Figure 8 shows both triangle and square network topologies. In this topology, no VLANs span access layer switches and the distribution layer interconnection is an L3 point-to-point link. Otherwise, multiple convergence events can occur for a single failure and undesirable traffic paths are taken after the spanning tree converges. However, this is no longer a concern in campus topologies with current hardware. When properly configured and tuned, this design is the recommended best practice. In Figure 53, the addition of a single switch to a very basic topology adds several orders of magnitude in complexity. This allows the network to converge in 60-200 milliseconds for EIGRP and OSPF. If the L2/L3 boundary is in the access layer of the network, a design in which a routing protocol is running in the access layer, then NSF with SSO provides an increased level of availability. All rights reserved. Convergence around a link or node failure in the L2/L3 distribution boundary model depends on default gateway redundancy and failover. When connecting a Cisco IOS software device to a CatOS device, make sure that PAgP settings are the same on both sides. Also a good design is the key to the capability of a network to scale. At the time of this writing, test results show that EIGRP is better suited to a campus environment than OSPF. The Cisco Nexus® 7000 F2-Series 48-Port 1 and 10 Gigabit Ethernet Module enables the deployment of high-density, low-latency, scalable data center architectures: Support of smart data cneter interconnect DCI technologies such as OTV that provide the ability to expand layer 2 network over a layer link/cloud, Ability to provide end to end unified fabric of IP and fiber channel over Ethernet FCoE, Fabric Extender Technology, Cisco Fabric Extender Technology comprises of technologies that enable fabric extensibility with simplified management enabling the switching access layer to extend and expand all the way to the server hypervisor as the customer’s business grows, Size of the network e.g. As shown in Figure 44, Tx-Queue starvation occurs when incoming packets are serialized faster than outgoing packets. This provides traffic classification and queuing as close to the ingress of the network as possible. The access-distribution block consists of two of the three hierarchical tiers within the multi-layer campus architecture: the access and distribution layers. 3. Each level, or tier in the hierarchy is focused on specific set of roles. In fiber topologies where fiber optic interconnections are used, which is common in a campus environment, physical misconnections can occur that allow a link to appear to be up/up when there is a mismatched set of transmit/receive pairs. The basic principles of the Borderless switched network are the following: 1. hierarchical network Design 2. This document is the first in a series of two documents describing the best way to design campus networks using the hierarchical model. Adding an L3 link between the distribution switches allows the distribution node that loses connectivity to a given VLAN or subnet to reroute traffic across the distribution-to-distribution link. With topologies that rely on indirect notification and timer-based detection, convergence is non-deterministic and convergence is measured in seconds. Rapid PVST+ is far superior to 802.1d and even PVST+ (802.1d plus Cisco enhancements) from a convergence perspective. The hierarchies tied together at the campus backbone. Figure 41 illustrates the STP topology after changing STP port cost on the secondary root switches interface facing the primary root switch (the distribution to distribution link) allowing traffic to flow up both uplinks from the access layer switches to both GLBP Virtual MAC addresses. The highest availability does not require STP/RSTP convergence, the distribution nodes are restored totally... Allows both uplinks are available to actively forward cisco campus network design, PortFast, BPDU if... L2 perspective and VLAN assignment and Cisco IOS software device if EtherChannels are not often today... 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