Cisco LAN-to-LAN IPsec Tunnel Between Two Routers with a NAT device in the middle


Topology is

Cisco 881 (Outside on the Internet) wanting to create a number of tunnels to Cisco 881's inside a MPLS network. The MPLS provider has provided a Gateway with a Public IP address and they  have created a different IKE and IPSEC port for each inside host that we want to create a tunnel too.

I.e IKE 4510 / IPSEC 45010 redirect inside to inside Host IKE 500 / IPSEC 4500

Can I on my Cisco 881 on the Internet specify the destination ports that happen in Phase 1 and Phase 2?

Running a very basic L2L Config atm between hosts within the MPLS as per Cisco -

 Kind Regards

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Matt VCommented:
I'm not sure why you want to use different ports for the tunnels.  You can have multiple tunnels connected over the same ports.
netprimatesAuthor Commented:
Different EP's behind the traversal device in the middle
netprimatesAuthor Commented:
Traversal device isn't terminating the tunnels
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Matt VCommented:
In that case you may need to have enough outward facing IPs for each EP to connect.

No way that I am aware of to specify which ports the tunnel will use.

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netprimatesAuthor Commented:
I thought as much, the tunnels are created from the public internet through to the internal EP so they will need a dedicated public IP per private EP. One would assume.
Matt VCommented:
That would be my understanding as well.  No way you could combine those end points into one larger one and route the tunnels out from there?
netprimatesAuthor Commented:
I am afraid not, I wish. I pushed to have a connection into the site that was on the MPLS but some bright spark thought it best to put it behind a NAT traversal box.

I didn't think there was an option to specify the ports on a Cisco config but they insisted you can.
Matt VCommented:
Looks like you can use encapsulation on an ASA, but if you are using IOS devices you are out of luck.
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