IP switch is basically an IP router with a switching hardware that has the ability to cache routing decisions. IP switching technologies are originally developed by Ipsilon Networks. An IP Switching device identifies a long flow of packets and switches the flow in layer 2 if possible, thus bypassing routers and improving throughput. IP Switching integrates fast ATM hardware directly with IP, thus preserving the connectionless nature of IP. To gain the benefits of switching, a mechanism has been defined to associate IP flows with the ATM labels. IP switching typically allocates a label per source/destination packet flow. An IP switch processes the initial packets of a flow by passing them to a standard router module that is part of the IP switch.
Following are some important features of IP Switching:
- Point-to-Point: IP Switching advocates point-to-point network model for ATM rather than a logical shared medium model as proposed by some competing approaches.
- Multicast: A flow coming to an IP Switch can branch out to multiple destinations. Each of these branches can be individually redirected. If the whole flow is labeled, then multicast capabilities of ATM can be used.
- Quality of Service: An IP Switch can make QoS decision according to its local policy. Individual QoS requests for each flow can be supported using resource reservation protocols like RSVP. An IP Switch can be configured to utilize traffic management capabilities of ATM to guarantee the desired QoS.
- Latency: The latency in setting up of a virtual channel from source to destination can be low for connection oriented protocols like TCP.
- Failure Tolerance: IP Switch has good tolerance at link failure because it can always go back to connectionless packet forwarding via a different route if any link fails.
IP switching is sometimes confused with other multiplayer switching techniques. IP switching is replaced by Multi-Protocol label switching (MPLS) technologies, which is the IETF standard combined advantages of multiple technologies such as Ipsillon IP switching, Cisco tag switching, IBM ARIS (Aggregate Route IP Switch) and Toshiba CSR (Cell Switched Router).
IP Switch
Related Terms: multilayer switch, Layer 2 router, Layer 3 switch, IP switch, routing switch, switching router, wirespeed router, tag switch, MPLS protocols
Reference Links: http://www.cse.ohio-state.edu/~jain/cis788-97/ftp/ip_switching/index.htm: IP Switching