Arista ACE Specialist - Data Center flashcards
Arista ACE Specialist - Data Center · Build recall with a focused review session.
31 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Leaf-spine topology
- A two-tier Clos fabric where every leaf connects to every spine. Servers attach only to leaves; spines provide pure transit, and equal-cost paths between leaves are load-balanced with ECMP.
- Oversubscription ratio
- The ratio of total host-facing downlink bandwidth to total uplink bandwidth at a leaf. A 1:1 ratio is non-blocking; 3:1 is typical for general-purpose compute workloads.
- East-west traffic
- Server-to-server traffic within the data center, as opposed to north-south client-to-server flows. It dominates modern fabrics and drives capacity and ECMP design decisions.
- VXLAN encapsulation
- A tunneling method that wraps Layer 2 frames in UDP (destination port 4789) with a 24-bit VNI, extending segments across a routed underlay and supporting about 16 million segments.
- VTEP
- VXLAN Tunnel Endpoint. A device that encapsulates and decapsulates VXLAN frames, identified by a loopback IP in the underlay that provides reachability between endpoints.
- MLAG
- Multi-Chassis Link Aggregation. Two switches share a peer link and present one logical LACP port-channel to servers, providing active-active attachment without relying on spanning tree.
- Spine layer role
- The transit tier of a leaf-spine fabric. Spines carry no server ports and enforce no policy; they provide equal-cost paths so leaf-to-leaf traffic can be load-balanced.
- EOS config session
- A staged configuration mode entered with 'configure session NAME'. Changes are reviewed with 'show session-config diff' and applied atomically with 'commit', or discarded with 'abort'.
- EOS multi-agent architecture
- EOS runs routing protocols and services as separate processes (agents) on a Linux-based foundation, so a single protocol failure does not stop packet forwarding.
- eAPI
- Arista's JSON-RPC interface over HTTP or HTTPS, enabled with 'management api http-commands'. Clients send a 'runCmds' request and receive structured results for automation.
- MLAG config sanity
- The 'show mlag config-sanity' command validates that peer settings match, including domain-id, peer link, and member port configurations, before and after bringing up MLAG.
- Zero Touch Provisioning
- A bootstrap mechanism where a switch obtains an IP via DHCP, then fetches a startup script or configuration file over HTTP or TFTP to provision itself without manual setup.
- Event handler
- An EOS feature that triggers a script or CLI action when a defined trigger occurs, such as a log pattern match or interface state change.
- Saving EOS configuration
- 'write memory' or 'copy running-config startup-config' persists the active configuration so it survives a reload. 'show running-config' displays the active state.
- CloudVision Change Control
- A workflow that stages configuration changes, runs pre-checks, requires approval before deployment, and supports rollback to a prior snapshot if problems arise.
- CloudVision Studios
- Intent-based configuration templates in CloudVision, such as base config, VLAN, and MLAG studios, that generate device configs based on applied device tags.
- Streaming telemetry
- A push model where EOS devices send state data to CloudVision or collectors via gNMI/gRPC, providing near-real-time visibility compared with periodic SNMP polling.
- CloudVision device tags
- Hierarchical labels applied to devices in CloudVision that determine which studios and configlets apply, and drive topology and compliance views.
- pyeapi
- An Arista Python library that wraps eAPI, letting scripts send CLI commands and receive structured JSON output for network automation tasks.
- CloudVision compliance view
- A dashboard that compares each device's running configuration against its tagged studios and configlets, flagging devices whose configuration has drifted.
- CloudVision deployment models
- CloudVision is available as an on-premises appliance or VM (CVP) and as a cloud-hosted service (CVaaS); both provide change control, telemetry, and compliance.
- eAPI runCmds request
- A JSON-RPC call to the /command-api endpoint containing a 'runCmds' array of CLI commands and a format field; the response returns a results array in order.
- eBGP underlay
- A common leaf-spine underlay where each leaf and spine peers via eBGP, often with unique ASNs, providing loop-free multipath routing and clear failure domains.
- ECMP
- Equal-Cost Multi-Path routing. EOS installs multiple equal-cost next hops (bounded by 'maximum-paths') and hashes flows across them using L3/L4 fields.
- Anycast gateway
- A design where every leaf uses the same virtual IP and MAC for a subnet gateway (VARP), so hosts keep the same gateway after migration and traffic routes optimally.
- VARP
- Virtual ARP. An Arista feature configured with 'ip virtual-router mac-address' and 'ip address virtual' on SVIs, giving all leaves a shared gateway MAC for anycast routing.
- EVPN route type 2
- The MAC/IP advertisement route in EVPN, carried in MP-BGP, which distributes host MAC and IP reachability between VTEPs for the Layer 2 overlay.
- EVPN multihoming
- An active-active host attachment method using Ethernet Segment Identifiers (ESI) and EVPN type-1/type-4 routes with designated-forwarder election, an alternative to MLAG.
- CRC error counters
- Counters shown by 'show interfaces counters errors'. Rising CRC or alignment errors usually indicate faulty cabling or optics rather than software or configuration problems.
- Layered troubleshooting order
- A sequence for isolating faults: physical link status, then Layer 2 (MAC/VLAN), then Layer 3 (routes, ping), then overlay (VTEP and EVPN state).
- EOS default spanning tree
- EOS defaults to MSTP (multiple spanning tree). Rapid-PVST is also available; in MLAG or EVPN leaf pairs, STP scope is largely limited to the pair.