[Asterisk-Users] QoS TOS numbers and Cisco IOS

[Eric Wieling]

tos=0xb8 will set the the packet to be DSCP EF (Cisco likes to use DSCP)

Rich Adamson wrote:

>>Does anyone know how setting the TOS bits in iax.conf corresponds to 
>>the Cisco TOS types?
>>
>>For example, if I set:
>>
>>tos=0x04
>>
>>in iax.conf, and on the Cisco, I use:
>>
>>access-list 110 permit ip any any tos 4
>>
>>I can't get the Cisco to match any packets.  I've tried various 
>>combinations of numbers on both asterisk and the cisco.  I've also 
>>tried hex to decimal conversion.  I just can't get the Cisco to see the 
>>TOS bits that I set in iax.conf.
> 
> 
> Here's what I'm using.
> 
> sip.conf:
> tos=0x18  ;lowdelay     ;sets ip tos bits (=lowdelay, throughput)  
> iax.conf:
> tos=lowdelay
> 
> Cisco:
> class-map match-all voice-rtp
>   match access-group 103
> 
> access-list 103 permit ip any any tos min-delay
> access-list 103 permit ip any any tos 12
> 
> C1750#show access-list 103
> Extended IP access list 103
>     permit ip any any tos min-delay (2077271 matches)
>     permit ip any any tos 12 (651833 matches)
> 
> The NAI Sniffer does a better job of showing the bits. Here's two
> samples for the above:
> 
> sip packet (tos=0x18):
>       IP: Type of service = 18
>       IP:       000. ....   = routine
>       IP:       ...1 .... = low delay
>       IP:       .... 1... = high throughput
>       IP:       .... .0.. = normal reliability
>       IP:       .... ..0. = ECT bit - transport protocol will ignore the CE bit
>       IP:       .... ...0 = CE bit - no congestion
> 
> iax packet (tos=lowdelay):
>       IP: Type of service = 10
>       IP:       000. ....   = routine
>       IP:       ...1 .... = low delay
>       IP:       .... 0... = normal throughput
>       IP:       .... .0.. = normal reliability
>       IP:       .... ..0. = ECT bit - transport protocol will ignore the CE bit
>       IP:       .... ...0 = CE bit - no congestion
> 
> Study the above and the bits become very clear. :)
> 
> 
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