When we want to collect some show information by Telemetry, we will face the 1st question that how to find the correct/resolved sensor path. The first step often traps us. Is there any good way to easily find the sensor path? The answer is “Yes”. I had summarized a way that can help you quickly find the sensor path.

Before read the article，there is a file that mapping between YANG and Sensor Path in XR, you can check by keyword(e.g fan, cpu and so on) first, if not found, then check my article.

RP/0/RP0/CPU0:XTC#run
Tue Jan 22 06:58:56.512 UTC
[xr-vm_node0_RP0_CPU0:~]$cd /pkg/telemetry/mdt/protogen
[xr-vm_node0_RP0_CPU0:/pkg/telemetry/mdt/protogen]$ls
yang_to_schema.txt
[xr-vm_node0_RP0_CPU0:/pkg/telemetry/mdt/protogen]$

yang_to_Schema.txt has all yang path to xml schema path maps. https://github.com/AlexFengCisco/Telemetry_Receiver

Cisco finally published the YangSuit at Devnet at Feb 2021, that can be downloaded and used by customer, and it is Free! I updated the installation section of the article to use the public version, other section should similar and not update.

Cisco YANG Suite provides a set of tools and plugins to learn, test, and adopt YANG programmable interfaces such as NETCONF, RESTCONF, gNMI and more.

YANG Suite will provides network operators with a common tool to interact with Cisco IOS XE, IOS XR, and the NX-OS Network Operating Systems as they look to modernize their network management and migrate from traditional network management tools.

https://developer.cisco.com/yangsuite/?utm_campaign=yang21&utm_source=social&utm_medium=dntwitter-yang-ww

Install

xxx:~ xxx$ git clone https://github.com/CiscoDevNet/yangsuite
xxx:~ xxx$ cd yangsuite/docker/ ; ./gen_test_certs.sh
xxx:docker xxx$ pwd
/Users/xxx/yangsuite/docker
xxx:docker xxx$ docker-compose up
Creating network "docker_default" with the default driver
Creating volume "docker_static-content" with default driver
Creating volume "docker_uwsgi" with default driver
Building yangsuite
……

Problem

Customer get HostOS when connect to XRVM console after installing ISSU SMU, and confirmed XRVM normal work.

Background

• SAVM and XRVM on all RPs and LCs, FC only have SAVM, check by “show vm” in admin vm, SAVM and XRVM mapping to console 0 & 1, as follow:
  
• Except SAVM and XRVM, have key components that is host system in RPs or LCs, you can check host by follow steps, login by “ssh ” after “chvrf 0 bash”.

完整阅读

Intro

很多客户在部署VPLS时，当核心有负载链路或者Bundle时，常常会碰到负载不均的现象，为什么会发生这种问题？首先看下常规ASR9k在不同场景下是用什么元素去做Hash的：

A: src-ip, dst-ip, src-port, dst-port, router_id
B: bottom_most_label, router_id
C: 4th_label, router_id

2020-6-24 更新：Multi-Label MPLS Load-Balancing Hash Algorithm Update

原有ASR9k ECMP的Hash 算法：在MPLS报文时，只有4层label以下的数据报文才可以使用IP 5元组Hash，超过4层的只能用单个label做raw hash。此算法在之前问题不大，label数很少超过4个，但在SR 的环境下，可能会有更多的label，因此BU更新了此场景的Hash算法：

1. 5-8个label，不再使用单个label做hash，而是采用IP 5元组来做hash
2. 9个或更多label，使用新的hash 算法：multi-label MPLS hashing，label3-5中的label作为raw hash

Tomahawk从623开始使用新的算法；Lightspeed和Xrv9k从652开始使用新的算法

Ok，我们可以看到在L2VPN中，用的是bottom label来做的负载均衡，这是因为系统无法跳过L2VPN中的MAC头，去读L3的IP头。在这里拿Bundle端口举例，说说不同场景下bundle的HASH方法（在9k上，所有HASH动作都是在进口NP上做的，这个HASH结果会直接被出口NP调用）：
完整阅读

跟同事讨论了下关于*PVID_Inc的问题，收益颇丰！估计没几个人能悟出在VPLS中PVID_inc的真谛。
为了验证讨论的内容，特意做下面的实验：

Topology

天蓝色属于一个bridge-domain vplstest1000；而红色属于bridge-domain vplstest6002
本文只讨论天蓝色的bridge-domain!

测试目的

验证下为什么会有PVID_inc的问题出现，及抓包分析，用有力的证据来验证
完整阅读