EP1712035A1 - Ethernet differentiated services - Google Patents
Ethernet differentiated servicesInfo
- Publication number
- EP1712035A1 EP1712035A1 EP05706399A EP05706399A EP1712035A1 EP 1712035 A1 EP1712035 A1 EP 1712035A1 EP 05706399 A EP05706399 A EP 05706399A EP 05706399 A EP05706399 A EP 05706399A EP 1712035 A1 EP1712035 A1 EP 1712035A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- frame
- ethernet
- per
- class
- network
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
- H04L12/46—Interconnection of networks
- H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L41/00—Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
- H04L41/50—Network service management, e.g. ensuring proper service fulfilment according to agreements
- H04L41/5003—Managing SLA; Interaction between SLA and QoS
- H04L41/5019—Ensuring fulfilment of SLA
- H04L41/5022—Ensuring fulfilment of SLA by giving priorities, e.g. assigning classes of service
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/13—Flow control; Congestion control in a LAN segment, e.g. ring or bus
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/20—Traffic policing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/22—Traffic shaping
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
- H04L47/2408—Traffic characterised by specific attributes, e.g. priority or QoS for supporting different services, e.g. a differentiated services [DiffServ] type of service
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
- H04L47/2441—Traffic characterised by specific attributes, e.g. priority or QoS relying on flow classification, e.g. using integrated services [IntServ]
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
- H04L47/2491—Mapping quality of service [QoS] requirements between different networks
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/31—Flow control; Congestion control by tagging of packets, e.g. using discard eligibility [DE] bits
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L47/00—Traffic control in data switching networks
- H04L47/10—Flow control; Congestion control
- H04L47/32—Flow control; Congestion control by discarding or delaying data units, e.g. packets or frames
Definitions
- Ethernet is a widely installed local area network (LAN) technology. Ethernet technology can be cost effective, easy to configure, and is widely understood by network managers. Ethernet technology is increasingly being deployed in service provider metro and wide-area networks. Success of Ethernet in provider networks depends on the ability to provide service level agreements (SLAs) that can guarantee bandwidth, delay, loss, and jitter requirements to end-users. Service providers can offer multiple services with different quality-of-service (QoS) characteristics and performance guarantees.
- SLAs service level agreements
- QoS quality-of-service
- the base Ethernet technology is specified in the IEEE 802.3 standard. Traditionally,
- Ethernet did not include QoS capabilities. More recently, the IEEE has introduced the user priority capability that enables the definition of up to eight classes of service (CoS).
- the user priority capability is often referred to as "the p-bits.”
- the p-bits are carried in the
- An Ethernet network may include multiple customer edge (CE) devices, switches, and routers. These devices may communicate using the Ethernet protocols and/or other networking technologies and protocols.
- CE customer edge
- a method for conditioning Ethernet traffic includes receiving an Ethernet frame, classifying the frame based on a set of priority bits in a frame header of the Ethernet frame, and determining a per-hop behavior for the frame based on the classification.
- Embodiments may include one or more of the following.
- the set of bits can include a set of p-bits in the Ethernet header.
- Setting the set of bits can include mapping the Ethernet per-hop behaviors to a set of bits in a frame according to a core network technology.
- Setting the set of bits can include mapping the Ethernet per-hop behaviors to a set of connections according to a core network technology.
- the method can also include metering the frame. Metering the frame can include modifying the drop precedence and per-hop behavior of the frame.
- the method can also include determining a forwarding treatment for the frame based on the per-hop behavior or dropping the frame based on the per-hop behavior.
- the method can also include marking the frame based on the assigned PHB.
- the method can also include shaping the frame based on the assigned PHB.
- the method can include scheduling the frame for delivery on the Ethernet network.
- Scheduling can include allocating a link bandwidth based on the PHBs.
- Scheduling can include allocating a link bandwidth among multiple virtual local area networks (NLANs), the VLANs including multiple E-Diff traffic classes and allocating portions of the allocated bandwidths for the multiple virtual local area networks among at least one VLAN class for the multiple local area networks based on the priority bits.
- Scheduling can include allocating a bandwidth among a set of service classes, allocating portions of the allocated bandwidths for the set of service classes among at least one particular service class, the service class including multiple VLAN classes, and allocating portions of the allocated bandwidths for the particular service classes among a particular VLAN class based on the priority bits.
- the forwarding treatment can be based on an Ethernet differentiated services class.
- the Ethernet differentiated services class can include one or more of Ethernet expedited forwarding (E-EF), Ethernet assured forwarding (E-AF), Ethernet class selector (E-CS), and Ethernet default forwarding (E-DF).
- Determining a forwarding treatment can include defining additional per-hop behaviors based on networking or application needs.
- the frame can include a canonical format indicator (CFI) bit, which can be used for CoS indication.
- Classifying the frame based on a set of predetermined criteria associated with combinations of the priority bits can include classifying the frame based a set of predetermined criteria associated with combinations of the priority bits and the CFI bit.
- the priority bits can include a congestion indication.
- the congestion indication can include at least one of a forward and a backward congestion indication.
- a system includes an Ethernet network.
- the Ethernet network includes a set of edge nodes configured to define per-hop behaviors using a set of p-bits in the Ethernet header and a set of core nodes configured to forward the frame according to the per-hop-behaviors as indicated in the p-bits.
- a network includes a first Ethernet network and a second Ethernet network.
- the first Ethernet network includes an edge node configured to define per-hop behaviors using a set of bits in an Ethernet header of a frame and a core node configured to receive the frame and to forward the frame according to the per-hop behaviors as indicated in the set of bits.
- the second network includes a second edge device in the second network configured to determine the Ethernet per-hop behavior for the frame.
- Embodiments may include one or more of the following.
- the set of edge nodes can provide conditioning of the frames.
- the set of core nodes can forward the frame according to the per-hop behaviors indicated in the p-bits.
- the set of edge nodes can include an ingress device and an egress device.
- the edge node can include a classifier device, a marker device configured to mark the frame with a particular per-hop behavior indicated in the p-bits, and a shaper.
- the edge node can include a classifier device, a marker device configured to mark the frame with a particular per-hop-behavior indicated in the p-bits, and a dropper.
- the edge node can also include a meter device.
- the set of core nodes can forward, the frame according to a subset of all per-hop- behaviors.
- the set of edge nodes can add a tunnel header to the frame.
- the tunnel header can include a set of bits that indicate a per-hop behavior.
- the tunnel header can use a Q-in- Q or MAC-in-MAC Ethernet Encapsulation method.
- the system can preserve the information in the original frame.
- the system can also include boundary nodes between the multiple Ethernet domains.
- the boundary nodes can map a per-hop behavior of the frame between the multiple networks.
- the boundary nodes can provide traffic conditioning for the frame.
- the system can also include customer edge device that sets the p-bits for the frame.
- a system includes an Ethernet network.
- the Ethernet network includes a set of edge nodes configured to define Ethernet per-hop behaviors using a set of bits h a frame and a set of core nodes configured to forward the frame according to the Ethernet per-hop-behaviors, the core nodes using a different network technology than the edge nodes.
- Embodiments can include one or more of the following.
- the different network technology can be an asynchronous transfer mode technology, a multi-protocol label switching technology, a frame relay technology, or an Internet protocol technology.
- the set of edge nodes can map the Ethernet per-hop behaviors to a set of bits in a frame according to the different network technology.
- the set of edge nodes can map the Ethernet per-hop behaviors to a set of connections in the different network technology.
- a networking device includes a behavior aggregate classifier device configured to receive an Ethernet frame and classify the frame based on the priority bits in the Ethernet header.
- Embodiments can include one or more of the following.
- the device can determine a band width profile based oh the classification.
- a meter device can meter the frame based on the bandwidth profile.
- a marker device can mark the frame header with a particular per-hop-behavior indication.
- a shaper device can receive a frame from the marker and determine a behavior based on the per-hop behavior. The marker can set the priority bits in the frame to a particular combination.
- the system can also include a frame meter device.
- the frame meter device can determine temporal properties of a set of frames.
- the shaper device can be a dropper and the dropper can drop the frame based on the per-hop behavior.
- the networking device can include a core switch configured to receive a frame from an ingress switch or another core switch.
- the core switch can apply a particular forwarding behavior to the frame based on the per-hop behavior as indicated in the priority bits.
- the networking device can include an egress switch configured to receive a frame from the ingress or the core switch.
- the ingress switch can include an encapsulation device and the core switch is one of an asynchronous transfer mode switch, a multiprotocol label switching switch, a frame relay switch, or an Internet protocol router.
- a system and method includes defining a set of differentiated service classes, each differentiated service class associated with a set of per-hop behaviors, and indicating a particular per-hop behavior for an Ethernet frame in a set' of priority bits in a header of the Ethernet frame.
- the differentiated service classes can include an Ethernet expedited forwarding (E-EF) class.
- the E-EF class can require delivery of a frame within a particular amount of time.
- the differentiated services class can include an Ethernet assured forwarding (E-AF) class.
- the Ethernet assured forwarding (EAF) classes can include a plurality sub-classes based on a bandwidth allocation.
- the method can include assigning a drop precedence for an E-AF class.
- the differentiated services classes can include an Ethernet class selector (E-CS) class.
- the Ethernet class selector (E-CS) class can include multiple sub-classes.
- the method can include assigning preferential treatment to a particular sub-class.
- the differentiated services classes can include a default-forwarding (E-DF) class.
- the method can include assigning a lower level of service to an E-DF class frame than to frames from other classes.
- Ethernet differentiated services architecture can allow for incremental deployment, and permit interoperability with non-Ethernet differentiated services compliant network nodes.
- a variation of the architecture where Ethernet is used at the access and a different technology at the network core provides an advantage of allowing differentiated services across heterogeneous networks.
- Ethernet differentiated services domains are multiple enterprise and/or provider networks/segments that employ different Ethernet differentiated services methods and policies within each domain, such as different p-bits interpretations, number/type of PHBs, etc. Mapping or traffic conditioning can be used at the boundary, nodes between different domains.
- Ethernet class of service (CoS) bits identify nodal behavior (e.g., how an incoming frame should be handled at queuing and scheduling levels based on p-bits encoding) and allows frames to be forwarded according to the specified nodal behaviors.
- Ethernet per- hop-behaviors are determined or encoded by a specific assignment of the p-bits.
- the p-bits can also include congestion information to indicate network congestion.
- the particular use of the 802.1Q NLAN Tag Control Information e.g., p-bits
- the use of the p-bits allows the definition of a number of defined per-hop behaviors (PHBs) that determine the forwarding treatment of the Ethernet frames throughout the network.
- FIG. 1 is a block diagram of a tagged Ethernet frame.
- FIG. 2 is a block diagram of a Ethernet differentiated services architecture.
- FIG. 3 is a block diagram of a set of components included in a device at an edge node of a network.
- FIG. 4 is a block diagram of a Ethernet differentiated services architecture.
- FIG. 5 is a block diagram of Ethernet differentiated services per-hop behaviors
- FIG. 6 is block diagram of a class-based scheduler using multiple queues
- FIG. 7 is table of priority bit assignments.
- FIG. 8 is a block diagram of a differentiated services network having multiple domains
- FIG. 9 is a architecture for end-to-end service across multiple provider networks. DETAILED DESCRIPTION
- the frame 10 Referring to FIG. 1, an example of an Ethernet frame 10 is shown.
- the frame 10 is shown.
- the header 12 includes a destination address 16, a source address 18, an 802. IQ. tag 20, and aprotocol type 22.
- the histitute for Electrical Engineers (IEEE) standard 802. IQ describes the 802. IQ tag 20.
- the 802. IQ tag in an Ethernet frame that defines a virtual-LAN (NLAN) membership.
- the three priority bits 50 provide eight combinations and describe up to eight levels of service.
- the three priority bits can be used to describe the per-hop behavior of a frame. Per-hop behaviors include for example, externally observable forwarding behavior applied to a frame by a frame forwarding device 20 in an Ethernet differentiated services architecture 30. Referring to FIG.
- the Ethernet differentiated services architecture 30 is shown. This architecture 30 forwards frames based on the per-hop-behaviors defined by the p-bits 24 for the frames.
- One embodiment of the architecture 30 includes a frame forwarding device 20 that includes an ingress switch 34, a core switch 38, and egress switch 46.
- the ingress switch 34 performs traffic conditioning functions and class-based forwarding functions.
- the core switch 38 includes a behavior aggregate (BA) classifier 40 and a class-based egress scheduler that uses multiple queues 44.
- the egress switch 46 may perform similar functions to either the ingress switch 34 or core switch 38 (or a subset of those functions), depending on network configurations and policies.
- BA behavior aggregate
- the egress switch 46 can perform core node-like forwarding functions.
- the egress switch 46 is connected to another provider network using a network-network interface (NNi)
- the egress switch 46 performs traffic conditioning functions according to the service contract between the two providers.
- the architecture 30 includes Ethernet differentiated services functions implemented at both the edge and the network core 36, although other arrangements may be possible. Unlike the IP DiffServ ("Differentiated services") Architecture, described in RFC
- the architecture 30 shown in FIG. 2 does not use the LP DSCP for indicating frame per-hop behaviors. Instead, the architecture 30 uses the Ethernet p-bits 24.
- Architecture 30 assumes that edge and core nodes are p-bit aware nodes, meaning that e.g., that the nodes can set, clear and/or process frames based on the states of the p-bits. For example, all edge and core nodes are NLAN-aware Ethernet nodes that can set and/or interpret the p-bits.
- the network core 36 may be an Ethernet
- the architecture 30 separates edge and network core node functions. That is, the edge includes traffic conditioning that may include multi-field classification, metering, and marking of the per-hop behavior (PHB) in the p-bits 24, together with class-based forwarding. On the other hand, the edge functions may occur at the user-network interface (UNI) for example, between the customer edge (CE) node and service provider, or at the network-network interface (NNI) between networks/domains.
- UNI user-network interface
- CE customer edge
- NNI network-network interface
- the core node 36 is scalable and performs simple behavior and aggregate classification based on the frame per-hop-behavior (PHB) (indicated in the p-bits 24), and class-based forwarding based on the PHB value.
- PHB frame per-hop-behavior
- FIG. 3 components 50 included in a device at the network edge nodes are shown.
- the set of components 50 are included in an ingress switch such as switch 34 (FIG. 2).
- the set of components 50 includes a classifier 52, meter 54, marker 56, and shaper/dropper 58. These components 50 perform Ethernet traffic conditioning functions at the network edge nodes to classify incoming traffic based on predetermined criteria.
- the classification identifies flows and correlates the flows to corresponding bandwidth profiles for the flows and corresponding forwarding treatments defined or provided for the flows.
- the classifier 52 selects frames in a traffic stream based on content of some portion of the frame header (e.g., based on the p-bits).
- Two types of classifiers include behavior aggregate (BA) classifiers and multi-field (MF) classifiers.
- BA classifier classifies frames based on the p-bits only.
- the MF classifier selects frames based on the value of a combination of one or more header fields, such as source and destination address, p-bits, protocol LD, source and destination port numbers, and other information such as incoming interface/connection, hi general, classifier 52 (e.g., a behavior aggregate (BA) classifier or multi-field (MF) classifier) is used to "steer" frames matching a rale to a different element of the traffic conditioner for further processing. Frames enter classifier 52 (indicated by arrow 51) and may or may not be
- BA behavior aggregate
- MF multi-field
- Metered frames are passed to meter 54.
- Meter 54 measures the temporal properties of the stream of frames selected by a classifier and compares the properties to a traffic profile.
- a meter 54 passes state information to other components to trigger a particular action for each frame that is either in- or out-of- profile.
- Non-metered frames are passed from classifier 52 to marker 56.
- Flows are marked (or remarked) by marker 56 to identify the Ethernet PHB applied to the incoming frame. For instance, frame marker 56 sets a particular field of a frame to a particular p-bit combination, adding the marked frame to a particular behavior aggregate.
- the marker 56 can be configured to mark all received frames to a single p-bit combination, or can be configured to mark a frame to one of a set of p-bit combinations used to select a particular PHB from a PHB group according to the state of the meter 54.
- a PHB group is a set of one or more PHBs that can be specified and implemented simultaneously, due to a common constraint applying to all PHBs in the set such as a queue servicing or queue management policy.
- a PHB group allows a set of related forwarding behaviors to be specified together (e.g., four dropping priorities).
- PHB is a special case of a PHB group.
- the marker 54 changes the p-bit combination in a frame it is referred to as having "re-marked" the frame. Remarking may also occur across Ethernet-differentiated services domain boundaries, such as a user to network interface (UNI) or network to network interface
- NNI NetworkNI
- Remarking could be used for such purposes as performing PHBs mapping or compression, or to effect p-bits translation.
- the outer tunnel p-bits are usually also set to the desired PHB indication for forwarding through the aggregated core.
- the p-bits in the original Ethernet frame may be preserved through the network, or changed by the edge nodes. Frames that exceed their assigned rates may be dropped, shaped, or remarked with a drop precedence indication.
- the shaper/dropper 58 shapes the traffic before sending the frames to the network as indicated by arrow 60. Shaper/dropper 58 discards some or all of the frames in a traffic stream in order to bring the stream into compliance with a traffic profile. This discarding is sometimes referred to as "policing" the stream.
- a dropper can be implemented as a special case of a shaper by
- multi-field traffic classification is based on any of the L1-L7 protocol layer fields, either individually or in combination.
- Common L2 Ethernet fields used are the incoming Ethernet Interface (port), the Destination/Source MAC addresses, the virtual local area network identification (NLAN LD or VID), and the User Priority (p-bits).
- MAC Destination/source media access, control
- MAC Based on the Destination/source media access, control (MAC) addresses all of the frames originating at a certain source and/or destined to a certain destination are assigned to the same flow.
- MAC Destination/source media access
- MAC Based on the Destination/source media access, control (MAC) addresses all of the frames originating at a certain source and/or destined to a certain destination are assigned to the same flow.
- MAC Destination/source media access, control
- MAC Based on the Destination/source media access, control (MAC) addresses all of the frames originating at a certain source and/or destined to a certain destination are assigned to the same flow.
- the user priority bits provide a finer granularity for flow identification.
- the L2 Ethernet fields can be combined for traffic classification. Common combinations include: "port + p-bits", “VID(s) + p-bits.” Common upper layer fields include IP differentiated services, L? source, IP Destination, IP Protocol Type, TCP port number, UDP port number. Frame classification determines the forwarding treatment and metering of frames.
- Determining the forwarding treatment (e.g., congestion control, queuing and scheduling) by the edge nodes includes assigning PHBs to the group of frames that require the same treatment (e.g., Voice is assigned E-EF PHB, and Data is assigned E-AFx PHB).
- Metering can be used for determining and enforcing the bandwidth profile / traffic contract, and verifying the Service Level Agreements (SLAs), and allocating nodal resource to the flow.
- SLAs Service Level Agreements
- the classification function may be different for the purpose of forwarding and metering. For example, voice and data typically receive different forwarding treatment, but their traffic bandwidth profile could be combined into a single traffic contract to resemble a leased line service. Referring to FIG. 4, another example of an Ethernet differentiated services architecture 70 is shown.
- the architecture 70 includes an ingress switch 84 at an interface between an Ethernet network 82 and a non-Ethernet network core 86.
- the architecture 70 also includes an egress switch 88. h this example, different technologies are used for forwarding the Ethernet frames through the non-Ethernet network core 86.
- the non-Ethernet network core 86 could use
- the ingress switch 84 includes a classifier 72, traffic meter 74, marker 76, shaper/dropper 78, and a mapping unit 80.
- the classifier 72, traffic meter 74, marker 76, and shaper/dropper 78 function in a similar manner to those described above in FIG. 3.
- the mapping unit 80 maps and encapsulates the Ethernet frames for forwarding on the core network 86.
- the architecture 70 shown in FIG. 4 is similar to architecture 30 shown in FIG. 2, however, architecture 70 uses Ethernet at the access and a different networking technology in the core 86.
- the edge conditioning functions are similar to the edge conditioning functions in architecture 30.
- the Edge node performs the class of service (CoS) mapping from the Ethernet PHB into the core network 86.
- Many mapping methods are possible such as mapping the PHB to an ATM virtual channel connection (VCC) (e.g., E-EF to constant bit rate (CBR) VCC), a link-state packet (LSP), an IP Differentiated services core, etc.
- VCC virtual channel connection
- CBR constant bit rate
- LSP link-state packet
- IP Differentiated services core etc.
- edge CoS functions define per-hop behaviors for a frame.
- a frame is forwarded based on per-hop behaviors indicated in the p-bits 24, whereas in architecture 70, a frame is forwarded based on the core network technology CoS transport mechanism.
- FIG. 5 a grouping 90 of the nodal behaviors into, e.g., four categories is shown.
- the grouping 90 includes an Ethernet expedited forwarding category 92 (E-F), Ethernet assured forwarding 94 (E-AP), Ethernet class selector 96 (E-CS), and Ethernet default-forwarding category 98 (E-DF).
- E-F Ethernet expedited forwarding category 92
- E-AP Ethernet assured forwarding 94
- E-CS Ethernet class selector 96
- E-DF Ethernet default-forwarding category 98
- Ethernet expedited forwarding category 92 (E-EF) is primarily for traffic sensitive to delay and loss. This category is suitable for implementing services that require delivery of frames within tight delay and loss bounds and is characterized by a time constraint.
- E-EF allows for frame loss when buffer capacity is exceeded, however, the probability of frame loss in this service is typically low (e.g., 10 "5 - 10 7 ).
- E-EF identifies a single drop precedence and frames that exceed a specified rate are dropped.
- a complete end-to-end user service can include edge rules or conditioning in addition to forwarding treatment according to the assigned PHB. For example, a
- premium service level (also be referred to as virtual leased line), uses E-EF PHB defined by a peak rate only. This "premium” service has low delay and small loss performance.
- a frame in the E-EF category can have forwarding treatment where the departure rate of the aggregate frames from a diff-serv node is set to equal or exceed a configurable rate. This rate is available independent of other traffic sharing the link, h addition, edge rules describe metering and peak rate shaping. For example, the metering/policing can enforce a peak rate and discard frames in excess of the peak rate. The metering/policing may not allow demotion or promotion. Peak rate shaping can smooth traffic to the network and convert traffic to constant rate arrival pattern.
- a combination of the forwarding behaviors and edge rales offer a "premium"service level.
- a premium service queue typically holds one frame or a few frames.
- An absolute priority scheduler increases the level of delay performance and could be offered initially on over-provisioning basis.
- Ethernet Class Selector provides compatibility with legacy switches.
- Ethernet Class Selector includes up to eight p-bit combinations.
- E-CS frames can be metered at the network edge.
- E-CS does not allow significant re-ordering of frames that belong to the same CS class.
- the node will attempt to deliver CS class frames in order, but does not guarantee that reordering will not occur, particularly under transient and fault conditions.
- All E-CS frames belonging to the same class are carried at the same drop precedence level.
- the fourth category, a default-forwarding category 98 (E-DF) is suitable for implementing services with no performance guarantees. For example, this class can offer a "best-effort" type of service.
- E-DF frames can be metered at the network edge.
- This class of service should not allow (significant) re-ordering of E-DF frames that belong to the same flow and all E-DF frames are carried at the same drop precedence level.
- Frame treatment can provide "differentiated services", for example, policing, marking, or re-coloring of p-bits, queuing, congestion control, scheduling, and shaping.
- the proposed Ethernet per-hop behaviors include expedited forwarding (E- EF), assured forwarding (E-AF), default forwarding (E-DE), and class selector (E-CS), additional custom per-hop behaviors PHBs can be defined for a network.
- the three p-bits allow up to eight PHBs) .
- Ethernet connections e.g., Ethernet interfaces or VLANs
- VLANs virtualized local area network
- the mapping of the p-bits to PHBs may be signaled or configured for each interface/connection.
- tunnels may be, used for supporting a larger number of PHBs. Referring to FIG. 6, an arrangement 100 for placing an incoming frame 101 in
- the arrangement 100 includes four queues 102, 104, 106, and 108.
- the queues 102, 104, 106, and 108 are assigned different priorities for forwarding the frame based on the different levels of services defined in, e.g., the Ethernet differentiated, service protocol.
- frames with p-bits mapped to E-EF differentiated service behaviors are placed in the highest priority queue 102.
- This queue does not allow frames to be discarded and all frames are of equal importance, hi this example, queues 104 and 106 are allocated for forwarding frames with the assured service class of the differentiated services and frames are placed in this queue according to their p-bit assignment.
- each queue may be assigned a guaranteed minimum link bandwidth and frames are not re-ordered. However, if the network is congested the queues discard frames based on the assigned drop precedence.
- Queue 108 corresponds to a "best effort" queue. Frames placed in this queue are typically given a lower priority than frames in queues 102, 104, and 106. Queue 108 does not re-order the frames or allow for drop precedence differentiation. While in the example above, at incoming frame was placed in one of four queues based on the p-bits 24, any number of queues could be used. For example, eight queues could provide placement of frames with each combination of p-bits 24 in a different queue.
- the p-bits 24 can include congestion information in the forward and/or backward direction.
- This congestion information can be similar to forward explicit congestion notification (FECN) and backward explicit congestion notification (BECN) bits of the frame relay protocol.
- the congestion information signals a network device, for example, edge nodes or CEs, to throttle traffic until congestion abates.
- edge nodes or CEs to throttle traffic until congestion abates.
- two combinations can be used for FECN (signaling congestion and no congestion) and two for the BECN direction.
- the canonical format indicator (CFI) a one bit field in the Ethernet header, can be used for signaling congestion, or other QoS indicators such as frame drop precedence.
- the use of the CFI field in addition to (or in combination with) the p-bits 24 allows for support of additional PHBs.
- the p-bits can be used for signaling up to eight emission classes, and the CFI is used for drop precedence (two values) or a more flexible scheme, where the combined (p-bits + CFI) four bits can support 16
- PHBs (instead of 8).
- FIG. 7 an example of the assignment of p-bits 24 to represent nodal behaviors by mapping the p-bits 24 to combinations of the Ethernet differentiated service PHBs is shown. This assignment designates four groupings of nodal behaviors: E-EF, E- AF2, E-AF1, and E-DF. Each of the E-AF levels includes two drop precedence levels (i.e., E-AFX2 and E-AFXl) and thus, is assigned to two combinations of p-bits.
- the E-EF nodal behavior is mapped to the ' 111 ' combination 120 of p-bits
- the E-AF2 nodal behaviors are mapped to the' '110' and '101' combinations 122 and 124
- the E-AFl nodal behaviors are mapped to the '100' and 'Oil' combinations 126 and 128, and the E-DF nodal behavior is mapped to the '010' combination 130.
- two p-bits combinations 132 and 134 are reserved for congestion indication in the forward or backward direction. For example, if the p-bits are assigned according to the mapping shown in FIG. 7 and the network includes a set of queues as shown in FIG.
- frames can be routed to the appropriate queue based on the p-bit combination.
- Frames with a p-bit combination of ' 111 ' are placed in queue 102 and frames with a p-bit combination of '010' are placed in queue 108 frames with either a 'Oil ' or '100' p-bit combination are placed in queue 106 and frames with either a ' 101' or ' 110' p-bit combination are placed in queue 106.
- the network is congested (e.g., the queue is full)
- frames in queue 104 or 106 are dropped according to their drop precedence based on the p-bit combination.
- a high drop precedence (e.g., AF22) frame is discarded before a low drop precedence frame (e.g., AF21) under congestion
- hi queue 106 frames with the E-AF12 designation are discarded before frames with the E-AFl 1 designation.
- dropping frames having an E-AF 12 designation before dropping frames having an E-AFl 1 designation corresponds to frames with a p-bit combination of '100' being dropped before frames with a p-bit combination of 'Oi l '.
- the assignment of p-bits shown in FIG. 7 is only one possible assignment. Other service configurations and p-bit assignments are possible.
- the assignment can include three levels of assured services (E-AF), each having two different assignments to define the drop precedence of the frames and two remaining combinations of p-bits for congestion indication. Alternately, four assured services
- the edge node (at either customer or provider side) may perform IP differentiated services to Ethernet differentiated services mapping if the application traffic uses IP differentiated services.
- mapping could be straightforward (e.g., IP-EF to E-EF, IP-AF to E-AF) if the number of IP PHBs used is limited to 8. Otherwise, some form of compression may be required to combine multiple LP PHBs into one E-PHB.
- multiple Ethernet connections e.g., VLANs
- VLAN-A supports E- EF/E-AF4/E-AF3
- VLAN-B supports E-AF2/E-AF1/DF
- a class-based queuing (CBQ) or a weighted fair queuing (WFQ) scheduler is used for forwarding frames on the egress link, at both edge and core nodes.
- the scheduling can be based on the PHB (subject to the constraints that some related PHBs such as an AFx group follow the same queue).
- the use of p-bits to indicate per-hop behaviors allows for up to eight queues, or eight queue/drop precedence combinations. Additional information may be available/acquired through configuration, signaling, or examining frame headers, and used for performing more advanced scheduling/resource management. Additional information can include, for example, service type, interface, or VLD.
- a 2-level hierarchical scheduler where the first level allocates the link bandwidth among the VLANs, and the second level allocates the BW among the VLAN Differentiated services classes according to their PHB.
- Another example includes a 3- level hierarchical scheduler, where the first level allocates the link bandwidth among the service classes (e.g., business vs. residential), the second level allocates BW among the service VLANs, and the third level allocates the BW among the VLAN differentiated services classes according to their PHB.
- Non-differentiated services capable nodes may forward all traffic as one class, which is equivalent to the E-DF class.
- Other 801. IQ nodes that use the p-bits simply to designate priority can interwork with Ethernet differentiated services nodes supporting the E-CS PHB.
- Some CoS degradation may occur under congestion in a network that uses a combination of E-differentiated services and legacy nodes.
- an Ethernet differentiated services network 150 having multiple domains 160 and 162 is shown.
- An Ethernet differentiated services domain has a set of common QoS Policies, and may be part of an enterprise or provider network.
- the set of QoS policies can include Ethernet PHBs support, p-bits interpretation, etc.
- Edge nodes interconnect sources external to a defined network (e.g., customer equipment).
- the Ethernet edge node 152 typically performs extensive conditioning functions.
- Interior Nodes 154 connect trusted sources in the same differentiated services domain. Interior nodes 154 perform simple class-based forwarding.
- Boundary nodes 156 interconnect differentiated services domains and may perform E-Differentiated services conditioning functions similar to edge nodes. This may include performing p-bit mapping, due to of different domain capabilities or policies. Traffic streams may be classified, marked, and otherwise conditioned on either end of a boundary node. The service level agreement between the domains specifies which domain has responsibility for mapping traffic streams to behavior aggregates and conditioning those aggregates in conformance with the appropriate behavior.
- the downstream E-DS domain may re-mark or police the incoming behavior aggregates to enforce the service level agreements.
- more sophisticated services that are path-dependent or source-dependent may require MF classification in the downstream domain's ingress nodes. If an ingress node is connected to an upstream non-Ethernet differentiated services capable domain, the ingress node performs, all necessary traffic conditioning functions on the incoming traffic. Referring to FIG. 9, an example 170 for end-to-end service across multiple
- provider networks is shown.
- the example architecture shows the connection of two enterprise campuses, campus 172 and campus 194 through provider networks 178, 184, and 190.
- a user network interface (UNI) is used between the enterprise and provider edges and a network-network interface (NNI) is used between two providers.
- the end-to- end service level agreements are offered through bilateral agreements between the enterprise 172 and provider 178 and enterprise 194 and provider 190.
- Provider 178 has a separate SLA agreement with provider 184 and provider 190 has a separate SLA agreement with provider 184 to ensure that it can meet the enterprise end-to-end QoS.
- Three Ethernet differentiated services domains are shown: Enterprise A, Access Provider 1, and Backbone Provider 2. Each domain has its own set of Ethernet PHBs and service policies.
Abstract
Description
Claims
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US10/868,568 US8804728B2 (en) | 2004-01-20 | 2004-06-15 | Ethernet differentiated services conditioning |
US10/868,607 US7843925B2 (en) | 2004-01-20 | 2004-06-15 | Ethernet differentiated services architecture |
PCT/CA2005/000057 WO2005069540A1 (en) | 2004-01-20 | 2005-01-20 | Ethernet differentiated services |
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US11223437B1 (en) | 2020-08-24 | 2022-01-11 | Ciena Corporation | Differential clock recovery using a global reference time |
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US11539452B2 (en) | 2021-06-01 | 2022-12-27 | Ciena Corporation | Signaling the distributed 1588v2 clock accuracy relative to UTC |
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EP1294134B1 (en) * | 2001-09-12 | 2005-01-12 | Alcatel | Method and apparatus for differentiating service in a data network |
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US20030126286A1 (en) * | 2001-12-28 | 2003-07-03 | Lg Electronics Inc. | Method for interfacing between different QoS offering methods |
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ALJ T ET AL: "Admission control and bandwidth management for VLANs" HIGH PERFORMANCE SWITCHING AND ROUTING, 2001 IEEE WORKSHOP ON 29-31 MAY 2001, PISCATAWAY, NJ, USA,IEEE, 29 May 2001 (2001-05-29), pages 130-134, XP010542785 ISBN: 978-0-7803-6711-1 * |
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Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
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US11212068B1 (en) | 2020-08-24 | 2021-12-28 | Ciena Corporation | Carrying a timestamp in radio over ethernet |
US11223437B1 (en) | 2020-08-24 | 2022-01-11 | Ciena Corporation | Differential clock recovery using a global reference time |
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