Tuesday is a big day for core routers: Alcatel-Lucent (NYSE: ALU) is finally announcing one, while Juniper Networks Inc. (NYSE: JNPR) is adding multichassis capability to its latest model.

The AlcaLu Extensible Routing System (XRS) 7950 family is essentially the 7750 Service Router in a bigger suit. The XRS uses the same processing chip on its line cards -- the FP3, introduced last year -- but comes in a full rack, not one-third of a rack, giving it room for more ports and more switching cards.

One customer already has the XRS running in a live network as of last Wednesday, says Lindsay Newell, AlcaLu's VP of marketing. It's not BT Group plc (NYSE: BT; London: BTA), NTT Group (NYSE: NTT) or Verizon Communications Inc. (NYSE: VZ) -- all of which are lending quotes to AlcaLu's media launch Tuesday, but none of which are being called XRS customers yet, he says.

Of course, any big router comes with big marketing numbers. AlcaLu says the 7950 XRS-20 -- the full-rack version of the system -- has 16 Tbit/s of capacity (80 100Gbit/s Ethernet ports). Two of the chassis can be linked together to operate as a single router; AlcaLu calls this the 7950 XRS-40, and it is due to ship in the first half of 2013.

AlcaLu gets to that multichassis capability without employing a separate switching chassis, which is what Cisco and Juniper have previously done. Instead, an interchassis optical backplane means the boxes get connected directly to one another. For Cisco and Juniper architectures, the multichassis capability is made possible by having a separate rack acting as a switch fabric.

Juniper, meanwhile, is adding multichassis capability to its new T4000 core router by introducing the TXP multichassis routing system, which can connect four T4000s or eight of the older T1600s. (The T1600 had previously gotten multichassis capability through the TX Matrix Plus, which could connect 16 of those routers.)

Juniper is quoting a maximum capacity of 22 Tbit/s for the TXP-connected routers and says it will expand that to 64 Tbit/s eventually. The TXP upgrades will ship in the fourth quarter, Juniper says.

For what it's worth, here's how the numbers stack up, at least in terms of marketing.

Table 1: Core-Router Claims

Core issues
AlcaLu has long had the capacity to be in some network cores, but the 7750 is really designed for the edge. It's now done well enough in that market to have the pull of an incumbent vendor in some networks. What it's been missing is a massive core router, particularly something with multichassis capability.

"They would be leaving money on the table if they didn't do this," says Ray Mota, an analyst with ACG Research .

AlcaLu's entry into multichassis routers would have left Juniper behind, as the T4000 didn't appear to have such a capability until now. "If they didn't do that, I'd have been bombarded with calls," Mota says.

Separately, AlcaLu's XRS can double as a label-switched router, the extremely dense, MPLS-driven Layer 2 element that could offload some traffic away from core routers. Cisco likewise offers its CRS-3 core router for this LSR function, while Juniper uses a separate packet-optical system, the PTX.

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— Craig Matsumoto, Managing Editor, Light Reading