[Asterisk-Users] QOS / Cisco / Asterisk

[Julio Arruda]

Matt Schulte wrote:
> We're trying to PQ (Priority Queue) packets on a Cisco using ACL's. What
> we're trying to avoid is hardcoding the IP address in the ACL. We were
> trying to match by TOS set by Asterisk however it seems we've run into a
> snag where the packet TOS tends to get reset somewhere on our network.
> Has anyone had this issue? We're running Cisco everywhere inbetween
> (even the switches). Is there an alternative way to match these? We've
> thought of by port but that's kind of ad-hoc IMHO.

I know some LAN switching devices, in a default "QoS" configuration, 
would treat ports as "diffserv" untrusted ports, or access ports, 
meaning, the DSCP (a reuse of the TOS also) in packets inbound at that 
port are not to be trusted. Have you looked at your switches documentation ?

> 
> Asterisk1 --> 3560 --> 2600 -- (T1) --> 7500 --> 2900 --> 3550 -->
> Asterisk2 
> 
> Sniff: (note the dumps between the 2 machines are diff times however
> they show the same occurance)
> 
> Asterisk1: 1.1.1.1
> 09:09:10.019191 IP (tos 0x10, ttl  64, id 58, offset 0, flags [DF],
> proto 17, length: 60) 1.1.1.1.12056 > 1.1.1.2.19726: [no cksum] UDP,
> length 32
> 09:09:10.030146 IP (tos 0x0, ttl  62, id 63, offset 0, flags [DF], proto
> 17, length: 60) 1.1.1.2.19726 > 1.1.1.1.12056: [no cksum] UDP, length 32
> 
> Asterisk2: Dump on 206.80.70.55
> 09:34:34.418386 IP (tos 0x0, ttl  62, id 261, offset 0, flags [DF],
> proto 17, length: 60) 1.1.1.1.14796 > 1.1.1.2.18996: [no cksum] UDP,
> length 32
> 09:34:34.422974 IP (tos 0x10, ttl  64, id 273, offset 0, flags [DF],
> proto 17, length: 60) 1.1.1.2.18996 > 1.1.1.1.14796: [no cksum] UDP,
> length 32