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This chapter describes the required and optional tasks for configuring the Multiprotocol over ATM (MPOA) Server. For a complete description of the MPOA Server commands used in this chapter, refer to the "MPOA Commands" chapter in the Cisco IOS Switching Services Command Reference. For documentation of other commands that appear in this chapter, you can use the command reference master index or search online.
The MPOA Server supplies the forwarding information used by the MPOA Clients (MPCs). The MPOA Server (MPS) responds with the information after receiving a query from a client. To support the query and response functions, MPOA has adopted the Next Hop Resolution Protocol (NHRP). The MPS on the router can also terminate shortcuts.
The MPS software module implements the functionality of the MPS in compliance with the ATM Forum MPOA specification. The following sections describe the functions of MPS:
MPS has to interact with the NHRP module in the router to smoothly propagate MPOA/NHRP packets end to end. MPOA frames are identical to NHRP frames except for some specific op-codes and extensions for MPOA.
The following process explains the interaction of MPS and NHRP:
1. MPS converts MPOA resolution requests to NHRP requests and sends it either to the next hop MPS or to the Next Hop Server (NHS) depending on the configuration. MPS searches for the next hop routing information to determine the interface and sends the packet with correct encapsulation to an MPS or an NHS.
2. NHS sends resolution requests to MPS when the next hop is on a LAN Emulation (LANE) cloud or when NHS is unsure of the packet destination. MPS may do further processing, such as prompt NHS to terminate the request or throw away the packet.
3. NHS sends resolution replies to MPS when the next hop interface is LANE or when the replies terminate in the router. Then MPS sends an MPOA resolution reply to the MPC.
Within a router, it is possible to permit shortcuts between one group of LAN Emulation Clients (LECs) and deny it between some other groups of LECs. Cisco introduces a notion of network ID associated with an MPS. By default, all the MPSs in a router get a network ID of 1.
If the administrator wants to segregate traffic, then MPSs can be given different network IDs, in effect preventing shortcuts between LECs served by different MPSs. This can be configured in the definition of an MPS database.
If a router has both MPS and NHRP configured, then the same network ID is required to facilitate requests, replies, and shortcuts across the MPS and NHRP. The interface-specific NHRP command (ip nhrp network-id) must be the same for an MPS; otherwise, there will be a disjointed network.
To configure an MPS on your network, perform the following tasks. Only the first two tasks are required; the remaining two tasks are optional.
For MPOA to work properly, a LANE client must have an ELAN ID for all ELANs represented by the LANE clients. To configure an ELAN ID, use either of the following commands in lane database configuration mode or in interface configuration mode when starting up the LAN Emulation Client Server (LES) for that ELAN:
| Command | Purpose |
|---|---|
name elan-name elan-id id | Configure the ELAN ID in the LECS database to participate in MPOA. |
lane server-bus {ethernet | tokenring} elan-name [elan-id id] | Configure the LAN Emulation Server (LES) with the ELAN ID to participate in MPOA. |
 | Caution If an ELAN ID is supplied by both commands, make sure that the ELAN ID matches in both. |
To configure an MPS, use the following commands. The MPS starts functioning only after it is attached to a specific hardware interface:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| mpoa server config name mps-name | In global configuration mode, define an MPS with the specified name. | ||
| interface atm {slot/port | number} | Specify the ATM interface to attach the MPS. | ||
| mpoa server name mps-name | In interface configuration mode, attach the MPS to the ATM interface. | ||
| interface atm {slot/port.subinterface-number | number.subinterface-number} | Specify the ATM interface to bind the MPS to a LEC. | ||
| lane client mpoa server name mps-name | In subinterface configuration mode, bind a LANE client to the specified MPS. |
An MPS has to be defined with a specified name before you can change the MPS variables specific to that MPS.
To change MPS variables specific only to a particular MPS, use the following commands starting in MPS configuration mode:
| Step | Command | Purpose | ||
|---|---|---|---|---|
| mpoa server config name mps-name | Define an MPS with the specified name. | ||
| atm-address atm-address | (Optional) Specify the control ATM address that the MPS should use (when it is associated with a hardware interface). | ||
| network-id id | (Optional) Specify the network ID of the MPS. | ||
| keepalive-time time | (Optional) Specify the keepalive time value for the MPS-p1 variable of the MPS. | ||
| holding-time time | (Optional) Specify the holding time value for the MPS-p7 variable of the MPS. |
To monitor and maintain the configuration of an MPS, use the following commands in EXEC mode:
| Command | Purpose |
|---|---|
Display default ATM addresses for an MPS. | |
show mpoa server [name mps-name] | Display information about a specified server or all servers depending on the specified name of the required server. |
show mpoa server [name mps-name] cache | Display ingress and egress cache entries associated with a server. |
show mpoa server [name mps-name] statistics | Display all the statistics collected by a server including the ingress and egress cache entry creations, deletions, and failures. |
clear mpoa server [name mps-name] cache [ingress | egress] [ip-addr ip-addr] | Clear cache entries. |
mpoa server name mps-name trigger ip-address ip-address [mpc-address mpc-address] | Originate an MPOA trigger for the specified IP address to the specified client. If a client is not specified, the MPOA is triggered to all the clients. |
This section contains an example of the commands needed to configure an MPS. The lines beginning with exclamation points (!) are comments explaining the command shown on the following line. Figure 40 shows an example of how you can configure your system to utilize MPOA.
The following example configures the MPS and attaches the MPS to a hardware interface:
! Define the MPS "MYMPS" mpoa server config name MYMPS ! Leave everything as default exit ! Enter into interface config mode interface ATM 1/0 ! Attach MPS MYMPS to the HW interface mpoa server name MYMPS ! Go back up to global config mode exit
The following example shows a typical MPS configuration file:
version 11.3 hostname MPS ! Define the MPS "mps" mpoa server config name mps ! Specify the ATM interface to which the MPS is attached interface ATM4/0
! Specify the ATM interface that contains the LEC to which you will bind the MPS interface ATM4/0.1 multipoint
interface ATM4/0.2 multipoint
end
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