[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [RRG] Tunnel fragmentation/reassembly for RRG map-and-encaps architectures
Just to have disclosure for the current understanding
of this out on the list, the full proposal is given
below. LISP is used as the example RRG map-and-encaps
architecture, but the same approach can be applied to
any such scheme:
See comments inline. For full disclosure, I don't endorse this proposal.
2) Before the ITR knows whether the ITR->ETR tunnel
pathMTU can handle original packets up to 1500 bytes,
it sends 1500- original packets into the tunnel as
either 1-fragment or 2-fragment packets of no more
So we are going to double the packets sent everywhere until we find
out? This doesn't sound like a good idea to me.
4) While sending 2-fragment packets, the ITR sends
1500 byte sprite-mtu probes to the ETR. If it gets
probe replies back, it can stop sending 2-fragment
packets and begin sending 1-fragment packets. If the
ITR subsequently gets a packet-too-big, it can resume
sending 2-fragment packets and try probing again later.
This requires the ITR to keep state for each ETR. It doesn't do this
now. This is a huge requirement on the ITR which I object to.
6) The ETR must reassemble any 2-fragment packets. It
This is a non-starter in router products unless you *force* software
switching. And even if you *force* software switching, it's a great
DOS attack against the buffer system of the router. Leave malicious
out of the way. If a Google ETR is recieving from 100K places, you
think the router can store 100K 1500-byte sized packet for any length
of time (1-2 seconds).
reduce the memory required for reassembly buffers by
actively discarding any reassemblies that appear to
have no chance of completion. This assumes that any
And how does the ETR determine there is no chance of completion?
Please don't answer.
Dino
--
to unsubscribe send a message to rrg-request@psg.com with the
word 'unsubscribe' in a single line as the message text body.
archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg