Volga DWDM System I OTN X-Connect

Russian backbone OTN cross-connect for DWDM networks

Volga OTN cross-connect switches ODU streams at ODU1/2/3/4 levels in a non-blocking mode. The XC2T model has a bandwidth of up to 2 Tbit/s. A centralized OTN cross-connect fabric (OTN XC) system with a capacity of 4 Tbit/s is under development. The cross-connect matrix provides the possibility to place a variety of client signals in the payload of OTN containers ODU-k (k = 0/1/2/3/4), and then programmatically redistribute them between different OTN optical channels OTU-k (k = 1/2/3/4), i.e. between line ports tuned to different wavelengths.

This allows the operator to manage the distribution of client port traffic across transport channels more efficiently. Each client port is no longer rigidly associated with a specific transport channel (as in a muxponder). Traffic can be switched to any transport interface through the NMS or automatic traffic redistribution can be configured depending on the channel load.
OTN technology is the successor to SDH circuit switching technology, with VC-x cross-connect as a key element. OTN cross-connect ODU-k channels includes the best SDH features such as:

• Add-Drop & Continue: copy the same service channel, for example, in two independent directions (line outputs) and at different wavelengths
• SNCP protection switches at the ODU-k level organization

The hardware architecture of the WDM/OTN cross-switch implies the presence in the chassis of separate line cards (DWDM side) and tributary cards (client interface side), interconnected by an OTN cross-connect matrix. Along with this, for example, in the new XC900 chassis it will be possible to use two slots for conventional transponders.

OTN technology is used in conjunction with DWDM technology, where several OTN ODU-k channels of different levels at different wavelengths can be transmitted simultaneously on one fiber. Today, a combination of OTN and DWDM technologies is the most common solution for building modern fiber-optic telecommunication networks.

Parameters / ChassisXC9R2V10R2-X2V10R2-X4*
Chassis switching capacity900 G2 T4 T
Number of cards11+2 (out of cross connect for transponders)13
X-connect cards23
Line cards100G1x200G, 2х100G, 2x200G
Types of client cards10х10G (10GE, STM-64, OTU2, 10GFC, 100GE)2x100G, 20x10G (10GE, STM-64, OTU2), 10GFC, 100GE, 40G, STM-256
Redundancy X-connect cards1+12+1
Redundant control units1+1
Sync block reservations1+1
Power supply redundancy1+1

*in developing

Line Card Features

Line Cards

Operating Mode





Number of interfaces





Interface type




Modulation format



Frequency grid

 50/100 GHz

Automatic dispersion correction

up to ± 20 ns/nm

до ± 50 ns/nm

до ± 40 ns/nm

Wavelength range

1528.7-1567.1 nm

OSNRτ (0,1 nm, BER=10-¹²)

18.1 dB
19.2 dB

12.5 dB

11.4 dB


SD-FEC 15%

Output power (BER=10-¹²)

-15…+1 dBm

-5...0 dBm

-15…+1 dBm

Receiver sensitivity

-22 dBm

-18 dBm

-22 dBm

Receiver overload

0 dBm

Lightning protection

1.6 Mrad/s

1.6 Mrad/s

50 Krad/s

5 Mrad/s

Power consumption

150 W

130 W

110 W

130 W

Client Card Features

Client Cards

Operating Mode





Quantity and interface type

10 (SFP+)

20 (SFP+ / SFP28)

2 x (QSFP+/QSFP28)

2 x (QSFP+/QSFP28) + 1 x SFP+/SFP28

Interface standard


10GE, OTU2,
STM-64, 8/10GFC,
CPRI 4.9G/6.1G/9.8G,
16/32GFC, 25GE


10GE, OTU2, STM-64,
CPRI 4.9G/6.1G/9.8G,
8/10/16/32GFC, 25GE OTU3/

Power consumption

100 W

150 W

110 W

130 W