3com S7906E Instruccion De Instalación

 

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3)  If the protocol types have the same precedence, look at the source IP address wildcard masks. 

Then, compare packets against the rule configured with more zeros in the source IP address 

wildcard mask. 

4)  If the numbers of zeros in the source IP address wildcard masks are the same, look at the 

destination IP address wildcard masks. Then, compare packets against the rule configured with 

more zeros in the destination IP address wildcard mask.  

5)  If the numbers of zeros in the destination IP address wildcard masks are the same, look at the 

Layer 4 port number ranges, namely the TCP/UDP port number ranges. Then compare packets 

against the rule configured with the smaller port number range. 

6)  If the port number ranges are the same, compare packets against the rule configured first. 

The following shows how your switch performs depth-first match in an Ethernet frame header ACL:  

1)  Sort rules by source MAC address mask first and compare packets against the rule configured with 

more ones in the source MAC address mask.  

2)  If two rules are present with the same number of ones in their source MAC address masks, look at 

the destination MAC address masks. Then, compare packets against the rule configured with more 

ones in the destination MAC address mask.  

3)  If the numbers of ones in the destination MAC address masks are the same, compare packets 

against the one configured first.  

The comparison of a packet against an ACL stops once a match is found. The packet is then processed 

as per the rule.  

When defining rules in an IPv4 ACL, you do not necessarily assign them numbers; the system can do 

this automatically, and the step defines the increment between two neighboring numbers. For example, 

with a step of 5, rules are automatically numbered 0, 5, 10, 15, and so on. By default, the step is 5. 

Whenever the step changes, the rules are renumbered, starting from 0. For example, if four rules are 

numbered 5, 10, 15, and 20 respectively, changing the step from 5 to 2 will cause the rules to be 

renumbered 0, 2, 4, and 6.  

With the step and rule numbering/renumbering mechanism, you do not need to assign rules numbers 

when defining them. The system will assign a newly defined rule a number that is the smallest multiple 

of the step bigger than the currently biggest number. For example, with a step of five, if the biggest 

number is currently 28, the newly defined rule will get a number of 30. If the ACL has no rule defined 

already, the first defined rule will get a number of 0. 

Another benefit of using the step is that it allows you to insert new rules between existing ones as 

needed. For example, after creating four rules numbered 0, 5, 10, and 15 in an ACL with a step of five, 

you can insert a rule numbered 1.  

You can control when a rule can take effect by referencing a time range in the rule.