3Com (R) Corporation EtherDisk (R) Diskette for the 3C90X Fast EtherLink XL/EtherLink XL Bus Master NIC Family Fast IP Questions and Answers Q: What is Fast IP? A: Fast IP is an innovative software-based solution that provides an easy and low cost mechanism to improve performance on today's switched networks. Fast IP allows end systems (desktops and servers) to discover switched, Layer 2 communication paths. By creating switched short-cuts, Fast IP allows end stations to bypass the router and transfer data across wire-speed switched paths. Fast IP is part of 3Com's DynamicAccess software, an advanced network driver that brings intelligence to the end systems to provide improved network performance and control. Q: What are the motivation & benefits of Fast IP? A: Today's networks are evolving to an Intranet based model where network managers are not able to predict traffic flows any more and where IP is becoming the predominant network protocol. Most of the network platforms in place today relay on general purpose, CPU-based routers to provide inter-subnet communication. With the exponential increase of network users, faster connections, more demanding applications and omnidirectional traffic flow, those routers are becoming bottlenecks that slow down the network and reduce users productivity. Fast IP delivers a mechanism to improve network performance by bypassing those router bottlenecks. By allowing desktops and servers to automatically find available switched paths to communicate at wire-speeds, Fast IP delivers dramatic improvement over router's performance. Still, Fast IP maintains the control of routing. Initial Fast IP connection requests traverse the router on initiation, where net managers can configure traffic policies. Easy to implement, Fast IP is a software based technology that is available for 3Com NICs today. Q: What is the performance gain when using Fast IP? A: The fact that Fast IP bypasses the router in any communication provides increased performance in switched networks even if there are just a small number of network nodes using Fast IP. The performance gain obtained when deploying Fast IP is directly related to traffic load on the backbone router. The more traffic is pumped to it, the bigger the latency and response time and the higher the performance gain. Internal tests show performance increases in the order of 600% when routers are loaded at 70 to 75%. Q: How does Fast IP work? A: Fast IP leverages the processing power of the end station. Based on data to be forwarded to a separate subnet: The end system will issue an NHRP request. The NHRP request is a standard IP format packet with source and destination MAC and IP addresses. Contained in the data portion of the packet is the source end system's MAC address. The NHRP packet is forwarded to a router in accordance with normal intersubnet forwarding policies. The router retains its function as a control point and filters or forwards the packet according to configured policies. The destination station, also running Fast IP, recognizes the NHRP request and issues an NHRP response directly to the originating source end system using the source MAC address received in the data portion of the NHRP request. When the NHRP reply is received by the originating source end system, it will then redirect data packets directly to the destination end system using its MAC address, rather than going through the router, resulting in wire-speed switching. The NHRP request-response process happens in parallel to data traffic flow going through the router. Besides providing traffic control, this process assures that data communication will not be interrupted while the Fast IP short-cut is being established. If there is no switched path available between end stations, traffic will continue flowing through the router. Q: What level of security is provided by Fast IP? A: Fast IP relies on the router's configuration for security. Since the first NHRP packet flows through the router, any restriction or filter that has been configured on it will be applied. Communications that were not allowed to happen before will not take place with Fast IP since they follow the same routed path at initiation. Fast IP short-cuts are initiated per IP session. Therefore, even in the case that two different applications operate on the same server, there will be a Fast IP request per application. If the source station is restricted to either one, the router will not forward the request to that server and the Fast IP short-cut will not succeed for that application, whereas the other application's connection can be set up for a short-cut. Q: How to position Fast IP and how does it contrast to Layer 3 Switching? A: 3Com is a long time leader in NICs and Layer 3 switching. Layer 3 Switches are designed to replace or displace the bottlenecked router moving it to the edge of the network for LAN/WAN use where forwarding performance is less of an issue. Layer 3 switches are multiprotocol and allow higher level of security, plus they also offer advanced features like bandwidth allocation and, in conjunction with DynamicAccess software, end-to-end LAN Traffic Prioritization (CoS). Fast IP is designed to improve network performance in today's environments where the router is a bottleneck, extending existing network investment. The target customer for Fast IP are those networks that have a switched infrastructure but rely on a traditional backbone router to provide inter-subnet traffic communication. These customers want to improve network performance but have budget limitations or are not ready to displace the router. With Layer 3 switching and Fast IP, 3Com offers a wide range of solutions to meet customers' needs. Q: Is Fast IP a proprietary 3Com solution for 3Com NICs? A: Fast IP is a solution based on the IETF NHRP (Next Hop Resolution Protocol) draft. This ensures that Fast IP can work over existing network devices (switches and routers), both 3Com and non-3Com. Fast IP will also support the IEEE 802.1p/Q specification, providing a standard solution to improve traffic forwarding over 802.1p enabled switches. Q: When will Fast IP be available for other vendors NICs? A: The first release of Fast IP is part of DynamicAccess software release 1.2 and it is focused on our current 3Com customers. Therefore, it works on 3Com Ethernet XL and Fast Ethernet XL NICs only. With DynamicAccess Software release 1.5 (1QCY98) Fast IP will be available for other 3Com Ethernet cards as well as for customers with non-3Com Ethernet NICs. Q: When will Fast IP be available for UNIX systems (e.g., Sun, HP, IBM, Silicon Graphics, etc.)? A: We are currently in discussions with a number of UNIX systems vendors. Announcement of their support for Fast IP will be made soon. Q: Does Fast IP work over ATM? A: Yes. Although we do not support short-cuts between ELANs today, Fast IP will create short-cuts where multiple subnets are within the same ELAN. The reason why Fast IP does not short-cut between ELANs is that in sending the NHRP reply, it will be contained to the senders ELAN. 3Com is working on a software upgrade which will assist Fast IP in short-cutting between ELANs. This software will be available in 1Q98 as a free upgrade for the CB7000 family. Q: When will Fast IP be available on ATM and FDDI NICs? A: DynamicAccess software will be available for ATM and FDDI NICs at a later release in 1998. Q: What other protocols are supported by Fast IP? A: The use of IP as the main protocol has increased over the last years and it is expected to be the dominant protocol in customer networks. Because of the performance issues that this brings, Fast IP is targeted to solve traffic problems for IP networks. Q: What are the end system requirements for Fast IP? A: Fast IP will be supported on desktops and servers running NDIS 3 network drivers. Therefore Win95, Win NT 3.51 and Win NT 4.0 systems will be able to support it. There are no special requirements for other network devices such as routers or switches in order to support Fast IP. There will be support for NDIS 3.0, 4.0 and 5.0, NetWare and UNIX drivers in 1998. Q: What are the network configuration requirements for Fast IP? A: Fast IP is designed to bypass the router, particularly where the router is a bottleneck, as well as to leverage the switched infrastructure. For Fast IP to create short-cuts around routers, there must be a switched path between source and destination. Q: Do I need any hardware upgrades to support Fast IP? A: No. Being software-based, Fast IP can be implemented in any network regardless of the switching and routing infrastructure that is in place. Q: What types of applications will benefit from Fast IP? A: Fast IP will show dramatically improved performance for long lasting communication flows or for applications that make frequent use of a intersubnet resource. Before issuing a short-cut request, Fast IP waits for a short number of packets are sent through the routed path eliminating unnecessary connection requests for short-lived flows such as web-browsing. In addition Fast IP periodically ages out unused short-cuts. Therefore the type of applications which will benefit from Fast IP most are long lasting traffic flows, e.g., files transfers, server backup, document imaging, etc. Also applications which send out frequent periodic updates such as stock updates, manufacturing equipment status updates, hospital equipment monitoring updates, etc. will use Fast IP as long as the short-cut address is contained in the address cache. Q: How many short-cuts are maintained in cache memory? A: The number of short-cuts per station is 256. Q: How do we compare ICMP Redirect Message function to Fast IP? A: ICMP (Internet Control Message Protocol, RFC 792) and is an integral part of IP. ICMP is necessary for reporting errors occurred when processing IP datagrams. ICMP messages are several and provide information to solve datagram delivery problems. Among those messages, the Redirect Message has been mistakenly compared to Fast IP as an existing IP mechanism to provide short-cuts in router-based networks. The ICMP Redirect Message is used when more than one router is attached to a LAN. End stations typically have only one default router. The default router (also called a default gateway) is used when sending packets to destinations that are not on the end station's local LAN. The end station sends all non-local traffic to its default router, which then forwards it to its destination. If this router can tell (by information learned from its routing protocols) that another router on this LAN is closer to the destination, it uses the ICMP Redirect message to tell the end-station that when talking to this destination it should use a different egress router. Fast IP provides a mechanism to discover switched paths across corporate networks to provide improved performance (by minimizing router hops). ICMP Redirects only optimize the exit path for traffic from an end-station to a non-local destination, but all the non-local traffic must still cross at least one router, even if there is a layer 2 switched path available. Q: Will I see an increase in CPU utilization with Fast IP. A: In a Fast IP enabled network you will see an increase in CPU utilization at the client when you enable Fast IP. This is due to the increased throughput on the wire achieved with Fast IP. If your system has limited CPU resources you may want to leave Fast IP disabled. (%VER FASTIP.TXT - Fast IP FAQ v1.0a)