Benefits of segment Routing

Benefits of segment Routing are as follows:-

1. SDN ready

      a) Foundation for Application engineered routing( AER)

      b) Can provide strict performance guarantees

      c) Efficient use of network resources

      d) Router can inject traffic with the segment list without any additional need of signaling protocol in the network.

2. Simplified
        a) Simple operation without any separate protocols like LDP and RSVP.
        b) No complex LDP or IGP synchronization issues to troubleshoot.

3. Support Fast rerouting
a) Convergence time in sub seconds (50msec)

4. Scalable
a) Due to simplified behavior
        b) Avoid thousands of labels in LDP database unlike MPLS
c) Avoid thousands of TE LSP’s
d) Avoid complex configuration of TE(traffic Engineering)

5. Efficient 
a) Support ECMP (equal cost multipath)
b) Better utilization of installed infrastructure

6. Plug and Play
a) Segment routing is inter operatable with existing MPLS control and dataplanes. 
b) It can be implemented in existing MPLS deployment.

7. Centralized TE
a) Controllers and orchestration platform can interact with segment routing to optimize the TE centrally.
        b) Network changes such as congestion can trigger an application to optimize the placement of segment routing traffic engineering tunnels and will re route the traffic to path with available bandwidth.

Segment Routing – Important Points

Segment Routing is the new generation source based routing and simplified version of MPLS. Instead of using label for each prefix, segment routing are identifying the segments. Below are few important points about segment routing.

Segment Routing – Important Points

1. Flexible and simple version of MPLS

2. Scalable

3. Source Choose the path- Source based routing

4. Every pacckets has a ordered list of segments

5. Network devices now will not calculate the path but will follow the instruction provided in the packet.

6. Doesn’t require LDP or RSVP

7. Relies on small extensions on IS-IS and OSPF

8. Can operate with IS-IS

9. Utilizes more effective use of bandwidth

10. Lower Latency

11. Each segment is identify by segment ID(32- bit) integer rather than using labels for each prefix.

PFR version 1 Vs 2 Vs 3

PFR stands for performance routing which is the building block for the iWAN. Intelligent WAN can reroute traffic not only based on the link up/down but also based on the performance of the link. You can route traffic based on application based performance as well.

Below is the difference between PFR version 1, 2 and 3.

APIC to factory default reset configuration

Login to APIC using admin credentials

apic1:~> eraseconfig  setup

Blackout Vs Brownout network failure

Blackout:-  When the data plane is down whereas the control plan is up. Routing protocol neighborship is establish but for some reason, like routing loop issues, source is not able to reach the destinations.

Brownout:-  High packet loss in the path or very high latency WAN issues.