[rrg] Summary of GLI-Split

Michael Menth <menth@informatik.uni-wuerzburg.de> Tue, 22 December 2009 15:41 UTC

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Date: Tue, 22 Dec 2009 16:40:43 +0100
From: Michael Menth <menth@informatik.uni-wuerzburg.de>
Organization: University of Wuerzburg
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Cc: Lixia Zhang <lixia@CS.UCLA.EDU>
Subject: [rrg] Summary of GLI-Split
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Hi all,

here is the summary of GLI-Split.

Merry Christmas and a happy new year!


Proposal: Global Locator, Local Locator, and Identifier Split (GLI-Split)

Key Idea:

GLI-Split implements a separation between global routing (in the
global Internet outside edge networks) and local routing (inside
edge networks) and  using global and local locators (GLs, LLs). In
addition, a separate static identifier (ID) is used to identify
communication endpoints (e.g. nodes or services) independently of
any routing information. Locators and IDs are encoded in IPv6
addresses to enable backwards-compatibility with the IPv6
Internet. The higher order bits store either a GL or a LL while
the lower order bits contain the ID. A local mapping system maps
IDs to LLs and a global mapping system maps IDs to GLs. The full
GLI-mode requires nodes with upgraded networking stacks and
special GLI-gateways. The GLI-gateways perform stateless locator
rewriting in IPv6 addresses with the help of the local and global
mapping system. Non-upgraded IPv6 nodes can also be accommodated
in GLI-domains since an enhanced DHCP service and GLI-gateways
compensate their missing GLI-functionality. This is an important
feature for incremental deployability.


The benefits of GLI-Split are
 * Hierarchical aggregation of routing information in the global
   Internet through separation of edge and core routing
 * Provider changes not visible to nodes inside GLI-domains
   (renumbering not needed)
 * Rearrangement of subnetworks within edge networks not visible
   to the outside world (better support of large edge networks)
 * Transport connections survive both types of changes
 * Multihoming
 * Improved traffic engineering for incoming and outgoing traffic
 * Multipath routing and load balancing for hosts
 * Improved resilience
 * Improved mobility support without home agents and triangle routing
 * Interworking with the classic Internet
   - without triangle routing over proxy routers
   - without stateful NAT

These benefits are available for upgraded GLI-nodes, but
non-upgraded nodes in GLI-domains partially benefit from these
advanced features, too. This offers multiple incentives for early
adopters and they have the option to migrate their nodes gradually
from non-GLI stacks to GLI-stacks.


 * Local and global mapping system
 * Modified DHCP or similar mechanism
 * GLI-gateways with stateless locator rewriting in IPv6 addresses
 * Upgraded stacks (only for full GLI-mode)


GLI is only a theoretical proposal. A protocol simulation has been
shown at EuroView 2009. We believe that GLI-Split offers many
features and methods that may be reused in a future Internet
routing architecture. The full description is available at

Dr. Michael Menth, Assistant Professor
University of Wuerzburg, Institute of Computer Science
Am Hubland, D-97074 Wuerzburg, Germany, room B206
phone: (+49)-931/31-86644 (new), fax: (+49)-931/888-6632