Riverstone is demonstrating the new routers this week in Salt Lake City at
Broadband Cities 2005, an industry conference bringing together community
leaders from around the world interested in building municipal networks.

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The introduction of these routers fulfills the market's previously unaddressed
need for a compact, fully-featured platform that extends the benefits of VPLS
as close to the service-users as possible."
UTOPIA , a municipal FTTx network in Utah, is planning to trial the
Riverstone 15100 and 15200. Both of
the new access routers support VPLS, RFC-2547 MPLS-VPNs, and Layer 3 routing
protocols including BGP , OSPF, multicast, and IS-IS.

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The Piranha 600 and 600EX platforms
provide powerful flow classification and QoS capabilities required for mixing
video, voice and data applications in the same aggregation network.

About Mangrove Systems
Founded in 2002 by one of the industry's most experienced technology
leadership teams, Mangrove is the industry leader in Pseudowire Access,
Aggregation and Transport. For more information visit http://www.

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"We believe
these new routers have great potential . These risks and
uncertainties include unforeseen delays in commercial release of the products,
costs to manufacture or procure components that could affect pricing,
development delays that could impact which features are available immediately
upon commercial release of the products, and future changes in customer
evaluation and deployment plans of which Riverstone is currently unaware,
along with those risks and uncertainties detailed from time to time in
Riverstone Networks' SEC reports, including the reports on Form 10-Q and Form
8-K filed on September 2, 2004 .
The Piranha 600 and 600EX are the first products in their class to offer
dynamic pseudowire signaling with robust per flow traffic management, enabling
Mangrove's customers to rapidly provision subscriber services over a shared
infrastructure. Packet layer multiplexing together with next
generation SONET/SDH transport technology enables network operators to
implement intelligent, efficient packet transport over a cost-optimized
transmission network.
Mangrove will demonstrate its MetroMPLS solution at SUPERCOMM 2005, Booth
#42046 and are featured in the 10 Hottest Technologies Pavilion, Booth
#82015-T.

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PK ) today introduced the newest members of its
Riverstone 15000 product line: the Riverstone 15100 and 15200 Carrier
Ethernet Access Routers. "There has been a need for a solution like
this for a long time," said Henrik Bremerskov, Head of Technology, Updata. The company assumes no obligation to update
or revise these forward-looking statements. The Piranha family, with its combined packet and circuit
capability efficiently aggregates multi-service customer traffic over multiple
transport networks, including SONET/SDH, Gigabit Ethernet and multi-wavelength
fiber infrastructures.

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This unique capability at the network edge,
combined with the resiliency and traffic engineering attributes of MPLS, gives
service providers a truly carrier-grade Ethernet solution. These forward-looking statements
speak only as of the date hereof and are subject to risks and uncertainties
that may cause actual results to differ materially.

Mangrove Announces Piranha 600EX Pseudowire Transport Hub for 3G Wireless and Broadband Network Migration

The Piranha 600EX provides native
support for high density, protected ATM IMA, PPP, Frame Relay and Ethernet
service aggregation, in addition to pseudowire encapsulation , a dynamic MPLS
control plane and multi-wavelength optical transport."
The Piranha 600 platforms offer a number of technical innovations that
position them for the unique challenges of broadband infrastructure migration. SUPERCOMM, which is produced and managed by the Telecommunications
Industry Association (TIA), will be held at McCormick Place in Chicago,
June 6 - 9.

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In doing so, they
have had to compromise network reliability, scalability, QoS and operations. is a leading provider of carrier Ethernet
infrastructure solutions for business and residential communications services.

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, Mangrove Systems, the industry
leader in pseudowire access, aggregation and transport, announces Piranha
600EX , the first integrated platform designed specifically for wireless and
wireline operators to address the challenge of migrating between TDM, ATM and
Ethernet/IP access networks.

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"Operators are looking for reliability and performance at the access layer
that is comparable to what they enjoy at the edge and core, but without added
cost," said Stan Hubbard, Heavy Reading."
Like the 15008 , the newest members of the 15000 family are equipped with a
modular operating system to dramatically reduce router software outages and
reboots.

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Riverstone Networks, Inc.
Riverstone allows carriers to offer new services over existing revenue-
generating networks permitting them to evolve to a next generation Ethernet
infrastructure.

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Riverstone Introduces Ground-Breaking Ethernet Access Routers Extending 15000 Product Line

Riverstone Contact:
Amy Huitt
Riverstone Networks
1-408-878-6918
ahuitt@riverstonenet.
"During the same timeframe , bandwidth requirements will increase by a factor
of 5 or more, yet the need to support existing applications will remain.
For example, the universal line card interfaces on the Piranha 600 and 600EX
are configurable to offer TDM, ATM IMA or HDLC processing for Frame Relay,
Ethernet and PPP under software control.

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"The irresistible price point, added capacity and reliability, and the
availability of both MPLS/VPLS downlinks and uplinks -- an industry first --
gives service providers greater freedom in designing their networks than ever
before. The 15200 extends this by supporting dual 10 Gig-E uplinks.com

Agency Contact:
Natalie Godsell
Fleishman-Hillard
44-20-7395-7068
godselln@fleishmaneurope.

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"
While service providers have been quick to embrace MPLS in the core and
aggregation layers of their networks, many have opted for other technologies
in the access layer to minimize their capital expenditure. MetroMPLS
platforms combine pseudowire, ATM, Ethernet and data-over-SONET/SDH
technologies to integrate with existing networks and provide an elegant
migration to a converged MPLS infrastructure.

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Riverstone 15100 and 15200 Tear Down Barriers to Mass Carrier Ethernet
Deployments

SANTA CLARA, Calif.
Riverstone is the platinum sponsor of this DynamicCity event and will be at
the heart of the conference's network, demonstrating the UTOPIA network and
allowing attendees to experience the power of carrier Ethernet first hand. "This migration is
being driven by the need to deliver cost effective triple play solutions to a
rapidly expanding customer base, but many Ethernet based DSL or PON systems
lacks the robust QoS that ATM provided.

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Priced significantly less than any comparable technology on the market
today, the Riverstone 15100 and the 10 Gig-E Riverstone 15200 extend the
industry-leading feature set of the 15008 Ethernet Edge Router into the access
layer , providing MPLS from the core to the network edge.
Updata Infrastructure UK Ltd.

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, a municipal service provider in England
plans to deploy the new routers.
Like the RS family of routers , the expanded Riverstone 15000 product line
uses the Riverstone Management Center framework to deliver end-to-end OSS,
including device configuration, inventory management, and performance and
fault data collection."
"In the wireline community, broadband operators are facing a similar
migration challenge, beginning to cap investment in ATM based DSLAMs and
moving the customer base to Ethernet based DSL or PON equipment," said
Jonathan Reeves, President and CEO of Mangrove Systems. Previous approaches have required
individual line cards and a different control and management plane for each
technology.

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Except for the historical information contained herein, the matters set
forth in this press release, including without limitation statements regarding
the availability of the Riverstone 15100 and 15200 Ethernet Access Routers,
the features and pricing of the routers when they are made available, and
customers' plans to test and/or deploy the routers are forward-looking
statements within the meaning of the "safe harbor" provisions of the Private
Securities Litigation Reform Act of 1995. This
re-use of the same MPLS technology present within the mobile core network
provides a viable alternative to "islands of ATM" access and greatly
simplifies the transition to the next-generation Ethernet and IP
infrastructure specified by the 3GPP for the Release 5 and Release 6 IP UTRAN.
The Piranha 600 product family has been honored by SUPERCOMM as recipient
of the top SUPERQuest award in the Optical Networking category for 2005.

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Combined with line-rate
IPv6, multi-layer OAM and Hierarchical QoS, they play a key role in supporting
converged business and residential services, as well as VoIP and 3G wireless
infrastructure deployments.com

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New MetroMPLS(TM) family member combines TDM, ATM, Ethernet/IP and Optical
technologies to provide the first integrated solution for migration of
broadband services and the 3G RAN

WALLINGFORD, Conn. Mangrove's solution
provides end-to-end service management , along with the grooming, aggregation
and optimization required for the access and metro infrastructure .
"Mobile wireless network operators face a complex migration challenge as
they evolve from the second generation TDM access network through ATM to an
Ethernet/IP based network all in the space of 5 years," said Keith Mumford,
Executive Director Product Management and Marketing of Mangrove Systems. Mangrove is located in
Wallingford, CT.

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, Carrier Ethernet pioneer
Riverstone Networks (OTC: RSTN. Such an operating system can increase routing reliability by a full
order of magnitude , according to a recent report by the consulting firm
Network Strategy Partners(1). Mangrove MetroMPLS (TM) platforms bridge the gap
between TDM-based access and metro networks and the MPLS core.

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The end -to-end
solution gives service providers the ability to maintain a single operational
model as well as mix-and-match VLAN and MPLS access technologies, helping
optimize functionality and cost in both large and small network deployments. "Compact and affordable MPLS / VPLS
access solutions can be particularly liberating for small service providers
and municipal network operators for whom the cost barrier is
disproportionately high. "This fills a significant gap in the industry,
bridging the features and functionality previously only available on high-end
edge platforms with a smaller , more cost-effective form factor," said Jeff
Fishburn, CTO of DynamicCity, operators of the UTOPIA network.

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Available in fourth quarter 2005, the 15100 provides an Ethernet-optimized
alternative to Riverstone's multi-service oriented RS 1100 and 3100.
Mangrove's unique ATM IMA over MPLS pseudowire approach enables the
wireless operator to deploy converged ATM access in support of 3GPP Release 99
and Release 4 without investing in legacy ATM core switching equipment.

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Mangrove 's MetroMPLS platforms enable wireless and wireline service
providers to bridge the gap between today 's incumbent technologies and the
converged MPLS network of the future.
Mangrove's solution is uniquely positioned to accommodate this migration by
enabling three generations of technology to co-exist within a single,
integrated radio access network.

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The two new MPLS-based Ethernet routers tear down the
barriers to mass carrier Ethernet deployments by giving Tier One carriers and
competitive service providers the high reliability and scalability needed to
successfully deliver next generation business and residential triple play
services in a high quality, low-cost platform. It
supports up to 20 triple-speed copper or fiber downlinks, and four Gig-E
uplinks.
Riverstone's Ethernet router portfolio uniquely delivers the reliability that
allows carriers to meet the triple play -- voice, video and data -- service
requirements of their customers in a cost-effective and scalable way.mangrovesystems.com