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EoIP tunnel hops

Posted: Sun Nov 05, 2017 6:36 am
by christopherANSA
Hi All,

With EoIP tunneling, is there a way to make the EoIP tunnel show up as a hop in the traceroute? Below, is Site A and is Site B, with an EoIP tunnel between them.

PS C:\Windows\system32> tracert
Tracing route to over a maximum of 30 hops
1 <1 ms <1 ms <1 ms
2 20 ms 20 ms 20 ms
Trace complete.

Re: EoIP tunnel hops

Posted: Sun Nov 05, 2017 7:41 am
by payam124
Please post:
- purpose of having EoIP in the trace
- post the netmasks
- post detailed configuration for the existing network

Generally speaking, it is possible. You can allocate a small network for the EoIP link and pick 2 IPs from this network and set it on both side of EoIP tunnel.
in this way you can treat EoIP as a layer 3 link

Re: EoIP tunnel hops

Posted: Sun Nov 05, 2017 9:00 am
by christopherANSA
Hi payam124,

The guy who I am doing this for wants the tunnel to show.

Each site has an external public IP address, an internal network with a prefix of 10.nn.101.0/24 and is connected to every other site via an EoIP tunnel with /30 subnets configured on the interfaces. I have configured static routes on the routers to route the traffic (e.g. Site A has an internal subnet of and a tunnel IP of, Site B has and a tunnel IP of, Site A will route to and Site B will route to The subnets are below (and the routers are on the internal .254 addresses):

Site A Internal Network -
Site B Internal Network -
Site C Internal Network -
Site D Internal Network -
Site E Internal Network -

A to B Tunnel -
A to C Tunnel -
A to D Tunnel -
A to E Tunnel -

B to C Tunnel -
B to D Tunnel -
B to E Tunnel -

C to D Tunnel -
C to E Tunnel -

D to E Tunnel -

Currently if a desktop computer at A on IP tries to ping another desktop at C on it will show the tunnel hop. I guess a more appropriate question would be if the router at A on tried to ping the router at B on, is it possible to show the tunnel hop between the two? I don't think it is, but wanted to confirm.

Re: EoIP tunnel hops

Posted: Sat Nov 11, 2017 3:17 am
by payam124
while still I can not understand why you want to see any hop with you ping a router connected to you using EoIP, let me explain you how the network works in your case and you would realize why you don't see any hop
Also I'm not clear about: "A to B Tunnel -" when you mentioned you used and for the tunnel between A and B. Please explain

when you try trace address of router B ( from Router A, router A checks its routing table and sees is readable through over tunnel. so it would pick (by default) as the source of packet, and create a packet which its destination is and set TTL=1 and send the packet to as it is directly connected to this Router using the Tunnel. Attention: when 2 nodes are directly connected, there isn't any hop in between.
then (Router B) receives the packet (whose source is and check the destination which is it finds that the destination is an IP address of its own. so just reply back. no any hop in between.

Re: EoIP tunnel hops

Posted: Sat Nov 11, 2017 2:19 pm
by docmarius
To trace the tunnel hops and to be visible to the tunnel traffic, this would mean that ALL routers along the way need to support EoIP, unpack the packet inside, decrease its TTL, repack it and send it to the destination. To expect something like this is hilarious at best, and totally inefficient.
If you need to trace the tunnel hops, explore the endpoint IP by a regular trace, not the tunnel itself. EoIP is just a payload in an IP data flow and there is nothing you can do about it.
In Linux, this is possible on VPNs because there is an option to set the endpoint connection's TTL to be inherited from the tunnel interface's one. But this is a synthetic solution, and I really see no benefit since it would expect the tunneled traffic to need high TTL's without added benefits because the number of hops would not be perdictible like in the regular behavior.