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Integrated Routing and Bridging on JCNR

Integrated Routing and Bridging (IRB) is a networking concept that combines the functionalities of routing and bridging within a single network infrastructure. This integration allows for seamless communication between devices on different network segments or subnets.

In a router, packets are forwarded based on their destination IP addresses. Routers operate at Layer 3 (Network Layer) of the OSI model and make decisions about the best path for a packet to reach its destination. In a bridge, frames are forwarded based on MAC addresses. Bridges operate at Layer 2 (Data Link Layer) and use MAC addresses to determine the appropriate segment for a frame.

IRB combines the features of routing and bridging in a single device, typically a router. This allows the device to make forwarding decisions based on both IP addresses and MAC addresses. IRB is particularly useful when you want to enable communication between devices on different subnets in a network. It allows the router to route traffic between subnets based on IP addresses. Instead of having separate routers and bridges, IRB simplifies network design by consolidating these functions into a single device. In VLAN environments, each VLAN can be considered a separate subnet, and the router with IRB capability can route traffic between these VLANs.

Starting with Juniper Cloud-Native Router (JCNR) Release 23.4, JCNR supports IRB, using which you can configure both routing and bridging settings in a unified manner. You can configure IRB interfaces and connect Bridge Domains (BD’s) to perform routing between bridge domains.

To learn more about IRB, see Integrated Routing and Bridging.

Note:
  • Configurable MAC address on IRB is not supported in JCNR Release 23.4

  • MTU is not configurable on IRB

  • BGP unnumbered is not supported on IRB interfaces

Configuring IRB

A pair of IRB interfaces are created for each BD, one for host connectivity (i.e., tap IRB interface) and another for forwarding traffic on fabric (i.e., fabric IRB interface). A single tap interface is created per L2 instance and all tap IRB interfaces that are configured in that L2 instance are created as sub-interfaces on that tap interface.

Consider the following topology shown below and configure IRB on JCNR.

Configuring IRB

Configuring an IRB interface

Note:

Use the configlet resource to configure the cRPD pods.

Attaching an IRB interface as an L3-routing interface to a Bridge

Attach an IRB interface as an L3-routing interface to a Bridge using the example below.

Attaching an IRB interface to VRF

An IRB interface can be a part of VRF-0 or VRF-N. The example shown below demonstrates how you can attach IRB.419 to a VRF Blue19.

Troubleshooting IRB

Use the commands listed in the sections below to troubleshoot an IRB setup.

cRPD CLI Commands

The following CLI commands can be executed on the cRPD CLI. To access the cRPD CLI, see Access cRPD CLI.

  • show bridge mac-table vlan-id <id>: Provides the Bridge MAC table details.

  • show bgp summary: Provides a summary of the BGP session running on the IRB.

  • show bfd session: Provides a summary of the BFD session running on the IRB.

  • ping routing-instance blue19 1.104.19.3 source 1.104.19.4 count 1 rapid: Provides a confirmation of the network connectivity to the IRB interface from CE2.

  • ping routing-instance blue19 6.1.19.1 source 1.104.19.4 count 1 rapid: Provides a confirmation of the network connectivity to remote prefixes from CE2 through the IRB interface.

  • traceroute routing-instance blue19 6.1.19.1 source 1.104.19.4 no-resolve: Provides the trace routes to remote prefixes from CE2 through the IRB interface.

vRouter CLI Commands

The following CLI commands can be executed on the vRouter CLI. To access the vRouter CLI, see Access vRouter CLI.

  • vif --list | grep <interface ID>: Provides the VIF ID of the specified interface.

  • vif --get 26: Provides the VRF ID where IRB.419 is attached to.

  • rt --get 1.104.19.4/32 --vrf 2: Provides the data plane encapsulation for CE2’s IP.

  • purel2cli --mac show: Provides the MAC table in the vRouter.