xtmClassTable 1.3.6.1.4.1.838.3.2.1.2

This table is a 'flattened' version of a hierarchical class trees that specify the bandwidth allocation for the CBQ interfaces of the system. Each tree is rooted at an interface. A class may either be a leaf, meaning it has no children, or it may be an interior class which has children. As packets are forwarded out an interface, they are compared to the 'flow definition' of each class down the tree until a matching leaf is found or until all classes are traversed. Once a matching class is found, the packet is transmitted or not based on the constraints configured for the class, most importantly the allocated bandwidth as identified by xtmClassRate. If no matching class is found, the packet is dropped. The 'flow definition' for a class can be defined based on inclusive ranges of the following packet fields: o Source IP Address (or a domain name) o Destination IP Address (or a domain name) o Protocol above layer 3 (e.g., UDP, TCP, ICMP, etc.) o Source Port (which identifies service, e.g., FTP, Telnet, SMTP, etc.) o Destination Port It is important that packets only match zero or one traffic class. In order for this to be true, certain rules must be enforced when classes are defined. Specifically, all 'sibling' classes must be defined using the same criteria. Also, children must use criteria not already specified by one of their ancestors or they must specify a subrange of an already specified criteria. Therefore, this tree would be legal: interface 1 subnet A protocol UDP port SNMP protocol TCP subnet B But this tree would be illegal: interface 2 subnet A subnet B (illegal -- not subrange of parent) protocol TCP (illegal -- different criteria than sibling)