SLAC's Network Principles

We have identified a set of key points (principles) that should be applied when designing future network upgrades and making new purchases of network equipment:

• Focus on 10/100/1000 Mbps Ethernet
  • Phase out the Micom switch by 1998 - Done
  • Phase out use of LocalTalk/PhoneNet by end 1999 - Done
  • Phase out FDDI. Do not add any more FDDI network infrastructure as of the start of 1999. All new servers to use Ethernet NICs as of start of 1998.
• Deploy "structured wiring", 70% to be completed by end 1997,
  • Use fiber in new building distribution to get between buildings and between closets.
  • When pulling fiber between buildings make sure some (at least 1/3 of the the total new strands) single mode is also pulled (probably at first leave leave dark).
  • Use unshielded twisted pair (UTP) category 5 (or better) in local drops to the users.
• Increase the aggregate bandwidth available by a factor of 2 every 12-18 months
• To avoid excessive delays limit collision domains to 10 to 20 end-users.
• Stay between 6 and 12 collision domains per subnet.
• Aim for around 128 users per subnet.
• Move to enabling variable sized subnets (VLSM), so we can most effectively use our IP address space.
• Manage multicasting/broadcasting.
• Over-provision the network in order to avoid constant trouble shooting caused by being close to the edge of the envelope
  • Progressively provide switched 10Mbps Ethernet (or better) to the desktop, 50% to be completed by the year 2000.
  • Limit the use of shared 100Mbps Ethernet (since in terms of bits/dolar it is not competitive with switched 100Mbps Ethernet).
  • Provide 100 Mbps connections to high volume servers. In general, we expect servers requiring > 10 Mbps to be SLAC wide servers with critical needs. Thus, they are expected to be modern machines capable of fully utilizing a 100Mbps interface (e.g. at least a Pentium II or equivalent with > 200 Mhz and a 64-bit PCI and RAID). Also they are expected to be backed up, for their Operating System to be kept current, to have high availability which is monitored (see for example Server Status and Full Network Services Report), often supported by Uninterruptible Power Sources (UPS), with automatic paging to someone on call 24 hours by 7 days per week etc., be located in a secure locked area, and usually located in the computer center so they can be close to the core networking.
  • Provision the network core with Gbps Ethernet interconnects and provide Gbps connections to a few high volume central Enterprise servers.
  • Plan to ensure net is not bottleneck, centralize servers & storage to reduce costs, migrate to a single architecture, with gigabit Ethernet as the clear choice forward (fastest, simplest lowest cost solution) for the core interconnections.
  • Deploy 100 Mbps to the desktop starting in mid to late 1998 for power users.
  • Monitor and track requirements for backbone upgrades. Provide monitoring and management capabilities for gigabit Ethernet.
• Design the network to accomodate change. For example network product cycles are only about 3 years, and we may expect a given routing infrastructure to be in place for only about 3 years.
• Design the network to facilitate ongoing maintenance. For example provide redundancy so can take parts of the network out of service with limted impact on the users.
• Provide redundancy for critical components.
• Place the critical core network components on UPS.
• Invest in network management and monitoring:
  • To enable setting and maintenance of network performance expectations
  • To leverage our proactive trouble shooting and planning resources
  • To provide accurate documentation for trouble shooting
  • Make sure that all new network devices support SNMP.
  • Make sure that all new network devices of a certain class also support RMON.
  • Provide appropriate tools for diagnosing problems down to the wire level.
  • Invest in tools to enable asset management, in particular to keep track of network and device configurations and topology.
• Reduce complexity.
  • Minimize the number of vendors providing backbone/core networking components and maintenance, and foster strategic relations with those vendors. At the moment all backbone/core routers and switches are manufactured by Cisco.
  • Reduce the protocols carried in native form - target only the IP protocol family for the long term. Come up with a plan to phase out AppleTalk, remove bridging of DEC suite protocols (MOP, LAT etc.) in the core, remove support for native DECnet phase IV. Do not route IPX, and actively discourage use of IPX.