Hi all. I need some help with a BGP prefix list. A consulting group has recommended the following prefix list in order to deny learning networks that should not be learnt from the internet. I don't entirely trust these guys to know what they are doing, so I would like to see what you all say about this before I ask them specific questions. For simplicity, the first part of each line - ip prefix-list <word> seq <number> deny has been left off. All of these lines are deny statements 0.0.0.0/32 0.0.0.0/8 le 32 0.0.0.0/1 ge 20 10.0.0.0/8 le 32 127.0.0.0/8 le 32 128.0.0.0/2 ge 17 128.0.0.0/16 le 32 172.16.0.0/12 le 32 192.0.2.0/24 le 32 192.0.0.0/24 le 32 192.168.0.0/16 le 32 191.255.0.0/16 le 32 192.0.0.0/3 ge 25 223.255.255.0/24 le 32 224.0.0.0/3 le 32 I've tried to work my way through this, and this is what I've got so far: These I understand: 10.0.0.0/8 le 32 = 10.x.x.x (private 10 networks) 127.0.0.0/8 le 32 = 127.x.x.x (127 loopback addresses) 172.16.0.0/12 le 32 = 172.16.x.x-172.31.x.x (private 172 addresses) 192.168.0.0/16 le 32 = 192.168.x.x (private 192 addresses) 224.0.0.0/3 le 32 = 224.0.0.0-255.0.0.0 (class D & E addresses) Are both of these statements necessary? Doesn't the second one include the first? 0.0.0.0/32 = 0.0.0.0 0.0.0.0/8 le 32 = 0.x.x.x I think I can understand this, I've heard that anything less then /19 is not advertised across the internet. But, if that is true, what about the rest of the networks? 0.0.0.0/1 ge 20 = 0.x.x.x thru 127.x.x.x, with mask /20 or more Do these have somehthing to do with the above statement? 128.0.0.0/2 ge 17 = 128.x.x.x-191.x.x.x, with mask /17 or more 192.0.0.0/3 ge 25 = 192.x.x.x-223.x.x.x, with mask /25 or more What the heck are these addresses? 128.0.0.0/16 le 32 = 128.0.x.x 192.0.2.0/24 le 32 = 192.0.2.x 192.0.0.0/24 le 32 = 192.0.0.x 191.255.0.0/16 le 32 = 191.255.x.x 223.255.255.0/24 le 32 = 223.255.255.x Any help would be appreciated _________________________________________________________________________ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. _________________________________ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]