Step-by-Step: Configuring SameView VLAN for Multi-Site NetworksSameView VLAN is a solution for logically segmenting traffic across multiple sites while preserving centralized management and consistent policies. This article walks through planning, design, configuration, and verification steps to deploy SameView VLAN in a multi-site environment. It assumes familiarity with basic networking concepts (VLANs, trunking, routing) and access to your network devices’ management interfaces.
Overview and benefits
SameView VLAN enables you to:
- Isolate traffic by department or function across geographically dispersed locations.
- Maintain consistent policies (security, QoS) for a VLAN regardless of site.
- Simplify management by reducing the number of unique VLANs and configurations per site.
- Reduce broadcast domains while allowing controlled inter-site communication.
Pre-deployment planning
- Inventory and requirements
- List all sites, their physical topology, and available links (MPLS, VPN, dark fiber).
- Identify which host groups need the same VLAN across sites (e.g., POS systems, VoIP, CCTV).
- Collect device models and firmware versions for switches, routers, and firewalls.
- Addressing and routing plan
- Decide whether SameView VLANs will use the same IP subnet across sites (layer 2 stretched) or unique subnets with routed inter-site connectivity (layer 3).
- Pros of stretched L2: same addressing, simpler host moves.
- Cons of stretched L2: higher broadcast/multicast traffic, potential spanning tree complexity.
- If using L3, prepare routing and DHCP relay strategies.
- Transport selection
- Choose underlying transport: MPLS VPN, L2TPv3, VXLAN, EVPN, GRE over IPsec, or site-to-site VPNs. VXLAN/EVPN is modern and scalable; MPLS is common in service-provider networks.
- Ensure MTU supports encapsulation overhead (e.g., VXLAN adds ~50–60 bytes).
- High-level security and QoS
- Define ACLs, firewall rules, and QoS profiles to apply consistently.
- Decide where to enforce segmentation (edge devices vs. centralized firewalls).
Design choices and examples
-
Layer-2 stretched SameView VLAN (VXLAN EVPN)
- Use VXLAN to extend VLANs over IP; EVPN for control-plane MAC learning.
- Best when hosts require same subnet or vendor protocols that need L2 adjacency.
-
Layer-3 distributed (Routed)
- Each site keeps local subnet; routing or firewall handles inter-site access.
- Better scalability and isolation; recommended for most enterprise deployments.
Example: Three-site deployment
- Site A (HQ), Site B (Branch1), Site C (Branch2).
- SameView VLAN 100 for VoIP. Option A: VXLAN stretches VLAN 100 across all sites. Option B: VLAN 100 at each site with routes and SIP-aware SBC at HQ.
Step-by-step configuration (VXLAN EVPN example)
Prerequisites:
- IP underlay between sites configured and reachable.
- Devices that support VXLAN EVPN (modern campus/data-center switches or routers).
- Sufficient MTU (jumbo frames recommended).
- Configure IP underlay
- Assign loopback addresses for BGP EVPN routers.
- Configure IGP (OSPF/IS-IS) or static routes for reachability. Example (brief):
- Loopbacks: 10.0.0.⁄32 (Site A), 10.0.0.⁄32 (Site B), 10.0.0.⁄32 (Site C).
- Ensure IP connectivity and low latency between loopbacks.
- Enable BGP EVPN
- Configure BGP sessions between sites or to a route-reflector.
- Configure address-family l2vpn evpn and advertise EVPN routes.
- Configure VXLAN and VNI mapping
- Map VLAN 100 to VNI (e.g., VNI 10100).
- Configure VTEP interfaces bound to loopbacks.
- Configure VLAN interfaces and bridging
- Create VLAN 100 on each switch.
- Bridge VLAN 100 to VNI 10100 so local ports participate in the EVPN.
- Configure multicast or ingress replication (if needed)
- EVPN typically handles unknown unicast via control plane; for flood/unknowns, choose ingress replication or IP multicast.
- Validate MAC learning and ARP
- Ensure MAC addresses learned locally are advertised via EVPN and visible at remote sites.
- Apply security and QoS
- Deploy ACLs either on VTEPs or edge switches to restrict unwanted traffic.
- Apply QoS markings for voice/video traffic and configure DSCP trust on access ports.
Step-by-step configuration (Routed approach with DHCP relay example)
- Create local VLANs at each site (VLAN 100).
- Assign unique subnets per site, e.g., Site A 192.168.100.0/24, Site B 192.168.101.0/24.
- Configure DHCP servers:
- Centralized DHCP: Configure DHCP relay (ip helper) on each site’s SVI pointing to central DHCP server.
- Distributed DHCP: Local DHCP server instances with synchronized options.
- Configure routing
- Ensure routes between sites via MPLS/VPN/BGP or site-to-site tunnels.
- Use route filters and policies to control which networks are reachable.
- Implement inter-site security
- Place a centralized firewall or use distributed firewalls to enforce policies.
- For services that must appear identical, use NAT or proxy services.
Verification and testing
- Connectivity tests:
- Ping across sites (L2: same IP; L3: gateway and host-to-host).
- Verify MAC/ARP presence in EVPN tables (for VXLAN).
- Traffic tests:
- Simulate voice or video to verify QoS and latency.
- Generate broadcast/multicast to observe flood behavior.
- Failover tests:
- Bring down a VTEP or transport link to validate redundancy and reconvergence.
Key checks:
- VXLAN EVPN: EVPN routes in BGP, VNI mappings, MAC mobility if hosts move.
- Routed: Correct routes, DHCP leases, firewall policies.
Common pitfalls and troubleshooting
- MTU issues causing fragmentation or dropped VXLAN traffic — increase MTU or adjust MSS.
- Asymmetric routing when using centralized services — use policy-based routing or hairpinning.
- Spanning Tree loops if parts of L2 are bridged unintentionally — prefer EVPN control plane over manual STP hacks.
- Excessive broadcast domains in stretched L2 — monitor and limit broadcast domains; consider L3 segmentation.
Troubleshooting commands (examples depends on vendor):
- Show BGP EVPN routes.
- Show VXLAN VNI status and peers.
- Show MAC address table and ARP for specific VLANs.
- Packet captures on VTEP and underlay links.
Operational considerations
- Monitoring and visibility: use telemetry and flow-export (sFlow/NetFlow) to track inter-site traffic.
- Change control: treat SameView VLAN additions/changes carefully — they can impact multiple sites.
- Automation: codify VXLAN/VTEP and route configurations in IaC tools (Ansible, Terraform) to reduce drift.
- Documentation: keep a clear mapping of VLAN-to-VNI, IP addressing, and site roles.
Example configuration snippets (vendor-neutral pseudocode)
# Underlay: configure loopback and routing loopback 0 ip address 10.0.0.1/32 router ospf 1 network 10.0.0.0/24 area 0 # BGP EVPN router bgp 65001 neighbor 10.0.0.2 remote-as 65002 address-family l2vpn evpn # VXLAN VTEP and VNI interface loopback0 ip address 10.0.0.1/32 vtep source-interface loopback0 vni 10100 associate-vlan 100 # VLAN and SVI vlan 100 interface vlan 100 ip address 192.168.100.1/24 When to choose which approach
- Choose VXLAN EVPN when you need true L2 adjacency and are operating in data center or modern WANs with capable hardware.
- Choose routed per-site VLANs when scalability, security, and simpler failure domains are higher priorities.
Summary
Deploying SameView VLANs across multiple sites requires careful planning of transport, addressing, and security. VXLAN EVPN offers L2 stretch with centralized control, while routed designs improve scalability and isolation. Validate MTU, route distribution, and policy enforcement, and automate repetitive tasks to keep configurations consistent across sites.
If you want, I can produce vendor-specific configuration examples (Cisco IOS XE, Juniper Junos, Arista EOS, or a VXLAN EVPN with NSX/Tanzu), or design templates for your exact topology — tell me the vendor and topology details.
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