Choosing between Arista Networks and Juniper Networks for an enterprise deployment is one of the most consequential — and most debated — vendor decisions in modern networking. Both platforms deliver carrier-grade routing, high-density switching, and deep automation support. Yet they diverge sharply in CLI philosophy, configuration model, hardware architecture, and ecosystem tooling. This article provides a thorough side-by-side technical comparison, complete with real configuration examples, to help network engineers and architects make an informed decision.
Configuration Philosophy: EOS Versus Junos
Arista EOS (Extensible Operating System) uses a Cisco IOS-style CLI that is immediately familiar to engineers with a Cisco background. Configuration lives in a running-config that is optionally persisted to startup-config. Juniper Junos uses a fundamentally different commit-based model: all changes are staged in a candidate configuration and only activated when the operator issues a commit command. This provides atomic transactions, diff previews, and built-in rollback.
Junos's commit confirmed is a standout operational safety net — changes are automatically rolled back after a configurable timer unless the operator issues a second commit to confirm. Arista EOS addresses this with configure session, which enables transactional staging similar to Junos, but it is not the default workflow and is less commonly used in practice.
Arista EOS — Transactional Configuration Session
sw-infrarunbook-01# configure session STAGING-UPLINK
sw-infrarunbook-01(config-s-STAGING-UPLINK)# interface Ethernet1
sw-infrarunbook-01(config-s-STAGING-UPLINK-if-Et1)# description UPLINK-TO-SPINE-01
sw-infrarunbook-01(config-s-STAGING-UPLINK-if-Et1)# no switchport
sw-infrarunbook-01(config-s-STAGING-UPLINK-if-Et1)# ip address 10.1.1.1/30
sw-infrarunbook-01(config-s-STAGING-UPLINK-if-Et1)# bfd interval 300 min-rx 300 multiplier 3
sw-infrarunbook-01(config-s-STAGING-UPLINK)# show session-config diffs
sw-infrarunbook-01(config-s-STAGING-UPLINK)# commitJuniper Junos — Commit Confirmed with Rollback Safety
infrarunbook-admin@sw-infrarunbook-01# edit interfaces ge-0/0/0
infrarunbook-admin@sw-infrarunbook-01# set description UPLINK-TO-SPINE-01
infrarunbook-admin@sw-infrarunbook-01# set unit 0 family inet address 10.1.1.1/30
infrarunbook-admin@sw-infrarunbook-01# top
infrarunbook-admin@sw-infrarunbook-01# show | compare
infrarunbook-admin@sw-infrarunbook-01# commit confirmed 5
commit confirmed will be rolled back in 5 minutes
commit complete
infrarunbook-admin@sw-infrarunbook-01# commitBGP Configuration and Routing Policy
Both platforms implement a full BGP feature set: iBGP, eBGP, route reflectors, confederations, communities, large communities, ADD-PATH, and graceful restart. The meaningful difference is in how routing policy is expressed. Arista EOS uses route maps and prefix lists — the standard IOS construct — which are linear and match/set driven. Juniper Junos uses a policy framework with named terms, from/then conditions, and chainable policy statements. The Junos policy model is more expressive for complex scenarios: a single policy can match on prefix, community, AS path, and protocol simultaneously, and policies chain cleanly without the numbered sequence constraints of route maps.
Arista EOS — BGP with Prefix List and Route Map
sw-infrarunbook-01(config)# ip prefix-list PL-LOOPBACKS seq 10 permit 10.0.0.0/24 le 32
sw-infrarunbook-01(config)# ip prefix-list PL-LOOPBACKS seq 20 permit 172.16.0.0/22 le 32
sw-infrarunbook-01(config)# route-map RM-EXPORT-TO-SPINE permit 10
sw-infrarunbook-01(config-route-map-RM-EXPORT-TO-SPINE)# match ip address prefix-list PL-LOOPBACKS
sw-infrarunbook-01(config-route-map-RM-EXPORT-TO-SPINE)# set community 65001:100 additive
sw-infrarunbook-01(config)# router bgp 65001
sw-infrarunbook-01(config-router-bgp)# router-id 10.0.0.1
sw-infrarunbook-01(config-router-bgp)# neighbor 10.1.1.2 remote-as 65000
sw-infrarunbook-01(config-router-bgp)# neighbor 10.1.1.2 description SPINE-01
sw-infrarunbook-01(config-router-bgp)# neighbor 10.1.1.2 send-community extended
sw-infrarunbook-01(config-router-bgp)# neighbor 10.1.1.2 maximum-routes 12000
sw-infrarunbook-01(config-router-bgp)# address-family ipv4
sw-infrarunbook-01(config-router-bgp-af)# neighbor 10.1.1.2 activate
sw-infrarunbook-01(config-router-bgp-af)# neighbor 10.1.1.2 route-map RM-EXPORT-TO-SPINE outJuniper Junos — BGP with Policy Chain
infrarunbook-admin@sw-infrarunbook-01# set policy-options prefix-list PL-LOOPBACKS 10.0.0.0/24 upto /32
infrarunbook-admin@sw-infrarunbook-01# set policy-options prefix-list PL-LOOPBACKS 172.16.0.0/22 upto /32
infrarunbook-admin@sw-infrarunbook-01# set policy-options community COM-LEAF members 65001:100
infrarunbook-admin@sw-infrarunbook-01# set policy-options policy-statement PS-EXPORT-TO-SPINE term MATCH-LOOPBACKS from prefix-list PL-LOOPBACKS
infrarunbook-admin@sw-infrarunbook-01# set policy-options policy-statement PS-EXPORT-TO-SPINE term MATCH-LOOPBACKS then community add COM-LEAF
infrarunbook-admin@sw-infrarunbook-01# set policy-options policy-statement PS-EXPORT-TO-SPINE term MATCH-LOOPBACKS then accept
infrarunbook-admin@sw-infrarunbook-01# set policy-options policy-statement PS-EXPORT-TO-SPINE term DENY-ALL then reject
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS type external
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS peer-as 65000
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS neighbor 10.1.1.2 description SPINE-01
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS export PS-EXPORT-TO-SPINE
infrarunbook-admin@sw-infrarunbook-01# set routing-options router-id 10.0.0.1
infrarunbook-admin@sw-infrarunbook-01# set routing-options autonomous-system 65001VXLAN and BGP EVPN Fabric
VXLAN with BGP EVPN is the dominant overlay standard for modern data center fabrics, and both vendors implement RFC 7432 and RFC 8365 faithfully. Arista's approach is operationally clean: define a Vxlan1 interface, map VLANs to VNIs, activate the EVPN address family under BGP, and distribute Type-2 (MAC/IP) and Type-3 (IMET) routes. Juniper's QFX implementation is similarly robust but places the VNI mapping under the VLAN stanza rather than the VXLAN interface, and EVPN is activated as a protocol alongside BGP — a structural difference that affects how troubleshooting tools present state.
Arista EOS — VXLAN EVPN Leaf Configuration
sw-infrarunbook-01(config)# interface Loopback0
sw-infrarunbook-01(config-if-Lo0)# ip address 10.0.0.1/32
sw-infrarunbook-01(config)# interface Vxlan1
sw-infrarunbook-01(config-if-Vx1)# vxlan source-interface Loopback0
sw-infrarunbook-01(config-if-Vx1)# vxlan udp-port 4789
sw-infrarunbook-01(config-if-Vx1)# vxlan vlan 100 vni 10100
sw-infrarunbook-01(config-if-Vx1)# vxlan vlan 200 vni 10200
sw-infrarunbook-01(config-if-Vx1)# vxlan learn-restrict any
sw-infrarunbook-01(config)# vlan 100
sw-infrarunbook-01(config-vlan-100)# name TENANT-A-WEB
sw-infrarunbook-01(config)# vlan 200
sw-infrarunbook-01(config-vlan-200)# name TENANT-B-APP
sw-infrarunbook-01(config)# router bgp 65001
sw-infrarunbook-01(config-router-bgp)# neighbor 10.0.0.10 remote-as 65001
sw-infrarunbook-01(config-router-bgp)# neighbor 10.0.0.10 update-source Loopback0
sw-infrarunbook-01(config-router-bgp)# neighbor 10.0.0.10 send-community extended
sw-infrarunbook-01(config-router-bgp)# address-family evpn
sw-infrarunbook-01(config-router-bgp-af)# neighbor 10.0.0.10 activate
sw-infrarunbook-01(config-router-bgp)# address-family ipv4
sw-infrarunbook-01(config-router-bgp-af)# network 10.0.0.1/32Juniper QFX — VXLAN EVPN Leaf Configuration
infrarunbook-admin@sw-infrarunbook-01# set interfaces lo0 unit 0 family inet address 10.0.0.2/32
infrarunbook-admin@sw-infrarunbook-01# set protocols evpn encapsulation vxlan
infrarunbook-admin@sw-infrarunbook-01# set protocols evpn default-gateway no-gateway-community
infrarunbook-admin@sw-infrarunbook-01# set protocols evpn extended-vni-list all
infrarunbook-admin@sw-infrarunbook-01# set vlans TENANT-A-WEB vlan-id 100
infrarunbook-admin@sw-infrarunbook-01# set vlans TENANT-A-WEB vxlan vni 10100
infrarunbook-admin@sw-infrarunbook-01# set vlans TENANT-B-APP vlan-id 200
infrarunbook-admin@sw-infrarunbook-01# set vlans TENANT-B-APP vxlan vni 10200
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-EVPN type internal
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-EVPN local-address 10.0.0.2
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-EVPN neighbor 10.0.0.10
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-EVPN family evpn signaling
infrarunbook-admin@sw-infrarunbook-01# set routing-options router-id 10.0.0.2MLAG vs MC-LAG: Active-Active ToR Redundancy
Active-active dual-homing at the access layer is a foundational design requirement. Arista uses MLAG (Multi-Chassis Link Aggregation) and Juniper uses MC-LAG backed by ICCP (Inter-Chassis Control Protocol). Both allow a downstream server or switch to LAG across two independent switches as if they were a single device. The operational difference is significant: Arista MLAG uses a dedicated peer-link port-channel and an in-band peer address for heartbeating, keeping configuration compact and highly readable. Juniper MC-LAG requires ICCP configuration, ICL (Inter-Chassis Link) definition, and explicit chassis-id assignment — more moving parts, but ICCP's BGP transport provides richer state visibility.
Arista MLAG — Peer Configuration
sw-infrarunbook-01(config)# interface Port-Channel1
sw-infrarunbook-01(config-if-Po1)# description MLAG-PEER-LINK
sw-infrarunbook-01(config-if-Po1)# switchport mode trunk
sw-infrarunbook-01(config-if-Po1)# switchport trunk allowed vlan all
sw-infrarunbook-01(config-if-Po1)# spanning-tree portfast network
sw-infrarunbook-01(config)# interface Ethernet47
sw-infrarunbook-01(config-if-Et47)# description MLAG-PEER-Et47
sw-infrarunbook-01(config-if-Et47)# channel-group 1 mode active
sw-infrarunbook-01(config)# interface Ethernet48
sw-infrarunbook-01(config-if-Et48)# description MLAG-PEER-Et48
sw-infrarunbook-01(config-if-Et48)# channel-group 1 mode active
sw-infrarunbook-01(config)# interface Vlan4094
sw-infrarunbook-01(config-if-Vl4094)# description MLAG-PEER-HEARTBEAT
sw-infrarunbook-01(config-if-Vl4094)# ip address 172.16.255.1/30
sw-infrarunbook-01(config-if-Vl4094)# no autostate
sw-infrarunbook-01(config)# mlag configuration
sw-infrarunbook-01(config-mlag)# domain-id INFRARUNBOOK-MLAG
sw-infrarunbook-01(config-mlag)# local-interface Vlan4094
sw-infrarunbook-01(config-mlag)# peer-address 172.16.255.2
sw-infrarunbook-01(config-mlag)# peer-link Port-Channel1
sw-infrarunbook-01(config-mlag)# reload-delay mlag 300
sw-infrarunbook-01(config-mlag)# reload-delay non-mlag 330Juniper MC-LAG — ICCP-Based Peer Configuration
infrarunbook-admin@sw-infrarunbook-01# set interfaces ae0 aggregated-ether-options lacp active
infrarunbook-admin@sw-infrarunbook-01# set interfaces ae0 aggregated-ether-options mc-ae mc-ae-id 1
infrarunbook-admin@sw-infrarunbook-01# set interfaces ae0 aggregated-ether-options mc-ae chassis-id 0
infrarunbook-admin@sw-infrarunbook-01# set interfaces ae0 aggregated-ether-options mc-ae mode active-active
infrarunbook-admin@sw-infrarunbook-01# set interfaces ae0 aggregated-ether-options mc-ae status-control active
infrarunbook-admin@sw-infrarunbook-01# set interfaces ae0 unit 0 family ethernet-switching
infrarunbook-admin@sw-infrarunbook-01# set protocols iccp local-ip-addr 10.0.0.2
infrarunbook-admin@sw-infrarunbook-01# set protocols iccp peer 10.0.0.1 session-establishment-hold-time 50
infrarunbook-admin@sw-infrarunbook-01# set protocols iccp peer 10.0.0.1 liveness-detection minimum-interval 500
infrarunbook-admin@sw-infrarunbook-01# set protocols iccp peer 10.0.0.1 liveness-detection multiplier 3Network Automation: gNMI and OpenConfig
Network automation is now a first-class architectural requirement, and both vendors support the same suite of open interfaces: NETCONF, RESTCONF, gNMI, and OpenConfig models. The depth of implementation differs. Arista EOS natively exposes every show command as structured JSON via eAPI — a capability that makes ad-hoc automation trivially easy. Arista also supports gNMI subscribe for streaming telemetry and OpenConfig YANG models via the management API. Juniper was one of the first vendors to implement NETCONF (RFC 6241) and its PyEZ Python SDK abstracts Junos XML RPCs cleanly. Junos also supports gNMI and JTI (Junos Telemetry Interface) for streaming, though the OpenConfig model coverage is broader on EOS for newer features.
Arista EOS — gNMI and OpenConfig API Enablement
sw-infrarunbook-01(config)# management api gnmi
sw-infrarunbook-01(config-mgmt-api-gnmi)# transport grpc default
sw-infrarunbook-01(config-mgmt-api-gnmi)# provider eos-native
sw-infrarunbook-01(config-mgmt-api-gnmi)# no shutdown
sw-infrarunbook-01(config)# management api models
sw-infrarunbook-01(config-mgmt-api-models)# provider openconfig
sw-infrarunbook-01(config-mgmt-api-models)# no shutdown
sw-infrarunbook-01(config)# management api http-commands
sw-infrarunbook-01(config-mgmt-http-cmds)# protocol https port 443
sw-infrarunbook-01(config-mgmt-http-cmds)# no protocol http
sw-infrarunbook-01(config-mgmt-http-cmds)# no shutdown
sw-infrarunbook-01(config)# username infrarunbook-admin privilege 15 role network-admin secret sha512 $6$REDACTEDJuniper Junos — gNMI and NETCONF Enablement
infrarunbook-admin@sw-infrarunbook-01# set system services netconf ssh port 830
infrarunbook-admin@sw-infrarunbook-01# set system services extension-service request-response grpc clear-text port 32767
infrarunbook-admin@sw-infrarunbook-01# set system services extension-service request-response grpc max-connections 8
infrarunbook-admin@sw-infrarunbook-01# set system services rest http port 8080
infrarunbook-admin@sw-infrarunbook-01# set system login user infrarunbook-admin class super-user
infrarunbook-admin@sw-infrarunbook-01# set system login user infrarunbook-admin authentication ssh-rsa "REDACTED"QoS Implementation
Quality of Service is critical for enterprise networks carrying VoIP, video, and latency-sensitive storage replication. Arista EOS QoS follows an IOS-style class-map and policy-map model, using DSCP trust or remarking at the interface level. Juniper Junos implements QoS via behavior aggregate (BA) classifiers, forwarding classes, and loss priority — a more powerful model that natively differentiates drop probability within a single queue, but one that requires familiarity with Juniper's four-plane traffic separation model to use effectively.
Arista EOS — DSCP Trust and Traffic Class Mapping
sw-infrarunbook-01(config)# qos map dscp 46 to traffic-class 7
sw-infrarunbook-01(config)# qos map dscp 34 to traffic-class 5
sw-infrarunbook-01(config)# qos map dscp 18 to traffic-class 3
sw-infrarunbook-01(config)# qos map dscp 0 to traffic-class 0
sw-infrarunbook-01(config)# interface Ethernet1
sw-infrarunbook-01(config-if-Et1)# qos trust dscp
sw-infrarunbook-01(config-if-Et1)# description SERVER-VOIP-01
sw-infrarunbook-01(config)# interface Ethernet2
sw-infrarunbook-01(config-if-Et2)# qos trust cos
sw-infrarunbook-01(config-if-Et2)# description UPLINK-TRUNKJuniper Junos — DSCP BA Classifier and Forwarding Class
infrarunbook-admin@sw-infrarunbook-01# set class-of-service classifiers dscp INFRARUNBOOK-DSCP forwarding-class expedited-forwarding loss-priority low code-points ef
infrarunbook-admin@sw-infrarunbook-01# set class-of-service classifiers dscp INFRARUNBOOK-DSCP forwarding-class assured-forwarding loss-priority low code-points af41
infrarunbook-admin@sw-infrarunbook-01# set class-of-service classifiers dscp INFRARUNBOOK-DSCP forwarding-class best-effort loss-priority low code-points be
infrarunbook-admin@sw-infrarunbook-01# set class-of-service interfaces ge-0/0/1 classifiers dscp INFRARUNBOOK-DSCP
infrarunbook-admin@sw-infrarunbook-01# set class-of-service interfaces ge-0/0/1 scheduler-map INFRARUNBOOK-SCHEDZero Touch Provisioning
ZTP significantly reduces the operational cost of deploying large numbers of switches. Arista EOS ZTP boots the switch, acquires a DHCP lease, and retrieves a provisioning script from DHCP option 67. The script is typically a Python file that leverages EOS's built-in Python environment and eAPI to apply a full startup configuration. Juniper Junos ZTP uses DHCP option 43 for Junos Space or TFTP-based delivery of an initial configuration and optional activation script. Both approaches work well; Arista's Python-native ZTP is easier to integrate with modern CI/CD pipelines and inventory management systems like NetBox.
Arista ZTP — Python Bootstrap Script
#!/usr/bin/env python3
# ZTP bootstrap for solvethenetwork.com leaf switches
# Served from: http://172.16.0.10/ztp/bootstrap.py
import ztplib
import json
import urllib.request
PROV_SERVER = "http://172.16.0.10"
def get_hostname_by_mac(mac):
url = "{}/api/v1/devices?mac={}".format(PROV_SERVER, mac)
resp = urllib.request.urlopen(url)
data = json.loads(resp.read())
return data.get("hostname", "sw-infrarunbook-01")
def main():
device = ztplib.ZtpDevice()
mac = device.system_mac()
hostname = get_hostname_by_mac(mac)
config_url = "{}/configs/{}.cfg".format(PROV_SERVER, hostname)
config = device.get_url(config_url)
device.write_startup_config(config)
device.reload()
if __name__ == "__main__":
main()High Availability: BFD and Graceful Restart
Sub-second failure detection via BFD is essential in enterprise data center fabrics where BGP hold timers alone would cause seconds of blackholing. Both Arista EOS and Juniper Junos support BFD with minimum intervals down to 50ms for hardware-assisted BFD on supported ASICs. Both also support BGP graceful restart (RFC 4724) to prevent route table churn during planned maintenance or control plane restarts.
Arista EOS — BFD for BGP and OSPF
sw-infrarunbook-01(config)# router bgp 65001
sw-infrarunbook-01(config-router-bgp)# neighbor 10.1.1.2 bfd
sw-infrarunbook-01(config-router-bgp)# neighbor 10.1.1.2 bfd interval 300 min-rx 300 multiplier 3
sw-infrarunbook-01(config-router-bgp)# graceful-restart
sw-infrarunbook-01(config-router-bgp)# graceful-restart-helper
sw-infrarunbook-01(config)# router ospf 1
sw-infrarunbook-01(config-router-ospf)# bfd default
sw-infrarunbook-01(config-router-ospf)# bfd per-link
sw-infrarunbook-01(config-router-ospf)# graceful-restart grace-period 120Juniper Junos — BFD for BGP
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS bfd-liveness-detection minimum-interval 300
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS bfd-liveness-detection multiplier 3
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp group SPINE-PEERS bfd-liveness-detection session-mode automatic
infrarunbook-admin@sw-infrarunbook-01# set protocols bgp graceful-restart
infrarunbook-admin@sw-infrarunbook-01# set protocols ospf graceful-restart restart-duration 120
infrarunbook-admin@sw-infrarunbook-01# set protocols ospf area 0.0.0.0 interface ge-0/0/0.0 bfd-liveness-detection minimum-interval 300Hardware Platforms and ASIC Ecosystems
Arista's data center switching portfolio is built primarily on Broadcom Trident4, Jericho2, and Tomahawk4 ASICs for the 7050, 7060, 7280, and 7300 series. Arista also offers the 7130 series built on FPGA-based microsecond latency silicon for financial trading environments. Juniper's QFX5100, QFX5110, and QFX5120 use Broadcom Trident ASICs, while the QFX10000 series uses Juniper's proprietary Express4 ASIC which offers deeper buffer, higher programmability, and better telemetry granularity — a genuine differentiator for environments with bursty elephant flows.
For campus and enterprise distribution switching, Arista's 720XP and 722XPM series compete with Juniper's EX4400 series. Juniper's Virtual Chassis technology — which stacks up to 10 EX switches as a single logical management domain — has a more mature operational track record than Arista's equivalent topology management through CloudVision. For environments with large numbers of campus closets, Virtual Chassis simplifies IDF management considerably.
Management Planes: CloudVision vs Apstra
Arista CloudVision provides centralized configuration management, streaming telemetry, network-wide change control with approval workflows, and topology visualization. It integrates directly with EOS via gRPC streaming and is the recommended operational model for large Arista deployments. Juniper's equivalent is Apstra (formerly AiME), an intent-based networking platform that provides vendor-agnostic fabric automation including support for Arista, Juniper, and other vendors. Apstra's intent model is more abstract — you define the desired network behavior, and Apstra renders the device configuration — making it more powerful for heterogeneous environments but introducing an additional abstraction layer that can complicate troubleshooting.
Total Cost of Ownership
Hardware list prices favor Arista in the data center segment — comparable port density and line-rate throughput can frequently be achieved at 15–25% lower hardware cost versus Juniper QFX for the same tier. Arista EOS base features are included with hardware. CloudVision and advanced features like CV-Pathfinder for SD-WAN carry additional per-device licensing. Juniper Junos is similarly bundled, but Apstra and Junos Space licensing for large deployments adds materially to TCO. In campus environments, Juniper EX with Virtual Chassis and built-in RADIUS, 802.1X, and PoE management tends to offer competitive TCO versus Arista 720XP deployments that require CloudVision for equivalent management capability.
Verdict: Which Platform Wins?
For greenfield data center deployments based on VXLAN/EVPN fabrics, Arista EOS delivers lower hardware cost, a simpler operational model for IOS-experienced teams, and a mature automation story through eAPI and CloudVision. For environments where the Junos commit model, policy expressiveness, Virtual Chassis campus stacking, or Apstra's intent-based management are priorities, Juniper remains a compelling and operationally proven choice. In heterogeneous or multi-vendor environments, both platforms' support for OpenConfig and gNMI enables vendor-neutral automation that neutralizes much of the operational gap. The honest answer is that neither vendor is universally superior — the right choice depends on your team's existing expertise, your dominant use case (data center versus campus), and your automation toolchain investment.
Frequently Asked Questions
Q: What is the fundamental CLI difference between Arista EOS and Juniper Junos?
A: Arista EOS uses a Cisco IOS-style CLI with a running-config/startup-config model where commands take effect immediately. Juniper Junos uses a commit-based model where changes are staged in a candidate configuration and only activated upon a commit command. The Junos model provides atomic transactions and automatic rollback via commit confirmed, while EOS offers similar functionality optionally via configure session.
Q: Can Arista and Juniper switches interoperate in the same BGP EVPN fabric?
A: Yes. BGP EVPN is an open standard (RFC 7432, RFC 8365) and both vendors implement it in a standards-compliant manner. Arista EOS and Juniper QFX can act as leaf or spine nodes in the same fabric. The primary consideration is ensuring consistent VXLAN encapsulation, uniform VNI assignment, and compatible EVPN route type usage across vendors. Both platforms support Type-2 (MAC/IP advertisement) and Type-3 (IMET) routes required for basic L2VPN operation.
Q: What is the difference between Arista MLAG and Juniper MC-LAG?
A: Both technologies allow two switches to present a single logical LAG to a downstream device for active-active redundancy. Arista MLAG uses a dedicated peer-link port-channel and an in-band VLAN interface for heartbeating, with simple mlag configuration stanza. Juniper MC-LAG uses ICCP (Inter-Chassis Control Protocol) running over BGP as the control plane, which is more complex to configure but provides richer session state visibility. Both operate comparably in production; Arista MLAG is generally considered simpler to deploy and troubleshoot.
Q: Does Arista EOS support NETCONF?
A: Yes. Arista EOS supports NETCONF (RFC 6241) via the management API framework. It also supports gNMI, RESTCONF, eAPI (JSON-RPC over HTTPS), and OpenConfig YANG models. NETCONF is enabled under management api netconf and can be used with tools like ncclient or Ansible's netconf_config module to manage EOS devices in a vendor-neutral way.
Q: Which vendor has better OpenConfig model coverage?
A: Both vendors have made significant investments in OpenConfig, but coverage varies by feature area. Arista EOS generally has broader OpenConfig coverage for data center features like BGP EVPN, VXLAN, and interface statistics. Juniper Junos has strong OpenConfig coverage for routing protocol state and interface management, and the Junos YANG model is among the most comprehensive in the industry for classical routing features. For new deployments prioritizing OpenConfig-first automation, it is worth validating which specific models are supported on the target platform and software version.
Q: What is Arista CloudVision and does Juniper have an equivalent?
A: CloudVision is Arista's centralized network management, automation, and telemetry platform. It provides topology visualization, configuration templating with change control workflows, streaming telemetry aggregation, and integration with Git-based network-as-code pipelines. Juniper's closest equivalent is Apstra, an intent-based networking platform acquired by Juniper in 2021. Apstra is more abstract and vendor-agnostic (it can manage Arista, Juniper, Cisco, and open-source NOS devices), while CloudVision is tightly integrated with EOS and provides deeper per-device telemetry for Arista fabrics.
Q: Is Arista EOS Linux-based and can I run custom applications on the switch?
A: Yes. Arista EOS is built on top of a standard Linux kernel, and the switch exposes a Linux shell accessible via bash from the EOS CLI. You can run Python scripts, install Linux packages, and deploy containerized applications using Arista's EOS SDK or directly via the Linux environment. This makes EOS a highly programmable platform for on-box automation. Juniper Junos also runs on a FreeBSD kernel and supports on-box scripting via commit scripts, op scripts, and the Junos extension toolkit (JET) for custom applications.
Q: How does Juniper Virtual Chassis compare to Arista switch stacking?
A: Juniper Virtual Chassis is a mature technology that logically stacks up to 10 EX-series switches into a single management domain with one control plane, one routing table, and unified interface numbering. It is widely deployed in enterprise campus environments. Arista does not offer a direct equivalent traditional stacking feature; instead, Arista addresses multi-switch management through CloudVision and its topology-aware configuration templating. For environments where a single-pane-of-glass CLI experience across multiple access switches is operationally critical, Juniper Virtual Chassis currently has a functional advantage over Arista's approach.
Q: Which vendor offers better Zero Touch Provisioning for large-scale deployments?
A: Both vendors support ZTP via DHCP option-based script or configuration delivery. Arista's ZTP implementation allows a full Python script to be delivered and executed on first boot, leveraging EOS's native Python environment and eAPI for dynamic configuration generation based on LLDP neighbors, MAC address, or serial number lookups against an inventory system. Juniper ZTP works well for static configuration delivery via TFTP or HTTP but requires additional tooling (Junos Space or a third-party system) for dynamic, data-driven provisioning. For Python-centric automation pipelines, Arista's ZTP integrates more natively.
Q: For a new campus network deployment, which vendor should I choose?
A: For pure campus deployments prioritizing PoE, 802.1X, Virtual Chassis stacking, and integrated wired/wireless management, Juniper EX series with Mist AI (Juniper's AI-driven networking platform acquired via Mist Systems) is a compelling choice with industry-leading wireless integration. For campuses that are part of a larger data center-centric environment already running Arista in the DC, extending Arista 720XP and 750X series to the campus with unified CloudVision management may offer operational simplicity. Evaluate your wireless strategy first — if Juniper Mist Wi-Fi is in scope, the EX switching portfolio integrates seamlessly.
Q: What is the difference between Arista eAPI and Juniper PyEZ?
A: Arista eAPI is a JSON-RPC API built into EOS that accepts any CLI command and returns structured JSON output. It is accessible over HTTPS and requires no additional software installation on the switch. PyEZ is a Python micro-framework for Junos that abstracts Junos XML RPCs, provides Table/View definitions for parsing operational state, and supports both NETCONF and Junos XML API transports. eAPI is simpler for one-off automation and ad-hoc queries; PyEZ is more powerful for building structured, reusable automation workflows with rich state parsing. Both integrate well with Ansible, Nornir, and Nautobot.
Q: How do BFD timer capabilities compare between Arista and Juniper?
A: Both vendors support hardware-assisted BFD with minimum intervals as low as 50ms on supported ASIC platforms, and software BFD with intervals typically 300ms or higher. Arista EOS enables BFD per-neighbor in BGP (neighbor x.x.x.x bfd) or globally per protocol (bfd default under OSPF). Juniper Junos enables BFD per peer group or per interface with explicit interval and multiplier settings. Both support asynchronous and demand modes. For BFD in EVPN fabrics, both vendors support BFD for VXLAN tunnel health monitoring on newer software releases, though the specific feature name and configuration path differ.