在此篇文章里，简单总结下通过SRTE调度EVPN ELAN的流量，然后通过show信息，来查看引流及相关内容，并熟悉EVPN，EVPN基础部分，可以参考之前的文章，里面包含Route Type的信息：EVPN Summary

另外对于ELAN的引流，有很多种选择，常见的是通过对RT1打Color，调用单播流量；对RT3打Color，调用多播流量；对于RT1我们可以看成L3VPN中的“VRF”，也就是基于“VRF”颗粒度进行引流，这么理解可能更好理解

物理拓扑

Introduction

I summarized SR/SRTE hands-on-deck that includes our highlight features and show information in the same topology, content includes the following topic, now revised version is v3:

• Hands-on Brief
• Segment Routing Basic
• L3VPN in Segment Routing
• Interworking between LDP and SR
• TI-LFA in Segment Routing
• SRTE Solution in MPLS SR
• SR IGP Flexible Algorithms
• Egress Peer Engineering(EPE)
• SRv6 Solution

• Choose 2-3 router for FAD, but not all router
• Config follows configuration at FAD router:

router isis srte
affinity-map red bit-position 23
flex-algo 128
 priority 200
 metric-type delay
 advertise-definition
 affinity exclude-any red

• Config follows configuration at exclude/include function router:

router isis srte
affinity-map red bit-position 23
flex-algo 128
 metric-type delay <-- define in FAD
 affinity exclude-any red
!
inter gix/x/x/x
 affinity flex-algo red

• Config follows configuration at normal router:

router isis srte
flex-algo 128
  metric-type delay <-- define in FAD

对于SR的微环避免，很多人不是特别清楚细节，所以我将在此简单总结下，希望对阅读此篇文章的人有所帮助，我会围绕以下几个话题展开讨论：

• 微环路是什么？微环避免能做什么？
• 微环避免跟TI-LFA有什么关系？
• 微环避免和TI-LFA同时存在的情况下，是否都会有作用？

为了方便大家理解，我将用一个topology来讨论我们今天涉及的所有内容，关于这部分更详细的内容，可以参阅SR卷一的9.10章节，以及SR卷二的8.11.1章节；另外此分析只作为问题验证说明，不能直接拿到现网使用，如40s的delay等，这些需要根据IGP的Scales以及硬件的收敛性能来做调整

Introduction

Now more customer complains their Peering network not flexible and hard to control, that will cause peering link’s utilization not balance and waste of resources. As follow the example on Router-2, customer peering device connect to multi ISP, each ISP sends full internet route, select only based on the BGP. BGP select rule only based on the route but not real traffics, that may be cause port-A’s traffics have 8G, but port-B and port-C only have 4G, if want to adjust BGP select, only change RPL that more complex, and due to route from internet and multi ISP, so route maybe change at some time, in order to balance peering link, customer must continue to adjust their RPL.

Could we have more flexible and simplest way to resolve the issue? The answer is Yes 🙂 we can achieve the task by Segment Routing – Egress Peer Engineering. Now some customer had deployed the solution, that combine NetFlow, Openbmp to check AS/traffics of prefix, then send BGP LU(EPE label) to ingress node, and easy to control traffics.

完整阅读