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FEC types

Ratheesh mv
Level 1
Level 1

Hi

 

Ratheeshmv_0-1733219459324.png

When I ping from PE1 to PE5 by "ping mpls ipv4 5.5.5.5/32" command, FEC target is

Ratheeshmv_1-1733219518436.png

 

When I ping from PE1 to PE5 by "ping mpls ipv4 5.5.5.5/32 fec-type  generic" command, FEC target is

Ratheeshmv_1-1733219518436.png

I am bit confused about these 2 diff FEC target . Could someone explain the difference and relevance of the FEC target?

FEC type : IPv4 IGP-prefix segment ID is having protocol information too . What is the use of addressing protocol in the data plane verification.

 

Thanks in advance. 

 

 

1 Reply 1

AshSe
VIP
VIP

Hey @Ratheesh mv 

The two screenshots that you shared are absolutely same. Please check.


FEC type : IPv4 IGP-prefix segment ID is having protocol information too . What is the use of addressing protocol in the data plane verification.


In the context of Segment Routing (SR) and MPLS (Multiprotocol Label Switching), the FEC (Forwarding Equivalence Class) type "IPv4 IGP-prefix segment ID" is used to represent a specific prefix in the IGP (Interior Gateway Protocol) routing domain. This FEC type is associated with a Segment ID (SID), which is used to identify a particular segment in the SR architecture.

When you mention "protocol information" in the context of the data plane verification, it likely refers to the protocol (e.g., OSPF, IS-IS) that is used to advertise and manage the prefix and its associated SID in the control plane. Here's how protocol information is useful in the data plane verification:

1. Validation of Control Plane and Data Plane Consistency

  • The protocol information helps verify that the data plane (forwarding plane) is consistent with the control plane (routing plane). For example, if a prefix is advertised by OSPF with a specific SID, the data plane can be checked to ensure that the forwarding entries (e.g., MPLS label stack) match the expected behavior as per the OSPF advertisement.
  • This ensures that the forwarding path in the data plane aligns with the routing decisions made in the control plane.

2. Troubleshooting and Debugging

  • During troubleshooting, knowing the protocol that advertised the prefix can help identify the source of any inconsistencies or issues. For example, if a prefix is missing in the data plane, you can trace back to the protocol (e.g., OSPF or IS-IS) to see if it properly advertised the prefix and SID.
  • It also helps in identifying protocol-specific issues, such as misconfigurations or bugs in OSPF or IS-IS.

3. Protocol-Specific Behavior

  • Different IGP protocols (e.g., OSPF, IS-IS) may have specific behaviors or extensions for Segment Routing. For example, IS-IS might use TLVs (Type-Length-Value structures) to advertise SIDs, while OSPF uses LSAs (Link-State Advertisements). The protocol information helps ensure that the data plane is correctly interpreting and implementing the protocol-specific mechanisms.
  • This is particularly important in multi-protocol environments where both OSPF and IS-IS might be used.

4. Interoperability in Multi-Vendor Environments

  • In multi-vendor networks, different devices may implement Segment Routing differently based on the IGP protocol. Verifying the protocol information ensures that all devices interpret and forward traffic consistently, regardless of the vendor.

5. Data Plane Verification Tools

  • Tools used for data plane verification (e.g., ping, traceroute, or SR-specific tools) may rely on protocol information to simulate or verify the forwarding behavior. For example, they might check if the SID advertised by OSPF is correctly mapped to the MPLS label in the data plane.

6. Network Optimization and Planning

  • Protocol information can also be used to optimize the network. For example, if a prefix is advertised by multiple protocols, the network operator can decide which protocol's advertisement to prioritize based on the data plane behavior.

In summary, the protocol information associated with the "IPv4 IGP-prefix segment ID" FEC type is crucial for ensuring that the data plane correctly implements the forwarding behavior defined by the control plane. It aids in consistency checks, troubleshooting, protocol-specific optimizations, and overall network reliability.

 

Hope This Helps!!!

AshSe

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