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Kurlec
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Joined: Wed Mar 16, 2016 9:07 am

Vlan Showing up in traceroute from internal and external

Wed Mar 13, 2019 7:16 pm

Hi guys,

I'm struggling to get rid of this Vlan IP showing up in my trace route, it shows up in a internal and external case.

I am running a BGP/OSPF network and my eBGP core is only advertising my Public Addresses no private addresses yet my Vlan keeps popping up in my trace routes, anyone knows why that would be? if you need any info please ask im happy to share

Image

Image

if you look at the 10.32.32.1/10.32.32.6 IP address that is the address i'm using on my Vlan, but its only this Vlan address showing up, none of my other 10 Vlans show up here.

The first 3 HOPS belong to my network, the 4th hop is my ESP and after that its random hops
 
mkx
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Re: Vlan Showing up in traceroute from internal and external

Wed Mar 13, 2019 9:56 pm

It doesn't matter which addresses you advertise via BGP or OSPF or whatever. As long as your private IPs are used by equipment which participates in routing of packets across your network, it'll show on traceroutes.
The only way of hiding it from the world would be by performing NAT on ICMP TTL EXPIRED messages ... but I don't know if that's doable on ROS.
Another possibility would be to use some kind of a tunnel between routers 102.141.192.2 and 102.132.64.5 ... which would make network between them transparent to traceroute.
Or you could simply block ICMP TTL EXPIRED messages from private IPs to exit from your network.
BR,
Metod
 
Kurlec
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Re: Vlan Showing up in traceroute from internal and external

Thu Mar 14, 2019 12:19 am

Hi Mkx,

First of thanks for the reply.

Could it be possible for you to give me an example how this is done? and tell me what kind of tunnel are we talking about?
 
mkx
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Re: Vlan Showing up in traceroute from internal and external

Thu Mar 14, 2019 10:57 pm

Any kind of tunnel would do: GRE as the most simple kind would do nicely. If you have a whoke mesh of routers, you might want to think about MPLS ... it hides infrastructure and adds some useful functions ...

Why does it bother you so much?
BR,
Metod

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