We said ICMP error messages shouldn't be broadcast. ICMP is mostly used to report a problem. Ping is the exception and yes you can send a ping to a broadcast address. It's not a nice thing to do, but that doesn't stop people! ;-)
Here's a list of ICMP messages: ICMP Types and Codes Type Code Meaning 8 0 Echo (ping) 0 0 Echo reply (ping reply) 3 x Destination unreachable (generic category) 3 0 Network unreachable 3 1 Host unreachable 3 2 Protocol unreachable 3 3 Port unreachable 3 4 Fragmentation was needed and the don't fragment (DF) bit was set 3 5 Source route failed 3 13 Packet administratively prohibited 4 0 Source quench 11 x Time exceeded (generic category) 11 0 Time-to-live (TTL) exceeded 11 1 Fragment reassembly time exceeded Priscilla At 10:50 AM 12/26/01, Alejandro Acosta wrote: >Hi All, > Why some you have said that ICMP packets should not be broadcasted?. I >mean, many people ping the broadcast address to know which hosts are >working. Right?, this kind of ping does not work on Windows systems, but in >Unix does. > >Thks, > >Alejandro > > >-----Original Message----- >From: Phil Barker >To: [EMAIL PROTECTED] >Sent: 12/24/01 3:06 PM >Subject: Re: ICMP Error [7:30030] > >Have you got a sniffer to trace the error ? > >It would be interesting to see the packet in question >since ICMP has 20 ish different error codes. > >The ICMP error should not be broadcast either, it >should be unicast back to the originator of the >erroring device. Off the top of my head I cannot think >of a purpose for b/cast ICMP. I'll have a dig around >in the RFC to confirm. > >Phil. >--- Cisco Breaker wrote: > Hi >All, > > > > I have a client that installed a Linux NIS server > > which is working with > > broadcasts. That server is connected to cisco 4908. > > Server IP is > > 192.168.5.2. He is saying that when NIS server > > starts to work all clients > > and NIS server is receiving a message at below, > > > > " 192.168.5.2 sent an invalid ICMP error to > > broadcast" > > > > What is the meaning of this message, I searched on > > cisco but didnt find > > anything. Can it be because of "no ip > > directed-broadcast" command on the > > interface. > > > > Any help will be appreciated? > > > > Best regards, >[EMAIL PROTECTED] > >__________________________________________________ >Do You Yahoo!? >Everything you'll ever need on one web page >from News and Sport to Email and Music Charts >http://uk.my.yahoo.com ________________________ Priscilla Oppenheimer http://www.priscilla.com Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=30114&t=30030 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]