Posts Tagged ‘networking’
In a previous post I listed and described various organizations which are considered highly influential and authoritative across the wide field of information technology. These organizations are deeply involved in setting standards and best practices for nearly all facets of modern computing. One group which I neglected to include (but should have) is the North American Network Operators’ Group, or NANOG. Founded in 1994, NANOG describes itself as a “professional association for Internet engineering and architecture. Our core focus is on the technologies and systems that make the Internet function: core routing and switching; Internet inter-domain routing; the domain name system; peering and interconnection; and Internet core security. We also cover associated areas…such as data centers and optical networking.”
Although not a standards-setting body, NANOG provides a platform for knowledge exchange and professional networking opportunities in the form of their triannual meetings. These events serve as venues for some of the top minds in the industry to detail the findings of their research and to present the lessons learned from their real world work experiences. Recordings of the presentations are uploaded to the NANOG website and can be downloaded for free. This content serves as a fantastic educational resource for IT professionals who are seeking to keep their subject matter expertise sharp and relevant.
The technical standards that govern how the Internet and modern computer networks operate are debated and approved by a number of organizations. These organizations exist to ensure the proper functionality and long term feasibility of network transmission methods. IT professionals should be familiar with these organizations, how they operate, and what their specific roles and responsibilities are. After all, it is clearly within our professional purviews to intimately know the standards which dictate how the Internet’s core technologies work. For example, detailed knowledge of IPv4 (and very soon, IPv6) is a must for today’s system and network administrators. But who determines how the IP protocol operates? Who sets the standards regarding networking technologies? Read on to find out.
Internet Protocol version 6 (IPv6) is the next generation networking protocol that is slated to replace Internet Protocol version 4 (IPv4) as the dominant protocol powering modern computer networks and the global Internet.
The problem with IPv4 is that it was developed and initially rolled out in the 1970s and 80s, long before anyone had any idea of what the Internet would become (IPv4 is defined in RFC 791, published in 1981). Simply put, the ability for IPv4 to support modern Internet traffic is decreasing steadily. The Internet Engineering Task Force (IETF) recognized the potential for a crisis and commenced work on IPv4’s replacement in the mid-1990s.
The rest of this article will assume that you know why the Internet needs to evolve from IPv4 to IPv6. If you do not understand this, please stop reading and view this Youtube video of Vinton Cerf explaining the rationale behind the protocol migration (Cerf is considered one of the “fathers of the Internet”).
The death of IPv4 as a relevant networking protocol was delayed considerably by the deployment of two addressing-related solutions: Network Address Translation (NAT) and Classless InterDomain Routing (CIDR). However, given the current and projected growth in human population and the ever expanding quantity of devices connecting to the Internet, IPv6 is required to accommodate and sustain the necessary expansion of Internet availability and services. For example, two well-known technology growth sectors, mobile devices (e.g., smartphones) and cloud-based computing, require public IPv4 connectivity to function and therefore, they are contributing to the exhaustion of the public IPv4 address space (even with NAT relieving some pressure).
Image source: Wikimedia Commons
Despite their differences in age, IPv4 and IPv6 do share some characteristics. Both protocols were designed to allow for host identification, host discovery, and optimal routing. They both work at Layer 3 of the OSI networking model and at the internet layer of the TCP/IP networking model. In order for hosts to properly communicate using IPv4 or IPv6, they must be assigned a unique IP address. IPv6 hosts need the same information as IPv4 hosts to properly network, e.g., they need to know the IP addresses of DNS servers (to translate host names to IP addresses) and default gateways (to transmit to remote destinations). As in IPv4, IPv6 hosts will send packets directly to destinations on the same subnet.
However, as IPv6 was developed from the ground up to be a future-oriented redesign and modernization of the IP structure, IT professionals will notice that it offers many distinct advantages over its aging cousin. Some noteworthy differences are:
- IP addressing – as described below, IPv6 addresses use a different format and can provide an astonishingly huge address space for network hosts, far larger than what IPv4 can offer.
- Multicast and broadcast – IPv6 utilizes more multicast traffic while dropping broadcast functionality altogether.
- Multi-address interfaces – In IPv6, interfaces (such as network interface cards, or NICs) can natively operate using several IP addresses. IPv6 offers improved support for multiple addresses sharing one interface.
- Automatic IP address assignment – While IPv4 clients can receive address assignments via DHCP, IPv6 hosts are capable of autoconfiguration with stateless address autoconfiguration (SLAAC) via Neighbor Discovery Protocol (NDP). Alternatively, IPv6 hosts can utilize the new DHCPv6 in a manner similar to traditional DHCP.
- Packet fragmentation – Routers processing IPv6 will not fragment packets. Instead, fragmentation responsibility belongs to the originating hosts.
- Checksum – the IPv6 header does not include a checksum while IPv4 does. Removing the checksum from OSI Layer 3 should improve IP throughput.
- Layer 2 (data link) address discovery – while IPv4 uses Address Resolution Protocol (ARP), IPv6 uses ICMPv6-based Neighbor Discovery Protocol (NDP).
- IPSec – IPSec support is optional in IPv4 but is required in IPv6.
- IGMP – IPv6 replaces Internet Group Management Protocol (IGMP) with Multicast Listener Discovery (MLD).
Any student of computer networking has surely heard it repeated a thousand times: switches work at Layer 2 of the OSI model and interpret MAC addresses, while routers work at Layer 3 and interpret IP addresses. In other words, a switch looks at the MAC address of the destination host and sends the frame only to that recipient (thus conserving bandwidth). A router directs network traffic in a similar manner, but references the target IP address instead of its MAC address (on a side note, those devices marketed as “routers” for home users generally provide more functionality than mere packet routing, such as IP address assignment (DHCP) and firewall filtering). Broadly speaking, switches connect hosts from the same network together while a router can connect whole networks together. To say this in IT Speak: switches connect hosts to form local area networks (LANs) while routers connect multiple LANs into wide area networks (WANs).
In addition to traffic forwarding based on MAC address, switches also detect packet collisions and can simultaneously manage multiple data streams destined to multiple ports. Routers, for their part, can perform network address translation (NAT) and basic packet filtering based on access control lists (ACLs).
With conventional switches and routers performing markedly different functions at layer 2 and layer 3 respectively, just what is meant by the term “layer 3 switch”? Isn’t this contradictory?