When using the “ge” (greater than or equal to) and “le”(less than or equal to) values, you must satisfy the condition: Len < ge <= le. The first line block all the network with subnet mask /32, while the last line permit any. Ip prefix-list Ciscozine-PL permit 0.0.0.0/0 le 32 Example #6: Deny all the loopback network (/32) ip prefix-list Ciscozine-PL deny 0.0.0.0/0 ge 32 le 32 Only the second statement is valid the third and fourth are not valid due to lesser subnet mask and the first one is not valid due the different network. Example #5: Permits all prefixes in the 192.168.0.0/24 with subnet mask between 26 and 30 bits ip prefix-list Ciscozine-PL permit 192.168.0.0/24 ge 26 le 30 The second is not valid due to different prefix, while the fourth due to a greater subnet mask. This check the first 16 bits of the prefix 10.0.0.0, where the subnet mask must be less than or equal to 30. Example #4: Permit all prefixes in the 10.0.0.0/16 with subnet mask less or equal /30 ip prefix-list Ciscozine-PL permit 10.0.0.0/16 le 30 This match only the network 0.0.0.0 with the prefix length 0. Note: the first line can be written like: ip prefix-list Ciscozine-PL deny 10.0.0.0/24 ge 24 le 24 Example #3: Permit only the default route ip prefix-list Ciscozine-PL permit 0.0.0.0/0 Example #2: Block the prefix 10.0.0.0/24 ip prefix-list Ciscozine-PL deny 10.0.0.0/24ĭue to the implicit deny of the prefix list, a second line is required to permit the other networks: ip prefix-list Ciscozine-PL permit 0.0.0.0/0 le 32 This check the first 0 bits of the prefix 0.0.0.0 and the subnet mask must be less than or equal to 32: it permits all the network. Example #1: Permit all the prefix ip prefix-list Ciscozine-PL permit 0.0.0.0/0 le 32 The power of the prefix list happens when you use the “ge” or/and “le” keyword. Prefix list syntax is: ip prefix-list list-name deny | permit network/len įor instance, to block 200.200.200.0/24 network, the command would be: ip prefix-list Ciscozine-PL deny 200.200.200.0/24 Moreover, the prefix-list also allows you to specify networks in much more natural format that ACLs. ACLs used in distribute list filter networks only by network addresses but they do not perform matching on subnet mask in other words, for an ACL used in distribute list, the networks 192.168.100.0/24 and 192.168.100.0/28 are indistinguishable. The most notable and important difference is that a prefix-list allows you to filter networks based on their subnet mask. I fear that this isn't a simple question to answer, but as I said, I know too little about networking to say for sure.Prefix lists are used in route maps and route filtering operations and can be used as an alternative to access lists in many route filtering commands. But, (and here come's my acual question), besides the IP itself (192.168.1.1), Windows also wants to know the subnet prefix length, a gateway and a preferred DNS, and I have absolutely no clue what's supposed to go there or what that even is. To install the new firmware, I have to give my PC a static IP. Meaning the subnets will all be multiples of this number. The decimal bit value row is also the same number as the 'block size' for newly created subnets. Some googling later, it looks like it has a "special" firmware version installed that blocks the access to this web interface. The chart allows you to practise by filling in the appropriate subnet mask or prefix length and then read the other value from the chart. While setting up the modem I encountered a problem where I can't access its web interface, which is needed to finish the setup process. Because I already had a good router lying around, I ordered a modem (Zyxel VMG1312-B30A) to use it with the new connection. The backstory here is quite long but I'll try to keep it short.īasically, my new internet connection got installed today.
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