Summary
This article describes network separation requirements for MOTOTRBO Capacity Plus Multi-Site and Single Site systems, including VLAN-based and router-based topologies, and provides a reference network diagram.
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According to the Motorola System Planner, all radio sites must be logically separated to prevent Rest Channel broadcasts from propagating outside their intended site. This applies to all Capacity Plus Multi-Site systems, and to Capacity Plus Single Site systems with more than one repeater.
Reason for Network Separation
The Rest Channel repeater periodically sends broadcast announcements (to 255.255.255.255). If multiple sites or unrelated network devices share the same LAN segment, these broadcasts may lead to:
• Incorrect roaming behavior (rest channel hopping)
• Unintended network traffic load
• System instability
Network Design Requirements
Each radio site must operate on its own dedicated LAN segment, isolated both:
• From general IT devices (PCs, printers, IoT devices, etc.), and
• From other MOTOTRBO radio sites, since each site has its own Rest Channel.
When Operating with Hairpin NAT (Firmwares before R02.20.00)
• All repeaters at the same site must be within their own subnet.
• All repeaters must have a static IP address.
• Disable UDP Port Address Translation (PAT) on the router.
• The site router must support hairpin (NAT loopback) behavior.
• This was the standard deployment approach in earlier systems.
When Operating Without Hairpinning (Firmware R02.20.00 and newer)
Firmware R02.20.00+ allows operation without NAT hairpinning, simplifying network design.
| Requirement | Description |
|---|---|
| Repeater IP Addressing | Each repeater must have a unique static IP |
| UDP Ports | Each repeater must use a unique UDP port |
| Rest Channel (Site IP) | Must also use unique IP + port |
| Router Behavior | Disable UDP Port Address Translation (PAT) |
VLAN Switch-Only Topology
Starting with firmware R02.20.00, multiple radio sites can be logically separated on a single physical switch using VLAN segmentation, reducing hardware requirements while maintaining site isolation.
Some Multisite Capacity Plus deployments can operate without routers, using only Layer-2 switches between sites. In this case:
• Each site must use a separate IP subnet.
• The switch must be able to prevent broadcast packets to 255.255.255.255 from leaving the site.
• VLANs must be used to maintain site isolation.
Nuances of Routerless Deployment:
| Consideration | Impact |
|---|---|
| IP Addressing | Requires more IPv4 space (1 subnet per site) |
| Security | Repeaters become visible on the network (reduced isolation) |
| Control | Routers allow firewall, VPN, redundancy — switches do not |
Use router-based site separation unless there is a specific design requirement to avoid routers. For a detailed explanation of this design approach and its considerations, see this article by Wayne Holmes.
Example Network Layout for Capacity Plus Multi-Site
The following diagram shows a recommended reference topology for Capacity Plus Multi-Site deployments. The same layout is also applicable to Capacity Plus Single Site systems when the site contains more than one repeater.
+Corporate Network-+ | | IP addresses are given as example | LAN: 192.168.1.1 | ++-----------------+ All ports are UDP | | | | +TRBOnet PC--------------+ | | | |--Software-Site-0-| LAN: 192.168.1.10 | | | DDMS (optional) | | | MNIS TCP | | +------------------------+ | | | +Master Site Router------+ +Master Repeater--------------------+ | | | | | | | WAN: 192.168.1.11 | | Ethernet Addr: 10.10.1.2:50011 | | | LAN: 10.10.1.1 +-+-+ Master LE Addr: 192.168.1.11:50011| |--Radio-Site-1--| | | | Rest Channel: 10.10.1.9:55100 | | | Forwarding Rules: | | | | | | WAN to 10.10.1.2:50011 | | +-----------------------------------+ | | WAN to 10.10.1.X:5001X | | | | WAN to 10.10.1.9:55100 | | +N+1 Peer Repeater------------------+ | +------------------------+ | | | | | | Ethernet Addr: 10.10.1.X:5001X | | +-+ Master LE Addr: 192.168.1.11:50011| | | Rest Channel: 10.10.1.9:55100 | | | | | +-----------------------------------+ | | +Site Router-------------+ +Peer Repeater----------------------+ | | | | | | | WAN: 192.168.1.12 | | Ethernet Addr: 10.10.2.2:50021 | | | LAN: 10.10.2.1 +-+-+ Master LE Addr: 192.168.1.11:50011| |--Radio-Site-2--| | | | Rest Channel: 10.10.2.9:55200 | | | Forwarding Rules: | | | | | | WAN to 10.10.2.2:50021 | | +-----------------------------------+ | | WAN to 10.10.2.X:5002X | | | | WAN to 10.10.2.9:55200 | | +N+1 Peer Repeater------------------+ | +------------------------+ | | | | | | Ethernet Addr: 10.10.2.X:5002X | | +-+ Master LE Addr: 192.168.1.11:50011| | | Rest Channel: 10.10.2.9:55200 | | | | | +-----------------------------------+ | | +Site Router-------------+ +Peer Repeater----------------------+ | | | | | | | WAN: 192.168.1.13 | | Ethernet Addr: 10.10.3.2:50031 | | | LAN: 10.10.3.1 +-+-+ Master LE Addr: 192.168.1.11:50011| | | | | | Rest Channel: 10.10.3.9:55300 | +--Radio-Site-3--| Forwarding Rules: | | | | | WAN to 10.10.3.2:50031 | | +-----------------------------------+ | WAN to 10.10.3.X:5003X | | | WAN to 10.10.3.9:55300 | | +N+1 Peer Repeater------------------+ +------------------------+ | | | | | Ethernet Addr: 10.10.3.X:5003X | +-+ Master LE Addr: 192.168.1.11:50011| | Rest Channel: 10.10.3.9:55300 | | | +-----------------------------------+