Dell Force10 Z9000 FTOS Configuration Guide for Z9000 System - Page 110

www.dell.com | support.dell.com If you want to forward all routes that do not match the prefix list criteria, you must configure a prefix list filter to permit all routes (permit 0.0.0.0/0 le 32). The "permit all" filter should be the last filter in your prefix list. To permit the default route only, enter permit 0.0.0.0/0. Figure 6-13 illustrates how the seq command orders the filters according to the sequence number assigned. In the example, filter 20 was configured before filter 15 and 12, but the show config command displays the filters in the correct order. Figure 6-13. Command Example: seq FTOS(conf-nprefixl)#seq 20 permit 0.0.0.0/0 le 32 FTOS(conf-nprefixl)#seq 12 deny 134.23.0.0 /16 FTOS(conf-nprefixl)#seq 15 deny 120.23.14.0 /8 le 16 FTOS(conf-nprefixl)#show config ! ip prefix-list juba seq 12 deny 134.23.0.0/16 seq 15 deny 120.0.0.0/8 le 16 seq 20 permit 0.0.0.0/0 le 32 FTOS(conf-nprefixl)# Note the last line in the prefix list Juba contains a "permit all" statement. By including this line in a prefix list, you specify that all routes not matching any criteria in the prefix list are forwarded. To delete a filter, use the no seq sequence-number command in the PREFIX LIST mode. If you are creating a standard prefix list with only one or two filters, you can let FTOS assign a sequence number based on the order in which the filters are configured. The FTOS assigns filters in multiples of five. To configure a filter without a specified sequence number, use these commands in the following sequence starting in the CONFIGURATION mode: Step Command Syntax 1 ip prefix-list prefix-name 2 {deny | permit} ip-prefix [ge min-prefix-length] [le max-prefix-length] Command Mode CONFIGURATION CONFIG-NPREFIXL Purpose Create a prefix list and assign it a unique name. Create a prefix list filter with a deny or permit action. The optional parameters are: • ge min-prefix-length: is the minimum prefix length to be matched (0 to 32). • le max-prefix-length: is the maximum prefix length to be matched (0 to 32). Figure 6-14 illustrates a prefix list in which the sequence numbers were assigned by the software. The filters were assigned sequence numbers based on the order in which they were configured (for example, the first filter was given the lowest sequence number). The show config command in the PREFIX LIST mode displays the two filters with the sequence numbers 5 and 10. 110 | Access Control Lists (ACLs)