Hi,
I am reading this document for the first time and had a few
comments to share below.
Thanks - Fred
fred.l.temp...@boeing.com
1) Section 2.5 ("Tunnel Routers Behind NAT"), this seems to
show a limitation in that there can be only one xTR behind
a NAT. I would like to address the case when there may be
many xTRs behind the NAT - can LISP do that?
2) Section 2.6, I don't understand why it says "MTU/PMTUD
issues minimized" for the recursive scenario?
3) Section 6.1, number 4, should say "request increase in MTU
to 1556 *or greater* on service provider connections".
However, controlling just the first-hop interface MTU
does not assure MTU mitigations across the entire path.
Similarly, "care must be taken that ICMP is not being
filtered" cannot be assured along the entire path. And,
studies have shown that ICMP filtering does impact MTU
handling in current operational practices:
http://www.nlnetlabs.nl/downloads/publications/pmtu-black-holes-msc-thesis.pdf
Additionally, I have a use case that I'm not sure is well addressed by
the document. I would like to address the use case of mobile networks
configured as stub sites that connect to ISPs via a mobile router. Each
mobile router may have multiple ISP connections, and can change its ISP
addresses dynamically as it moves around. Some of the ISP addresses may
be global and others may be private, such as behind a carrier-grade NAT.
Many such mobile routers may be located behind the same NAT.
I want to give each mobile router an EID prefix that it can use to number
interfaces within the mobile network. The mobile network may contain just
one interface, a few interfaces, or it may contain many interfaces.
I now want that the mobile network can remain reachable from the outside
world by the same EID prefix addresses even as the mobile router travels
around dynamically. The mobile router will need an xTR so that its ISPs
will not filter its packets that use EID source addresses. I also want
the mobile router to be able to traffic engineer in both the outgoing
*and* incoming directions. For this, there needs to be some sort of
server sitting outside of any NATs that the mobile router can "register"
itself with. The mobile router should be able to change between different
servers as it moves around, e.g., to reduce path stretch or in the
event of a server failure. The servers in turn associate with proxy
xTRs so that outgoing packets destined to EIDs located in distant
networks can be routed appropriately.
This is the way IRON sets things up. Can it also be done with LISP?
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