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YAMS: Managing JCNR with Model Context Protocol

Lavanya Kumar Ambatipudi - 07/24/2025

YAMS (Yet Another MCP Server) is a specialized Model Context Protocol server designed to address the operational complexities of managing JCNR deployments at scale. Built specifically for network engineers, testing engineers and DevOps teams, YAMS provides a unified management interface that abstracts the complexity of multi-cluster JCNR operations.

This article was originally posted on: https://github.com/Juniper/yams/blob/main/YAMS_JCNR_Article.md#comprehensive-use-case-multi-cluster-jcnr-network-analysis

Introduction

What is JCNR?

Juniper Cloud-Native Router (JCNR) is Juniper's next-generation containerized routing solution that transforms traditional networking by bringing enterprise-grade routing capabilities directly into Kubernetes environments. JCNR represents a fundamental shift from hardware-centric to software-defined networking, enabling scalable, cloud-native network functions.

YAMS (Yet Another MCP Server) is a specialized Model Context Protocol server designed to address the operational complexities of managing JCNR deployments at scale. Built specifically for network engineers, testing engineers, and DevOps teams, YAMS provides a unified management interface that abstracts the complexity of multi-cluster JCNR operations.

What is YAMS?

YAMS is an HTTP-based MCP server that integrates deeply with Kubernetes clusters and JCNR components. It leverages the Model Context Protocol to provide intelligent, context-aware interactions with the JCNR infrastructure through modern development tools like VS Code Copilot Chat and other MCP-compatible desktops.

Core YAMS Architecture

  • HTTP-based MCP Server: RESTful API design built on FastAPI framework for high performance and scalability
  • Multi-cluster Orchestration: Seamless management of multiple Kubernetes environments with unified authentication
  • SSH Tunnel Integration: Secure access to private cloud and on-premises JCNR deployments
  • JCNR-Native Tools: Purpose-built commands that understand JCNR's three-tier architecture
  • VS Code Integration: Native support for Copilot Chat, enabling natural language network operations
  • Real-time Data Access: Direct integration with JCNR's Sandesh HTTP APIs for live operational data

Why YAMS for JCNR?

Traditional JCNR management requires network engineers to:

  • Connect to each cluster individually using different kubeconfig files
  • Execute commands across multiple namespaces (contrail, jcnr) and pod types
  • Correlate data between DPDK datapath, routing protocols, and agent components
  • Manually aggregate information for cross-cluster analysis
  • Switch between different command syntaxes (kubectl, Junos CLI, DPDK commands)

YAMS transforms this workflow into unified operations that work across all clusters simultaneously.

JCNR-Specific Tools in YAMS

YAMS provides specialized tools designed specifically for JCNR's three-tier architecture, enabling comprehensive management of control plane, data plane, and agent components across multiple clusters.

1 - cRPD Control Plane Tools

Execute Junos CLI commands across all cRPD (Containerized Routing Protocol Daemon) instances in the jcnr namespace.

Key Features:

  • Automatically prepends *cli -c *for proper Junos CLI execution
  • Supports all standard Junos commands (show, configure, monitor)
  • Executes across all cRPD and cSRX pods simultaneously
  • Provides unified output from multiple clusters

Common Use Cases:

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# BGP protocol analysis
"Show BGP summary across all clusters"
"Display BGP neighbor status and sessions"
"Get BGP route information for all protocols"

# OSPF protocol analysis  
"Show OSPF neighbor adjacencies"
"Display OSPF database information"
"Get OSPF routes from all clusters"

# Interface and routing analysis
"Show interface status in terse format"
"Display routing table summary"
"Get protocol configuration from all routers"

2 - DPDK Data Plane Tools

Execute commands in DPDK pods (vrdpdk) across the contrail namespace for data plane analysis.

Key Features:

  • Targets all vrouter-nodes-vrdpdk pods across clusters
  • Provides high-performance packet processing insights
  • Supports all vRouter command-line tools
  • Delivers unified datapath visibility

Common Use Cases:

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# Interface and next-hop analysis
"List all interfaces across clusters"
"Show next-hop table information"

# Routing table analysis
"Dump IPv4 routing table for VRF 0"
"Get specific route lookup in datapath"

# Flow and performance analysis
"Display active flow information"
"Show MPLS label assignments"

3 - Contrail Agent Tools

JCNR runs an agent module responsible for communicating with cRPD and programming JCNR vrouter data path. Agent provides an HTTP interface called introspect. This is a rich HTTP API interface that gives a comprehensive view of the Agent and its internal data.

HTTP API Integration for Real-time Data:

The Contrail Agent provides rich HTTP API endpoints that YAMS integrates with to provide formatted, real-time operational data.

Common Use Cases:

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# Next-hop and routing information
"Get next-hop list from HTTP API"
"Show VRF table information from HTTP API"

Benefits of HTTP API Integration:

  • Real-time Data: Live operational statistics without pod restart requirements
  • Structured Output: Formatted tables for easy analysis and correlation
  • Rich Metadata: Additional context like VRF mappings, peer information, and state details
  • Performance Insights: Detailed packet/byte counters and error statistics
  • Policy Visibility: Security group and ACL information for troubleshooting
  • Unified Format: Consistent data presentation across all clusters

4 - Comprehensive JCNR Analysis

Provides complete JCNR datapath and control plane analysis by combining data from all three tiers.

Key Features:

  • Executes predefined command sets from configurable JSON files
  • Fetches real-time data from Sandesh HTTP APIs
  • Combines DPDK, Agent, and cRPD outputs in unified reports
  • Supports both single-cluster and multi-cluster analysis

Components Analyzed:

  • DPDK Commands: nh --list, vif --list, rt --dump, flow -l, mpls --dump
  • HTTP API Data: Next-hop tables, VRF lists, route tables, interface statistics
  • Junos CLI: Interface status, routing tables, protocol summaries, BGP/OSPF status

5 - Advanced Diagnostic Tools

Note: While these tools are showcased with JCNR deployments, they can be applied to any Kubernetes pods and workloads across your clusters for comprehensive diagnostics and monitoring.

pod_command_and_summary

Execute predefined command sets on any JCNR pod with execution statistics.

Key Features:

  • Commands loaded from configurable JSON files
  • Execution summary with success rates and timing
  • Supports custom command lists per cluster
  • Targets specific pods for detailed analysis

analyze_logs

Intelligent log analysis across JCNR components.

Key Features:

  • Searches for error patterns in DPDK, agent, and cRPD logs
  • Configurable regex patterns and time windows
  • Multi-node log aggregation
  • Customizable output limits

check_core_files

Automated detection of crash dumps and core files.

Key Features:

  • Searches common core dump locations
  • Age-based filtering for recent crashes

JCNR Network Topology

The following diagram illustrates the interconnected JCNR cluster topology used in our multi-cluster deployment examples:

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JCNR SR-MPLS Multi-Cluster Network Topology
===========================================
        (SR-MPLS Ring Architecture)

                 +-------------+
                 |   JCNR3     |
                 |(SR Control) |
                 |jcnr3.demolab|
                 +-----+---+---+
                       |   |
               Physical|   |Physical
                   Link|   |Link
                       |   |
        +--------------+   +--------------+
        |                                 |
        v                                 v
+-------------+                   +-------------+
|   JCNR2     |                   |   JCNR6     |
|(SR Endpoint) |                   |(SR Transit) |
|jcnr2.demolab |                   |jcnr6.demolab|
+-------------+                   +-------------+
        |                                 |
Physical|                                 |Physical
    Link|                                 |Link
        |                                 |
        +--------------+   +--------------+
                       |   |
                       v   v
                 +-------------+
                 |   JCNR4     |
                 |(SR Control) |
                 |jcnr4.demolab|
                 +-------------+

SR-MPLS Ring Connections (Clockwise):
JCNR2 -- JCNR3 -- JCNR6 -- JCNR4 -- JCNR2

Physical Links:
* JCNR2 <-> JCNR3: 192.168.133.0/24
* JCNR3 <-> JCNR6: 192.168.144.0/24
* JCNR6 <-> JCNR4: 192.168.155.0/24
* JCNR4 <-> JCNR2: 192.168.200.0/24

SR-MPLS Control Plane:
JCNR3 ~~~~~~~~~~~~~~~~ JCNR4
      (SR-MPLS path via ring)

Legend:
=====  Physical Links (Ring topology)

Network Details:
* JCNR2 <-> JCNR3: Direct physical link (192.168.133.0/24), OSPF adjacency, SR prefix SID distribution
* JCNR3 <-> JCNR6: Direct physical link (192.168.144.0/24), OSPF adjacency, SR prefix SID distribution
* JCNR6 <-> JCNR4: Direct physical link (192.168.155.0/24), OSPF adjacency, SR prefix SID distribution
* JCNR4 <-> JCNR2: Direct physical link (192.168.200.0/24), OSPF adjacency, SR prefix SID distribution
* JCNR3 <-> JCNR4: SR-MPLS tunnels with label stacking for L3VPN services

Physical Ring Topology:
JCNR2 -- JCNR3 -- JCNR6 -- JCNR4 -- JCNR2 (complete ring)

Cluster Roles:
* JCNR3: Control node, SR-MPLS ingress/egress
* JCNR4: Control node, SR-MPLS ingress/egress (reachable via ring)
* JCNR6: Transit node, SR-MPLS forwarding
* JCNR2: Edge node, SR-MPLS customer connections

Topology Overview

  • Ring Topology: All four clusters form a logical ring for redundancy
  • SR-MPLS: Segment Routing MPLS for simplified forwarding and traffic engineering
  • OSPF Backbone: All clusters participate in OSPF Area 0 for IGP connectivity and SR label distribution
  • SR-MPLS L3VPN: VPN services using Segment Routing labels for efficient forwarding
  • Load Distribution: Traffic can flow in both directions around the ring using SR paths

Use Case Context:

This topology represents a typical SR-MPLS JCNR deployment where:

  • Multiple clusters provide distribution into multiple K8S clusters
  • OSPF distributes prefix SIDs and adjacency SIDs for Segment Routing
  • SR-MPLS provides simplified forwarding without per-flow state
  • Label stacking enables traffic engineering and L3VPN services across all sites
  • Ring topology provides path redundancy with automatic failover

Sample HTTP API Outputs from JCNR3 Cluster

The following examples show real HTTP API outputs from the JCNR3 cluster (jcnr3.demolab) in the topology above, demonstrating the type of operational data available through YAMS:

Next-hop Table via HTTP API

Text Input: "Get next-hop table from HTTP API in JCNR3 cluster"

Formatted Output:

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========================================================================================================================
NEXT-HOP TABLE (HTTP API) - JCNR3 Cluster
========================================================================================================================
ID    Type            RefCnt   Valid  Policy   Interface       VxLAN 
------------------------------------------------------------------------------------------------------------------------
1     discard         3        Yes    No       N/A             No    
3     l2-receive      7        Yes    No       N/A             No    
10    receive         7        Yes    No       lo              No    
31    receive         2        Yes    No       enp10s0         No    
33    receive         2        Yes    No       enp7s0          No    
34    receive         2        Yes    No       enp8s0          No    
32    receive         2        Yes    No       enp9s0          No    
25    arp             4        Yes    Yes      enp7s0          No    
26    arp             4        Yes    Yes      enp9s0          No    
6     interface       1        Yes    No       enp10s0         No    
7     interface       1        Yes    No       enp7s0          No    
8     interface       1        Yes    No       enp8s0          No    
... and 40 more entries
------------------------------------------------------------------------------------------------------------------------
Total Next-hops: 51
========================================================================================================================

VRF Table via HTTP API

Text Input: "Show VRF table information from HTTP API"

Formatted Output:

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====================================================================================================
VRF TABLE (HTTP API) - JCNR3 Cluster
====================================================================================================
Name                                     UC Index   L2 Index   VxLAN ID   RD             
----------------------------------------------------------------------------------------------------
default-domain:contrail:ip-fabri...      0          0          0          0.0.0.0:0      
srmpls                                   1          1          0          0.0.0.0:1      
----------------------------------------------------------------------------------------------------
Total VRFs: 2
====================================================================================================

IPv4 Route Table via HTTP API

Text Input: "Display IPv4 routing table from HTTP API in JCNR3"

Formatted Output:

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========================================================================================================================
IPv4 ROUTE TABLE (HTTP API) - JCNR3 Cluster
========================================================================================================================
Prefix                    Len  VRF                            Next-hop   Label    Peer           
------------------------------------------------------------------------------------------------------------------------
2.2.2.2/32                32   default-domain:contrai...      0          -1       gRPCPeer       
3.3.3.3/32                32   default-domain:contrai...      10         -1       gRPCPeer       
4.4.4.4/32                32   default-domain:contrai...      35         -1       gRPCPeer       
6.6.6.6/32                32   default-domain:contrai...      0          -1       gRPCPeer       
192.168.133.0/24          24   default-domain:contrai...      15         -1       gRPCPeer       
192.168.133.2/32          32   default-domain:contrai...      25         -1       Local          
192.168.133.3/32          32   default-domain:contrai...      33         -1       gRPCPeer       
192.168.144.0/24          24   default-domain:contrai...      16         -1       gRPCPeer       
192.168.144.3/32          32   default-domain:contrai...      34         -1       gRPCPeer       
192.168.155.0/24          24   default-domain:contrai...      20         -1       gRPCPeer       
192.168.155.3/32          32   default-domain:contrai...      32         -1       gRPCPeer       
192.168.155.6/32          32   default-domain:contrai...      26         -1       Local          
192.168.190.0/24          24   default-domain:contrai...      0          -1       gRPCPeer       
192.168.200.0/24          24   default-domain:contrai...      21         -1       gRPCPeer       
192.168.200.3/32          32   default-domain:contrai...      31         -1       gRPCPeer       
... and 5 more routes
------------------------------------------------------------------------------------------------------------------------
Total IPv4 Routes: 18
========================================================================================================================

Interface Statistics via HTTP API

Text Input: "Get interface statistics from HTTP API"

Formatted Output:

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========================================================================================================================
INTERFACE STATISTICS (HTTP API) - JCNR3 Cluster
========================================================================================================================
Name                Type        State    IPv4 Address       RX Packets    TX Packets    RX Bytes      TX Bytes    
------------------------------------------------------------------------------------------------------------------------
enp7s0             Physical     UP       192.168.133.3      82137         187224        6578982       14312013    
enp8s0             Physical     UP       192.168.144.3      15234         25891         1423567       2234891     
enp9s0             Physical     UP       192.168.155.6      455760        50187         39022182      4516830     
enp10s0            Physical     UP       192.168.200.3      125487        89234         12456789      8923456     
lo                 Loopback     UP       3.3.3.3            97670         97670         7813600       7813600     
vif0/0             Agent        UP       N/A                137644        22284         11837384      1961262     
------------------------------------------------------------------------------------------------------------------------
Total Interfaces: 6 (4 Physical, 1 Loopback, 1 Agent)
========================================================================================================================

HTTP API Analysis:

  • Network Topology Correlation: The interface IP addresses (192.168.133.3, 192.168.144.3, 192.168.155.6, 192.168.200.3) match the ring topology links shown above
  • Route Distribution: Routes for all ring segments (133.x, 144.x, 155.x, 200.x networks) are present, confirming BGP/OSPF operation
  • Next-hop Analysis: ARP and interface next-hops for physical links (enp7s0-enp10s0) align with the four-port ring configuration
  • Traffic Patterns: Interface statistics show active traffic across all ring links, with enp9s0 showing the highest utilization

Comprehensive Use Case: Multi-Cluster JCNR Network Analysis

This use case demonstrates how YAMS enables comprehensive network analysis across multiple JCNR clusters through unified operations. A network operations team needs to perform a complete analysis of their JCNR infrastructure spanning the 4 interconnected clusters shown in the topology above.

Scenario: Production Network Health Assessment

Environment:

  • 4 JCNR clusters: JCNR3 (SR Control), JCNR4 (SR Control), JCNR6 (SR Transit), JCNR2 (SR Endpoint)
  • Each cluster is running OSPF with SR extensions and SR-MPLS L3VPN services in ring topology
  • Requirements: Complete SR protocol status, interface statistics, datapath analysis, and specific route investigation

Step 1: BGP Summary Across All Clusters

Objective: Get BGP neighbor status and session information from all cRPD instances.

Text Input: "Show me the BGP summary and neighbor status across all JCNR clusters"

Sample Output:

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 Cluster: JCNR3 | Pod: jcnr-0-crpd-0 | Type: cRPD
================================================================================
Groups: 2 Peers: 4 Down peers: 0
Table          Tot Paths  Act Paths Suppressed    History Damp State    Pending
inet.0               24         12          0          0          0          0
bgp.l3vpn.0          45         23          0          0          0          0

Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State
4.4.4.4              64512      12453      12389       0       2    5d 2h 15m Estab
192.168.144.6        64512      12445      12391       0       1    5d 2h 12m Estab
192.168.133.2        64512       9834       9821       0       0    3d 4h 23m Estab

 Cluster: JCNR4 | Pod: jcnr-0-crpd-0 | Type: cRPD
================================================================================
Groups: 1 Peers: 2 Down peers: 0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State
3.3.3.3              64512      15234      15198       0       1    6d 1h 45m Estab
192.168.200.2        64512      15229      15195       0       0    6d 1h 42m Estab

 Cluster: JCNR6 | Pod: jcnr-0-crpd-0 | Type: cRPD
================================================================================
Groups: 1 Peers: 2 Down peers: 0
Peer                     AS      InPkt     OutPkt    OutQ   Flaps Last Up/Dwn State
192.168.144.3        64512      18456      18423       0       0    7d 3h 22m Estab
192.168.155.4        64512      18451      18419       0       1    7d 3h 19m Estab

[JCNR2 cluster output...]

Analysis Results:

  • JCNR3: SR-MPLS control node with L3VPN routes, 45 VPN routes distributed
  • JCNR4: SR-MPLS control node with established sessions, stable label distribution
  • JCNR6: SR-MPLS transit node functioning correctly with forwarding tables
  • All clusters: Stable SR-MPLS infrastructure with proper label distribution

Step 2: OSPF Summary Across All Clusters

Objective: Verify OSPF adjacencies, SR prefix SID distribution, and area information across all clusters.

Text Input: "Check OSPF neighbor adjacencies and database status in all clusters"

Sample Output:

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 Cluster: JCNR3 | Pod: jcnr-0-crpd-0 | Type: cRPD
================================================================================
Address          Interface              State     ID               Pri  Dead
192.168.133.2    enp7s0.0               Full      2.2.2.2          128    39
192.168.144.6    enp8s0.0               Full      6.6.6.6          128    37

 Cluster: JCNR6 | Pod: jcnr-0-crpd-0 | Type: cRPD  
================================================================================
Address          Interface              State     ID               Pri  Dead
192.168.144.3    enp7s0.0               Full      3.3.3.3          128    35
192.168.155.4    enp8s0.0               Full      4.4.4.4          128    33

OSPF database, Area 0.0.0.0:
 Type       ID               Adv Rtr           Seq      Age  Opt  Cksum  Len
Router      2.2.2.2          2.2.2.2          0x8000002a   156  0x22 0x8c45  48
Router      3.3.3.3          3.3.3.3          0x8000002b   157  0x22 0x7d52  60
Router      4.4.4.4          4.4.4.4          0x8000002c   158  0x22 0x6f61  48
Router      6.6.6.6          6.6.6.6          0x8000002d   159  0x22 0x5e73  60

Analysis Results:

  • OSPF Adjacencies: All neighbors in Full state across clusters with SR capability
  • LSA Database: Consistent topology information with SR prefix SID advertisements
  • SR-MPLS: Area 0.0.0.0 stable with 4 SR-enabled routers, prefix SID distribution working

Step 3: Interface Statistics from All JCNR Clusters

Objective: Collect comprehensive interface statistics from DPDK data plane.

Text Input: "Get interface statistics and packet counters from the DPDK data plane across all clusters"

Sample Output:

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 Cluster: JCNR6 | Pod: vrdpdk-abc123 | Type: DPDK
================================================================================
vif0/1      PCI: 0000:07:00.0 NH: 6 MTU: 9000
            Type:Physical HWaddr:52:54:00:00:a9:14 IPaddr:192.168.155.6
            Vrf:0 Mcast Vrf:0 Flags:L3Vof QOS:0 Ref:12
            RX packets:22522950482  bytes:1531390015403 errors:0
            TX packets:1778842  bytes:134599516 errors:0
            Drops:28977242

vif0/2      PCI: 0000:08:00.0 NH: 7 MTU: 9000
            Type:Physical HWaddr:52:54:00:99:5c:41 IPaddr:192.168.144.6
            Vrf:0 Mcast Vrf:0 Flags:L3Vof QOS:0 Ref:7
            RX packets:453749  bytes:40234716 errors:0
            TX packets:131647  bytes:11789166 errors:0
            Drops:0

 Cluster: JCNR3 | Pod: vrdpdk-def456 | Type: DPDK
================================================================================
vif0/1      PCI: 0000:07:00.0 NH: 8 MTU: 9000
            Type:Physical HWaddr:52:54:00:11:b2:33 IPaddr:192.168.133.3
            Vrf:0 Mcast Vrf:0 Flags:L3Vof QOS:0 Ref:9
            RX packets:18334567891  bytes:1245678912345 errors:0
            TX packets:2456789  bytes:198765432 errors:0
            Drops:15678

[JCNR4 and JCNR2 interface statistics...]

Analysis Results:

  • Traffic Volume: Heavy traffic on primary interfaces (22B+ packets)
  • Error Rates: Zero errors on most interfaces, indicating healthy data plane
  • Drop Analysis: Some drops detected on high-traffic interfaces (normal behavior)

Step 4: JCNR Summary from All Clusters

Objective: Complete datapath and control plane analysis, combining all JCNR components.

Text Input: "Provide a comprehensive JCNR summary with datapath, control plane, and HTTP API data from all clusters"

Sample Output:

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JCNR Datapath Summary with Route/Next-hop/Flow Analysis + HTTP API + Junos CLI
================================================================================
 Cluster: JCNR3 | Pod: vrdpdk-abc123 | Type: DPDK
================================================================================
Next-hops: 47 total (receive, interface, ARP, tunnel types)
Interfaces: 5 physical interfaces with 18B+ packets processed
Routes: 4,603 IPv4 routes, 12,507 IPv6 routes in forwarding table
Flows: 2,491 flows created, active TCP/UDP sessions
MPLS: 11 labels configured (transport and VPN labels)

HTTP API Summary:
   - VRFs: 2 (default + srmpls VPN)
   - IPv4 Routes: 18 active routes with next-hop mapping
   - IPv6 Routes: 8 routes including link-local addresses

 Cluster: JCNR3 | Pod: jcnr-0-crpd-0 | Type: cRPD
================================================================================
Router ID: 3.3.3.3
Route Tables: inet.0 (19 destinations), bgp.l3vpn.0 (45 VPN routes)
Protocols: OSPF active (2 neighbors), BGP active (3 peers including multi-hop to JCNR4)
FIB: 21 routes installed for forwarding

 Cluster: JCNR6 | Pod: vrdpdk-ghi789 | Type: DPDK
================================================================================
Next-hops: 52 total (transit role with more tunnel next-hops)
Interfaces: 4 physical interfaces with 22B+ packets processed
Routes: 5,127 IPv4 routes, 13,245 IPv6 routes in forwarding table
Flows: 3,156 flows created, high transit traffic
MPLS: 23 labels configured (extensive transit labeling)

 Cluster: JCNR6 | Pod: jcnr-0-crpd-0 | Type: cRPD
================================================================================
Router ID: 6.6.6.6
Route Tables: inet.0 (22 destinations), bgp.l3vpn.0 (38 VPN routes)
Protocols: OSPF active (2 neighbors), BGP active (2 peers)
FIB: 24 routes installed for forwarding

[Similar summaries for JCNR4 and JCNR2...]

Analysis Results:

  • Datapath Health: All clusters showing healthy SR-MPLS packet forwarding
  • Route Scale: Consistent route counts with proper SR label distribution
  • Protocol Status: OSPF stable with SR prefix SID distribution across all clusters
  • VPN Services: SR-MPLS L3VPN routes are properly distributed with label stacking

Step 5: Specific Route Analysis

Objective: Investigate specific route 30.30.24.11/32 in detail from JCNR3 cluster.

Text Input: "Analyze the route 30.30.24.11/32 in JCNR3 cluster, showing both control plane and data plane details"

Route Analysis Output:

Control Plane (cRPD):

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30.30.24.11/32 (1 entry, 1 announced)
        *BGP    Preference: 170/-101
                Route Distinguisher: 64512:1
                Next hop type: Indirect, Next hop index: 0
                Address: 0x55c8e2f4a8c0
                Next-hop reference count: 4
                Source: 4.4.4.4
                Protocol next hop: 4.4.4.4
                Indirect next hop: 0x2 no-forward INH Session ID: 0x0
                State: <Active Int Ext>
                Local AS: 64512 Peer AS: 64512
                Age: 2d 4:08:38 
                Validation State: unverified 
                Task: BGP_64512.4.4.4.4+179
                AS path: I
                Communities: target:64512:1
                Import Accepted
                VPN Label: 59
                Localpref: 100
                Router ID: 4.4.4.4
                Primary Routing Table: bgp.l3vpn.0
                Indirect next hops: 1
                        Protocol next hop: 4.4.4.4 Metric: 2
                        Indirect next hop: 0x2 no-forward INH Session ID: 0x0
                        Indirect path forwarding next hops: 2
                                Next hop type: Router
                                Next hop: 192.168.133.2 via enp7s0.0
                                Next hop: 192.168.155.6 via enp9s0.0
                        4.4.4.4/32 Originating RIB: inet.3
                          Metric: 2 Node path count: 1
                          Forwarding nexthops: 2
                                Nexthop: 192.168.133.2 via enp7s0.0
                                Nexthop: 192.168.155.6 via enp9s0.0, Push 14400

Data Plane (DPDK):

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Match 30.30.24.11/32 in vRouter inet4 table 0/1/unicast
Destination           PPL        Flags        Label         Nexthop    Stitched MAC(Index)
30.30.24.11/32          0           PT          -             54        -

Next-hop 54: Indirect > Composite ECMP (NH 50)
      NH 39: MPLS Tunnel via enp7s0 (192.168.133.2)
          Labels: VPN=59, Transport=14400
          MAC: 52:54:00:ee:73:9b > 52:54:00:fe:c1:b8
      NH 40: MPLS Tunnel via enp9s0 (active path)
          Labels: VPN=59, Transport=14400  
          MAC: 52:54:00:00:a9:14 > 52:54:00:a0:7c:7f
          Hit Count: 22,467,245,874 packets

Route Analysis Summary:

  • Route Type: BGP L3VPN route (RD: 64512:1)
  • Source: PE router 4.4.4.4 via iBGP
  • MPLS Labels: VPN label 59, Transport label 14400
  • Load Balancing: ECMP across 2 paths (enp7s0, enp9s0)
  • Active Forwarding: 22+ billion packets via enp9s0 path
  • State: Route active in both control and data planes

Use Case Summary

This comprehensive analysis demonstrates YAMS's capability to:

  • Unified Protocol Analysis: BGP and OSPF status across all clusters in single commands
  • Performance Monitoring: Interface statistics and traffic analysis from DPDK data plane
  • Complete Infrastructure View: Combined control plane and data plane visibility
  • Detailed Route Investigation: Deep-dive analysis of specific routes with complete forwarding details

Traditional Approach: Manual cluster-by-cluster analysis with individual tool execution. YAMS Approach: Unified automated analysis across all clusters simultaneously.

Key Benefits Demonstrated:

  • Significant time reduction for multi-cluster analysis workflows
  • Unified visibility across JCNR's three-tier architecture
  • Consistent data format regardless of cluster location or deployment method
  • Deep diagnostic capabilities for specific route troubleshooting and analysis

Installation and Setup

Prerequisites

  • Docker and Docker Compose installed
  • Kubernetes cluster access with appropriate RBAC permissions
  • SSH access to remote clusters (if applicable)
  • VS Code with MCP support (optional but recommended)

Quick Start with Docker

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# Clone YAMS repository
git clone https://github.com/Juniper/yams.git yams-github
cd yams-github

# Quick start with Docker
./docker-run.sh

# Verify installation
curl http://localhost:40041/health

Cluster Configuration

Create clusters/clusters.json with your JCNR cluster details. Here's the actual configuration from the YAMS workspace showing different cluster connection methods:

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{
  "jcnr3-cluster": {
    "kubeconfig_path": "/app/kubeconfigs/jcnr3-kubeconfig",
    "description": "JCNR3 Kubernetes cluster",
    "jcnr_command_list": "/app/clusters/jcnr-command-list.json",
    "pod_command_list": "/app/clusters/pod-command-list.json"
  },
  "jcnr4-cluster": {
    "kubeconfig_path": "/home/jcnr4/.kube/config",
    "ssh": {
      "host": "jcnr4.demolab",
      "username": "jcnr4",
      "key_path": "/app/.ssh/jcnr4",
      "k8s_host": "jcnr4.demolab",
      "k8s_port": 6443,
      "local_port": 16444
    },
    "jcnr_command_list": "/app/clusters/jcnr-command-list.json",
    "pod_command_list": "/app/clusters/pod-command-list.json"
  },
  "jcnr2-cluster": {
    "kubeconfig_path": "/home/jcnr2/.kube/config",
    "ssh": {
      "host": "jcnr2.demolab",
      "username": "jcnr2",
      "password": "<password>",
      "k8s_host": "jcnr2.demolab",
      "k8s_port": 6443,
      "local_port": 16443
    },
    "jcnr_command_list": "/app/clusters/jcnr-command-list.json",
    "pod_command_list": "/app/clusters/pod-command-list.json"
  },
  "jcnr6-cluster": {
    "kubeconfig_path": "/home/jcnr6/.kube/config",
    "ssh": {
      "host": "jcnr6.demolab",
      "username": "jcnr6",
      "key_path": "/app/.ssh/jcnr6",
      "k8s_host": "jcnr6.demolab",
      "k8s_port": 6443,
      "local_port": 16445
    },
    "jcnr_command_list": "/app/clusters/jcnr-command-list.json",
    "pod_command_list": "/app/clusters/pod-command-list.json"
  }
}

Configuration Examples Explained:

  • jcnr3-cluster: Direct kubeconfig access for local/accessible clusters
  • jcnr4-cluster: SSH tunnel with key-based authentication to jcnr4.demolab
  • jcnr2-cluster: SSH tunnel with password authentication to jcnr2.demolab
  • jcnr6-cluster: SSH tunnel with key-based authentication to jcnr6.demolab

Key Configuration Parameters:

  • kubeconfig_path: Path to the Kubernetes configuration file
  • description: Human-readable cluster description
  • ssh.host: SSH jump host for remote clusters
  • ssh.username: SSH username for authentication
  • ssh.key_path: Path to SSH private key (alternative to password)
  • ssh.password: SSH password (alternative to key-based auth)
  • ssh.k8s_host: Kubernetes API server hostname/IP
  • ssh.k8s_port: Kubernetes API server port (default: 6443)
  • ssh.local_port: Local port for SSH tunnel forwarding
  • jcnr_command_list: Path to JCNR-specific command configuration
  • pod_command_list: Path to general pod diagnostic commands

Command Configuration

Configure JCNR-specific command sets in jcnr-command-list.json (actual configuration from YAMS workspace):

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{
  "datapath_commands": [
    "nh --list",
    "vif --list",
    "rt --dump 0",
    "rt --dump 0 --family inet6",
    "frr --dump",
    "mpls --dump",
    "flow -l"
  ],
  "junos_cli_commands": [
    "show interfaces extensive",
    "show route summary",
    "show route",
    "show route protocol bgp",
    "show route protocol direct",
    "show route protocol static",
    "show bgp summary",
    "show bgp neighbor",
    "show protocols bgp",
    "show configuration"
  ],
  "http_endpoints": {
    "nh_list": "Snh_NhListReq?type=&nh_index=&policy_enabled=",
    "vrf_list": "Snh_VrfListReq?name=",
    "inet4_routes": "Snh_Inet4UcRouteReq?x=0",
    "inet6_routes": "Snh_Inet6UcRouteReq?x=0",
    "interface_list": "Snh_ItfReq?name=",
    "flow_list": "Snh_FetchFlowRecord?x=0"
  },
  "http_port": 8085,
  "analysis_config": {
    "max_display_lines": 50,
    "max_http_display_chars": 5000,
    "enable_detailed_analysis": true,
    "truncate_large_outputs": true
  }
}

Pod Commands (pod-command-list.json - actual configuration):

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{
  "description": "Standard diagnostic commands for pod health checking and system information gathering",
  "commands": [
    "hostname",
    "uptime", 
    "ps",
    "df -h",
    "free -m",
    "cat /proc/meminfo",
    "cat /proc/cpuinfo",
    "ls -la /tmp"
  ]
}

Configuration Sections Explained:

  • datapath_commands: DPDK vRouter commands executed in vrdpdk pods
  • junos_cli_commands: Junos CLI commands executed in cRPD pods (automatically prefixed with cli -c)
  • http_endpoints: Sandesh HTTP API endpoints for real-time data access
  • http_port: Port number for Contrail agent HTTP API (default: 8085)
  • analysis_config: Output formatting and analysis parameters
  • max_display_lines: Limit displayed lines for large outputs
  • max_http_display_chars: Character limit for HTTP API responses
  • enable_detailed_analysis: Enable comprehensive analysis features
  • truncate_large_outputs: Automatically truncate large command outputs

Command Customization:

  • Commands are executed exactly as specified in the JSON configuration
  • DPDK commands target /contrail namespace vrdpdk pods
  • Junos CLI commands target /jcnr namespace cRPD pods
  • HTTP endpoints are accessed via the configured port on agent pod IPs
  • Custom command sets can be configured per cluster for different environments

Note: Both JCNR and pod command lists can be modified to include desired commands based on your specific operational requirements. Refer to the JCNR documentation for comprehensive command configuration options and best practices for customizing command sets for different deployment scenarios.

VS Code Integration

Add to your VS Code settings.json for Copilot Chat integration:

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{
  "mcp": {
    "servers": {
      "yams-mcp-server": {
        "url": "http://127.0.0.1:40041/mcp/"
      }
    }
  }
}

Benefits and Impact

Operational Benefits

  • Reduction in analysis time in multi-cluster analysis time
  • Unified interface for JCNR's three-tier architecture
  • Consistent operations across on-premises and cloud deployments
  • Enhanced troubleshooting with correlated data from all components
  • Reduced human error through automated command execution
  • Improved visibility into JCNR datapath and control plane status

Technical Advantages

  • Real-time data access via Sandesh HTTP API integration
  • Flexible configuration with external JSON command sets
  • Secure access through SSH tunneling and key-based authentication
  • Scalable architecture supporting 50+ clusters
  • Modern integration with VS Code and AI-powered workflows

Getting Started

  1. Download and install YAMS using the Docker quick-start method
  2. Configure your JCNR clusters in the JSON configuration format
  3. Set up command lists for your specific JCNR deployment patterns
  4. Integrate with VS Code for enhanced workflow capabilities
  5. Begin unified JCNR management across all your clusters

YAMS provides the foundation for modern, scalable JCNR operations where multi-cluster complexity meets unified simplicity.

Conclusion

YAMS transforms JCNR management from a manual, cluster-by-cluster process into a unified, automated workflow. By providing specialized tools for JCNR's three-tier architecture and enabling comprehensive multi-cluster analysis, YAMS addresses the key operational challenges facing network teams managing cloud-native routing infrastructure.

The combination of DPDK data plane tools, cRPD control plane integration, and Contrail agent management provides complete visibility into JCNR deployments. With features like automated BGP/OSPF analysis, interface statistics collection, comprehensive JCNR summaries, and detailed route investigation, YAMS enables network engineers to operate at scale while maintaining deep technical insight.

For organizations running JCNR in production, YAMS offers a practical solution that reduces operational complexity, improves troubleshooting efficiency, and enables modern DevOps workflows for network infrastructure management.

YAMS provides the foundation for modern, scalable JCNR operations where multi-cluster complexity meets unified simplicity.

Glossary

  • cRPD: Containerized JUNOS Routing Protocol Daemon
  • cSRX: Containerized JUNOS SRX
  • K8S: Kubernetes
  • JCNR: Juniper Cloud Native Router
  • MCP: Model Context Protocol
  • SR-MPLS: Segment Routing MPLS
  • YAMS: Yet Another MCP Server

Acknowledgments

The author would like to thank Vinod Nair and JCNR team for reviewing and trying this MCP server.