, bandwidth 15300, real bandwidth 15338, scramble 0


ICF-FRX2851#sh policy-map int ser1/0

Serial1/0


Service-policy output: VPNPriority


Class-map: VPN (match-any)

555364 packets, 301398490 bytes

5 minute offered rate 1135000 bps, drop rate 0 bps

Match: protocol ipsec

554104 packets, 301331404 bytes

5 minute rate 1134000 bps

Match: protocol pptp

1260 packets, 67086 bytes

5 minute rate 0 bps

Queueing

Output Queue: Conversation 265

Bandwidth 5000 (kbps) Max Threshold 64 (packets)

(pkts matched/bytes matched) 106511/76482141

(depth/total drops/no-buffer drops) 0/0/0


Class-map: class-default (match-any)

2246589 packets, 841337005 bytes

5 minute offered rate 4565000 bps, drop rate 0 bps

Match: any



Can someone explain, why it shows the available bandwidth at 6502 kilobits/sec. I was hoping to see at least 10000 kilobits available.


Thanks


Kumar

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mheusing Mon, 07/09/2007 - 08:46
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  • Cisco Employee,

Hi,


the available bandwidth is calculated like this:


AvailBW = (interface bandwidth)*max-reservable-bandwidth - allocatedBW


where max-reservable-bandwidth=0.75 by default and allocatedBW=sum(allocated BW of all classes)


In your case this means:

AvailBW = 15338*0.75 - 5000 = 6503


AvailBW is the bandwidth you could allocate in your service-policy to additional classes or increase bandwidth for existing classes.


Hope this helps!


Regards, Martin

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