Subject: Re: [MOBILE-IP] R-P agent should listen on port 434?

From: Patrice Calhoun <[email-masked]>
Date: Mon, 7 Feb 2000 13:21:14 -0800

But the replies from the Home Agent would come back on port 434, unless the
FA forwarded the request from another port (and I am not sure that all
implementations support this). Therefore, it sounds like this is *still*
a problem.

No?

PatC
>
>Yes, everything is going over the same ethernet interface, but the
>R-P messages are going "raw" IP over ethernet, and the Mobile IP
>advertisements/requests are encapsulated inside the R-P GRE tunnel.
>Each tunnel has a separate GRE key field and is in fact a separate
>logical interface.
>
>-Pete
>
>Patrice Calhoun <[email-masked]> (PC) writes:
>
>PC> Why *must* they listen on different interfaces? Is it not conceivable that
>PC> a PDSN (TR45.6 term for FA with lots of other functionality) can have
>PC> a single ethernet interface?
>
>

---

From: Pete McCann <[email-masked]>
Date: Mon, 7 Feb 2000 15:41:10 -0600

Ahh, you are talking about the registration requests/replies with the HA.

Yes, if these come in on the same physical interface that supports the
R-P tunnels, and if a user-space process is there to receive them,
then port 434 there might be confusing.  If your FA doesn't support
sending the requests on a different port (which is explicitly allowed
by RFC2002), and you only have one physical interface, then you could
run into trouble if your implementation tries to separate the two
agents into separate processes.

However, most of the time, a PDSN will have at least two physical
interfaces and will behave much like a firewall.  That is, one
interface will face inwards towards the RAN and one outwards towards
the Internet.  Communication with HAs will always take place on the
outward interface, and R-P tunnels will always be set up on the inward
interface.  If you don't do things this way then elements of your RAN
will be exposed to the Internet at large, which is not a good idea.
Go look under your couch cushions for some change and buy a second
ethernet card.

-Pete

PC> But the replies from the Home Agent would come back on port 434, unless the
PC> FA forwarded the request from another port (and I am not sure that all
PC> implementations support this). Therefore, it sounds like this is *still*
PC> a problem.

PC> No?