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Community Member

extended ping - source:?

Why does the extended ping source have to be an IP or interface on the router? I thought the point of the extended ping was to make the router make the ping look like it's from a device on the network. I have used IOSs from 12.2 to 12.4 and have never been able to do this.


Re: extended ping - source:?

How could you ever get a reply if you used a source other than the router? You use other source interfaces for testing NAT, ACLs etc. If it replies on the source interface theres a good chance it will respond from a client beyond it, validating your config.

Re: extended ping - source:?

By default, ping(s) originated from the router would source the egress (outbound) interface IP. Instead, you can choose a difference interface/IP to be the source to test network connectivity between that subnet and the destination.

Sourcing the IP of another device on the network would be using a duplicate address and the IOS wouldn't facilitate that function. What if an alternate route (eg, host route) exists to the actual source itself then the echo-replies wouldn't make it back to the router and would make you believe there's a network connectivity problem when, actually, there is no problem.



Community Member

Re: extended ping - source:?

I asked the question because the CCNA books I used stated you could use an extended ping with an IP of a device on the network rather than from an IP on the router. It's the only reason I was asking.

Hall of Fame Super Gold

Re: extended ping - source:?


Thank you for clarifying the context of your question. And score another one (-1 actually) for those people who write the certification questions based on a half understanding of what the material is talking about.

I would agree that some of the official documentation is slightly vague about what the source address of extended ping really is. And someone expanded on what they thought that meant. And the reality is that extended ping will only accept source addresses that are interface addresses on that router (and the justification for the restriction is well explained by several of the previous posts).



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