Month: November 2024

CML 2.7 – Adding the IOS-XRv image

Cisco Modeling Labs 2.7

As of Cisco Modeling Labs (CML) version 2.7, the standard IOS-XRv image has limited support and fewer features compared to the newer IOS-XRv 9000 image, which is the preferred option for IOS XR simulations in CML. The IOS-XRv image is not included in the refplat ISO and the only option available after a fresh CML 2.7 install is XRV9K. 

The IOS-XRv 9000 image includes more robust MPLS and VRF capabilities, such as successful L3 MPLS VPN implementations, making it a better choice for complex routing scenarios. However, the IOS-XRv image itself remains available with limitations, including a lack of L2 MPLS VPN support in certain scenarios.

XRv vs XRv9K resources

The only challenge with the IOS-XRv 9000 image is that it requires slightly more resources than the IOS-XRv image.

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MPLS – Segment Routing (MPLS-SR) Theory

MPLS – Segment Routing (MPLS-SR)

Multiprotocol Label Switching (MPLS) is a data-forwarding technique that uses labels to route packets along predefined paths, rather than traditional IP routing, which relies on layer-3 addresses. By attaching labels to packets, MPLS allows for high-speed data transfers and efficient traffic engineering, making it a go-to for large-scale carrier and enterprise networks.

Segment Routing (SR), is an extension for link-state IGPs (OSPF and IS-IS). Traditional MPLS forms Label Switched Paths (LSPs) through label distribution protocols such as LDP or RSVP-TE. SR simplifies this by eliminating these protocols and allowing source-based routing. In SR, the source node attaches a list of segments (labels) to the packet, guiding it through the desired path without the need for intermediate nodes to compute routing decisions. This shift enables networks to be more adaptable and scalable.

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