Hardware–At a Glance

Types of Hard Drivers

SATA: Commodity SATA drivers

Cheapest in Capacity, but medium in IOPS ( I/O Operations Per Second). Reliability of commodity SATA is their biggest issue.

SAS: Enterprise SAS drivers

SAS drives are usually only used in servers. They’re more expensive because they have better error correction and can come in speeds of up to 15,000 RPM, 2x-3x that of most SATA drives (4500-7200 RPM). More pricy than SATA driver in Capacity. 2 times more expensive than SATA driver in IOPS.

SSD: Solid State Drivers

Far too expensive in capacity, but much more cheaper than SATA and SAS in IOPS.

Input / Output Operations Per Second (IOPS)

RAID-WikiPage

Virtual Device Contexts (VDC)

What is VDC and how it works

VMware aims at server & application virtualization, while VDC is a virtualization technology for Networking devices and it enables several Virtual Multilayer Switches Instances (also named VDC instance or logical device) in a single physical Cisco Nexus device. Each Virtual Multilayer Switch Instance has its own independent and isolated control plane (a set of processes running in their protected memory space) which are, in particular, Layer 2 & Layer 3 protocols and services. Likewise, data plane can also be virtualized by allocating specific physical ports on line cards to a certain VDC instance. NX-OS is based on Cisco MDS 9000 SAN-OS platform, it introduces VDCs to enable device level virtualization. At the heart of NX-OS is the kernel and infrastructure layer. At any one point time, only a single instance of kernel will exist and provide an interface between higher layer processes and hardware resource of physical switches. Besides, only one single instance of kernel simplifies hardware resource management. VRF aims at network virtualization on Forwarding Table level, while VDC improves that to Process level, and finally, it will reach Haredware (CPU & Memory) leve.

VDC Architecture

Continue reading ‘Virtual Device Contexts (VDC)’ »

Virtual Port Channel (vPC) Basics

vPC Technology has been introduced by Cisco Nexus OS as a key component of Cisco Data Center Networking architecture. The major benefits it brings are:

  • Loop avoidance logic allows 2 physical connections from 1 device to 2 Nexus Switches to operate in active/active mode and eliminate STP blocked port to fully utilize the uplink bandwidth.
  • Layer 2 Loop avoidance logics implemented directly in hardware while STP relies on control plane to do that, thus it provides faster convergence upon link or device failure.
  • more efficient load balance than STP.

Most components or concepts of vPC technology are entailed in below picture.

vPC Basics

Continue reading ‘Virtual Port Channel (vPC) Basics’ »

Basic Tips for CUCM Troubleshoot & Verification

This thread focuses on the basic troubleshooting of those simple problems arising from install & initial setup, system configuration, daily maintenance tasks etc.

Monitoring TFTP / SFTP / FTP / Signaling events

Whenever you upload phone firmware or upgrading package through SFTP / FTP / TFTP, to verify if the uploading is in progress, you can capture relevant packets under CUCM OS CLI. This method also benefits your monitoring of signaling event on specific ports (2000 for SCCP, 1720 for H323, 1719 for GK, 5060 for SIP etc)

admin: utils network capture src <source IP addr> dest <destination IP addr> port <port number>

admin: utils network capture host <ip/arp/all …> <host ip address> port <port num>  // capture all IP packets to & from the host ip address with source or destination port equals to port num.

CUCM CLI Packet Capture

Continue reading ‘Basic Tips for CUCM Troubleshoot & Verification’ »

Networking in VMware World

Terminologies in VMware Networking:

VMware Networking

The key virtual networking components provided by Virtual Infrastructure are:

  • Virtual Ethernet Adapters, used by individual virtual machines.
    In most cases, a virtual machine uses only one of the three types of virtual adapters.
    • vmxnet: works only if VMware Tools is installed in the guest operating system. The vmxnet adapter is designed for high performance. In most cases, when you select the flexible network adapter, this is the adapter used after VMware Tools is installed in the guest operating system.
    • vlance:  a virtual device that provides strict emulation of the AMD Lance PCNet32 Ethernet adapter. It is compatible with most 32-bit guest operating systems. This adapter is used when you select the flexible network adapter but VMware Tools is not installed in the guest operating system.
    • e1000: a virtual device that provides strict emulation of the Intel E1000 Ethernet adapter. This is the virtual Ethernet adapter used in 64-bit virtual machines. It is also available in 32-bit virtual machines. Continue reading ‘Networking in VMware World’ »

Windows 常用网络命令

Netstat;

用于显示与IP、TCP、UDP和ICMP协议相关的统计数据,一般用于检验本机各端口的网络连接情况。

  • netstat –s;按照协议种类分别列出统计信息。
  • netstat –e; 概况的列出以太网的统计信息,包括收、发的总包数,单播包,组播包,错误包和丢弃包等。
  • netstat –r;显示路由信息,类似于route print命令。
  • netstat –a;显示所有的有效连接(已建立Established、监听Listening)信息的列表。
  • netstat –n;显示所有已建立(Established)的有效连接,并以数字格式显示地址和端口号。
  • netstat –o;显示相对应的进程ID,然后通过Resource Monitor找到对应的具体应用程序。

IPConfig

  • ipconfig /release; 归还IP地址,
  • ipconfig /renew; 重新联系DHCP服务器,获取IP地址。

ARP

  • arp –a / –g; 查看本地ARP表中的所有项目。
  • arp –d; 清除本地ARP缓存条目。
  • arp –a <ip add>; 查看某IP对应的MAC地址。
  • arp –s <ip add> <MAC add>; 手动添加静态的ARP条目。
  • arp –d <ip add> <MAC add>; 手动删除静态的ARP条目。 Continue reading ‘Windows 常用网络命令’ »

Inspection of UCS C240 Rack Mount Server

Major Hardware Components:

  • UCS Chassis & bundled HW components
    Single or Dual CPU, DIMM Sockets, SAS Expander, Embedded & Internal pluggable (Optional) RAID card.
  • Hard Drivers (SFF: small form factor; LFF: Large form factor);
    24 SFF Drivers with SAS Expander.
    16 SFF Drivers without Expander.
    12 LFF Drivers with SAS Expander.
  • DIMM Card & PCIe Cards;

UCS C240 M3

Continue reading ‘Inspection of UCS C240 Rack Mount Server’ »

Cisco Unified Contact Center Express (UCCX) Briefing

UCCX and IP IVR:

Initially, I was quite confused about the relationship between UCCX and Cisco Unified IP IVR. Lots of official docs reviewing & self-research finally clearly state that they are exactly the same software product using same software codes, the only difference is that they need different licenses be activated, and so do their relevant subsystems. In other words, Unified CCX provides the software capabilities for not just Unified CCX, but also Cisco Unified IP IVR. A single physical server can run only one of the Unified CCX packages, either Unified CCX or Cisco Unified IP IVR. Below is a high-level overview of Cisco UCCX system in terms of Supported HW platform, product components as well as functional roles.

UCCX Overview

Continue reading ‘Cisco Unified Contact Center Express (UCCX) Briefing’ »