- Telefónica’s video growth in one year has matched nine years of IP traffic growth
- Optical mesh network in Barcelona will use CDC-ROADMs and 200-gigabit coherent line cards
Telefónica has started testing an optical mesh network in Barcelona, adding to its existing optical mesh deployment across Madrid. Both mesh networks are based on 200-gigabit optical channels and high-degree reconfigurable add-drop multiplexers (ROADMs) that are part of the optical infrastructure that underpins the operator’s nationwide IP-MPLS network that is now under construction.
Maria Antonia CrespoThe operator decided to become a video telco company in late 2014 to support video-on-demand and over-the-top streaming video services.
Telefónica realised its existing IP and aggregation networks would not be able to accommodate the video traffic growth and started developing its IP-MPLS network.
“What we are seeing is that the traffic is growing very quickly,” says Maria Antonia Crespo, IP and optical networking director at Telefónica. “In one year we are getting the same [video traffic] figures as we got from internet traffic in the last nine years.”
The operator is rolling out the IP-MPLS network across Spain. Juniper Networks and Nokia are the suppliers of the IP router equipment, while Huawei and Nokia were chosen to supply the optical networking equipment.
IP-MPLS
Telefónica set about reducing the number of layers and number of hops when designing its IP-MPLS network. “At each hop, we have to invest money if we want to increase capacity,” says Crespo.
The result is an IP-MPLS network comprising four layers (see diagram). The uppermost Layer 1, dubbed HL1, connects the network to the internet world, while HL2 is a backbone transit layer. The HL3 layer is also a transit layer but at the provincial level. Spain is made up of 52 provinces. HL4 is where the services will reside, where Telefonica will deliver such services as Layer 2 and Layer 3 virtual private networks.
Between HL1 and HL2 is a national GMPLS-based photonic mesh, says Crespo, and between HL3 and HL4 there are the metro mesh networks. “Now we are deploying two GMPLS-based mesh networks, in Madrid and Barcelona,” she says. “Then, in the rest of the country, we are deploying [optical] rings.”
Systems requirements
Telefónica says it had several requirements when choosing the optical transport equipment, requirements common to both its backbone and regional networks.
One is the need to scale capacity at 10 gigabits and 100 gigabits, while network availability and robustness are also key. Telefónica says its network is designed to withstand two or more simultaneous fibre failures. “We have long experience with the GMPLS control plane to support different fibre impairments in the network,” says Alberto Colomer, optical technology manager at Telefónica.
The operator also wants its equipment to support high-speed interfaces and more granular rates to allow it to transition away from legacy traffic such as SDH and 1GbE. Operational improvements are another requirement: Telefónica wants to reduce the manual intervention its network needs. Optical time-domain reflectometers (OTDR) are being integrated into the network to monitor the fibre, as is the ability to automatically equalise the different optical channels.
Alberto ColomerLastly, Telefónica is looking to reduce its capital expenditure and operational expense. It is deploying flexible rate 200-gigabit transponders in its Barcelona and Madrid networks and the same line cards will support 400-gigabit and even 1 terabit channels in future, as well as flexible grid to support the most efficient use of a fibre’s spectrum.
The 200-gigabit transponders use 16-quadrature amplitude modulation (16-QAM). Such transponders have enough reach to span each of the two cities but Colomer says Telefónica is still studying how many ROADM stages the 16-QAM transponders can cross.
It is like a pilot changing the engines while flying a plane
The ROADMs Telefónica is deploying in Madrid are directionless and are able to support up to 20 degrees. “You need some connectivity inside the mesh but also the mesh has to be connected to rings that cover all the counties around Madrid,” says Colomer.
Barcelona will be the first location where the ROADMs will also be colourless and contentionless (CDC-ROADMs). “We need to understand in a better way what are the advantages that come with that functionality,” says Colomer.
Telefónica has deployed Huawei’s Optix OSN 9800 platform in Madrid while in Barcelona Nokia’s 1830 Photonic Service Switch with the latest PSE-2 Coherent DSP-ASIC technology is being deployed.
Nokia’s PSS-1830 is designed to support the L-band as well as the C-band but Telefonica does not see the need for the L-band in the near future. “We are going in the direction of increasing capacity per channel: 400-gigabit channels and one terabit channels,” says Colomer. By deploying a photonic mesh and high-degree ROADMs, it will also be possible to increase capacity on a specific link by adding a fibre pair.
Status
The mesh in Madrid is already completed while Telefónica is deploying optical rings around Barcelona while it tests the contentionless ROADMs. These deployments are aligned with the IP-MPLS deployment, says Crespo, which is expected to be completed by 2018.
Crespo says the nationwide IP-MPLS rollout is a challenge. The deployment involves learning new technology that needs to be deployed alongside its existing network. "My boss likens it to a pilot changing the engines while flying a plane," says Crespo. "We are testing in the labs, duplicating it [the network], and migrating the traffic without impacting the customer."