CURRENT_MEETING_REPORT_ Reported by George Clapp/Ameritech SMDS Minutes Review of Draft Document The IP over Switched Multi-megabit Data Service (SMDS) Working Group met for three half-day sessions. The majority of the time was spent reviewing the text of a draft document, A Proposed Standard for the Transmission of IP Datagrams over SMDS, written by Dave Piscitello and Joe Lawrence. The configuration assumed in the document was that of a Logical IP Subnet (dubbed an LIS), in which a virtual private network supported by SMDS was treated as an IP network/subnet. The following are the requirements for an LIS configuration: o All members have the same IP network/subnetwork number. o All stations within an LIS are accessed directly over SMDS. o All stations outside of the LIS are accessed via a router. o For each LIS, a single SMDS group address (smds$ip_ga) has been configured that identifies all members of the LIS. The protocol stack is assumed to be that depicted below in figure 1. --------------------------------------------- | IP/ARP | --------------------------------------------- | Subnetwork Access Protocol (SNAP) | --------------------------------------------- | IEEE 802.2 LLC Type 1 | --------------------------------------------- |SMDS Interface Protocol (SIP) Level 3 (MAC)| --------------------------------------------- | SIP Level 2 | --------------------------------------------- | SIP Level 1 | --------------------------------------------- Figure 1 In addition to the SMDS individual address associated with the Subscriber Network Interface (SNI), and to the SMDS group address associated with the LIS, the document referred to a third SMDS group address, the SMDS ARP Request Address (smds$arp_req). This group address is set to smds $ip_ga, but latter implementations may set the 1 address to a subset of the addresses in the LIS to deal with scaling issues. The dynamic mapping of 32 bit Internet addresses to 60 bit SMDS addresses is done via Address Resolution Protocol (ARP). ARP requests will be multicast to the smds$arp_req address. The ARP parameters which require specification are the following: ar$hrd 16 bits hardware type code ar$pro 16 bits protocol type code decimal 2048 for IP ar$hln 8 bits octets in hardware address decimal 8 for 64 bits ar$pln 8 bits octets in protocol address decimal 4 for 32 bits ar$op 16 bits operation code 1: request 2: reply Dave Piscitello volunteered to contact Joyce Reynolds to obtain a value for the hardware type code. An issue arose during the discussion of ARP over SMDS concerning the encoding of the SMDS address in the ARP reply message. Following the precedence of the IP over FDDI Working Group, the document specified that the SMDS address will be carried in ``canonical'' format, which is the format specified in the IEEE P802.1A/D10 draft standard, in which the least significant bit of the most significant octet is transmitted first. The encoding of the 60 bit address within the SIP L_3 PDU does not conform to the canonical format, and the bits of each octet would have to be reversed. The use of the canonical format is important in transparent bridging, when LANs of a similar address space but of dissimilar address encoding schemes may be bridged. However, the group questioned the utility of transparent bridging between 802 LANs with a 48 bit address space and SMDS with a 60 bit address space. This questionable utility was compared with the potential for confusion caused by the reversal of bits in the SMDS address. In the end, the group decided not to use the canonical format, but instead to use the format specified for the SMDS ``MAC'' header. No unresolved issues remained with the document and the group asked Joe Lawrence to incorporate the suggested modifications and to release the document to the email group for confirmation. Joe indicated that he might be able to release the document by mid-August. Public Connectivity It was felt that the draft document was adequate to define the operation of IP over small virtual private networks supported by SMDS. Discussion then turned to the issue of ``public connectivity,'' in which an SMDS device may communicate directly with any other SMDS device. The question was asked of this model ``What breaks?'', and the following items were listed: 2 o ARP o Routing: cost, traffic volume, table sizes o Address management The group was then asked whether there was any interest in pursuing this problem, and discussion led to an offer by Manoel Rodrigues and George Clapp to draft an ``issues'' document to attempt to clarify the issues left unresolved by the draft document. Support of Other Protocols Vicki Ralls pointed out that other protocols such as DECNET and XNS also need a specification to operate over SMDS, and asked whether this was of interest to the group. The group felt that IP was the appropriate topic for their work and suggested that Bellcore might be approached concerning these other protocols. Network Management Dave Piscitello distributed copies of three papers on network management relevant to SMDS. o Experimental Definitions of Managed Objects for the SMDS Interface Protocol (sip) Interface Type, Kaj Tesink o Experimental Definitions of Managed Objects for the t3-carrier Interface Type, Tracy Cox, Kaj Tesink o Internet Draft of T1-Carrier objects, Kaj Tesink, Tracy Cox These documents were distributed to the Working Group on an informational basis to the. The first two documents had been submitted for consideration by the TransMIB Working Group; the third had not been submitted since the points raised in the document had already been addressed by the TransMIB group. Future Work The work remaining for the group will be to review and possibly approve the draft document. The group may be able to approve the document at the upcoming meeting in December and, if possible, begin the process of submitting the document to become an RFC. At the same meeting, the group may review the document to be written by Manoel Rodrigues and George Clapp. During the IETF Plenary of Friday morning, August 3rd, Bob Hinden announced the formation of a new Working Group within the routing area, Address Resolution and Routing over SMDS and X.25 Public Data Networks. This group will be chaired by George Clapp and may investigate some of the issues left unresolved by the IP over SMDS Working Group. 3 Attendees Douglas Bagnall bagnall_d@apollo.hp.com Chet Birger cbirger@bbn.com Roger Boehner Roger.Boehner@StPaul.NCR.COM Caralyn Brown cbrown@ENR.Prime.com Asheem Chandna ac0@mtuxo.att.com George Clapp meritec!clapp@bellcore.bellcore.com Tracy Cox tacox@sabre.bellcore.com Caroline Cranfill rcc@bss.com Kevin Fall kfall@Berkeley.EDU Michael Fidler ts0026@ohstvma.ircc.ohio-state.edu James Forster forster@cisco.com Craig Fox foxcj@nsco.network.com Eugene Geer bcr!nvmxr!ewg Neil Haller nmh@bellcore.com Dave Kaufman dek@proteon.com Alex Koifman akoifman@bbn.com Joseph Lawrence jcl@sabre.bellcore.com Walter Lazear lazear@gateway.mitre.org Alan Menezes afm@cup.portal.com David Piscitello dave@sabre.bellcore.com Vicki Ralls ralls@cisco.com Michael Reilly reilly@nsl.dec.com Ron Roberts roberts@jessica.stanford.edu Manuel Rodrigues Jim Showalter gamma@mintaka.dca.mil Frank Slaughter fgs@shiva.com Zaw-Sing Su zsu@tsca.istc.sri.com Gregory Vaudreuil gvaudre@nri.reston.va.us Chris Weider clw@merit.edu Steve Willis swillis@wellfleet.com 4