• Author : Selmir


Enterprise Internet Routing

Overview The objective of this document is to cover the most common Enterprise Internet Routing use case. The information provided here is based on two Arista switches peering with two ISP’s (Internet Service Providers) for redundancy. There are many other valid deployment models that are not covered in this document. Terminology BGP – Border Gateway Protocol ISP – Internet Service Provider BGP Peering – a session between two BGP routers that allows exchange of routes Full Internet Routing Table – all public routes on the Internet AS – Autonomous System – defines domain boundaries IGP – Interior Gateway Protocol EGP...
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How to Minimize Impact when Port is Flapping

Intro A flapping port can cause network instability and disruption as L2/L3 protocols are constantly forced to re-converge and rebuild the topology with every port status change. If flapping happens at short intervals, it can cause a spike in the CPU utilization as well.  To minimize the impact in such scenarios, Arista introduced the ‘link-debounce’ feature. The idea is to wait until the port status is stable for a period of time before L2/L3 protocols are notified about the status change (up/down).  Feature Description The link-debounce command configures the link debounce under network interfaces. Link debounce time is the time...
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Interface Errors Explained

“show interface” is one of the more common commands that every network engineer uses. However, sometimes it’s not always clear what some of the displayed interface-level errors mean. This article explains some of the more common errors, their meaning, and possible causes. SymbolErrors * device receives invalid symbols in the frame * points to physical problems Alignment Errors – both conditions must be met: * The number of bits received is an odd byte count * The frame has a Frame Check Sequence (FCS) error * points to MAC layer or physical problems FCS Errors = frames failing FCS check...
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Arista 7150 Series Hardware Based NAT For Unicast Traffic

Arista 7150 series switches use Intel’s Fulcrum FM6000 (code named ‘Alta’) ASIC for packet processing. The ASIC includes several features for IP header translation including Network Address Translation (NAT). In doing so, packets to be NAT’d are processed by the ASIC which is known as Hardware NAT rather than by CPU known as Software NAT. Hardware NAT provides much better scale and performance compared to Software NAT.  The 7150 series switches can provide 10/40Gbps line rate hardware based NAT  across all Ethernet ports at the same time. The number of available ports varies depending on the particular model – it...
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