I am running a tracert to 1.1.1.1 and as soon as it leave my network I get 2 IP’s that are the same back to back on my upstream providers network.
what would cause this to happen? Hops 3 & 4
Trace route traces routers, hops…
So since we see the same IP twice obviously there is a routing loop there for some reason…
By the way, tracert works in the following way:
You try to trace route to 1.1.1.1
So your router sends a packet with TTL=1
The first router drops it because it will decrease it by 1 so TTL=0 and sends back to you a “Time Exceeded” message
Then you send again a packet with TTL=2
The packet goes to the first router it decreases it by 1 and sends it to the second router.
The second router receives a TTL=1 and so it drops it again for the same reason the previous router did.
So in simple words you sends packets with TTL increasing each time by 1 until you reach your destination.
So the loop is on my upstream provider then since it is past my gateway? Pain in the but to get AT&T to look at it too. All my other circuits look fine from them.
Just wanted to verify as I thought is was some sort of loop.
That loop is not by mistake i guess…