Place and route - Wikipedia
Therefore, these are the nets that face the problem of routing congestion most acutely. .. similar relationship can also be shown using more sophisticated delay models). in a functional failure (if the coupled noise causes the logic value stored in While computing net parasitics and net delays, several of today's place-. In the broadest sense, then, the relations that interest Serres are not just things That is, the channel should be understood in terms of its capacity to fail, in the of paths, or channels, as secondness (merely a connection between two places) or as As Serres puts it, “Every relation between two instances demands a route. You feel unhappy and worn out by your relationship; You feel happier away from a relationship to let it fail, so even when things don't seem to work any longer, we shift—for both planning and execution—to have alternative routes in place.
An update from a router R contains the cost to reach the destination network N from R. This cost is referred to as the reported distance RD. In other words, the RD for Ames to reach Just like Ames, Chicago will report its cost to reach Ames is a feasible successor for NewYork will then compare the metrics for the two paths. The lowest cost to reach a destination is referred to as the feasible distance FD for that destination.
The next-hop router in the lowest-cost path to the destination is referred to as the successor. Feasibility condition and feasible successor If a reported distance for a destination is less than the feasible distance for the same destination, the router that advertised the RD is said to satisfy the feasibility condition FC and is referred to as a feasible successor FS. Ames satisfies the FC.
Ames is an FS for NewYork to reach Loop freedom The feasibility condition is a test for loop freedom: Consider the network in Figure The metric values used in this example have been simplified to small numbers to make it easier to follow the concept.
Router X also knows how to get to network N; X advertises N to A in an update packet A copies this information into its topology table. Thus, the key question for A to answer is whether or not the path that X advertises is loop-free. Here is how A answers this question. A compares 90 RD with FD.
This comparison is the FC check. Topology table All destinations advertised by neighbors are copied into the topology table.
Each destination is listed along with the neighbors that advertised the destination, the RD, and the metric to reach the destination via that neighbor. There are two neighbors that sent updates with this destination: NewYork computes its own metric to NewYork uses the lower-cost path via Chicago. Next NewYork checks to see if Ames qualifies as a feasible successor.
This is checked against the FD. Note that not all loop-free paths satisfy the FC. The FC guarantees that the paths that satisfy the condition are loop-free; however, not all loop-free paths satisfy the FC. Ames sh ip route This will be the metric that Ames reports to NewYork. The RD is thus 2, The RD and the FD are equal, which is not surprising given the topology: Ames is not a feasible successor for The output of show ip eigrp topology all-links shows all neighbors, whether feasible successors or not.
Passive state indicates that the route is in quiescent mode, implying that the route is known to be good and that no activities are taking place with respect to the route.
Any of the following events can cause DUAL to reevaluate its feasible successors: The transition in the state of a directly connected link A change in the metric of a directly connected link An update from a neighbor If DUAL finds a feasible successor in its own topology table after one of these events, the route remains in passive state.
If DUAL cannot find a feasible successor in its topology table, it will send a query to all its neighbors and the route will transition to active state. The next section contains two examples of DUAL reevaluating its topology table.
AR# Route - Process "Place & Route" failed at Phase 6 of the router
In the first example, the route remains passive; in the second example, the route becomes active before returning to the passive state. NewYork sh ip route These routes become invalid. DUAL attempts to find new successors for both destinations -- DUAL checks the topology table for NewYork sh ip eigrp topology The FS check is: In plain words, this implies that the path available to NewYork via Ames the FS is independent of the primary path that just failed.
DUAL installs Ames as the new successor for In our case study, only one FS was available. Since DUAL is searching for the successor s for this destination, it will choose the minimum from this set of metrics via each FS.
Let the lowest metric be Dmin. If multiple FSs yield metrics equal to Dmin, they all become successors subject to the limitation in the maximum number of parallel paths allowed -- four or six, depending on the IOS version number.
Since the new successor s is found locally without querying any other routerthe route stays in passive state. After DUAL has installed the new successor, it sends an update to all its neighbors regarding this change.
Mapping design into LUTs Running delay-based LUT packing There is only a select set of IOBs that can use the fast path to the Clocker buffer, and they are not being used.
You may want to analyze why this problem exists and correct it. This constraint disables all clock placer rules related to the specified COMP. The use of this override is highly discouraged as it may lead to very poor timing results. It is recommended that this error condition be corrected in the design.
Routing with ExpressRoute for Office 365
Number of Slice Registers: Number of occupied Slices: A control set is a unique combination of clock, reset, set, and enable signals for a registered element. The Slice Logic Distribution report is not meaningful if the design is over-mapped for a non-slice resource or if Placement fails. Number of bonded IOBs: If you want all or a subset of your network locations to leverage ExpressRoute. What locations your chosen network provider offers ExpressRoute from. Once you determine the answers to these questions, you can provision an ExpressRoute circuit that meets the bandwidth and location needs.
For more network planning assistance, refer to the Office network tuning guide and the case study on how Microsoft handles network performance planning. Single geographic location This example is a scenario for a fictitious company called Trey Research who has a single geographic location. Employees at Trey Research are only allowed to connect to the services and websites on the internet that the security department explicitly allows on the pair of outbound proxies that sit between the corporate network and their ISP.
Trey Research plans to use Azure ExpressRoute for Office and recognizes that some traffic such as traffic destined for content delivery networks won't be able to route over the ExpressRoute for Office connection. Since all traffic already routes to the proxy devices by default, these requests will continue to work as before.
After Trey Research determines they can meet the Azure ExpressRoute routing requirements, they proceed to create a circuit, configure routing, and linking the new ExpressRoute circuit to a virtual network. Once the fundamental Azure ExpressRoute configuration is in place, Trey Research uses the 2 PAC file we publish to route traffic with customer specific data over the direct ExpressRoute for Office connections.
As shown in the following diagram, Trey Research is able to satisfy the requirement to route Office traffic over the internet and a subset of traffic over ExpressRoute using a combination of routing and outbound proxy configuration changes. Clients are configured with a default route towards Trey Research's proxies. In this example scenario, Trey Research is using an outbound proxy device. Similarly, customers who aren't using Azure ExpressRoute for Office may want to use this technique to route traffic based on the cost of inspecting traffic destined for well-known high volume endpoints.
With a single ExpressRoute circuit, there is no high availability for Trey Research. In the event Trey's redundant pair of edge devices that are servicing the ExpressRoute connectivity fail, there is not an additional ExpressRoute circuit to failover to. This leaves Trey Research in a predicament as failing over to the internet will require manual re-configuration and in some cases new IP addresses. Routing ExpressRoute for Office with multiple locations The last scenario, routing Office traffic over ExpressRoute is the foundation for even more complex routing architecture.
Regardless of the number of locations, number of continents where those locations exist, number of ExpressRoute circuits, and so on, being able to route some traffic to the Internet and some traffic over ExpressRoute will be required.
The additional questions that must be answered for customers with multiple locations in multiple geographies include: Do you require an ExpressRoute circuit in every location? See the Skype for Business media quality and network connectivity guide for more details.
If an ExpressRoute circuit isn't available in a particular region, how should Office destined traffic be routed?