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If I have a corporate network, no WWW Internet outside of it, only different subnets. Can a Cisco router or switch be configured to take information from one layer and embed it in another layer?

For example, the MAC address is a t lower layer. Could one of the routers be configured to put that MAC information in a higher layer, so a web server could read it? I don't mean not keeping the MAC where it is so the network will work, only the additional information in one of the layers that a server can read (http).

  • Do you mean a tunnel? – Ron Maupin Sep 14 '18 at 15:28
  • What exactly, are you trying to do? – Ron Trunk Sep 14 '18 at 15:29
  • I mean if a person makes a network request to a web server, and it goes through the various routers, can those routers be configured to put MAC information in one of the higher layers for consumption, since the MAC cannot be gotten without it. – johnny Sep 14 '18 at 15:30
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    Short answer:No. MAC later info is stripped off by the router. You could possibly run some JavaScript to grab that data and return it to the server. – Ron Trunk Sep 14 '18 at 15:53
  • MAC addresses are LAN addresses for some layer-2 protocols, and they are only meaningful on the local LAN. Layer-3 addresses are relevant to get traffic from one LAN to another LAN. The layer-2 frames are stripped by routers because the layer-2 frame is only needed on the local LAN. The remote LAN may be a completely different protocol, and it may not use MAC addresses, or it may use MAC addresses of a different size. The local MAC addresses simply are not relevant on a remote LAN. – Ron Maupin Sep 14 '18 at 16:09
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The only way you'd be able to do this is possibly with Netflow. You'd have to enable it on each device and have it reporting to a server. If you wanted MAC information though, you'd probably have create a script to login or poll over SNMP each router and switch to get the MAC tables, and match them to the Netflow data. There may be some network mapping software out there that can generate a MAC map for you that might give you everything you are looking for. If request is coming from outside network devices you control though, you'll never really know the MAC address of the requesting device unless it were written into that protocol to include the local MAC address for some reason.

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