I-D ACTION:draft-gibanez-trill-abridge-00.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories.

	Title		: Abridges as Rbridges: Transparent Routing with
                          Simplified Multiple Spanning Trees
	Author(s)	: G. Ibanez, et al.
	Filename	: draft-gibanez-trill-abridge-00.txt
	Pages		: 17
	Date		: 2005-12-9

Rbridges are link layer devices that use routing protocols as a control 
plane but do not target to scale up to large campus networks. This 
document contains an alternative proposal to link-state Rbridges, named 
Abridges. Abridges overcome Rbridges L2 network size restrictions 
allowing applicability to very large Ethernet campus networks while 
maintaining zero configuration and high performance, by assuming a 
topological restriction that is automatically performed. The proposal 
includes a two-layered network architecture with two hierarchical 
independent spanning tree layers. Expected convergence is fast, probably 
below two seconds.   

Abridges use multiple simplified spanning trees rooted at core edge 
bridges  to  achieve  results  comparable  to  Rbridges  with  lower 
computational complexity. Two implementation variants of simplified 
multiple spanning trees are proposed: The first one is a fundamental 
simplification of the standard Multiple Spanning Tree protocol and the 
second one (still in a very preliminary stage) consists of an N-multiple 
simultaneous execution of the Rapid Spanning Tree protocol at each 
Rbridge. 
An optional mechanism of ARP/Abridge servers/registrars (with load 
splitting) is proposed to limit ARP traffic in large scale Ethernet 
networks and to enhance scalability and security. This mechanism can also be used for host-Designated Rbridge resolution as an alternative to the interchange of Hosts Lists between Rbridges. 

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