Anyone smart on interworkings of Cisco routers care to clarify something for me? I was in a discussion with someone in another forum. It was being discussed how pings from a local ethernet interface to a local serial interface on the same router actually cross the WAN to which that serial interface is attached and are returned by the distand-end router. I know this has been discussed in the past but I didn't find anything in the archives that exactly answers my question.
It kinda makes sense that a local serial interface will encapsulate an echo packet that it receives and put it on the wire (it only knows how to encapsulate in one direction and de-encapsulate in the other). It makes sense that the distant-end router will return it, based on the destination IP in the packet. What I'm a little fuzzy on is why CCO says that the echo reply must also be sent accross the WAN and be returned by the distant end router. If it were the interface itself that had to generate the echo reply, I guess the same logic as before would apply. But does the router or the interface actually generate the reply? If it isn't the interface itself, it seems the router would simply generate a reply back towards the source IP (the ethernet interface - which is essentially itself). Is it required that an ICMP packet actually be given life on a hardware interface and thus the one-directional encapsulation issue comes back into play again? Or am I just really confused about it all? Thanks all, Scott Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=53148&t=53148 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
