Definitive MPLS Network Designs [Electronic resources] نسخه متنی

EuroBank's Network Environment

Across all its subsidiaries, EuroBank has more than 1100 branches across Europe (which we call branches). In addition, EuroBank runs more than 40 large office sites (which we call offices) across the UK, Spain, and Germany. Each office has tens to hundreds of employees working in different departments (front and back office).

EuroBank built a private core network composed of nine points of presence (POPs): five in the UK (including three in London), two in Germany (Berlin and Frankfurt), and two in Spain (Barcelona and Madrid).

All branches and offices are connected to the EuroBank core network. For the branches, this connection is provided in the UK and Germany by means of a managed Layer 3 MPLS VPN service provided by local service providers in these countries. In Spain this connection is achieved through a managed Frame Relay network provided by a local service provider. In all countries, offices are directly connected to the core network via one of the nine POPs using private leased lines (34 Mbps or 155 Mbps), ATM PVCs, Metro Ethernet connections, or, when co-located within the POP, using local Fast Ethernet or Gigabit Ethernet connections.

EuroBank core POPs are also attached to the Layer 3 MPLS VPN service and to the managed Frame Relay-based service of their local service providers in their respective country.

Each office usually is composed of server farms hosting various applications accessed by branch locations. As already pointed out, each branch also accesses applications hosted in the various data centers in Europe.

EuroBank has four data centerstwo in London, one in Frankfurt, and one in Madrid. These are interconnected to the local POP(s) by means of redundant high-speed links, Fast Ethernet or Gigabit Ethernet (wherever such metro services are available in that particular city), or 155-Mbps leased lines otherwise. Data centers are usually close to the core network POPs but are never co-located for availability reasons (thus keeping a power supply failure, for instance, from affecting both the POP and the data center). Such data centers host many applications on UNIX servers and mainframes that are accessed by the various branches and offices in the EuroBank group. In other words, although the branches usually connect to remote applications hosted in an office of their subsidiary, they also access applications hosted in the various data centers. Likewise, offices access applications hosted on servers located in other offices or within the data centers.

In the past, EuroBank operated nine data centers, but it reduced that number to four over the last two years to meet its cost-reduction objectives. This was made possible because the company's high-speed MPLS infrastructure offers the necessary performance levels, allowing transparent access to a remotely located data center and because of the Layer 3 MPLS VPN technology, which allows strict control of access to different resources in the same location.

Description of the Branch Office

Branch offices are small-to-medium locations with regular front-office banking services. They do not require the support of multiple VPNs. They are located in various towns and cities across the UK, Germany, and Spain.

[MLPPP]) to provide an equivalent bandwidth until the service is restored and the traffic is switched back to the local access link. Note that such backup technology is deployed both in the case of access to a Layer 3 MPLS VPN service provider core and in the case of the Frame Relay managed service used in Spain.

[L2VPN]. If you want to know more about this resource, look up the code in the "References" appendix to find out specific information about the resource.

Figure 6-1 shows the structure of a branch, as well as its connectivity to the EuroBank core network.

Description of an Office Location

As discussed, EuroBank offices potentially host hundreds of employees from different subsidiaries. They include all back-office processing in addition to the front-end applications. Outside the UK, the offices in Spain, Germany, and New York each support staff from a single subsidiary.

From a networking infrastructure perspective, the only difference between the UK offices and the offices outside the UK is how the CE routers are connected and how many VPNs each CE router needs to support. In the Spanish and German offices, two CE routers are connected to the EuroBank core network by means of leased lines or metro connections. This is also true for smaller office locations in the UK.

The office locations in the UK, an example of which is shown in UK Office Location Layer 3 MPLS VPN Design.") These CE routers attach to PE routers in the local POP via leased lines or metro connections. Hosts and servers are attached to the office network via Gigabit Ethernet switches dual-attached to the multi-VRF CE routers.

A separate virtual LAN (VLAN) is configured on the Ethernet switch for each VPN supported at that location. That VLAN is attached to the corresponding VRF in the multi-VRF CE routers. Finally, each host port at the switch is configured to be in the VLAN that corresponds to its VPN.

The CE routers of larger offices in the UK are generally connected to the EuroBank core network POPs (whose structure is described in the next section) via 34-Mbps (and sometimes 155-Mbps) leased lines. In large cities such as London, the larger office CE routers are connected to the core POPs via a metro Fast Ethernet or Gigabit Ethernet connection provided by a local service provider. For the smaller office locations, the medium used to connect these sites to the core network is leased lines from 8 Mbps to 34 Mbps.

When possible, EuroBank leases protected circuits from its local service provider. In the absence of such protection, it relies on its Interior Gateway Protocol (IGP) (OSPF) convergence to reroute the traffic in case of a leased line failure. EuroBank also relies on IGP convergence to handle CE router or PE router failure.

Observe that full redundancy is supported in the office locations by doubling all the network equipment. This redundancy is provided by two CE routers (dimensioned so that each can single-handedly deal with all the traffic to and from the location), dual Gigabit Ethernet switches, and dual connections to the core network via two different POPs (or, where not possible, via two different routers of one POP).

Description of a Core Network POP

The core network is composed of nine POPS: five in the UK (three in London, one in Manchester, and another in Newcastle), two in Germany (Berlin and Frankfurt), and two in Spain (Barcelona and Madrid).

The POP structure is shown in Figure 6-3. Each POP has two P routers connected to two PE routers via two Gigabit Ethernet switches. To ensure full redundancy, each P router and PE router is attached to the two switches.