confgraph

Arista EOS Parser Support Documentation

Overview

The Arista EOS parser (confgraph.parsers.eos_parser.EOSParser) provides comprehensive parsing support for Arista EOS network device configurations. The parser inherits from IOSParser since EOS uses IOS-style syntax for most configurations, with specific overrides for EOS-specific syntax variations.

Supported Versions

Validated Versions

Expected Compatibility

Configuration Syntax Support

1. VRF Configuration

Syntax:

vrf instance <name>
   rd <rd-value>
   route-target import evpn <rt-value>
   route-target export evpn <rt-value>

EOS-Specific Differences:

Supported Attributes:

Parsing Status: ✅ Overridden — parse_vrfs() handles vrf instance syntax and EVPN route-targets

Documentation Source: EOS 4.35.1F - VRF Configuration Guide

2. Interface Configuration

Syntax:

interface <type><number>
   description <text>
   ip address <address>/<prefix-length>
   vrf <vrf-name>
   ip ospf area <area-id>

EOS-Specific Differences:

Supported Attributes:

Interface Types Supported:

Parsing Status: ✅ Inherited from IOSParser with CIDR notation support

Documentation Source: EOS 4.35.1F - Interface Configuration Guide

3. BGP Configuration

Syntax:

router bgp <asn>
   router-id <router-id>
   neighbor <ip> remote-as <asn>
   neighbor <ip> peer group <name>
   !
   address-family ipv4
      neighbor <ip> activate
      network <prefix>/<length>
   !
   vrf <vrf-name>
      rd <rd-value>
      neighbor <ip> remote-as <asn>

EOS-Specific Differences:

Supported Attributes:

Parsing Status: ✅ Inherited from IOSParser

Documentation Source: EOS 4.35.1F - Border Gateway Protocol (BGP)

4. OSPF Configuration

Syntax:

router ospf <process-id>
   router-id <router-id>
   passive-interface default
   no passive-interface <interface>
   area <area-id> range <prefix>/<length> cost <cost>
   area <area-id> nssa no-summary
   redistribute bgp route-map <name>

EOS-Specific Differences:

Supported Attributes:

Parsing Status: ✅ Inherited from IOSParser

Documentation Source: EOS 4.35.1F - OSPF Configuration Guide

5. Route-Maps

Syntax:

route-map <name> permit <sequence>
   description <text>
   match ip address prefix-list <name>
   set local-preference <value>
   set community <value> additive

EOS-Specific Differences:

Supported Attributes:

Parsing Status: ✅ Inherited from IOSParser

Documentation Source: EOS 4.35.1F - ACLs and Route Maps

6. Prefix-Lists

Syntax:

ip prefix-list <name>
   seq <number> permit <prefix>/<length> le <max-length>
   seq <number> deny <prefix>/<length> ge <min-length> le <max-length>

EOS-Specific Differences:

Supported Attributes:

Parsing Status: ✅ Overridden — parse_prefix_lists() handles EOS hierarchical prefix-list syntax with CIDR notation

Documentation Source: EOS 4.35.1F - ACLs and Route Maps

7. Static Routes

Syntax:

ip route [vrf <vrf-name>] <prefix>/<length> [egress-vrf <vrf-name>] <next-hop> [<distance>] [tag <tag>] [name <name>]

EOS-Specific Differences:

Supported Attributes:

Example:

ip route 0.0.0.0/0 10.100.1.1 name DEFAULT_TO_ISP
ip route vrf CUSTOMER_A 10.0.0.0/8 egress-vrf default 10.0.0.1

Parsing Status: ✅ EOS-specific implementation

Documentation Source: EOS 4.35.1F - IPv4 Static Inter-VRF Route

8. Access Control Lists (ACLs)

Syntax:

ip access-list [standard] <name>
   [<seq>] remark <text>
   [<seq>] permit <source> [log]
   [<seq>] deny ip <source> <destination> [log]

EOS-Specific Differences:

Supported Attributes:

Example:

ip access-list standard MGMT_HOSTS
   10 permit 192.168.10.0/24
   20 permit host 10.0.0.100

ip access-list ALLOW_WEB_TRAFFIC
   10 permit tcp any any eq 80
   20 permit tcp any any eq 443

Parsing Status: ✅ EOS-specific implementation with auto-detection

Documentation Source: EOS 4.35.1F - ACLs and Route Maps

9. BGP Community Lists

Syntax:

ip community-list [regexp] <name> permit|deny <communities>

EOS-Specific Differences:

Supported Attributes:

Example:

ip community-list ALLOWED_COMMUNITIES permit 65000:100
ip community-list regexp CUSTOMER_COMMUNITIES permit _65[0-9]{3}:[0-9]+_

Parsing Status: ✅ EOS-specific implementation

Documentation Source: EOS 4.35.1F - Border Gateway Protocol (BGP)

10. BGP AS-Path Access Lists

Syntax:

ip as-path access-list <name> permit|deny <regex>

EOS-Specific Differences:

Supported Attributes:

Example:

ip as-path access-list ALLOW_OWN_AS permit ^65000_
ip as-path access-list BLOCK_PRIVATE_AS deny _64[5-9][0-9]{2}_

Parsing Status: ✅ EOS-specific implementation (identical to IOS)

Documentation Source: EOS 4.35.1F - Border Gateway Protocol (BGP)

11. IS-IS Configuration

Syntax:

router isis <instance-name>
   net <NET-address>
   is-type level-2
   address-family ipv4 unicast
      redistribute connected

EOS-Specific Differences:

Supported Attributes:

Parsing Status: ✅ EOS-specific implementation

Documentation Source: EOS 4.35.1F - IS-IS Configuration Guide

12. Extended Protocol Support (Inherited from IOSParser)

The following protocols use IOS-identical syntax in EOS and are parsed via IOSParser inheritance without modification:

Protocol Parsing Status
NTP ✅ Inherited from IOSParser
SNMP ✅ Inherited from IOSParser
Syslog ✅ Inherited from IOSParser
Banners ✅ Inherited from IOSParser
Line configs (con/vty) ✅ Inherited from IOSParser
QoS (class-map/policy-map) ✅ Inherited from IOSParser
NAT ✅ Inherited from IOSParser
Crypto/IPsec ✅ Inherited from IOSParser
BFD ✅ Inherited from IOSParser
IP SLA ✅ Inherited from IOSParser
EEM Applets ✅ Inherited from IOSParser
Object Tracking ✅ Inherited from IOSParser
Multicast (PIM/IGMP) ✅ Inherited from IOSParser
EIGRP ✅ Inherited from IOSParser
RIP ✅ Inherited from IOSParser

See IOS_PARSER_SUPPORT.md for full syntax and attribute details for each of these protocols.

Version Compatibility Matrix

Feature EOS 4.20+ EOS 4.25+ EOS 4.30+ EOS 4.35+ Notes
VRF (vrf instance) ✅ ✅ ✅ ✅ Core feature
Interfaces (CIDR) ✅ ✅ ✅ ✅ CIDR notation standard
BGP Basic ✅ ✅ ✅ ✅ Address-family model
BGP Graceful-Restart ✅ ✅ ✅ ✅ Standard feature
OSPF BFD ✅ ✅ ✅ ✅ BFD support
Static Routes (egress-vrf) ⚠️ ✅ ✅ ✅ Inter-VRF routing
ACLs (CIDR notation) ✅ ✅ ✅ ✅ Standard feature
Community Lists ✅ ✅ ✅ ✅ Standard feature
AS-Path Lists ✅ ✅ ✅ ✅ Standard feature
IS-IS (modern syntax) ✅ ✅ ✅ ✅ Instance-based
IS-IS Segment Routing ❌ ⚠️ ✅ ✅ EOS 4.26.1F+

Legend:

Parser Implementation Details

Inheritance Strategy

The EOS parser inherits from IOSParser because:

  1. 90% syntax similarity - Most configuration syntax is IOS-compatible
  2. Code reuse - VRF, BGP, OSPF, Route-maps use same parsing logic
  3. Maintenance efficiency - Only override EOS-specific differences

Overridden Methods

  1. parse_vrfs() - Handles vrf instance syntax and EVPN route-targets
  2. parse_prefix_lists() - Handles EOS hierarchical prefix-list syntax with CIDR notation
  3. parse_static_routes() - CIDR notation and egress-vrf support
  4. parse_acls() - Optional “standard” keyword and auto-detection
  5. parse_community_lists() - Regexp keyword instead of standard/expanded
  6. parse_as_path_lists() - Identical to IOS (included for completeness)
  7. parse_isis() - Modern instance-based IS-IS syntax

Known Limitations

  1. Numbered ACLs - Parser only handles named ACLs
    • Impact: Traditional numbered ACLs (1-99, 100-199) not supported
    • Priority: Low (EOS primarily uses named ACLs)
  2. IPv6 Support - Limited IPv6 parsing coverage
    • Impact: IPv6 configurations may not be fully captured
    • Priority: Medium
  3. VXLAN/EVPN - Not currently parsed
    • Impact: Data center fabric configurations not captured
    • Priority: High for DC deployments

Future Enhancements

  1. Multi-Agent Routing Model - Parse service routing protocols model multi-agent
  2. Management API - Parse management api http-commands
  3. MLAG Configuration - Parse MLAG peer and interface configs
  4. VXLAN/EVPN - Full VXLAN and EVPN configuration support

Testing and Validation

Test Coverage

Sample Configuration: samples/eos.txt (369 lines)

Test Scripts:

Validation Results:

✅ VRFs: 3 parsed (CUSTOMER_A, CUSTOMER_B, MGMT with EVPN route-targets)
✅ Interfaces: 14 parsed correctly
✅ BGP: 1 instance with 7 neighbors
✅ OSPF: 1 process with 3 areas
✅ Route-maps: 13 parsed
✅ Prefix-lists: 4 parsed (ISP1_PREFIX_IN, ISP1_PREFIX_OUT, CONNECTED_LOOPBACKS, CUSTOMER_A_ALLOWED)
✅ Static Routes: 5 parsed (including VRF and egress-vrf)
✅ ACLs: 3 parsed (1 standard, 2 extended with sequence numbers)
✅ Community Lists: 3 parsed (2 standard, 1 regexp/expanded)
✅ AS-Path Lists: 2 parsed (6 total entries)

Arista Documentation References

Primary Documentation Sources

  1. EOS 4.35.1F User Manual (January 2026)
    • https://www.arista.com/en/um-eos/
  2. Configuration Guides:
    • IPv4 Configuration: https://www.arista.com/en/um-eos/eos-ipv4
    • BGP Configuration: https://www.arista.com/en/um-eos/eos-border-gateway-protocol-bgp
    • OSPF Configuration: https://www.arista.com/en/um-eos/eos-ospf
    • IS-IS Configuration: https://www.arista.com/en/um-eos/eos-is-is
    • ACLs and Route Maps: https://www.arista.com/en/um-eos/eos-acls-and-route-maps
    • Static Routes: https://www.arista.com/en/um-eos/eos-static-inter-vrf-route
  3. Command Reference:
    • Section 24.7 - ACL, Route Map, and Prefix List Commands
    • Section 33.4 - BGP Commands

Quick Reference

Parser Class Location

from confgraph.parsers.eos_parser import EOSParser

parser = EOSParser(config_text)
parsed = parser.parse()

Supported OS Type

from confgraph.models.base import OSType

os_type = OSType.EOS  # "eos"

Sample Configuration

samples/eos.txt  # EOS 4.30.1F sample configuration

Test Script

uv run python test_eos_parser.py

Last Updated: 2026-03-28 Parser Version: 1.1.0 Documentation Version: EOS 4.35.1F

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