QuistED.net

https://www.cisco.com/c/dam/en/us/solutions/collateral/data-center-virtualization/data-center-interconnect/at_a_glance_c45-493703.pdf

• Types of Data Center Interconnections
  • Layer 1 DCI
    • Physical connection between Data Centers
      • Dark Fiber ( MetroE)
      • Fibrechannel
    • Not as flexible
  • Layer 2 DCI
    • Carrier appears as L2 Bridge
    • MPLS options
    • VPLS options
    • IP Mobility
  • Layer 3 DCI
    • IP Based connection
      • iSCSI
      • Routing
      • ATOMoGRE

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Software Defined Networking

• Advantages SDN
  • Automatic Infrastructure Provisioning
  • Multi-tenant enviornments
  • Flexible Placement of servers ( Mobility )
  • Health monitoring of applications
  • Application to NET ( Southbound ) and NET to application ( Northbound ) communication
• Cisco’s SDN implementation: Application Centric Infrastructure ( ACI )

Three key ingredients for ACI

• Nexus 9000 series / 9300 / 9500.
• Aplication Policy Infrastructure Controller ( APIC ).
  • Cisco recommends a minimum of three APIC servers.
• Policy Model ( “What talks to what and how” ).

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TRansparent Interconnection of Lots of Links

• https://en.wikipedia.org/wiki/TRILL_(computing)
• Often in datacenters a layer 2 design is implemented to span VLANs.
• First define your FabricPath domain, which disables Ethernet.
• IS-IS enabled Fabric Path Domain.
• Classic Switch data learned and IS-IS Level 2 ‘Routing Table’ Built.
• Opens L2 ECMP Capabilities.
• Leaf to servers with vPC / MEC

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What is a vPC (virtual Port Channel)

• Nexus series Network Virtualisation Technology.
• “Lightweight” VSS – Combine ports, not switches.
• Links on different switches to appear as the same device.
• Downstream device can be anything supoprting 802.3ad (LACP).
• Commonly called Multi Chassis Etherchannel ( MEC ).

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IS-IS History

https://en.wikipedia.org/wiki/IS-IS
https://en.wikipedia.org/wiki/OSI_protocols
https://en.wikipedia.org/wiki/Type-length-value

• Created for the OSI Protocol Suite
• Integrated IS-IS: the mutation.
• IS-IS dictionary:
  • IS = Intermediate System  (Routers)
  • ES = End System
  • TLV = Type Length Value
  • NSAP = Network Service Access Point
    • (OSI protocols equivilent of the TCP/IP’s IP Address)
• IS-IS features:
  • Link State Routing Protocol  (Same as OSPF)
  • NSAP address assigned per router
  • Dijkstra SPF powered (Same as OSPF)
    • PRC efficient
  • Hellos Establisch neighbors at Layer 2 ( source MAC, Multicast Mac )
  • Two routing levels ( Level 1 and Level 2 )
  • Area Based Design ( Routers know their area )
  • default link cost = 10

IS-IS High level Design

• Two routing databases
  • Level1 and Level2
    • Level 1 routers find closest Level2 Exit.
  • Area defined by
  • 49.0001  ( Area 1 )
    • 49 private adressing , 0001 is area 1
• Three router types

IS-IS Neighbors and Area Design

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Monitoring and Managing

• Know your network is doing well.
• Understand the trends in your network performance.
• Identify your bottlenecks and propose solutions.
• Proact – Don’t react.

Phases of optimizations and the tools

1. Create a baseline – Netflow, NBAR, IP SLA
2. Optimize Network – QoS, AutoQoS VoIP, AutoQoS Enterprise
3. Measure / Adjust – Netflow, NBAR, IP SLA, Syslog
4. Deploy Apps – Netflow, NBAR

• https://en.wikipedia.org/wiki/NetFlow
• Cisco NBAR
• WhitePaper AutoQoS
• Cisco IP SLA

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• Wireless Signal Mesured in dBm ( Power referenced against one Milliwatt )
• Range is roughly -30dBm to -90dBm
  • -30dBm = Max Achievable ( not desired ).
  • -67dBm = Mininum for real-time Apps.
  • -80dBm = Minimum for communication.
• Noise is always a challenge
• Signal to Noise Ratio ( SNR ) = ( Signal – Noise ) = Value
  • Mininum SNR of 25 is needed for real-time apps.

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Unicast vs Multicast

• Routed via PIM ( Protocol Independent Multicast ).
• Always UDP-Based ( Video, Audiostreams, some kinds of data ).
• Typical network challenges ( QoS, Security, Bandwidth consumption).
• Began as a ‘speciality’ technology, becoming heavily adopted in modern times.

Multicast Addresses

• Multicast group members receive all data center to a group.
• Multicast IPv4 Range: [ 224.0.0.0  239.255.255.255 ]
  • Filtering tip:
    • Last 23 bits of IP mapped to MAC
      • Can lead to overlapping addresses

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Remote Access VPN design

• For a VPN you need a termination device (vpn concentrator / Firewall), a client and the connecting technology for tunneling.
• Cisco Easy VPN.
• Client options
  • IPSEC VPN client
  • SSLVPN Clientless Access
  • SSLVPN Thin client
  • SSLVPN Thick client

Placement of the VPN Termination Device:

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Core layer

• Cisco 6509.
• Static routing used to ISP ( or basic BGP ).
• FWSM or ACE module used as initial filter.
• Static route down to VIP of aggregation layer FHRP.

Aggregation Layer

• Cisco 6506 ( MSFC ).
• Traffic received from core routed to CSM
  
• CSM load balances to VLANs at the access layer
• Simple Design allows inter-vlan routering ( web, app, db )
  • Inter-vlan routing without a FWSM can lead to access from the VLANs.

Access Layer

• Cisco 6509
• Servers typically devided into web, app, and database VLANS.
• Server gateways set to CSM, FWSM, or VIP of the FHRP on L3.
• Firewall restrictions between layers common.