Network Security Quest

What is VXLAN? VXLAN is an encapsulation protocol that provides data center connectivity using tunneling to stretch Layer 2 connections over an underlying Layer 3 network. In data centers, VXLAN is the most commonly used protocol to create overlay networks that sit on top of the physical network, enabling the use of virtual networks. The VXLAN protocol supports the virtualization of the data center network while addressing the needs of multi-tenant data centers by providing the necessary segmentation on a large scale. VXLAN Packet: • VXLAN is point to multi-point tunneling mechanism to extend Layer 2 networks over an IP network. • VXLAN uses MAC in UDP encapsulation (UDP destination port 4789) Two Modes of VXLAN: 1. Flood-and-Learn VXLAN:   • No control plane   • Data driven flood and learning   •  Ethernet in the overlay network  2. VXLAN EVPN:  • EVPN as control plane  • VTEPs exchange L2/L3 host and subnet reachability through EVPN co...

What is an ACI network? At a very basic level ACI is really just a Spine/Leaf network of Nexus 9k switches with a management platform The network management platform (APIC) provides you with a single place from which to manage the network  Is ACI an Overlay or Underlay network? ACI is an automated (VXLAN) overlay network running over an automated (ISIS) underlay network. ACI can transport any IP traffic including “Overlay” networks based on VXLAN*, NVGRE* etc. How ACI Fabric is Built - Zero Touch: What Do We Mean by Policy ? • Access Policies = Define how a switch or switch port is configured. Specifically Ethernet and link layer properties such as LLDP, LACP, CDP, speed/duplex, etc.  • Tenant Policies = Govern traditional networking. This is where logical connectivity is defined.  • Access policies and Tenant policies work in tandem to define where and how endpoints or applications are connected  1. Tenants: Isolated configuration “zones” on common physical infrastr...

When troubleshooting TCP connections through the ASA, the connection flags shown for each TCP connection provide a wealth of information about the state of TCP connections to the ASA. This information can be used to troubleshoot problems with the ASA, as well as problems elsewhere in the network. Here is the output of the show conn protocol tcp command, which shows the state of all TCP connections through the ASA. These connections can also be seen with the show conn command. ASA# show conn protocol tcp 101 in use, 5589 most used TCP outside 10.23.232.59:5223 inside 192.168.1.3:52419, idle 0:00:11, bytes 0, flags saA TCP outside 192.168.3.5:80 dmz 172.16.103.221:57646, idle 0:00:29, bytes 2176, flags UIO TCP outside 10.23.232.217:443 inside 192.168.1.3:52427, idle 0:01:02, bytes 4504, flags TCP outside 10.23.232.217:5223 inside 192.168.1.3:52425, idle 0:00:10, bytes 0, flags saAUIO TCP outside 10.23.232.57:5223 inside 192.168.1.3:52412, idle 0:0...