att_abstract={{To address the reliability challenges due to failures
and planned outages, Internet Service Providers (ISPs) typically
use two backbone routers at each central office in a dual-
home configuration. Thus at the IP layer, redundant backbone
routers as well as redundant transport equipment to interconnect
them are deployed to provide reliability through node and path
diversity. However, adding such redundant resources increases
the overall cost of the network. Hence, a fundamental redesign of
the backbone network which avoids such redundant resources by
leveraging the capabilities of an agile optical transport network
is a highly desirable objective.
In this paper, we propose such a fundamental redesign of
IP backbones that avoids redundant routers by exploiting the
capabilities of agile optical transport. Our alternative design uses
only a single router at each office but uses the agile optical
transport layer to carry traffic to remote Backbone Routers (BRs)
in order to survive failures or outages of the single local BR.
Optimal mapping of local Access Routers (ARs) to remote BRs
is determined by solving an Integer Linear Program (ILP). We
describe how our proposed design can be realized using current
optical transport technology. We evaluate network designs for
cost and performability, a metric combining performance and
reliability. Significant reduction in costs accrue for approximately
the same level of reliability as current designs.}},
	att_authors={kr2812, rs5419},
	att_copyright_notice={{This version of the work is reprinted here with permission of IEEE for your personal use. Not for redistribution. The definitive version was published in 2013. {{, 2013-03-04}}
	author={Kadangode Ramakrishnan and Rakesh Sinha and Byrav Ramamurthy},
	institution={{DRCN 2013}},
	title={{Multi-Layer Design of IP over WDM Backbone Networks: Impact on Cost and Survivability