[cisco-nas] 96K availainle bandwidth vs 128K BW on Vi1 bundle consisting of 2 B-channels during 64K Unrestrictet call via ISDN-TA PPP-multilink to 5350 NAS

[Tassos Chatzithomaoglou]

1 start bit + 8 data bits + 1 stop bit = 10 bits (8 of them are "real" data)

so 115200 * (8/10) = 92160 "real" data


PS: I had the same question quite a time ago ;-)

&y0 wrote on 28/1/2005 3:03 μμ:
>  According to customer he connects to COM1 with DTE rate of 112K (what is
> the standard of async rate???). Ok. But ~96K (as it can be seen from flood
> ping result below) is not 112K. Additional bandwidth in 112-96=16K just
> desappears :O) Why?
> 
>  Router#sh int virtual-access 1 | i rate|drop
>   Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 7940
>   Queueing strategy: weighted fair
>   Output queue: 64/1000/64/7940 (size/max total/threshold/drops)
>   30 second input rate 91000 bits/sec, 10 packets/sec
>   30 second output rate 124000 bits/sec, 12 packets/sec  
> Note customer cant make flood ping so I did it from my router and as I
> understand I must have near equal amount of input traffic to output one. 
> 
> 
>>-----Original Message-----
>>From: Tassos Chatzithomaoglou [mailto:achatz at forthnet.gr] 
>>Sent: Friday, January 28, 2005 2:41 PM
>>To: andyo at grass.org.ua
>>Cc: cisco-nas at puck.nether.net
>>Subject: Re: [cisco-nas] 96K availainle bandwidth vs 128K BW 
>>on Vi1 bundle consisting of 2 B-channels during 64K 
>>Unrestrictet call via ISDN-TA PPP-multilink to 5350 NAS
>>
>>If the ISDN-TA is connected to the user's PC though a serial 
>>(115200) port, then this might be "logical".
>>
>>&y0 wrote on 28/1/2005 1:51 ??:
>>
>>>Hi everybody. I have problem while customers places calls 
>>
>>to 5350 NAS 
>>
>>>via ISDN using ISDN-TA and PPP-multilink. During the call 2 
>>
>>B-channels 
>>
>>>are bound to Virtual-access interface which parameters then 
>>
>>looks like this:
>>
>>>Router#sh int virtual-access 1
>>>Virtual-Access1 is up, line protocol is up
>>>  Hardware is Virtual Access interface
>>>  MTU 1500 bytes, BW 128 Kbit, DLY 100000 usec,
>>>     reliability 255/255, txload 1/255, rxload 7/255
>>>  Encapsulation PPP, loopback not set
>>>  DTR is pulsed for 5 seconds on reset
>>>  Time to interface disconnect:  idle 3w3d
>>>  LCP Open, multilink Open
>>>  Open: IPCP
>>>  Last input 00:00:00, output never, output hang never
>>>  Last clearing of "show interface" counters 02:28:22
>>>  Input queue: 0/75/0/0 (size/max/drops/flushes); Total 
>>
>>output drops: 0
>>
>>>  Queueing strategy: weighted fair
>>>  Output queue: 0/1000/64/0 (size/max total/threshold/drops)
>>>     Conversations  0/50/256 (active/max active/max total)
>>>     Reserved Conversations 0/0 (allocated/max allocated)
>>>     Available Bandwidth 96 kilobits/sec
>>>  30 second input rate 4000 bits/sec, 2 packets/sec
>>>  30 second output rate 1000 bits/sec, 1 packets/sec
>>>     32892 packets input, 15179159 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
>>>     31164 packets output, 18584822 bytes, 0 underruns
>>>     0 output errors, 0 collisions, 0 interface resets
>>>     0 output buffer failures, 0 output buffers swapped out
>>>     0 carrier transitions
>>>Router#sy
>>>  Interface      User        Mode                     Idle  
>>
>>   Peer Address
>>
>>>  Vi1          fim        Virtual PPP (Bundle) 00:00:06 10.2.2.1
>>>  Se3/0:1      fim        Sync PPP                    -   
>>
>>Bundle: Vi1
>>
>>>  Se3/0:2      fim        Sync PPP                    -   
>>
>>Bundle: Vi1
>>
>>>Accordingly customer can obtain the data transfer speed no 
>>
>>more ~88K.
>>
>>>It looks like 16K is spent for unknown reason per each B-channel as 
>>>arithmetic of 2*(64K-16K)=96K shows I have ever trusted that 
>>>signalling bandwidth should be taken from D-channel 
>>
>>bandwidth (in my 
>>
>>>case Serial3/0:15).
>>>Am I correct? Have anybody solution for this problem? Below is 
>>>configuration of ISDN and D-channel isdn switch-type primary-net5 
>>>controller E1 3/0 framing NO-CRC4  pri-group timeslots 1-31 
>>
>>interface 
>>
>>>Serial3/0:15  ip unnumbered FastEthernet0/0  ip nat inside  
>>>encapsulation ppp  load-interval 30  dialer idle-timeout 2147483  
>>>dialer load-threshold 1 outbound dialer-group 1  autodetect 
>>>encapsulation ppp v120  isdn switch-type
>>>primary-net5  isdn incoming-voice modem  isdn 
>>
>>sending-complete  no cdp 
>>
>>>enable  ppp authentication pap contract_tac  ppp authorization 
>>>contract_tac ppp multilink  ppp timeout multilink link add 1
>>>
>>>--
>>>AO618-RIPE
>>>108248909
>>>
>>>_______________________________________________
>>>cisco-nas mailing list
>>>cisco-nas at puck.nether.net
>>>https://puck.nether.net/mailman/listinfo/cisco-nas
>>
> 
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