Description:TECHNICAL FIELD [0001] At least one embodiment pertains to Ethernet communications and particularly to global bandwidth-aware adaptive routing in Ethernet communications. BACKGROUND [0002] Communication protocols may be provided for certain network communications, such as Ethernet, to enable standards for communication. In an example, such network communications can support artificial intelligence (AI) training workloads that require large east-west network bandwidth. Adaptive routing may be provided in the network communications to maximize network utilization by load balancing traffic based on local switch states such as queue length and port utilization. Further, AI training may include performance that is highly sensitive to changes in network conditions (including, to congestion, latency, drops). A failed link in the network may cause a reduction in bandwidth and potentially congestion, especially as AI related aspects in the network communications may operates at high utilization. Adaptive routing allows rebalancing decisions that may be based on local states and that may not enable upstream switches or routers to shift traffic away from downstream devices that are subject to events causing reduced bandwidth capacity, such as in cases of failed or congested links. BRIEF DESCRIPTION OF DRAWINGS [0003] FIG. 1 illustrates a system that is subject to embodiments for global bandwidth-aware adaptive routing in Ethernet communications; [0004] FIG. 2 illustrates aspects of a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment; [0005] FIG. 3 illustrates a topology associated with a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment; [0006] FIG. 4 illustrates computer and processor aspects of a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment; [0007] FIG. 5 illustrates a process flow in a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment; [0008] FIG. 6 illustrates yet another process flow in a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment; and [0009] FIG. 7 illustrates a further process flow in a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment. DETAILED DESCRIPTION [0010] FIG. 1 illustrates a system 100 that is subject to embodiments for global bandwidth-aware adaptive routing in Ethernet communications, as detailed herein. The system 100 and a method for such a system 100 enables adaptive routing to rebalance transmission load distribution based on relative downstream capacity across multiple paths, indicated by events as they occur. This can result in optimal adjustments and reduced reliance on fabric-based flow control or endpoint-based congestion control. This ultimately minimizes performance impact with link failures in the fabric. For example, in a lossless fabric, congestion can trigger coarse grain flow control mechanisms such as, Per Priority Flow Control (PFC) which may cause head-of-line blocking or may cause a network spread across multiple hops. This can penalize unrelated traffic flows and can lead to significant performance degradation. [0011] Further, endpoint-based congestion control provides mitigation by reducing the transmission rate to avoid congestion all together. The system 100 includes at least one circuit that may be an execution unit of a processor within a leaf switch 106; 114. The leaf switch 106; 114 may be associated with a respective one rack or other Ethernet grouping 2 102; 1 110 of hosts or other endpoints 1-N 104; 1-N 112, as illustrated. Further, the system 100 includes at least a spine switch or gateway 108, as part of one or more interconnect devices 120, to provide Ethernet communications 116 between multiple leaf switches 106, 114. As such, each Ethernet grouping 2 102; 1 110 of hosts or other endpoints 1-N 104; 1-N 112 may communicate within the grouping using the leaf switches and may communicate across groupings using spine switches or gateways 108. However, as endpoints may not have full knowledge of its associated network, such endpoint-based congestion control may over-correct to a lowest denominator among multiple routes or paths, in terms of available downstream capacity, and may cause over-reduction of overall performance. [0012] In at least one embodiment, a system 100 for global bandwidth-aware adaptive routing in a network communication includes at least one switch, such as a leaf switch that is closest to a local host to determine an event associated with a change in network bandwidth between a local host and a remote host, representing separate endpoints in the network communication. For example, a remote leaf switch 106 that is closest to a failure or congestion link of a remote host 1-N 104 may have information associated with the failure or congestion link. The remote leaf switch 106 is downstream from a local host 112 and a local leaf switch LS1 114, and is able to communicate such information to a local leaf switch 114. The local leaf switch LS1 114 is able to provide routing protocols for the network communication, where the routing protocols can be used to modify an adaptive routing in the leaf switch for selection from different routes for the network communication between the local host and the remote host. In this manner, it is possible to account for changes in network bandwidth in a remote host that is downstream relative to the at least one switch and relative to the local host. [0013] In at least one embodiment, a system includes one or more circuits to be associated with at least one switch. The one or more circuits are to determine an event associated with a change in network bandwidth between a local host and a remote host. The one or more circuits are further to provide routing protocols for the network communication. The routing protocols is to be used to modify an adaptive routing in the at least one switch for selection from different routes for the network communication between the local host and the remote host. [0014] In at least one embodiment, a method for global bandwidth-aware adaptive routing in a network communication includes determining, using at least one switch, an event associated with a change in network bandwidth between a local host and a remote host. The method further includes modifying an adaptive routing in the at least one switch for selection from different routes for the network communication between the local host and the remote host. The method also includes providing routing protocols for the network communication to enable routing of communication between the local host and the remote host using one of the different routes that is based in part on the modification to the adaptive routing. [0015] In at least one embodiment, such systems and method provide changes to adaptive routing as an algorithm that is otherwise unaware of downstream capacity by using downstream capacity information to augment adaptive routing decisions and to rebalance traffic based on the weights determined from the downstream capacity information. For example, in Border Gateway Protocol (BGP) for Ethernet communications, Weighted - Equal Cost Multipath (W- ECMP) link bandwidth extended community attribute may be used with a transitive propagation option, also referenced herein as routing protocol to modify aspects of an adaptive routing algorithm. This is such that when a link fails or a congestion event occurs within a fabric, a nearest router or switch (for example, within a predetermined hop distance from a local host associated with the event) sends advertisement or communication updates for affected routes and for next-hops with reduced bandwidth. In at least one embodiment, instead of BGP, any other protocol that has the capability of signaling relevant metadata, such as routing information, may embody the approaches herein for global bandwidth-aware adaptive routing in Ethernet communications. [0016] In at least one embodiment, as a result, upstream routers or switches receiving the advertisements can determine different routes using updated relative weights in their respective adaptive routing algorithm. For example, an event may be converted to a weight, such as one of a lower, a neutral, or a higher weight, which may be used by a modification feature of the routing protocol to perform modification of the adaptive routing associated with the downstream traffic. This approach addresses failure or congestion events as they occur. An upstream router or switch’s adaptive routing algorithm can cause distribution of traffic load according to the changed weights therein, which may be changed from the local states, such as queue length and port utilization. This enables avoidance of congestion and failure events by routing around such points in a network communication. [0017] In at least one embodiment, a router or switch includes datapaths of different routes subject to selection as part of the adaptive routing algorithm therein, which can be modified using weights from the routing protocol so that the adaptive routing algorithm is both weight-aware and weight-unaware of any adaptive routing hardware. With weight-aware hardware, adaptive routing simply makes rebalancing decision based on the path weights. With weight-unaware hardware, calculations may be enabled by the routing protocols herein so that an amount of transmission capacity is reduced from lower weight paths. This can be achieved by removing next-hop interfaces (such as, for transmission purpose) towards lower weight neighbors from a next-hop group. Both such approaches reflect routing protocols to be used to modify an adaptive routing in the at least one switch for selection from different routes for the network communication between the local host and the remote host. Adaptive routing makes aware of global bandwidth to a remote or destination host and can derive an amount of traffic sent across members of an ECMP arrangement. The system herein uses an interface that is associated with at least one switch to receive instructions to enable the determination of the event associated with the change in network bandwidth and to enable a determination of the routing protocols for the network communication. Once an event is received in a communication associated with the remote host, at least one hop in a series of next-hops to the remote host may be removed, as part of the routing protocols, based in part on the communication to provide the modification of the adaptive routing in the at least one switch. [0018] FIG. 2 illustrates aspects of a system 200 for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment. The system 200 is subject, at least in part, to Border Gateway Protocol (BGP) that is used to determine best network routes for data communication links 206 using Ethernet. For example, switch or routers, including leaf switches and spine switches LSN 106, LS1 114, LSN2 114, SS1 202A, SSN 202B, can exchange routing information using advertisements 204 that are a specific type of configuration-based communication or messages about associated networks. This communication can include information about bandwidth associated with the networks. The leaf switches and spine switches LSN 106, LS1 114, LSN2 114, SS1 202A, SSN 202B capable of exchanging BGP or any other supported protocol’s routing information may be referred to herein as peers or BGP peers. Therefore, these peers are not limited to BGP but may be in reference BGP or any other protocols having capability of signaling relevant meta-data for global bandwidth-aware adaptive routing in Ethernet communications. [0019] Further, BGP may be considered as an exterior gateway protocol (EGP) that is used to exchange routing information among routers or switches that may be in different Ethernet groupings 1 110; 2 102. The routing information may include a complete route to each destination, such as, from a local host to a remote host. While BGP uses the routing information to prepare a routing table 220 and other tables associated with network reachability, it also enables switches or routers to exchange such information across the Ethernet groupings 1 110; 2 102. The BGP peers can, therefore, inform about routes between each other using the advertisements 204. For example, BGP peers can store routing tables 220 that may include routing information received from the advertisements 204, local routing information for local routes (such as not including a spine switch or gateway), and information that a BGP peer can advertise to other BGP peers in a separate advertisement. Further, the routing table 220 may be generated, in part, by an adaptive routing algorithm 208. The routing table 220 may be used by a routing process of the BGP peer to select a best or active route and may advertise this best or active route to other BGP peers. However, a BGP peer may be configured to advertise different routes to a same destination BGP peer or host. [0020] A BGP peer that sends out a first advertisement for a route may assign the route one of different values to at least identify its origin and so that, during selection from one of different routes a lowest origin value may be selected. BGP also provides Equal Cost Multi-Path routing (ECMP) that uses multiple routes that may have similar or identical characteristics, such as, with reference to latency in the routes or with reference to link capacity. ECMP-based load-balancing for data communication links 206 may be enabled over different routes. Further, ECMP may be configured using an interface of a switch or router to allow up to 512 different routes for external BGP (EBGP) peers. As a result, a network may be scaled to increase a number of BGP peer connections a specified router or switch to improv latency and data flow. [0021] In at least one embodiment, the advertisements 204 may include a BGP update. The BGP update may include a header; a listing of withdrawn routes, such as using internet protocol (IP) address prefixes associated with routes subject to being withdrawn from service or not reachable; infeasible route length of such withdrawn routes; route attributes, including a route origin, a multiple exit discriminator (MED), the origin’s route preference, aggregation information, communities information, confederations information, and route reflection; network layer reachability information (NLRI), including those IP address prefixes of reachable routes being advertised; and a total route attribute length directed to route attributes for a reachable route to a destination BGP peer or host. [0022] In at least one embodiment, weighted ECMP (or W-ECMP) herein can address a use of a bandwidth community attribute that is advertised as a reflection of the available capacity. For example, when one data communication link 206C between one spine switch SSN 202B and a leaf switch LSN 106 fails, representing a failure that is downstream from other leaf switches LS1-LSN2 114, LS2-LSN3 222 and a local host 1-N 112, these other leaf switches may receive a BGP update in an advertisement 204 with reduced weights for prefixes destined behind the leaf switch LSN 106 and for the next-hops till the spine switch SSN 202B at issue. Although illustrated as a direct coupling between each one spine switch SS1 202A, SSN 202B and a leaf switch LSN 106, there may be BGP peers, such as other routers or switches LS1-LSN2 114, LS2-LSN3 222 requiring the further hops between a local host and a remote host. The reduced weights for the prefixes destined behind leaf switch LSN 106 and for the next-hops till the spine switch SSN 202B (such as using another data communication link 206B) enable only the affected prefixes to experience a change in load distribution and can converge at predetermined capacity (such as, a ratio, 5/6th of a total theoretical bandwidth). [0023] Therefore, in at least embodiment, FIG. 2 illustrates a system 200 for global bandwidth-aware adaptive routing in a network communication using at least leaf switch LSN 106 to determine an event associated with a change in network bandwidth between a local host 1-N 112 and a remote host 1-N 104. The change may be a failure or a congestion event to one data communication link 206C. The at least leaf switch LSN 106 can provide routing protocols 214 for the network communication. The network communication can include the advertisements 204 sent from the at least one leaf switch LSN 106 to spine switches SS1 202A, LS1 114, LSN2 114, SSN 202B, LS2-N3 222 in the network. The routing protocols 214 can be used to modify 218 an adaptive routing, such as the adaptive routing algorithm 208, in the at least one switch LSN 106. The modification 218 is for selection from different routes, represented by different hops 212, for the network communication between the local host and the remote host. The different hops 212 enable the use of a different route, such as using a data communication link 206B from another leaf switch N2 114 to the spine switch SSN 202B. [0024] In at least one embodiment, FIG. 2 also illustrates that the system 200 includes multiple links between each leaf switch LSN 106 to each spine switch SSN 202B, even though this is not illustrated for all leaf switches and for all spine switches. The system 200 is able to recognize an event as being a failed or congested data communication link 206C in at least one of different routes between the local host 1-N 112 and the remote host 1-N 104. Such a failed or congested data communication link 206C may be one of the links (the other being data communication link 206B) between a leaf switch LSN 106 and a spine switch SSN 202B. Further, the failed or congested link may cause the change in the network bandwidth between the local host and the remote host. For example, the network bandwidth may be monitored based at least in part on a comparison to pre-determined hop times used for monitoring data packets transmitted through the different routes. When a hop time for at least one link exceeds a pre-determined hop time, the link may be considered in an event of failure or congestion. [0025] In at least one embodiment, the system 200 uses the routing protocols 214 with a BGP-enabled network that is enabled for communication of events, such as, routing information associated with the failed or congested data communication link 206C, between the at least one switch and other switches in the network communication. Further, the routing protocols 214 includes a conversion feature to convert the event from an advertisement 204 or from a monitored event to weighting values, such as the additional weights 216. The routing protocols 214 include a modification feature to be used to perform the modification 218 of the adaptive routing algorithm 208 using the weighting values. [0026] In at least one embodiment, the modification 218 to the adaptive routing algorithm 208 includes additional weights 216 to a number of different hops 212 that provides different data communication links 206A-C for the network communication between the local host and the remote host. The additional weights may be incorporated in any manner suitable to the disclosure herein, including to normalize or ration part of the weights 210 of the adaptive routing algorithm 208. The weight change removes at least one of the next-hops so that at least the failure or congestion data communication link 206C may be bypassed. Instead, another data communication link 206B may be used. In at least one embodiment, at least one leaf switch LSN 106 includes an interface, such as command line interface (CLI), to receive instructions to enable the determination of the event associated with the change in network bandwidth and to enable a determination of the routing protocols 214 for the network communication. For example, an administrator of one part or an entire network can enable at least software and firmware changes to provide the W-ECMP approaches herein. [0027] In at least one embodiment, the at least one leaf switch LSN 106 is within a predetermined hop distance from the remote host 1 104. For example, the leaf switch LSN 106 is the closest switch that is one hop from the remote host 1 104. The leaf switch LSN 106 includes an adaptive routing algorithm 208 to perform aspects described herein for the global bandwidth-aware adaptive routing in the network communication. Further, the at least one leaf switch LSN 106 is further able to receive the event in an advertisement 204 communication associated with the remote host, such as from the spine switch SSN 202B that is the highest grouping-related switch associated with multiple remote hosts 1-N 104. The at least one leaf switch LSN 106 is further able to remove at least one of the hops of a number of next-hops to the remote host. For example, the hops associated with the one leaf switch LSN 106 is enabled to be bypassed and, instead, a routing table 220 is updated by the adaptive routing algorithm 208 to include hops using a further leaf switch N2 114 to provide a different data communication link 206B, as part of the routing protocols. The further leaf switch N2 114 is also able to provide the different data communication link 206B based in part on the advertisements 204 communicated to the further leaf switch N2 114 to provide modification of its adaptive routing. [0028] In at least one embodiment, therefore the system 200 includes one or more circuits to be associated with at least one leaf switch N 114. However, the one or more circuits may be across multiple switches enabled to perform the W-ECMP approaches herein. The one or more circuits may include at least an execution unit of a processor to determine an event associated with a change in network bandwidth between a local host and a remote host. The one or more circuits can provide routing protocols for the network communication so that the routing protocols can be used to modify an adaptive routing in the at least one switch for selection from different routes for the network communication between the local host and the remote host. [0029] In at least one embodiment, Free Range Routing (FRR) may be used with W-ECMP approaches herein. FRR includes network routing software features to provide protocol daemons for BGP and can perform operations on Unix®-like platforms, including Linux®, Solaris®, OpenBSD®, FreeBSD®, and NetBSD®. Further, FRR in BGP can operate in multiple autonomous systems simultaneously with virtual routing and forwarding. In at least one embodiment, adaptive routing occurs in a transparent manner to the kernel of the operating system and to the FRR requirements. [0030] In at least one embodiment, FRR provides a next hop group (NHG) to reach a determined prefix. The NHG is provided whenever there is a change in next-hop weights, such as a reduction and/or increase in weight for some of the next-hops. The FRR may be enabled as part of the routing protocols 214 to include a conversion feature to convert a community value of an advertisement 204, such as an incoming community value reflecting a downstream bandwidth event, into proportionated weight to provide the additional weight 216, among the W-ECMP members in such a way that a cumulative value of individual weights 210 is normalized to 100. The adaptive routing algorithm 208 can rely on the weight associated with individual neighbor or next hop groups and the available active next-hop links to derive the actual number of links to be changed, which reflects the modification 218 of an adaptive routing in the at least one switch for selection from different routes for the network communication between the local host and the remote host. [0031] In at least one embodiment, a neighbor group is a grouping of different links between two or more switches. The neighbor group may be provided as a forwarding entity, such as a group of switches and routers, to enable rebalance of data communication towards a specific remote host that uses the grouping of different links and that uses a global identifier per switch in the different links. For example, to calculate an additional weights towards different peers, approaches herein account for all the next-hops, which may be more than one and which connect to the same peer. A determination of all the next-hops may be provided by a controller, which operates as a control plane of the network, such as a gateway or spine switch 108, in FIG. 1, herein. The controller provides all the next-hops to a forwarding entity, such as a switch or a router. Alternatively, the identification can be inferred by the forwarding entity from a next-hop attribute that is encoded with the global identifier, such as a next MAC address. [0032] In at least one embodiment, grouping of next-hops into unique neighbor groups may be performed as part of the routing protocols 214. There may be multiple links connecting a particular leaf switch and one or more spine switches. The routing protocols 214 ensures that the neighborship (or grouping) information to decide which link(s) to remove is in an order to reduce a bandwidth capacity to a specific spine switch. For example, to identify all the next-hops connected to a specific BGP peer, an assignment of a same base-MAC (media access control) address to all of the adaptive routing (AR)-enabled ports in a BGP peer may be performed. There may be no change in behavior for the non-AR enabled ports which may include unique MAC addresses assigned for each of the non-AR enabled physical ports. Application programming interfaces (APIs) may be provided for setting the base-MAC. This approach ensures that all the next-hops having the same neighbor MAC would be termed as “neighbor-group” and implies that the next-hops belonging to the same neighbor-group are hosted from the same BGP peer. [0033] FIG. 3 illustrates a topology 300 associated with a system for global bandwidth-aware adaptive routing in Ethernet communications, according to at least one embodiment. In at least one embodiment, global bandwidth-aware adaptive routing may be provided an algorithm represented by the routing protocols 214. The routing protocols 214 may be applied under certain conditions and following procedures described with respect to FIG. 3. For example, the routing protocols 214 may be applied only if all the next-hops are to be provided over ports of switches capable of adaptive routing 208. In addition, the routing protocols 214 may be applied only if there are more than one next-hop in the NHG, only if there are more than one neighbor group in the NHG (where the neighbor group can be identified with a unique next-hop MAC), or only if there are next-hops with varying weights (such as, if all the next-hops have a same weight, then there may be no exclusions or modifications associated with the next-hops). [0034] In at least one embodiment, when next-hops belong to a same neighbor group and include different weights, then routing protocols 214 need not perform exclusions to these next-hops as they represent an asymmetric topology. In at least one embodiment, the routing protocols 214 may be performed by a loop-through of all the next-hops to identify a next-hop and its associated neighbor group which has the highest weight (also referred to as a maximum weight, herein) among the other neighbor-group. Then, the routing protocols 214 can include an iteration process to iterate over each of the next-hops present in the NHG. In the iteration, if a particular neighbor group has only a single next-hop, then there may be no need to apply exclusions or modifications as described herein. Then, a next-hop may be added to the active next-hop list for an ECMP group. [0035] In at least one embodiment, the routing protocols 214 includes that if a weight of a next-hop matches with the maximum weight then also there may be no need to apply the exclusions or modifications as described herein. Instead, all such next-hops may be added to the active next-hop list for the ECMP group. Further, the routing protocols 214 includes determining a weight reduction ratio. The weight reduction ratio may be determined for each neighbor group other than the one having the maximum weight. Derivation of the weight reduction ratio may be performed between the weight of a current neighbor group and that of a neighbor group that has maximum weight. For example, when one of a neighbor group’s weight is 33 and a maximum weight is 66, then the ratio may be determined as 50%, 0.50, or ½). To derive the weight reduction ratio, a division of the neighbor group's weight by maximum weight may be performed. [0036] In at least one embodiment, the routing protocols 214 includes determination of an actual number of next-hops to be excluded or modified based on the weight reduction ratio. This may be performed for each such neighbor group which has a different weight than the maximum weight. Further, the exclusion or modification of the number of next-hops may be based on the weight reduction ratio (as determined above) and may be based on a total number of next-hops available in the neighbor group. For example, for a weight reduction ratio of current neighbor group that is 25%, a reduction of the next-hop capacity of the neighbor group to one-fourth of total next-hop count may be needed. Further, if there are four next-hops available in a neighbor group, then exclusions or modifications may be performed to three of the next-hop so as to achieve the 75% capacity reduction. However, if there are only two next-hops available in the neighbor-group, then the exclusions or modifications would be only to a single link since the value of 75% of two available links is one. In addition, if the weight reduction ratio of a current neighbor group is 50%, then a reduction of the next-hop capacity to half may be required; and if there are two next-hops available in the neighbor group, then exclusions or modifications may be performed to one of the next-hop. Similarly, if there are four next-hops available, then exclusions or modifications may be performed to two out of the four next-hops so as to achieve a 50% capacity reduction; and if there are three next-hops available, then exclusions or modifications may be performed to only a single link out of the three next-hops. [0037] In at least one embodiment, the routing protocols 214 includes if the ratio between the current neighbor group's weight and the weight of the neighbor group having a maximum weigh is 75%, then the next-hop capacity can be reduced to three-fourth of a total link capacity. When there are four next-hops available in the neighbor group, then exclusions or modifications may be performed to one of the next-hops so as to achieve the 25% capacity reduction. When a number of next-hops in the neighbor-group is two or three then then no need to perform exclusions or modifications to any links from the ECMP group as the resulting number of next-hops subject to such exclusions or modifications may not be present. [0038] In at least one embodiment, therefore, a derivation of a number of next-hops to be subject to exclusions or modifications for each neighbor group may be based on the weight reduction ratio and the total number of next-hops available in the neighbor-group, given by (1 - weight reduction ratio) x (no. of next-hops present in a neighbor group). In at least one embodiment, irrespective of the weight reduction ratio, at least one next-hop may be retained per neighbor group. Further, for any local link failure/recovery events, the routing protocols 214 herein may be repeated so that a weight-based link capacity reduction can consider a latest set of available links. A remaining number of next-hops may be added to the active next-hop list for the ECMP group and the ECMP group update may be applied to a software development kit (SDK) that is associated with the adaptive routing algorithm 208. In at least one embodiment, the link to be excluded towards a given spine may be selected by the modification 218 in a manner that is consistent across different instances of capacity reduction. This enables predictability in a system for global bandwidth-aware adaptive routing in Ethernet communications. As the next-hops may be stored in the NHG after sorting the next-hop based on port information for a switch, the routing protocols 214 herein allow selection of the first N next-hops to program into SDK out of M available next-hops (where N