Cisco Systems Inc. (Nasdaq: CSCO) announced today that AT&T Inc. (NYSE: T) has chosen the CRS-1 router for its core network.

AT&T's previous core IP equipment supplier, Avici Systems Inc. (Nasdaq: AVCI; Frankfurt: BVC7), exited the router business back in April. Light Reading reported then that AT&T would choose Cisco as its new core router supplier. (See Avici Abandons Routing, Targets PBT and Cisco Gets the Call for AT&T's Core.)

News of Cisco's contract win comes as AT&T continues to expand the capacity of its global IP network. The CRS-1 routers will be used mostly for those upgrades, while the old Avici routers will continue to play a significant role in AT&T's core. (See AT&T Parties Like It's 1999.)

"I can tell you that the Avici equipment is still being used for the current OC192 connections, and that will continue to be the case for some time," said an AT&T spokesman.

"For the routes that are being upgraded, those of course will shift over to the CRS-1 platform, while the Avici equipment will continue to support the 10-Gigabit routes."

Cisco has scored a number of core router wins recently that have helped its market share battle against Juniper Networks Inc. (NYSE: JNPR). The IP giant announced last week it had won core network upgrade business with XO Communications Inc. and Savvis (Nasdaq: SVVS). (See Cisco Scores Core Wins and Juniper Attacks Cisco's CRS-1.)

The rivals are also battling hard to gain the upper hand in the data center market, and are competing with Alcatel-Lucent (NYSE: ALU), Ericsson AB (Nasdaq: ERIC)'s Redback business, and Huawei Technologies Co. Ltd. in the IP edge router sector. (See Cisco, Juniper Ready Data Center Assault, AlcaLu Identifies Deep Packet Potential, AlcaLu Touts IP Upgrades, AlcaLu's Router Run Continues, and Redback Beats AlcaLu to French Deal.)

Avici, meanwhile, is now focusing on its new control plane software called Soapstone. Investors balked at the shift in direction, but Avici says it's generating tremendous interest from carriers about its new product. (See Avici Amped Up for Soapstone Launch.)

— Raymond McConville, Reporter, Light Reading