Dual 元 uplinks should connect to separate switches for resiliency.
The challenge of this design is that user VLAN segments can’t span to different closets, as an L2 network segment (a VLAN) will not extend beyond the 元 uplinks. With this approach, two 元 links don’t create a loop, because each link belongs to its own network segment isolated from the other. While the wiring looks the same, the end result offers better isolation from the rest of the network. One strategy for uplinking closet switches is to connect them to the rest of the network via routed (Layer 3) links as opposed to a switched (Layer 2) link. For diversity, link aggregation bundles can be split across two physical switches that act as one virtual switch, such as the stackable versions of Cisco’s Catalyst switches or Cisco chassis switches running the Virtual Switching System. Four- and eight-way link aggregation bundles are common. Link aggregation can scale parallel links beyond two. The link aggregation protocol makes the two links appear as a single link as far as spanning tree is concerned, while still maintaining a loop-free topology. This scheme allows for both links to be active and carry traffic. A parallel Layer 2 link between switches can be achieved with link aggregation protocols such as Cisco’s Port Aggregation Protocol (PAgP), or industry-standard Link Aggregation Control Protocol (LACP). Spanning tree will behave the same in either case-a loop will be detected and one link blocked until the primary path fails. A better alternative is to connect to multiple switches, rather than having both links running to the same switch. If the primary link fails, the backup link becomes active. Spanning tree will detect the loop and block the backup link. Topologically, this makes a loop between the closet switch and the uplink switch. A backup link is created when a second line is connected in parallel to the primary. There are several ways to safely achieve a dual uplink: While the simplest thing to do is to connect a closet switch via a single cable back to the rest of the network, a dual uplink is preferable for redundancy and possibly capacity.
Consider the uplink design between the closet switch and the rest of the network carefully Switches in dirty places should be cleaned periodically to reduce this risk, even in industrial models that are built for difficult environments. Switches get clogged with crud when they’re installed in filthy locations, and this can shorten their lifespan due to overheating. There’s still heat the chassis needs to radiate, which is part of the reason most switches come with rubber feet that can be applied to the bottom.ĭust and dirt are also a problem. Even for fanless switch designs with external power supplies, it’s usually a bad idea to put a switch right up against a wall. Study the switch you’re installing, figure out where the air intake and exhaust locations are, and keep them clear. That said, try your best to get the switch into a place with, at the least, airflow. I recognize that retrofitting aging buildings with wiring infrastructure is a challenge, and sometimes the solutions we’re stuck with aren’t ideal. I’ve seen switches in bathrooms, stuffed inside drop ceilings, hanging by a single screw on the wall, underneath cubicles, and on filthy shelves in a tiny closet with no airflow or climate control. Physical location considerations and connectivity options 1. No more! We’re here to talk about something every admin should have in their back pocket: the basics and best practices to setting up and configuring a reliable switch that will serve users well. Sadly, in business networks, the on-site switch is often neglected. If enough users have a bad experience, the entire business is going to be affected. If the service is poor, that user can’t do their job effectively. Even voice communications are likely provided through that jack.
When a user plugs their workstation into the network, it’s their single connection to email, messaging, financial systems, sales engines, and many, many other company resources. As part of effective switch management, you need to think of it as the mission-critical gateway to IT services that it is. Don’t think of that jack in the wall, or under the cubicle, as a simple Ethernet port. No matter how you decided to build out your network (tip: check out our new Network Device Buyer’s Guide!), an on-site switch plays a critical role in a network, connecting your users to the rest of your IT infrastructure.
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