Switching is a combination of routing and bridging in which these two entities are performed in one switch or a series of switches. He said that it enables the network administrator to partition his networks due to security and performance challenges while simultaneously allowing stations in the different segments to communicate. What is integrated routing and bridging, how does it function its similarities and differences with routing and bridging, its application, configuration, and some of the most asked questions have been outlined in this article.
what is bridge mode router and integrating routing?
Integrated routing and bridge mode on router are the functions handled by router with bridge mode in the OSI layer 3.
Integrated routing and bridging (IRB) is a feature that enables the router bridge mode to perform as bridges for the connection of different segments or subnets of the network yet it performs the routing function. In IRB, switches and routers can both do layer 2 broadcasting and layer 3 routing on a single port.
Restrictions
Restriction of the network is frequently applied to enhance the safety of the network dividing the various users, servers, applications, and so on. Integrated routing and bridging (IRB) is a feature that allows routers to act as bridge mode router between different network segments or subnets while still providing routing functionality. With IRB, devices like switches and routers can perform both layer 2 bridging and layer 3 routing on the same physical interface.
Network segmentation is commonly used to improve network security by isolating user groups, servers, applications, and more. However, routing is still required to allow communication between these segmented networks. IRB provides a way to achieve both segmentation and inter-network communication using a single network device or series of interconnected devices.
Key differences between traditional routing and bridging
The main differences between traditional routing/bridging and integrated routing and bridging are:
- Single device: IRB allows a single networking device like a bridge router or layer 3 switch to perform both routing and bridging functions. Traditionally these required separate routers and bridges/switches.
- Same interface: With IRB, a single physical or logical interface can operate both as a router interface and a bridge port. Traditional models required different interfaces for routing and bridging.
- VLAN routing: IRB supports routing between VLANs (Virtual LANs) configured on the same switch interface. Regular routing would require separate physical interfaces or more complex configurations.
- Configuration: IRB is configured by associating VLANs (layer 2 domain) to layer 3 interfaces and IP addresses in the same way virtual interfaces are mapped in traditional routers. This is simpler than separate configurations.
- Scalability: As IRB uses a single device, it has better scalability than separate routers and switches when networks grow in size and complexity. Resources are shared instead of multiplied.
How integrated routing and bridging works
The basic mechanism of integrated routing and bridging involves associating Virtual LANs (VLANs) on a physical interface to Layer 3 virtual interfaces configured on the networking device:
- Step 1: Configure VLANs on the physical switch/router interface using IEEE 802.1Q trunking to segment broadcast domains.
- Step 2: Create SVIs (Switch Virtual Interfaces) on the device and assign them an IP address from a routable network.
- Step 3: Associate the SVIs to the VLANs created in step 1 so the interface acts as a Layer 3 gateway for that VLAN.
- Step 4: Traffic from one VLAN is bridged locally while traffic meant for a different VLAN is routed through the SVI using its IP address.
This allows the networking device to bridge traffic within each VLAN locally for performance while also routing between VLANs/broadcast domains. Multiple VLANs can use the same physical interface and IP addressing schema for connectivity.
Common use cases
Some common applications of integrated routing and bridging include:
- Network segmentation: Segregate user types, servers, IoT devices, etc into security zones with isolated Layer 2 domains.
- VLAN routing: Route traffic between multiple VLANs configured on the same physical interface without requiring extra ports.
- VPN connectivity: IRB allows VPN tunnel interfaces to bridge local VLANs to remote sites via Layer 3 routing.
- Server virtualization: Datacenter and cloud deployments commonly use IRB to interconnect virtual servers in different VLANs.
- Campus/branch offices: Route traffic between different segments across a campus or between branch office networks over a WAN connection.
- Convergence: Collapse expensive routers and switches into a single device for cost-savings in smaller networks.
- Scalability: Add VLANs and IP schemas easily on existing interfaces as networks grow without new hardware.
So in summary, any application that requires network segmentation but also routing between segments can benefit from an IRB deployment.
Configuration and management
The configuration of integrated routing and bridging varies based on the vendor and platform but generally follows these common steps:
Configure VLANs
- Create VLAN IDs to segment broadcast domains
- Assign hosts, ports, trunks etc to the appropriate VLAN
Create SVIs
- Configure virtual “switch interfaces” using the SVI command
- Assign SVIs an IP address from the network
Associate VLANs to SVIs
- Use the encapsulation dot1q command to map VLAN IDs to the SVIs
- This associates the Layer 2 and Layer 3 configurations
(Optional) Enable routing protocols
- If dynamic routing is needed, enable protocols like OSPF or EIGRP
- Map protocols to the SVIs so routes are advertised
Configure security and management
- Apply firewall policies, and ACLs between VLANs for security
- Configure logging, SNMP, RADIUS, etc for ongoing management
Some platforms may require additional steps for specific features. But in general, once the above core tasks are completed devices will route between VLANs/segments using their integrated switching and routing capability.
Comparison with traditional models
Here’s a quick comparison table of integrated routing and bridging versus separate routers and switches:
| Parameter | Integrated Routing/Bridging | Traditional Routing and Bridging |
| Devices required | Single router/switch | Separate routers and switches |
| Configuration complexity | Simpler with consolidated IOS | More complex with multiple devices |
| Port/interface utilization | Makes best use of available ports | Requires more physical ports |
| Scalability | Scales well by adding VLANs/addresses | Hits capacity limits of individual boxes |
| Troubleshooting | Single management plane | Issues span multiple boxes |
| Cost | More affordable for smaller networks | Requires more capital expenditure |
| Performance | Can have lower performance than dedicated boxes | Dedicated appliances optimize routing/switching |
As the table shows, IRB provides consolidation benefits for smaller networks and campus environments, especially around cost, management, and scalability. However dedicated network appliances optimize performance for extremely large or critical infrastructures.
FAQs
Q. How is routing between VLANs achieved with IRB?
A. Routing between VLANs is enabled by associating each VLAN configured on the switch ports to a unique Layer 3 interface (SVI). The SVI acts as the default gateway for the VLAN and routes traffic to other SVIs/VLANs using standard routing protocols and IP forwarding.
Q. Can IRB support dynamic routing protocols?
A. Yes, all major dynamic routing protocols like OSPF, EIGRP, BGP, etc. can be configured on the SVIs to advertise routes and exchange routes between VLANs/segments in an IRB network. This allows automatic route updates.
Q. Is there a performance impact with IRB vs dedicated devices?
A. While IRB provides consolidation benefits, dedicated routers, and switches can perform switching and routing functions separately at wire speed on separate ASICs/hardware. So performance-critical networks may still require dedicated appliances to avoid any potential bottlenecks.
Q. Can I configure multiple IP subnets on the same VLAN?
A. No, each SVI/VLAN can have only one IP address configuration since they represent a single IP subnet/network. To use multiple IP ranges, they need to be configured on separate VLANs that are interconnected via IRB.
Conclusio
In conclusion, integrated routing and bridging provide an effective means of segmenting networks for security while still enabling routing between segments on the same physical networking device. Its single management plane, simpler configuration, and consolidation of resources make it preferable for smaller campus and branch office deployments compared to separate routers and Layer 2/3 switches. With a proper understanding of its capabilities and limitations, IRB remains a relevant architecture to consider for many modern network infrastructures today.
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