2.6 Multi-Region Fabric Design
| Field |
Value |
| Document Title |
Multi-Region Fabric Design |
| Section Number |
2.6 |
| Version |
1.0 |
| Last Updated |
December 30, 2025 |
| Author |
Network Architecture Team |
| Classification |
Internal Use |
2.6.1 Multi-Region Fabric Overview
Purpose and Business Drivers
Multi-Region Fabric (MRF) enables hierarchical SD-WAN deployments that scale beyond traditional single-region limitations while optimizing control plane efficiency and regional traffic localization. For Abhavtech.com's global deployment across India, EMEA, and Americas, MRF provides critical architectural benefits.
MRF Architecture Comparison
| Aspect |
Single Region |
Multi-Region Fabric |
Benefit |
| vSmart Scalability |
All sites to all vSmarts |
Regional vSmarts |
60% control plane reduction |
| Route Advertisement |
Full mesh |
Hierarchical summarization |
Faster convergence |
| Inter-Region Traffic |
Direct tunnels |
Border router aggregation |
Simplified topology |
| Failure Domain |
Global |
Regional isolation |
Localized impact |
| Policy Scope |
Global |
Regional + Global |
Granular control |
| Max WAN Edges |
6,000 |
20,000+ |
Future scalability |
MRF Topology Design
MULTI-REGION FABRIC ARCHITECTURE
+==============================================================================+
| |
| ACCESS REGIONS |
| +------------------------------------------------------------------+ |
| | | |
| | +------------+ +------------+ +-------------+ | |
| | | REGION 1 | | REGION 2 | | REGION 3 | | |
| | | INDIA | | EMEA | | AMERICAS | | |
| | +------+-----+ +------+-----+ +------+------+ | |
| | | | | | |
| | +---------+ +---------+ +---------+ | |
| | |vSmart-1 | |vSmart-3 | |vSmart-5 | | |
| | |Mumbai | |Chennai | |(Future) | | |
| | +---------+ +---------+ +---------+ | |
| | |vSmart-2 | |vSmart-4 | |vSmart-6 | | |
| | |Mumbai | |Chennai | |(Future) | | |
| | +---------+ +---------+ +---------+ | |
| | | | | | |
| +---------|------------------|------------------|------------------+ |
| | | | |
| v v v |
| +------------------------------------------------------------------+ |
| | TRANSPORT REGIONS | |
| | | |
| | +--------------+ +--------------+ +--------------+ | |
| | | BORDER | | BORDER | | BORDER | | |
| | | ROUTER 1 | | ROUTER 2 | | ROUTER 3 | | |
| | | Mumbai DC | | Chennai DR | | (Future) | | |
| | +--------------+ +--------------+ +--------------+ | |
| | | | | | |
| | +--------+---------+--------+---------+ | |
| | | | | |
| | v v | |
| | CORE TRANSPORT REGION | |
| | +--------------------------------------------------+ | |
| | | | | |
| | | +-----------+ +-----------+ | | |
| | | | Core |<========>| Core | | | |
| | | | vSmart-C1 | eBGP | vSmart-C2 | | | |
| | | | Mumbai | Peering | Chennai | | | |
| | | +-----------+ +-----------+ | | |
| | | | | |
| | +--------------------------------------------------+ | |
| | | |
| +------------------------------------------------------------------+ |
| |
+==============================================================================+
2.6.2 Region Design and Assignment
Region Hierarchy
| Level |
Role |
Components |
Scope |
| Core Region |
Inter-region routing |
Core vSmarts, Border Routers |
Global |
| Access Region |
Intra-region routing |
Regional vSmarts, WAN Edges |
Regional |
| Transport Region |
Physical connectivity |
Border Routers, Transports |
Transport |
Region Assignment for Abhavtech
| Region ID |
Region Name |
Region Role |
Sites Included |
Primary vSmart |
Secondary vSmart |
| 1 |
INDIA-ACCESS |
Access |
Mumbai, Chennai, Bangalore, Delhi, Noida |
vSmart-1 (Mumbai) |
vSmart-2 (Mumbai) |
| 2 |
EMEA-ACCESS |
Access |
London, Frankfurt |
vSmart-3 (Chennai) |
vSmart-4 (Chennai) |
| 3 |
AMERICAS-ACCESS |
Access |
New Jersey, Dallas |
vSmart-3 (Chennai) |
vSmart-4 (Chennai) |
| 0 |
CORE |
Core/Transport |
Mumbai DC, Chennai DR |
vSmart-C1 |
vSmart-C2 |
Site-to-Region Mapping
!======================================================================
! REGION ASSIGNMENT CONFIGURATION
!======================================================================
!
! Mumbai DC - Region 1 (India) + Core Border
system
system-ip 10.1.100.1
site-id 100
organization-name ABHAVTECH-COM
region 1
role border-router
secondary-region 0
!
! Chennai DR - Region 1 (India) + Core Border
system
system-ip 10.1.200.1
site-id 200
organization-name ABHAVTECH-COM
region 1
role border-router
secondary-region 0
!
! London Hub - Region 2 (EMEA)
system
system-ip 10.1.300.1
site-id 300
organization-name ABHAVTECH-COM
region 2
role edge-router
!
! Frankfurt Hub - Region 2 (EMEA)
system
system-ip 10.1.301.1
site-id 301
organization-name ABHAVTECH-COM
region 2
role edge-router
!
! New Jersey Hub - Region 3 (Americas)
system
system-ip 10.1.400.1
site-id 400
organization-name ABHAVTECH-COM
region 3
role edge-router
!
! Dallas Hub - Region 3 (Americas)
system
system-ip 10.1.401.1
site-id 401
organization-name ABHAVTECH-COM
region 3
role edge-router
!
! Bangalore Branch - Region 1 (India)
system
system-ip 10.1.103.1
site-id 103
organization-name ABHAVTECH-COM
region 1
role edge-router
!
! Delhi Branch - Region 1 (India)
system
system-ip 10.1.104.1
site-id 104
organization-name ABHAVTECH-COM
region 1
role edge-router
!
! Noida Branch - Region 1 (India)
system
system-ip 10.1.105.1
site-id 105
organization-name ABHAVTECH-COM
region 1
role edge-router
2.6.3 Border Router Design
Border Router Role and Placement
BORDER ROUTER ARCHITECTURE
+==============================================================================+
| |
| ACCESS REGION 1 (INDIA) | ACCESS REGION 2 (EMEA) |
| +---------------------------+ | +---------------------------+ |
| | Mumbai Chennai | | | London Frankfurt | |
| | Bangalore Delhi Noida | | +---------------------------+ |
| +-------------+-------------+ | | |
| | | | |
| v | v |
| +---------------------------+ | +---------------------------+ |
| | BORDER ROUTER 1 | | | (Via Core Region) | |
| | Mumbai DC | | +---------------------------+ |
| | C8500-12X4QC | | |
| | Role: border-router | | ACCESS REGION 3 (AMERICAS) |
| +-------------+-------------+ | +---------------------------+ |
| | | | New Jersey Dallas | |
| | | +---------------------------+ |
| v | | |
| +---------------------------+ | | |
| | BORDER ROUTER 2 | | v |
| | Chennai DR |<---+----+---------------------------+ |
| | C8500-12X4QC | | (Via Core Region) | |
| | Role: border-router | +---------------------------+ |
| +-------------+-------------+ |
| | |
| v |
| +----------------------------------------------------------+ |
| | CORE TRANSPORT REGION | |
| | | |
| | Mumbai Border <======= Core Mesh =======> Chennai Border |
| | | |
| | - Inter-region route exchange via OMP | |
| | - Route summarization at border | |
| | - Policy enforcement point | |
| +----------------------------------------------------------+ |
| |
+==============================================================================+
Border Router Configuration
!======================================================================
! BORDER ROUTER CONFIGURATION - MUMBAI DC
!======================================================================
!
! System Configuration
system
system-ip 10.1.100.1
site-id 100
organization-name ABHAVTECH-COM
vbond vbond.abhavtech.com
region 1
role border-router
secondary-region 0
affinity-group preference 1
!
! OMP Configuration for Border Role
omp
graceful-restart
no shutdown
advertise connected
advertise static
advertise aggregate
!
! Route Aggregation for Core Advertisement
route-aggregation
aggregate 10.1.100.0/22
summary-only
aggregate 10.10.0.0/16
summary-only
!
! Affinity Group Configuration
affinity-group preference 1
region 1
!
affinity-group preference 2
region 0
2.6.4 Route Exchange and Summarization
OMP Route Hierarchy
| Route Type |
Scope |
Advertisement |
Example |
| OMP Routes |
Intra-region |
Full routes within region |
10.10.100.0/24 |
| Summary Routes |
Inter-region |
Aggregated at border |
10.10.0.0/16 |
| Transport Routes |
Core region |
Border-to-border |
Via core vSmarts |
| Service Routes |
Global |
Service-specific |
Cloud OnRamp |
Route Summarization Design
ROUTE SUMMARIZATION HIERARCHY
+==============================================================================+
| |
| REGION 1 (INDIA) - Full Routes |
| +------------------------------------------------------------------+ |
| | Site | Network | Advertised Within Region | |
| +------------------------------------------------------------------+ |
| | Mumbai | 10.10.100.0/24 | Full /24 | |
| | Chennai | 10.10.200.0/24 | Full /24 | |
| | Bangalore | 10.10.103.0/24 | Full /24 | |
| | Delhi | 10.10.104.0/24 | Full /24 | |
| | Noida | 10.10.105.0/24 | Full /24 | |
| +------------------------------------------------------------------+ |
| | |
| v |
| +------------------------------------------------------------------+ |
| | BORDER AGGREGATION (Mumbai/Chennai) | |
| | Advertise to Core: 10.10.0.0/16 | |
| +------------------------------------------------------------------+ |
| | |
| v |
| +------------------------------------------------------------------+ |
| | CORE REGION (Region 0) | |
| | Receives: | |
| | - 10.10.0.0/16 from India Border | |
| | - 10.20.0.0/16 from EMEA Border | |
| | - 10.30.0.0/16 from Americas Border | |
| +------------------------------------------------------------------+ |
| | |
| v |
| INTER-REGION REACHABILITY |
| +------------------------------------------------------------------+ |
| | From Region 1 (India) to: | |
| | - EMEA: 10.20.0.0/16 via Core | |
| | - Americas: 10.30.0.0/16 via Core | |
| +------------------------------------------------------------------+ |
| |
+==============================================================================+
Route Policy Configuration
!======================================================================
! OMP ROUTE POLICY FOR MRF
!======================================================================
!
! Policy for advertising to Core Region
policy
route-policy ADVERTISE-TO-CORE
sequence 10
match
prefix-list INDIA-SUMMARY
action accept
set
aggregator
as-path prepend 65001
sequence 20
action reject
!
! Prefix List for Summarization
policy
prefix-list INDIA-SUMMARY
ip-prefix 10.10.0.0/16
!
! Policy for receiving from Core Region
policy
route-policy RECEIVE-FROM-CORE
sequence 10
match
as-path-list EMEA-ORIGINS
action accept
set
preference 100
sequence 20
match
as-path-list AMERICAS-ORIGINS
action accept
set
preference 100
sequence 30
action reject
!
! AS-Path Lists
policy
as-path-list EMEA-ORIGINS
regex "65002"
as-path-list AMERICAS-ORIGINS
regex "65003"
2.6.5 Affinity Group Design
Affinity Group Strategy
| Affinity Group |
Preference |
Sites Included |
Traffic Flow |
| AG-1 (India Primary) |
1 |
Mumbai, Chennai, Bangalore, Delhi, Noida |
Intra-India first |
| AG-2 (EMEA Primary) |
1 |
London, Frankfurt |
Intra-EMEA first |
| AG-3 (Americas Primary) |
1 |
New Jersey, Dallas |
Intra-Americas first |
| AG-0 (Global) |
2 |
All Border Routers |
Inter-region via core |
Affinity Configuration
!======================================================================
! AFFINITY GROUP CONFIGURATION
!======================================================================
!
! India Sites - Prefer local region
! Mumbai DC
affinity-group
group 1
preference
group 1 preference 1
group 0 preference 2
group 2 preference 3
group 3 preference 3
!
! London Hub - Prefer EMEA, then nearest regions
affinity-group
group 2
preference
group 2 preference 1
group 0 preference 2
group 1 preference 3
group 3 preference 4
!
! New Jersey Hub - Prefer Americas, then nearest regions
affinity-group
group 3
preference
group 3 preference 1
group 0 preference 2
group 2 preference 3
group 1 preference 4
Traffic Flow Optimization
AFFINITY-BASED TRAFFIC FLOW
+==============================================================================+
| |
| EXAMPLE: Bangalore to Delhi (Same Region) |
| +------------------------------------------------------------------+ |
| | Bangalore ---> Mumbai Border ---> Delhi | |
| | Path: Regional hub-and-spoke (Affinity Group 1) | |
| | Latency: ~25ms | |
| +------------------------------------------------------------------+ |
| |
| EXAMPLE: Bangalore to London (Cross-Region) |
| +------------------------------------------------------------------+ |
| | Bangalore ---> Mumbai Border ---> [Core] ---> Chennai Border --> | |
| | London | |
| | Path: Via Core Region (Affinity Group 0) | |
| | Latency: ~150ms | |
| +------------------------------------------------------------------+ |
| |
| EXAMPLE: London to Frankfurt (Same Region) |
| +------------------------------------------------------------------+ |
| | London <---> Frankfurt | |
| | Path: Direct regional tunnel (Affinity Group 2) | |
| | Latency: ~15ms | |
| +------------------------------------------------------------------+ |
| |
+==============================================================================+
2.6.6 vSmart Distribution for MRF
vSmart Placement Strategy
| vSmart |
Location |
Role |
Regions Served |
Capacity |
| vSmart-1 |
Mumbai DC |
Regional |
Region 1 (India) |
2,000 edges |
| vSmart-2 |
Mumbai DC |
Regional |
Region 1 (India) |
2,000 edges |
| vSmart-3 |
Chennai DR |
Regional |
Region 2 (EMEA), Region 3 (Americas) |
2,000 edges |
| vSmart-4 |
Chennai DR |
Regional |
Region 2 (EMEA), Region 3 (Americas) |
2,000 edges |
| vSmart-C1 |
Mumbai DC |
Core |
Core Region 0 |
Border routers |
| vSmart-C2 |
Chennai DR |
Core |
Core Region 0 |
Border routers |
vSmart Configuration for MRF
!======================================================================
! vSMART CONFIGURATION FOR MRF - REGIONAL vSMART
!======================================================================
!
! vSmart-1 Mumbai (Regional)
system
system-ip 10.255.255.1
site-id 100
organization-name ABHAVTECH-COM
vbond vbond.abhavtech.com
region 1
role vsmart
!
omp
no shutdown
graceful-restart
send-path-limit 16
send-backup-paths
policy
control-policy REGION-1-POLICY
sequence 10
match route
region 1
action accept
sequence 20
match route
region 0
action accept
sequence 30
action reject
!
! Apply Control Policy
apply-policy
site-list REGION-1-SITES
control-policy REGION-1-POLICY out
!======================================================================
! vSMART CONFIGURATION FOR MRF - CORE vSMART
!======================================================================
!
! vSmart-C1 Mumbai (Core)
system
system-ip 10.255.255.10
site-id 100
organization-name ABHAVTECH-COM
vbond vbond.abhavtech.com
region 0
role vsmart
!
omp
no shutdown
graceful-restart
send-path-limit 4
send-backup-paths
!
policy
control-policy CORE-AGGREGATION
sequence 10
match route
aggregated
action accept
sequence 20
action reject
!
apply-policy
site-list BORDER-ROUTERS
control-policy CORE-AGGREGATION in
2.6.7 MRF Verification and Troubleshooting
Verification Commands
!======================================================================
! MRF VERIFICATION COMMANDS
!======================================================================
!
! Verify region assignment
show sdwan system status
!
! Expected Output:
! Region ID: 1
! Role: border-router
! Secondary Region: 0
!
! Verify affinity group membership
show sdwan affinity-group all
!
! Verify OMP routes by region
show sdwan omp routes region 1
show sdwan omp routes region 0
!
! Verify border router status
show sdwan control connections | include border
!
! Verify route summarization
show sdwan omp summary
!
! Verify inter-region connectivity
show sdwan bfd sessions region 0
Troubleshooting Scenarios
| Issue |
Symptom |
Verification |
Resolution |
| Region misconfiguration |
Sites not communicating |
show sdwan system status |
Correct region ID |
| Border router down |
Inter-region traffic fails |
show sdwan control connections |
Check border router health |
| Route not summarized |
Full routes in core |
show sdwan omp routes |
Verify aggregate config |
| Affinity mismatch |
Suboptimal path |
show sdwan affinity-group |
Adjust preferences |
| Core vSmart failure |
Inter-region fails |
show sdwan control connections |
Failover to secondary |
2.6.8 MRF Scalability Considerations
Capacity Planning
| Component |
Current |
Year 1 |
Year 3 |
Capacity Limit |
| Total WAN Edges |
15 |
25 |
50 |
20,000 |
| Regions |
3 + Core |
4 + Core |
5 + Core |
64 |
| vSmarts per Region |
2 |
2 |
2-4 |
20 |
| Border Routers |
2 |
4 |
6 |
16 per region |
| OMP Routes (Core) |
100 |
200 |
500 |
500,000 |
Growth Path
MRF SCALABILITY ROADMAP
+==============================================================================+
| |
| YEAR 0 (Current) |
| +------------------------------------------------------------------+ |
| | 3 Access Regions + 1 Core Region | |
| | 2 Border Routers (Mumbai, Chennai) | |
| | 4 Regional vSmarts + 2 Core vSmarts | |
| | 15 WAN Edges | |
| +------------------------------------------------------------------+ |
| | |
| v |
| YEAR 1 |
| +------------------------------------------------------------------+ |
| | 4 Access Regions (add APAC) | |
| | 4 Border Routers (add Singapore, Sydney) | |
| | 6 Regional vSmarts + 2 Core vSmarts | |
| | 25 WAN Edges | |
| +------------------------------------------------------------------+ |
| | |
| v |
| YEAR 3 |
| +------------------------------------------------------------------+ |
| | 5 Access Regions (add LATAM) | |
| | 6 Border Routers (add Sao Paulo) | |
| | 10 Regional vSmarts + 4 Core vSmarts | |
| | 50 WAN Edges | |
| +------------------------------------------------------------------+ |
| |
+==============================================================================+
Document Control
| Version |
Date |
Author |
Changes |
| 1.0 |
December 30, 2025 |
Network Architecture Team |
Initial release |
This document is part of the Abhavtech.com SD-WAN Documentation Suite
Confidential - Internal Use Only