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ATM Signaling and Addressing - Part Two
Addressing on the ATM Switch Router The ATM address is used by the ATM switch router for signaling and management functions, and by protocols such as LAN emulation and PNNI. The ATM switch router ships with a preconfigured default address which allows it to function in a plug-and-play manner. You can change the default address if you need to; the main reasons for doing so are listed in the section "Manually Configured ATM Addresses" section on page 2-11. If you do not foresee needing to reconfigure the ATM address, then the details of the following sections might not concern you. Autoconfigured ATM Addressing Scheme During initial startup, the ATMswitch router generates an ATMaddress using the following defaults (see Figure 2-5): AFI=47indicates an address of type DCC ICD=0091(Cisco-specific) Cisco-specific address type (part of HO-DSP)=81000000 Cisco switch ID=MAC format address ESI=MAC address repeatedNote The MAC address used in the Cisco switch ID and ESI fields is the default MAC address for the ATM switch router. It might not be the same as the address printed on the chassis label. Selector equals 01 byteFigure 2-5 ATM Address Format
The autoconfigured address mechanism provides a default ATM address for the unconfigured switch. This default address is used by the following protocols: The Integrated Local Management Interface (ILMI)a protocol and part of the UNI specifications that facilitates sharing of management information across the UNI. ILMI uses the first 13 bytes of this address to hand to end systems for the generation of ESI addresses. Private Network-Network Interface (PNNI)a dynamic routing protocol for ATM networks. PNNI uses the 13-byte prefix to establish itself as a node in a single-level PNNI routing domain and the first 7 bytes to construct the default peer group identifier. Default Address Format Features and Implications Using the default address format has the following features and implications: All preconfigured addresses share the same 7-byte address prefix. In the autoconfigured address for a given ATM switch router, the same MAC address is used for bytes 8 through 13 and bytes 14 through 19. The default autoconfigured address provides plug-and-play operation. You can reconfigure the ATM address using your own addressing style, but you must use a globally unique MAC address to generate the ATM address.
The example display below shows the autoconfigured ATM addresses on the ATM switch router.
Note that the 13-byte ILMI switch prefix is the same for all addresses. Switch# show atm addresses Switch Address(es): 47.00918100000000E04FACB401.00E04FACB401.00 active Soft VC Address(es): 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.1000.00 ATM0/1/0 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.1010.00 ATM0/1/1 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.1020.00 ATM0/1/2 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.1030.00 ATM0/1/3 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.8000.00 ATM1/0/0 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.8010.00 ATM1/0/1 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.8020.00 ATM1/0/2 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.8030.00 ATM1/0/3 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.9000.00 ATM1/1/0 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.9010.00 ATM1/1/1 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.9020.00 ATM1/1/2 47.0091.8100.0000.00e0.4fac.b401.4000.0c80.9030.00 ATM1/1/3 47.0091.8100.0000.00e0.4fac.b401.4000.0c81.8030.00 ATM-P3/0/3 47.0091.8100.0000.00e0.4fac.b401.4000.0c81.9000.00 ATM3/1/0 47.0091.8100.0000.00e0.4fac.b401.4000.0c81.9010.00 ATM3/1/1 47.0091.8100.0000.00e0.4fac.b401.4000.0c81.9020.00 ATM3/1/2 47.0091.8100.0000.00e0.4fac.b401.4000.0c81.9030.00 ATM3/1/3 47.0091.8100.0000.00e0.4fac.b401.4000.0c82.0000.00 ATM-P4/0/0 Soft VC Address(es) for Frame Relay Interfaces : 47.0091.8100.0000.00e0.4fac.b401.4000.0c82.0010.00 Serial4/0/0:1 47.0091.8100.0000.00e0.4fac.b401.4000.0c82.0020.00 Serial4/0/0:2 47.0091.8100.0000.00e0.4fac.b401.4000.0c82.0030.00 Serial4/0/0:3 47.0091.8100.0000.00e0.4fac.b401.4000.0c82.0210.00 Serial4/0/1:1 47.0091.8100.0000.00e0.4fac.b401.4000.0c82.0220.00 Serial4/0/1:2 ILMI Switch Prefix(es): 47.0091.8100.0000.00e0.4fac.b401 ILMI Configured Interface Prefix(es): LECS Address(es): 47.0091.8100.0000.00e0.4fac.b401.0010.0daa.cc43.00 ILMI Use of the ATM Address The ILMI protocol uses SNMP format packets across the UNI to access an ILMI Management Information Base (MIB) associated with the link, within each node. The ILMI protocol facilitates network-wide autoconfiguration by allowing adjacent nodes to determine various characteristics of each otherfor example, the size of each other's connection space, the type of signaling used (UNI,NNI), hooks for network management autodiscovery, and so on. One of its most useful features, address registration, greatly facilitates the administration of ATM addresses. The ILMI address registration mechanism allows an ATM end system to inform an ATM switch of its unique MAC address and to receive the remainder of the node's full ATMaddress in return. ILMI uses the first 13 bytes of the ATM address as the switch prefix that it registers with end systems. When the an end system, such as a router (Figure 2-6), is attached to the ATM switch, ILMI is used to send all the routers MAC addresses (ESIs) to the switch. The ESI is appended to the switchs 13-byte ILMI prefix to make up a complete ATMaddress, which is then associated with the interface on which it received the ESI. This allows the ATMswitch router, upon receiving a call setup request, to know which interface to send on. Figure 2-6 ILMI Address Registration Across the UNI Additional ILMI Considerations During address migration (changing from one addressing scheme to another), multiple addresses can be configured for a single switch. ILMI registers end systems with multiple prefixes during this period until an old address is removed. (PNNI automatically summarizes all of the switchs prefixes in its reachable address advertisement.) Although the default, autoconfigured address provides for a fixed 13-byte ILMI prefix, the ATM switch router allows configuration of per-interface ILMI address prefixes, so that different address prefixes can be registered with end systems attached to different interfaces. When any per-interface ILMI address prefixes are configured, they override the prefix(es) derived from the first 13 bytes of the switch ATM address(es) for that specific interface. ILMI access filters can provide security by permitting or denying ILMI registration of different classes of addresses. PNNI Use of the ATM Address The preconfigured address provides plug-and-play operation in isolated flat topology ATM networks. All switches with autoconfigured ATMaddresses will form one peer group. Although the preconfigured addresses are globally unique, they are not suitable for connection to service provider networks or within hierarchical PNNI networks. Furthermore, address summarization, a key feature of hierarchical PNNI, is not possible beyond the level of one ATM switch. In addition, while E.164 numbers are supported on UNI and IISP interfaces, they are not directly supported by PNNI. Instead, these are supported indirectly through use of the E.164 AESA format. LAN Emulation Use of the ATM Address On a LAN, packets are addressed by the MAC-layer address of the destination and source stations. To provide similar functionality, LAN emulation (LANE) must support some form ofMAC-to-ATM address mapping. All LANE client and server components must therefore have a unique ATM address. The ATM switch router provides a means of automatically assigning ATM addresses for LANE components. Manually Configured ATM Addresses The following situations require manually configuring the ATM address: To configure a new ATM address that replaces the previous ATM address and generates a new PNNI node ID and peer group ID for migrating from flat to hierarchical PNNI.
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