What you have just described is commonly referred to as "A Duplicate IP Address," and is considered in some circles to be bad practice. ;)
Let's see if I can explain this well... A host device knows two categories of addresses... Those that are local, and those that are not. When a host attempts to send a packet to another host, it decides based on it's own address and locally configured subnet mask whether or not it will have to send the packet to a router in order to get the packet to the destination. To modify your scenario: Let's say Host A (172.16.1.1/16) wants to send a packet to Host B (172.16.2.1/24). Host A believes that his local network is 172.16.0.0, and that every other host with an IP address that begins with 172.16 is locally attached. Host A would send the packet out as though Host B were local, instead of sending it to a router. In the reverse case, where Host B wants to send a packet to Host A, Host B believes that his local network is 172.16.2.0 (And that the third octet, the '2', is part of the network identifation), and that Host A, with an address of 172.16.1.1, is not local. He would send the packet to a router. Subnet masks are a Local thing. I hope this helps... Alan~ ----- Original Message ----- From: "Steven A. Ridder" To: Sent: Friday, December 14, 2001 2:07 PM Subject: Re: Mask in L3 Packet [7:29182] > Say I have 2 networks: > > Network 1. 172.16.x.x/16 > and > Network 2. 172.16.2.x/24 > > We all agree that they are two different networks, right? > > Now if Host A on > Network 1 is 172.16.2.1/16 > > and > > Host B is on Network 2 is 172.16.2.1/24, > > How does the host know that the second host is on a different network? Are > they differnt addresses because of the mask, or are they considered the same > address regardless of mask, and therefore illegal? I understand ANDing on > the local host. It's just if 2 hosts had the same numbers, only marked > differently by the mask, are they the same or not? [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=29241&t=29182 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
