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New Member

traceroute and GRE

how traceroute display hops when there is a GRE tunnel in the middle of the path. for Example hop 1,2,3,4-------8 GRE,9,10,11,12,13,14,15. 

2 REPLIES
VIP Super Bronze

Re: traceroute and GRE

The GRE tunnel is one hop no matter how many devices it goes over.

HTH

Reza

New Member

Re: traceroute and GRE

Hi,

if we create GRE tunnel for hop1 to hop5 and then normal IP path ,traceroute first display 8 th hop IP address as 5th hop.

PC------------>1-------------------------GRE--------------------5,6,7,8,9,10

if we traceroute from PC,

1. * * * (say node 1 node allowed to display its IP)

2. * * *

3. * * *

4. * * *

5. IP address of 8 th hop

6. IP address of 8 th hop

7. IP address of 8 th hop

this mean TTL reduce process starts at the end of GRE tunnel and it will go to TTL=0 at 8th hop. so it will not display hop 5,6,7 IP addresses. can this happen or IP payload TTL value should reduce according to number of hops passed through GRE at GRE end point.

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