UDC 535.14:621.391 IP Photonic Node VHaruo Yamashita VTakashi Hatano VSatoshi Nojima VNobuhide Yamaguchi (Manuscript received February 28, 2001) This paper describes an IP photonic node architecture and its migration based on a single virtual-router view network. The IP photonic node features node cut-through at a various levels such as the wavelength, SONET frame, and/or packet path. Its coordi- nation capability for optical and packet paths enables efficient usage of network re- sources, for example, for the transportation and restoration of very large volumes of IP traffic. This paper also presents some recent photonic technology to make the IP photonic node configurable and expandable. 1. Introduction ing (WDM) transport, an optical amplifier for a The volume of IP traffic is growing exponen- large number of wavelengths, and tunable laser tially because of the widespread use of applications diodes and filters. such as the Internet; virtual private networks (VPNs); and communications between data cen- 2. IP photonic node architecture ters, between collocation facilities, and within based on a single virtual- storage area networks. Photonic networking is router view regarded as an essential and core technology to 2.1 Virtual-router view network cope with this trend. Vigorous efforts to accom- To cope with the ever-increasing IP traffic, modate a huge capacity have been made, and solve the processing bottleneck problem, and meet multi-vendor environment construction has been the demands for Class of Service (CoS) and Qual- promoted by organizations such as the ITU-T, In- ity of Service (QoS), we proposed an IP core ternet Engineering Task Force (IETF), and Optical transport network and transport node architec- Internetworking Forum (OIF). ture based on a single virtual-router view.2) Against this background, we have proposed Figure 1 shows our concept. Users are offered a a virtual network paradigm for the next-generation variety of services through a virtual router core network.1) This paper focuses on an IP photonic transport from application servers. Users do not node architecture based on this concept, its abili- need to know the network structure itself, but re- ty to coordinate between optical paths and packet quire networks to work as one huge virtual server flows, and a migration scenario for the IP photon- which provides requested services at the request- ic node. This paper also describes some of the ed network quality. latest wavelength routing equipment and device IP photonic networks based on a single technologies to realize the IP photonic node, for virtual-router view can configure virtual private example, terabit wavelength division multiplex- networks (VPNs) in a variety of ways to meet us- 22 FUJITSU Sci. Tech. J.,37,1,pp.22-30(June 2001) H. Yamashita et al.: IP Photonic Node (Virtual server) Data center Application L-SW server User site B SONET Virtual router User site A SONET WDM SONET (Node cut-through User VPN-b Best-effort path WDM WDM by wavelength, frame, router WDM or path) VPN-a User site C Edge Edge node Gateway node L-SW Guaranteed path Access server IP photonic network Access Access Access Cooperation Users Users L-SW: Label switching Figure 1 Figure 2 Virtual-router view network. Example of main services provided by a virtual router: VPN. ers’ demands. An example is shown in Figure 2. IP layer Point-to-point path IP-based virtual leased lines in VPNs are set-up IP node IP path: virtual connection between user sites in the point-to-point path or EF-PHB – Priority control (Diff-serve) DiffServ – Mutual interference Router multi-point-to-point paths with a variety of QoS – Abundant logical paths grades in terms of bandwidth, packet loss rate, Link layer priority, delay, delay variation, and so on. Because Label path: virtual connection LSP – MPLS path isolation is required between VPNs, rigid LSR – Mutual interference – Abundant logical paths paths such as wavelengths and SONET frames or SONET layer a f lexible granularity such as groomed IP packet GS8400FUJITSU SONET path: physical connection labels are used as shown in Figure 3. FUJITSU GS8400 GS8400FUJITSU – No interference (TDM) Path FUJITSU – SONET bandwidth granularity SONET GS8400 node 2.2 IP photonic node architecture Physical layer The key technology in a single virtual- λ path: physical connection router view is the node cut-through technology – No interference ( λ ) with multiple granularity achieved at 1) the wave- λ – Bandwidth free λ node – Limited to the number of λ length level by wavelength routing, 2) the frame wavelengths ( paths) level (e.g., SONET/SDH ) by electrical ADM and Figure 3 cross connection, and 3) the packet level by layer VPN implementation schemes. 2 label switching. We use the term “IP photonic node” to mean a conceptual node that coordinates optical paths and packet flows and then config- works simpler and enable economic configuration ures a single virtual network. Optical add/drop just by handling the wavelength level. multiplexer (OADM), optical cross-connect (OXC), An example IP photonic node configuration SONET/SDH equipment, and/or layer 2 packet is shown in Figure 4. The node cut through at switches can implement the node cut-through the wavelength level can be done such that only functionality in an IP photonic node. Therefore, the required wavelengths are added or dropped an IP photonic node is a single or composite mod- at the designated node and other wavelengths are ule that provides node cut-through for IP traffic passed through. Similarly, node cut-through will transportation. Especially, node cut-through at be done at the layer 2 packet level. IP packets the wavelength level will make transport net- can be encapsulated with a fixed length label, FUJITSU Sci. Tech. J.,37, 1,(June 2001) 23 H. Yamashita et al.: IP Photonic Node λ Backbone network λ Hierarchical network MUX/DMUX for network scalability Packet SW + OXC/OADM OXC Packet aggregation for full usage Fiber of λ bandwidth (Edge node) (Edge node) Optical SW IP traffic transport by λ cut-through path Figure 5 λ Network Network Collaborated work in and electrical levels. INF IP INF label SW Tributary Tributary INF INF network edges, as shown in Figure 5. The IP pho- Figure 4 tonic node aggregates and grooms IP packets sent Example configuration of IP photonic node. by connected nodes into the same destination or QoS and then accommodates them into the same which is used as a switching label between ingress optical path by a packet switch. The CoS/QoS and egress edge nodes/routers. This type of la- during packet aggregation/grooming should be beled packet can be dropped or added at the considered. In the future, if the economically avail- designated node and passed through the interme- able wavelength count increases, a more flexible diate nodes. In some cases, cut-through at the usage of wavelengths would be applicable, for ex- frame level can be applied such that payload in- ample, different QoS packets could be assigned to formation in only designated frames is added or different wavelengths. dropped at the designated node and others are Some of the advantages of coordinating opti- passed through. cal paths and packet flows from the viewpoint of optical path restoration or protection are described 2.3 Coordination function in the IP below.3) photonic nodes A simple IP photonic node is composed of a A wavelength or an optical path basically separate optical path switch and packet switch. works as a point-to-point path, so the wavelength In this case, if the utilization of each optical path count increases with the number of connected is low, the number of restored wavelengths be- points or nodes. An increase in the wavelength comes large. As a result, the optical path switch count requires an increase in the number of re- will need to be large. On the other hand, some lated optical transmitters/receivers and WDM integrated IP photonic nodes can be configured filters. The cost of a node will depend on how many by using an integrated optical-path and packet wavelengths need to be handled. Therefore, to switch, which replaces a part of the optical path make it possible to provide an economical service switch with packet switches, thereby reducing the to users, a highly-efficient bandwidth utilization hardware size. If we coordinate the operation of per wavelength should be considered. An aggre- the optical path and packet layer, the number of gation and grooming function for converting IP restored wavelengths can be reduced. Figure 6 packets into an appropriate wavelength or opti- shows a simple optical path protection scheme and cal path is essential for the IP photonic node at a coordinated optical path and packet layer pro- 24 FUJITSU Sci. Tech. J.,37, 1,(June 2001) H. Yamashita et al.: IP Photonic Node λ 1 (0.5) λ 1 (1.0) C C C C λ 3 (1.0) λ 2 (1.0) E E λ 2 (0.5) B D B D 1 (0.5) 2 (1.0) 3 (0.5) 3 (0.5) 2 (1.0) 1 (0.5) 1 (1.0) 2 (1.0) 2 (1.0) 1 (1.0) λ λ λ λ λ λ λ λ λ λ B D B D λ 2 (1.0) λ 2 (1.0) E E λ 1 (0.5) λ 1 (0.5) A A A A (Numbers in parentheses indicate utilization of optical path λ k) *low utilization of restored optical path *high utilization of restored optical path (reduced wavelength counts) (a) Simple optical-path protection (b) Coordinated optical path and packet layer protection Figure 6 Protection schemes in IP photonic nodes.