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diff --git a/doc/rfc/rfc2185.txt b/doc/rfc/rfc2185.txt new file mode 100644 index 0000000..afc7c56 --- /dev/null +++ b/doc/rfc/rfc2185.txt @@ -0,0 +1,731 @@ + + + + + + +Network Working Group R. Callon +Request for Comments: 2185 Cascade Communications Co. +Category: Informational D. Haskin + Bay Networks Inc. + September 1997 + + + Routing Aspects Of IPv6 Transition + +Status of this memo + + This memo provides information for the Internet community. This memo + does not specify an Internet standard of any kind. Distribution of + this memo is unlimited. + +Abstract + + This document gives an overview of the routing aspects of the IPv6 + transition. It is based on the protocols defined in the document + "Transition Mechanisms for IPv6 Hosts and Routers" [1]. Readers + should be familiar with the transition mechanisms before reading this + document. + + The proposals contained in this document are based on the work of the + Ngtrans working group. + +1. TERMINOLOGY + + This paper uses the following terminology: + + node - a protocol module that implements IPv4 or IPv6. + + router - a node that forwards packets not explicitly + addressed to itself. + + host - any node that is not a router. + + border router - a router that forwards packets across + routing domain boundaries. + + link - a communication facility or medium over which + nodes can communicate at the link layer, i.e., the layer + immediately below internet layer. + + interface - a node's attachment to a link. + + address - an network layer identifier for an interface or + a group of interfaces. + + + +Callon & Haskin Informational [Page 1] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + neighbors - nodes attached to the same link. + + routing domain - a collection of routers which coordinate + routing knowledge using a single routing protocol. + + routing region (or just "region") - a collection of routers + interconnected by a single internet protocol (e.g. IPv6) + and coordinating their routing knowledge using routing + protocols from a single internet protocol stack. A + routing region may be a superset of a routing domain. + + tunneling - encapsulation of protocol A within protocol B, + such that A treats B as though it were a datalink layer. + + reachability information - information describing the set of + reachable destinations that can be used for packet + forwarding decisions. + + routing information - same as reachability information. + + address prefix - the high-order bits in an address. + + routing prefix - address prefix that expresses destinations + which have addresses with the matching address prefixes. + It is used by routers to advertise what systems they are + capable of reaching. + + route leaking - advertisement of network layer reachability + information across routing region boundaries. + +2. ISSUES AND OUTLINE + + This document gives an overview of the routing aspects of IPv4 to + IPv6 transition. The approach outlined here is designed to be + compatible with the existing mechanisms for IPv6 transition [1]. + + During an extended IPv4-to-IPv6 transition period, IPv6-based systems + must coexist with the installed base of IPv4 systems. In such a dual + internetworking protocol environment, both IPv4 and IPv6 routing + infrastructure will be present. Initially, deployed IPv6-capable + domains might not be globally interconnected via IPv6-capable + internet infrastructure and therefore may need to communicate across + IPv4-only routing regions. In order to achieve dynamic routing in + such a mixed environment, there need to be mechanisms to globally + distribute IPv6 network layer reachability information between + dispersed IPv6 routing regions. The same techniques can be used in + later stages of IPv4-to-IPv6 transition to route IPv4 packets between + isolated IPv4-only routing region over IPv6 infrastructure. + + + +Callon & Haskin Informational [Page 2] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + The IPng transition provides a dual-IP-layer transition, augmented by + use of encapsulation where necessary and appropriate. Routing issues + related to this transition include: + + (1) Routing for IPv4 packets + + (2) Routing for IPv6 packets + (2a) IPv6 packets with IPv6-native addresses + (2b) IPv6 packets with IPv4-compatible addresses + + (3) Operation of manually configured static tunnels + + (4) Operation of automatic encapsulation + (4a) Locating encapsulators + (4b) Ensuring that routing is consist with + encapsulation + + Basic mechanisms required to accomplish these goals include: (i) + Dual-IP-layer Route Computation; (ii) Manual configuration of point- + to-point tunnels; and (iii) Route leaking to support automatic + encapsulation. + + The basic mechanism for routing of IPv4 and IPv6 involves dual-IP- + layer routing. This implies that routes are separately calculated for + IPv4 addresses and for IPv6 addressing. This is discussed in more + detail in section 3.1. + + Tunnels (either IPv4 over IPv6, or IPv6 over IPv4) may be manually + configured. For example, in the early stages of transition this may + be used to allow two IPv6 domains to interact over an IPv4 + infrastructure. Manually configured static tunnels are treated as if + they were a normal data link. This is discussed in more detail in + section 3.2. + + Use of automatic encapsulation, where the IPv4 tunnel endpoint + address is determined from the IPv4 address embedded in the IPv4- + compatible destination address of IPv6 packet, requires consistency + of routes between IPv4 and IPv6 routing domains for destinations + using IPv4-compatible addresses. For example, consider a packet which + starts off as an IPv6 packet, but then is encapsulated in an IPv4 + packet in the middle of its path from source to destination. This + packet must locate an encapsulator at the correct part of its path. + Also, this packet has to follow a consistent route for the entire + path from source to destination. This is discussed in more detail in + section 3.3. + + The mechanisms for tunneling IPv6 over IPv4 are defined in the + transition mechanisms specification [1]. + + + +Callon & Haskin Informational [Page 3] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + +3. MORE DETAIL OF BASIC APPROACHES + +3.1 Basic Dual-IP-layer Operation + + In the basic dual-IP-layer transition scheme, routers may + independently support IPv4 and IPv6 routing. Other parts of the + transition, such as DNS support, and selection by the source host of + which packet format to transmit (IPv4 or IPv6) are discussed in [1]. + Forwarding of IPv4 packets is based on routes learned through running + IPv4-specific routing protocols. Similarly, forwarding of IPv6 + packets (including IPv6-packets with IPv4-compatible addresses) is + based on routes learned through running IPv6-specific routing + protocols. This implies that separate instances of routing protocols + are used for IPv4 and for IPv6 (although note that this could consist + of two instances of OSPF and/or two instances of RIP, since both OSPF + and RIP are capable of supporting both IPv4 and IPv6 routing). + + A minor enhancement would be to use an single instance of an + integrated routing protocol to support routing for both IPv4 and + IPv6. At the time that this is written there is no protocol which + has yet been enhanced to support this. This minor enhancement does + not change the basic dual-IP-layer nature of the transition. + + For initial testing of IPv6 with IPv4-compatible addresses, it may be + useful to allow forwarding of IPv6 packets without running any IPv6- + compatible routing protocol. In this case, a dual (IPv4 and IPv6) + router could run routing protocols for IPv4 only. It then forwards + IPv4 packets based on routes learned from IPv4 routing protocols. + Also, it forwards IPv6 packets with an IPv4-compatible destination + address based on the route for the associated IPv4 address. There are + a couple of drawbacks with this approach: (i) It does not + specifically allow for routing of IPv6 packets via IPv6-capable + routers while avoiding and routing around IPv4-only routers; (ii) It + does not produce routes for "non-compatible" IPv6 addresses. With + this method the routing protocol does not tell the router whether + neighboring routers are IPv6-compatible. However, neighbor discovery + may be used to determine this. Then if an IPv6 packet needs to be + forwarded to an IPv4-only router it can be encapsulated to the + destination host. + +3.2 Manually Configured Static Tunnels + + Tunneling techniques are already widely deployed for bridging non-IP + network layer protocols (e.g. AppleTalk, CLNP, IPX) over IPv4 routed + infrastructure. IPv4 tunneling is an encapsulation of arbitrary + packets inside IPv4 datagrams that are forwarded over IPv4 + infrastructure between tunnel endpoints. For a tunneled protocol, a + tunnel appears as a single-hop link (i.e. routers that establish a + + + +Callon & Haskin Informational [Page 4] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + tunnel over a network layer infrastructure can inter-operate over the + tunnel as if it were a one-hop, point-to-point link). Once a tunnel + is established, routers at the tunnel endpoints can establish routing + adjacencies and exchange routing information. Describing the + protocols for performing encapsulation is outside the scope of this + paper (see [1]). Static point-to-point tunnels may also be + established between a host and a router, or between two hosts. Again, + each manually configured point-to-point tunnel is treated as if it + was a simple point-to-point link. + +3.3 Automatic Tunnels + + Automatic tunneling may be used when both the sending and destination + nodes are connected by IPv4 routing. In order for automatic + tunneling to work, both nodes must be assigned IPv4-compatible IPv6 + addresses. Automatic tunneling can be especially useful where either + source or destination hosts (or both) do not have any adjacent IPv6- + capable router. Note that by "adjacent router", this includes + routers which are logically adjacent by virtue of a manually + configured point-to-point tunnel (which is treated as if it is a + simple point-to-point link). + + With automatic tunneling, the resulting IPv4 packet is forwarded by + IPv4 routers as a normal IPv4 packet, using IPv4 routes learned from + routing protocols. There are therefore no special issues related to + IPv4 routing in this case. There are however routing issues relating + to how IPv6 routing works in a manner which is compatible with + automatic tunneling, and how tunnel endpoint addresses are selected + during the encapsulation process. Automatic tunneling is useful from + a source host to the destination host, from a source host to a + router, and from a router to the destination host. Mechanisms for + automatic tunneling from a router to another router are not currently + defined. + +3.3.1 Host to Host Automatic Tunneling + + If both source and destination hosts make use of IPv4-compatible IPv6 + addresses, then it is possible for automatic tunneling to be used for + the entire path from the source host to the destination host. In this + case, the IPv6 packet is encapsulated in an IPv4 packet by the source + host, and is forwarded by routers as an IPv4 packet all the way to + the destination host. This allows initial deployment of IPv6-capable + hosts to be done prior to the update of any routers. + + + + + + + + +Callon & Haskin Informational [Page 5] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + A source host may make use of Host to Host automatic tunneling + provided that the following are both true: + + - the source address is an IPv4-compatible IPv6 address. + - the destination address is an IPv4-compatible IPv6 address. + - the source host does know of one or more neighboring IPv4- + capable routers, or the source and destination are on the + same subnet. + + If all of these requirements are true, then the source host may + encapsulate the IPv6 packet in an IPv4 packet, using a source IPv4 + address which is extracted from the associated source IPv6 address, + and using a destination IPv4 address which is extracted from the + associated destination IPv6 address. + + Where host to host automatic tunneling is used, the packet is + forwarded as a normal IPv4 packet for its entire path, and is + decapsulated (i.e., the IPv4 header is removed) only by the + destination host. + +3.3.2 Host to Router Configured Default Tunneling + + In some cases "configured default" tunneling may be used to + encapsulate the IPv6 packet for transmission from the source host to + an IPv6-backbone. However, this requires that the source host be + configured with an IPv4 address to use for tunneling to the backbone. + + Configured default tunneling is particularly useful if the source + host does not know of any local IPv6-capable router (implying that + the packet cannot be forwarded as a normal IPv6 packet directly over + the link layer), and when the destination host does not have an + IPv4-compatible IPv6 address (implying that host to host tunneling + cannot be used). + + Host to router configured default tunneling may optionally also be + used even when the host does know of a local IPv6 router. In this + case it is a policy decision whether the host prefers to send a + native IPv6 packet to the IPv6-capable router or prefers to send an + encapsulated packet to the configured tunnel endpoint. + + Similarly host to router default configured tunneling may be used + even when the destination address is an IPv4-compatible IPv6 address. + In this case for example a policy decision may be made to prefer + tunneling for part of the path and native IPv6 for part of the path, + or alternatively to use tunneling for the entire path from source + host to destination host. + + + + + +Callon & Haskin Informational [Page 6] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + A source host may make use of host to router configured default + tunneling provided that ALL of the following are true: + + - the source address is an IPv4-compatible IPv6 address. + - the source host does know of one or more neighboring IPv4- + capable routers + - the source host has been configured with an IPv4 address of + an dual router which can serve as the tunnel endpoint. + + If all of these requirements are true, then the source host may + encapsulate the IPv6 packet in an IPv4 packet, using a source IPv4 + address which is extracted from the associated source IPv6 address, + and using a destination IPv4 address which corresponds to the + configured address of the dual router which is serving as the tunnel + endpoint. + + When host to router configured default tunneling is used, the packet + is forwarded as a normal IPv4 packet from the source host to the dual + router serving as tunnel endpoint, is decapsulated by the dual + router, and is then forwarded as a normal IPv6 packet by the tunnel + endpoint. + +3.3.2.1 Routing to the Endpoint for the Configured Default Tunnel + + The dual router which is serving as the end point of the host to + router configured default tunnel must advertise reachability into + IPv4 routing sufficient to cause the encapsulated packet to be + forwarded to it. + + The simplest approach is for a single IPv4 address to be assigned for + use as a tunnel endpoint. One or more dual routers, which have + connectivity to the IPv6 backbone and which are capable of serving as + tunnel endpoint, advertise a host route to this address into IPv4 + routing in the IPv4-only region. Each dual host in the associated + IPv4-only region is configured with the address of this tunnel + endpoint and selects a route to this address for forwarding + encapsulated packet to a tunnel end point (for example, the nearest + tunnel end point, based on whatever metric(s) the local routing + protocol is using). + + Finally, in some cases there may be some reason for specific hosts to + prefer one of several tunnel endpoints, while allowing all potential + tunnel endpoints to serve as backups in case the preferred endpoint + is not reachable. In this case, each dual router with IPv6 backbone + connectivity which is serving as potential tunnel endpoint is given a + unique IPv4 address taken from a single IPv4 address block (where the + IPv4 address block is assigned either to the organization + administering the IPv4-only region, or to the organization + + + +Callon & Haskin Informational [Page 7] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + administering the local part of the IPv6 backbone). In the likely + case that there are much less than 250 such dual routers serving as + tunnel endpoints, we suggest using multiple IPv4 addresses selected + from a single 24-bit IPv4 address prefix for this purpose. Each dual + router then advertises two routes into the IPv4 region: A host route + corresponding to the tunnel endpoint address specifically assigned to + it, and also a standard (prefix) route to the associated IPv4 address + block. Each dual host in the IPv4-only region is configured with a + tunnel endpoint address which corresponds to the preferred tunnel + endpoint for it to use. If the associated dual router is operating, + then the packet will be delivered to it based upon the host route + that it is advertising into the IPv4-only region. However, if the + associated dual router is down, but some other dual router serving as + a potential tunnel endpoint is operating, then the packet will be + delivered to the nearest operating tunnel endpoint. + +3.3.3 Router to Host Automatic Tunneling + + In some cases the source host may have direct connectivity to one or + more IPv6-capable routers, but the destination host might not have + direct connectivity to any IPv6-capable router. In this case, + provided that the destination host has an IPv4-compatible IPv6 + address, normal IPv6 forwarding may be used for part of the packet's + path, and router to host tunneling may be used to get the packet from + an encapsulating dual router to the destination host. + + In this case, the hard part is the IPv6 routing required to deliver + the IPv6 packet from the source host to the encapsulating router. For + this to happen, the encapsulating router has to advertise + reachability for the appropriate IPv4-compatible IPv6 addresses into + the IPv6 routing region. With this approach, all IPv6 packets + (including those with IPv4-compatible addresses) are routed using + routes calculated from native IPv6 routing. This implies that + encapsulating routers need to advertise into IPv6 routing specific + route entries corresponding to any IPv4-compatible IPv6 addresses + that belong to dual hosts which can be reached in an neighboring + IPv4-only region. This requires manual configuration of the + encapsulating routers to control which routes are to be injected into + IPv6 routing protocols. Nodes in the IPv6 routing region would use + such a route to forward IPv6 packets along the routed path toward the + router that injected (leaked) the route, at which point packets are + encapsulated and forwarded to the destination host using normal IPv4 + routing. + + Depending upon the extent of the IPv4-only and dual routing regions, + the leaking of routes may be relatively simple or may be more + complex. For example, consider a dual Internet backbone, connected + via one or two dual routers to an IPv4-only stub routing domain. In + + + +Callon & Haskin Informational [Page 8] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + this case, it is likely that there is already one summary address + prefix which is being advertised into the Internet backbone in order + to summarize IPv4 reachability to the stub domain. In such a case, + the border routers would be configured to announce the IPv4 address + prefix into the IPv4 routing within the backbone, and also announce + the corresponding IPv4-compatible IPv6 address prefix into IPv6 + routing within the backbone. + + A more difficult case involves the border between a major Internet + backbone which is IPv4-only, and a major Internet backbone which + supports both IPv4 and IPv6. In this case, it requires that either + (i) the entire IPv4 routing table be fed into IPv6 routing in the + dual routing domain (implying a doubling of the size of the routing + tables in the dual domain); or (ii) Manual configuration is required + to determine which of the addresses contained in the Internet routing + table include one or more IPv6-capable systems, and only these + addresses be advertised into IPv6 routing in the dual domain. + +3.3.4 Example of How Automatic Tunnels May be Combined + + Clearly tunneling is useful only if communication can be achieved in + both directions. However, different forms of tunneling may be used in + each direction, depending upon the local environment, the form of + address of the two hosts which are exchanging IPv6 packets, and the + policies in use. + + Table 1 summarizes the form of tunneling that will result given each + possible combination of host capabilities, and given one possible set + of policy decisions. This table is derived directly from the + requirements for automatic tunneling discussed above. + + The example in table 1 uses a specific set of policy decisions: It is + assumed in table 1 that the source host will transmit a native IPv6 + where possible in preference over encapsulation. It is also assumed + that where tunneling is needed, host to host tunneling will be + preferred over host to router tunneling. Other combinations are + therefore possible if other policies are used. + + Due to a specific policy choice, the default sending rules in [1] may + not be followed. + + Note that IPv6-capable hosts which do not have any local IPv6 router + must be given an IPv4-compatible v6 address in order to make use of + their IPv6 capabilities. Thus, there are no entries for IPv6-capable + hosts which have an incompatible IPv6 address and which also do not + have any connectivity to any local IPv6 router. In fact, such hosts + could communicate with other IPv6 hosts on the same local network + without the use of a router. However, since this document focuses on + + + +Callon & Haskin Informational [Page 9] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + routing and router implications of IPv6 transition, direct + communication between two hosts on the same local network without any + intervening router is outside the scope of this document. + + Also, table 1 does not consider manually configured point-to-point + tunnels. Such tunnels are treated as if they were normal point-to- + point links. Thus any two IPv6-capable devices which have a manually + configured tunnel between them may be considered to be directly + connected. + + -----------------+------------------+-------------------------- + Host A | Host B | Result + -----------------+------------------+-------------------------- + v4-compat. addr. | v4-compat. addr. | host to host tunneling + no local v6 rtr. | no local v6 rtr. | in both directions + -----------------+------------------+-------------------------- + v4-compat. addr. | v4-compat. addr. | A->B: host to host tunnel + no local v6 rtr. | local v6 rtr. | B->A: v6 forwarding plus + | | rtr->host tunnel + -----------------+------------------+-------------------------- + v4-compat. addr. | incompat. addr. | A->B: host to rtr tunnel + no local v6 rtr. | local v6 rtr. | plus v6 forwarding + | | B->A: v6 forwarding plus + | | rtr to host tunnel + -----------------+------------------+-------------------------- + v4-compat. addr. | v4-compat. addr. | end to end native v6 + local v6 rtr. | local v6 rtr. | in both directions + -----------------+------------------+-------------------------- + v4-compat. addr. | incompat. addr. | end to end native v6 + local v6 rtr. | local v6 rtr. | in both directions + -----------------+------------------+-------------------------- + incompat. addr. | incompat. addr. | end to end native v6 + local v6 rtr. | local v6 rtr. | in both directions + -----------------+------------------+-------------------------- + + Table 1: Summary of Automatic Tunneling Combinations + +3.3.5 Example + + Figure 2 illustrates an example network with two regions A and B. + Region A is dual, meaning that the routers within region A are + capable of forwarding both IPv4 and IPv6. Region B is IPv4-only, + implying that the routers within region B are capable of routing only + IPv4. The illustrated routers R1 through R4 are dual. The illustrated + routers r5 through r9 are IPv4-only. Also assume that hosts H3 + through H8 are dual. Thus H7 and H8 have been upgraded to be IPv6- + capable, even though they exist in a region in which the routers are + not IPv6-capable. However, host h1 and h2 are IPv4-only. + + + +Callon & Haskin Informational [Page 10] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + ......................... ....................... + . . . . + . h1 . . |-h2 . + . | . . | . + . H3---R1--------R2---------------r5----r9----+ . + . | | . . | |-H7 . + . | | . . | . + . | | . . | . + . H4---R3--------R4---------------r6----r8-----H8 . + . . . . + ......................... ....................... + Region A (Dual Routers) Region B (IPv4-only Rtrs) + + Figure 2: Example of Automatic Tunneling + + Consider a packet from h1 to H8. In this case, since h1 is IPv4-only, + it will send an IPv4 packet. This packet will traverse regions A and + B as a normal IPv4 packet for the entire path. Routing will take + place using normal IPv4 routing methods, with no change from the + operation of the current IPv4 Internet (modulo normal advances in the + operation of IPv4, of course). Similarly, consider a return packet + from H8 to h1. Here again H8 will transmit an IPv4 packet, which will + be forwarded as a normal IPv4 packet for the entire path. + + Consider a packet from H3 to H8. In this case, since H8 is in an + IPv4-only routing domain, we can assume that H8 uses an IPv4- + compatible IPv6 address. Since both source and destination are IPv6- + capable, H3 may transmit an IPv6 packet destined to H8. The packet + will be forwarded as far as R2 (or R4) as an IPv6 packet. + + Router R2 (or R4) will then encapsulate the full IPv6 packet in an + IPv4 header for delivery to H8. In this case it is necessary for + routing of IPv6 within region A to be capable of delivering this + packet correctly to R2 (or R4). As explained in section 3.3, routers + R2 and R4 may inject routes to IPv4-compatible IPv6 addresses into + the IPv6 routing used within region A corresponding to the routes + which are available via IPv4 routing within region B. + + Consider a return packet from H8 to H3. Again, since both source and + destination are IPv6-capable, a IPv6 packet may be transmitted by H8. + However, since H8 does not have any direct connectivity to an IPv6- + capable router, H8 must make use of an automatic tunnel. Which form + of automatic tunnel will be used depends upon the type of address + assigned to H3. + + + + + + + +Callon & Haskin Informational [Page 11] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + If H3 is assigned an IPv4-compatible address, then the requirements + specified in section 3.3.1 will all be satisfied. In this case host + H8 may encapsulate the full IPv6 packet in an IPv4 header using a + source IPv4 address extracted from the IPv6 address of H8, and using + a destination IPv4 address extracted from the IPv6 address of H3. + + If H3 has an IPv6-only address, then it is not possible for H8 to + extract an IPv4 address to use as the destination tunnel address from + the IPv6 address of H3. In this case H8 must use host to router + tunneling, as specified in section 3.3.2. In this case one or both of + R2 and R4 must have been configured with a tunnel endpoint IPv4 + address (R2 and R4 may use either the same address or different + addresses for this purpose). R2 and/or R4 therefore advertise + reachability to the tunnel endpoint address to r5 and r6 + (respectively), which advertise this reachability information into + region B. Also, H8 must have been configured to know which tunnel + endpoint address to use for host to router tunneling. This will + result in the IPv6 packet, encapsulated in an IPv4 header, to be + transmitted as far as the border router R2 or R4. The border router + will then strip off the IPv4 header, and forward the remaining IPv6 + packet as a normal IPv6 packet using the normal IPv6 routing used in + region A. + +4. SECURITY CONSIDERATIONS + + Use of tunneling may violate firewalls of underlying routing + infrastructure. + + No other security issues are discussed in this paper. + +5. REFERENCES + + [1] Gilligan, B. and E. Nordmark. Transition Mechanisms for IPv6 + Hosts and Routers, Sun Microsystems, RFC 1933, April 1996. + + +6. AUTHORS' ADDRESSES + + Ross Callon + Cascade Communications Co. + 5 Carlisle Road + Westford, MA 01886 + email: rcallon@casc.com + + + + + + + + +Callon & Haskin Informational [Page 12] + +RFC 2185 Routing Aspects Of IPv6 Transition September 1997 + + + Dimitry Haskin + Bay Networks, Inc. + 2 Federal Street + Billerica, MA 01821 + email: dhaskin@baynetworks.com + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Callon & Haskin Informational [Page 13] + |