We are using 3750 switches in our core & distribution layer in many sites. WAN links are at a variety of speed (2 M, 5M, 10M up to dark fiber running at 1G)through our MAN provider network. I'm actually designing the QoS strategy and implementation for support Voice, Mission critical traffics, best effort and so on. The only traffics I don't know how to mark them, are network management traffics generated by the network element itself: as SNMP, NTP, Syslog, TFTP, telnet, SSH. Do you have an idea how to do that? I know OSPF is marked by default to dscp 48 which is fine. What about the other net man traffics.
I found out, that for some management protocols (telnet, ssh, snmp) you can set a precedence, dscp or TOS value:
C2960(config)#ip telnet tos ?
<0-FF> TOS value
C2960(config)#ip ssh ?
dscp IP DSCP value for SSH traffic
precedence IP Precedence value for SSH traffic
C2960(config)#snmp-server ip ?
dscp IP DSCP value for SNMP traffic
precedence IP Precedence value for SNMP traffic
ip telnet tos C0
snmp-server ip precedence 0
According to IOS explanation, "ip ssh dscp 0" is default, but it remains in the config, whatever value you enter (did not try all 64 dscp values ;-)
For other protocols, I didn't find a way to set QoS values, but these three seem to be the most important to me.