Further Reading
Standards:
RFC 791, "Internet Protocol Specification": http://www.ietf.org/rfc/rfc791.
RFC 2474, "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers": http://www.ietf.org/rfc/rfc2474.
RFC 2597, "Assured Forwarding PHB Group": http://www.ietf.org/rfc/rfc2597.
RFC 2697, "A Single Rate Three Color Marker": http://www.ietf.org/rfc/rfc2697.
RFC 2698, "A Two Rate Three Color Marker": http://www.ietf.org/rfc/rfc2698.
RFC 3168, "The Addition of Explicit Congestion Notification (ECN) to IP": http://www.ietf.org/rfc/rfc3168.
RFC 3246, "An Expedited Forwarding PHB (Per-Hop Behavior)": http://www.ietf.org/rfc/rfc3246.
Cisco documentation:
Cisco IOS QoS Configuration Guide, Cisco IOS version 12.3: http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123cgcr/qos_vcg.htm.
Cisco IOS Configuration GuideConfiguring Data Link Switching Plus, Cisco IOS version 12.3: http://www.cisco.com/univercd/cc/td/doc/product/
software/ios122/122cgcr/fibm_c/bcfpart2/bcfdlsw.htm.Understanding how routing updates and Layer 2 control packets are queued on an interface with a QoS service policy (PAK_priority): http://www.cisco.com/warp/public/105/rtgupdates.html.