[rrg] GLI-Split Rebuttal

[Matthias Hartmann <[e-mail]>]

Hi Tony,

here comes the rebuttal for our GLI-Split proposal.

Best regards,
   Matthias Hartmann



The arguments in the GLI-Split critique are correct. There are only two points that 
should be clarified here. (1) First, it is not a drawback that hosts perform the 
mapping lookups. (2) Second, the critique proposed an improvement to the mobility 
mechanism, which is of general nature and not specific to GLI-Split.

(1)	The additional burden on the hosts is actually a benefit, compared to having the 
same burden on the gateways. If the gateway would perform the lookups and packets 
addressed to not yet cached EIDs arrive, a lookup in the mapping system must be 
initiated. Until the mapping reply returns, packets must be either dropped, cached, 
or the packets must be sent over the mapping system to the destination. All these 
options are not optimal and have their drawbacks. To avoid these problems in 
GLI-Split, the hosts perform the lookup. The short additional delay is not a big 
issue in the hosts because it happens before the first packets are sent. So no 
packets are lost or have to be cached. GLI-Split could also easily be adapted to 
special GLI-hosts (e.g., low power sensor nodes) that do not have to do any lookup 
and simply let the gateway do all the work. This functionality is included anyway for 
backward compatibility with regular IPv6-hosts inside the GLI-domain.
(2)	The critique proposes a DNS-based mobility mechanism as an improvement to 
GLI-Split. However, this improvement is an alternative mobility approach which can be 
applied to any routing architecture including GLI-Split and raises also some 
concerns, e.g., the update speed of DNS. Therefore, we prefer to keep this issue out 
of the discussion.






-- 
Dipl.-Inform. Matthias Hartmann
University of Wuerzburg, Institute of Computer Science
Chair of Distributed Systems (Informatik III)

Am Hubland, 97074 Wuerzburg, Germany

http://www3.informatik.uni-wuerzburg.de/staff/hartmann/
[e-mail]
phone: [phone]