Prefix-list quick ref

Prefix-list ‘magic’, 1st valid match counts (same as ACL matching)

Class A (0 – 127):

  • Classful = ip prefix-list class-A permit 0.0.0.0/1 ge 8 le 8
  • VLSM = ip prefix-list class-A-VLSM permit 0.0.0.0/1 ge 8
  • CIDR = ip prefix-list class-A-CIDR permit 0.0.0.0/1 le 32

Class B (128 – 191):

  • Classful = ip prefix-list class-B permit 128.0.0.0/2 ge 16 le 16
  • VLSM = ip prefix-list class-B-VLSM permit 128.0.0.0/2 ge 16
  • CIDR = ip prefix-list class-B-CIDR permit 128.0.0.0/2 le 32

Class C (192 – 223):

  • Classfull = ip prefix-list class-C permit 192.0.0.0/3 ge 24 le 24
  • VLSM = ip prefix-list class-C-VLSM permit 192.0.0.0/3 ge 24
  • CIDR = ip prefix-list class-C-CIDR permit 192.0.0.0/3 le 32

Class D (224 – 239):

  • Not Classfull / VLSM / CIDR as this range has no ‘default’ subnet mask
  • ip prefix-list class-D permit 224.0.0.0/4 le 32

Class E (240 – 255):

  • Not Classfull / VLSM / CIDR as this range has no ‘default’ subnet mask
  • ip prefix-list class-E permit 240.0.0.0/4 le 32

All routes:

  • ip prefix-lixt all-routes permit 0.0.0.0/0 le 32

(Special ranges)

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