Subject: [Mip6] [issue71] avoid configuration at the HA about port forwarder

From: Pascal Thubert <[email-masked]>
Date: Tue, 07 Mar 2006 12:49:24 +0000

New submission from Pascal Thubert <[email-masked]>:

When a HA is placed within a private network, the HA must enforce UDP
encapsulation whether or not the MN/MR owns a public address.

The draft does not enable the HA to discover that situation; implicitly, there
must be some configuration in the HA to let it know that it is behind a NAT, so
that the HA sends a NAT detection option.

Configuration is a hassle for customers, and it is error prone:
- There is a way to automate the NAT discovery and remove the manual configuration
- There is also a way to make it symmetrical, so that both ends reach a same
conclusion without the need to introduce an additional NAT detection option

If we decide to automate the discovery of the reverse NAT (== port forwarder)
then we might consider two alternatives:

option 1) Extends what is already done in 4.1 with the mapped address, by
modifying the format of the mapped address to include all the needed parameters
(IP and ports). This is what the doors proposal suggests, in order to leave most
of the HA code and data structures unchanged. 

option 2) add an option in the BU and BA where the sender exposes the IP
addresses and port as he sees them. 

A discrepancy can be found on the receiver and interpreted as a presence of a
NAT box on the way.

The drawback of the automation is that it can not detect a transparent device
such as a load balancer placed in front of a cluster of HAs. This might not be a
big issue if there is an optional config to force the UDP at all times, which
should be there anyway to enable faster roaming.

----------
category: Technical
draft: draft-ietf-mip6-nemo-v4traversal
messages: 231
nosy: pthubert
priority: Should fix
status: Pending
title: avoid configuration at the HA about port forwarder

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