Switching and routing
NetSim models enterprise networks at Layer 2 and Layer 3: VLANs and detailed Layer 3 switches, dynamic routing protocols, multicast and control-plane signalling, access control, address translation, and queue management. Configure each through the GUI or text files and trace packets end to end.
A routed and switched network in NetSim
Routers, Layer 2 and Layer 3 switches, and wired hosts, each with its own interface addresses.
Switching
VLAN segmentation and a detailed Layer 3 switch model.
Virtual LAN (VLAN)
A VLAN is a group of hosts that communicate as if attached to the same broadcast domain, regardless of physical location. A workgroup can share one VLAN even when its machines sit on different LAN segments or are intermingled with other teams.
- VLAN tagging, VLAN ID and VLAN name
- Access and trunk ports
- Inter-VLAN routing
- Configuration through GUI or text file
Detailed switch model
- Switching techniques
- Spanning tree protocol with multiple spanning tree instances per switch
- Unicast, broadcast and multicast switching
- Promiscuous mode
Routing and Layer 3 services
Multicast and control signalling, access control, address translation, and static routes.
IGMP
Internet Group Management Protocol for multicast group membership.
- IGMP messages: Query, Report
- Host state machine and router state machine
ICMP
Internet Control Message Protocol for diagnostics and signalling.
- ICMP control messages
- ICMP continuous polling
- Router advertisement
Static routes
Manually defined paths between two routers. They use less bandwidth than dynamic routes and suit predictable, simple network designs, but cannot react to topology changes and must be reconfigured by hand when the network changes.
Access Control List (ACL)
A sequential list of permit or deny statements that filters traffic by address or upper-layer protocol. A permit statement allows traffic; a deny statement blocks it.
- Action: permit, deny
- Direction: inbound, outbound, both
- Protocol-wise blocking
- Interface ID blocking
- Source and destination IP address
- Source and destination port numbers
Network Address Translation
NAT virtualizes IP addresses to improve security and reduce the number of public addresses an organization needs. A NAT device has at least one inside interface and one outside interface, translating local addresses to globally unique ones as packets cross the boundary.
- Public IP of a host obtained from the WAN router
- Hides the internal network behind one address
Routing protocols
Distance-vector and link-state routing, configurable down to the timer.
RIP
Routing Information Protocol with configurable timers.
- Update timer
- Timeout timer
- Garbage collection timer
OSPF
Open Shortest Path First, with the full set of configurable parameters:
- Area ID
- Hello Interval
- Router Dead Interval
- Router Priority
- Output Cost
- LSRefresh Time
- LSA Maxage
- Increment Age
- Maxage Removal Time
- MinLS Interval
- SPFCalc Delay
- Flood Timer
- Rxmt Interval
- Send Delay Update
- Advertise Self Interface
- Include Subnet Route
- External Routing Capability
Traffic management
Queue management and scheduling disciplines at the router interface.
Queue management
- RED (Random Early Detection)
- W-RED (Weighted RED)
- Drop Tail
Scheduling disciplines
- First-in-first-out (FIFO) queuing
- Round Robin
- Priority queuing (PQ)
- Weighted-fair queuing (WFQ)
- Earliest deadline first (EDF)
Standards followed
IETF RFCs implemented across the routing and switching stack.
Built to be extended
NetSim ships with protocol source code in C. Modify the routing and switching stack and develop your own protocols.
Documentation
Manuals, the Advanced Routing library, and the support knowledge base.