Don't enable ip directed broadcast. There's no need to and it's bad practice, from a security point of view. Enabling ip directed broadcast allows the router to forward directed broadcasts. For exmaple, if someone from another network pinged 10.0.0.255, a router that has an interface on 10.0.0.0/24 would forward that packet out that interface, if you enabled directed broadcasts. That's bad.
This has nothing to do with a router sending a packet to a broadcast address when you configure ip helper address. Karagozian Sarkis wrote: > > Yes, According to Cisco BSCN Book (Building Scalable Cisco > Networks) > pages 88-91. > and Exam Cram book ACRC (Advanced Cisco Router Congirn) pages > 46-47. > mentions using ip helper-address to forward to a directed > broadcast address (ie. for this specific subnet 172.16.2.0 > where the servers reside) If the book really says that, I would guess that the language got the author in trouble. IP helper address isn't just generic forwarding, like a router does normally. It's telling the router to be a relay agent or gateway of sorts, which is different. With DHCP, the client sends to 255.255.255.255. The router can forward that to 172.16.2.255, for example. Note that's different from the example above of the router forwarding a packet. See the extra work it's doing here? It's acting like a gateway with an advanced atypical job that is not its normal forwarding job. > > Remember, on the Interface you also need to enable the command: > ip directed-broadcast > (which is disabled by default on rel 12.0 and later) Yes, and it's a good thing that ip directed broadcast is disabled by default and you shouldln't change it in most cases, certainly not just to get DHCP to work. HTH _______________________________ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com > > > So here are the commands you need to add on the Remote Router > interface: > > Interface e0 > > ip helper-address 172.16.2.255 > ip helper-address 172.16.3.2 > ip directed broadcast > > So Braodcasts arriving on e0 will be forwarded to all servers > on the 172.16.2.0 subnet and to the designated server > 172.16.3.2. > > Hope this helps. > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61316&t=61249 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
