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This chapter describes native client interface architecture (NCIA) support for Systems Network Architecture (SNA) devices. NCIA server and the NCIA client/server model extends the scalability of NCIA I, the earlier NCIA implementation, by minimizing the number of central-site remote source-route bridging (RSRB) or data-link switching plus (DLSw+) peer connections required to support a large number of NCIA clients. For a complete description of the NCIA client/server commands mentioned in this chapter, refer to the "NCIA Server Configuration Commands" chapter of the Cisco IOS Bridging and IBM Networking Command Reference, Volume I. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
This chapter contains the following sections:
Cisco's NCIA server feature implements RFC 2114, Data Link Switch Client Access Protocol. Using Cisco's RSRB technology, NCIA I encapsulates the Token Ring traffic inside IP datagrams passed over a TCP connection between a router and a client. A virtual ring is created to allow the router to interconnect any client. The virtual ring acts as a logical Token Ring in the router, so that all the Token Rings connected to the router are treated as if they are all on the same Token Ring. The virtual ring is called a ring group. The ring group number is used just like a physical ring number and shows up in any route descriptors contained in packets being bridged. A ring group must be assigned a ring number that is unique throughout the network.
An NCIA I client acts as both an RSRB router and an end station. It must have a "fake" ring number and a "fake" bridge number so that it looks like an end station sitting on a real Token Ring. The fake ring and bridge numbers are visible to both the RSRB router and the NCIA client. The client must also have an LLC2 so that it can handle the LLC2 sessions.
The NCIA Server feature extends the scalability of NCIA I, enhances its functionality, and provides support for both the installed base of RSRB routers and the growing number of DLSw+ routers. The NCIA Server feature includes the following enhancements:
The NCIA Server feature uses a client/server model (Figure 199), where the NCIA server is a software module on a Cisco router and the NCIA client is a PC or workstation. The NCIA server performs two major functions:
NDLC is the protocol used between clients and servers. NDLC serves two purposes:
The peer session must be established before an end-to-end circuit can be set up. During the set up period for the peer session, the MAC address representing a client is defined. The MAC address can be defined by the client or by the server when the client does not have a MAC address.
The NCIA Server feature supports connect-in and connect-out (from the server's perspective), but connect-out is not supported if the client station does not listen for the incoming connection. For a server to connect-out, clients must connect to the server first. After registering itself by providing its own MAC address, the client can then optionally disconnect from the server. When a server receives an explorer, and its destination MAC address is registered, an NCIA server will connect to that client if it is not connected. For NetBIOS explorers (addressed to functional address 0xC00000000080), the TCP session must remain up so that the server can broadcast the explorers to the client. If the TCP session is down, the server will not send the NetBIOS explorers to a client, even when the client is registered.
After the peer session has been established, the NDLC protocol establishes the circuit between the client and server. This circuit is used to transfer end-user data between the client and the server. Because the client and its target station are not on the same transport, they cannot form a direct, end-to-end circuit. Each client must form a circuit between the client and server, and the server must form another circuit between the server and the target station. The server links those two circuits to form an end-to-end circuit. The server acts as a mediator between the client and the target station so that packets can be transferred between them.
In the NCIA server only peer keepalive is maintained. There is no keepalive at circuit level.
The NCIA server acts as a data-link provider, like Token Ring or Ethernet, in the router. It uses CLSI to communicate with other software modules, just as other data-link providers do. The network administrator configures the router to communicate with specific modules. For data-link users, such as SNASw, DLSw+, and DSPU, the NCIA server can interface to them directly. For other data-link providers, the NCIA server must go through a DLSw+ local peer to communicate with them. The DLSw+ local peer passes packets back and forth among different data-link providers.
The client/server model used in the NCIA Server feature extends the scalability of NCIA. In addition, it provides support for both the installed base of RSRB routers and the growing number of DLSw+ routers.
The client/server model minimizes the number of central site RSRB or DLSw+ peer connections required to support a large network of NCIA clients (Figure 200). Rather than each client having a peer connection to a central site router, the clients attach to an IP backbone through an NCIA server that, in turn, has a single peer connection to a central site router. This scheme can greatly reduce the number of central site peer connections required. For example, in a network with 1000 clients and 10 NCIA servers, there would be only 10 central site peer connections. Note that there would still be 1000 LLC2 connections that must be locally acknowledged at the central site router, but this can easily be handled in a single central site router. When the number of LLC2 connections (or the number of clients) is in the tens of thousands, NCIA servers can take advantage of downstream PU concentration to minimize the number of LLC2 connections that must be supported by the central site routers.
Using a client/server model allows the NCIA Server feature to be independent of the upstream implementation, allowing it to be implemented in a network that is still using RSRB, as well as in a DLSw+ network. It also greatly simplifies migration from RSRB to DLSw+, because it requires no changes at the client. A single NCIA server can support either approach (but not both). As Figure 201 illustrates, a central site router can support RSRB and DLSw+ concurrently, allowing a portion of the NCIA servers to communicate using RSRB and another portion to communicate using DLSw+.
The network configuration shown in Figure 202 includes NCIA clients that connect to a front-end processor (FEP) on a Token Ring through a local router (the NCIA server). The virtual ring is used in conjunction with DLSw+ local switch. The routing information field (RIF) of each circuit is terminated on the virtual ring. Figure 203 shows a logical view of an NCIA server session using a DLSw+ local switch (connected to a local Token Ring). In addition to Token Ring, an NCIA server also supports Ethernet, Synchronous Data Link Control (SDLC) Protocol, and Qualified Logical Link Control (QLLC) network connections as well as Channel Interface Processor (CIP) connections through a DLSw+ local switch. For more information on the different media types that a DLSw+ local switch supports, refer to the "Configuring DLSw+" chapter.
To configure an NCIA server session connected to a local Token Ring, perform the tasks in the following sections:
For a configuration example, see ""NCIA Server Session to Local Token Ring Using DLSw+ Local Switch Example" section".
In DLSw+, the source-bridge ring group specifies the virtual ring that will appear to be the last ring in the RIF. This ring is transparent to the NCIA client. From the host's point of view, all NCIA clients look like stations sitting on the virtual ring. To define a source-bridge ring group for DLSw+, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
source-bridge ring-group ring-group [virtual-mac-address] | Defines a ring group. |
Defining a DLSw+ local peer for a router enables a DLSw+ local switch. You specify all local DLSw+ parameters as part of the local peer definition. To define a local peer, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
dlsw local-peer [peer-id ip-address] [group group] [border] [cost cost] [lf size] [keepalive seconds] [passive] [promiscuous] [biu-segment] | Defines the DLSw+ local peer. |
Configuring an NCIA server on a router enables the router to perform two roles:
To configure an NCIA server, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
ncia server server-number server-ip-address server-virtual-mac-address virtual-mac-address virtual-mac-range [inbound-only] [keepalive seconds] [tcp_keepalive minutes] | Configures the NCIA server. |
In the network configuration shown in Figure 204, the NCIA server uses DLSw+ to connect its clients to the FEP through a remote router. Figure 205 shows a logical view of the NCIA Server session with DLSw+.
For a configuration example, see the "NCIA Server Session with DLSw+ Example" section.
The source-bridge ring can be shared between DLSw+ and SRB/RSRB. In DLSw+, the source-bridge ring group specifies the virtual ring that will appear to be the last ring in the RIF. Because RIFs are terminated at the router, there is no correlation between the ring-group number specified in DLSw+ peers. The numbers can be the same for management simplicity, but they do not have to be. To define a source-bridge ring group for DLSw+, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
source-bridge ring-group ring-group [virtual-mac-address] | Defines a ring group. |
| Command | Purpose |
|---|---|
dlsw local-peer [peer-id ip-address] [group group] [border] [cost cost] [lf size] [keepalive seconds] [passive] [promiscuous] [biu-segment] | Defines the DLSw+ local peer. |
| Command | Purpose |
|---|---|
dlsw remote-peer list-number tcp ip-address [backup-peer ip-address] [bytes-netbios-out bytes-list-name] [cost cost] [dest-mac mac-address][dmac-output-listaccess-list-number] [dynamic] [host-netbios-out host-list-name] [inactivity minutes] [keepalive seconds] [lf size] [linger minutes] [lsap-output-list list] [no-llc minutes] [priority] [tcp-queue-max size] [timeout seconds] | Defines a TCP encapsulation remote peer. |
Configuring an NCIA server on the local router enables the router to perform two roles:
To configure an NCIA server, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
ncia server server-number server-ip-address server-virtual-mac-address virtual-mac-address virtual-mac-range [inbound-only] [keepalive seconds] [tcp_keepalive minutes] | Configures the NCIA server. |
In the network configuration shown in Figure 206, the NCIA server uses DSPU to connect its clients to the FEP through a remote router. Figure 207 shows a logical view of the NCIA server session with RSRB/DLSw+ and DSPU.
For a configuration example, see ""NCIA Server Session with DSPU Example" section".
| Command | Purpose |
|---|---|
dspu host host-name xid-snd xid rmac remote-mac [rsap remote-sap] [lsap local-sap] [interface slot/port] [window window-size] [maxiframe max-iframe] [retries retry-count] [retry-timeout retry-timeout] [focalpoint] | Defines a DSPU host over Token Ring, Ethernet, FDDI, RSRB, or VDLC connections. |
| Command | Purpose |
|---|---|
dspu pu pu-name [rmac remote-mac] [rsap remote-sap] [lsap local-sap] [xid-rcv xid] [interface slot/port] [window window-size] [maxiframe max-iframe] [retries retry-count] [retry-timeout retry-timeout] | Explicitly defines a DSPU over Token Ring, Ethernet, FDDI, RSRB, VDLC, or NCIA connections. |
| Command | Purpose |
|---|---|
dspu lu lu-start [lu-end] {host host-name host-lu-start | pool pool-name} [pu pu-name] | Defines a dedicated LU or a range of dedicated LUs for a DSPU. |
| Command | Purpose |
|---|---|
dspu ncia [server-number] | Configures the NCIA server as the underlying transport mechanism. |
| Command | Purpose |
|---|---|
dspu ncia enable-pu [lsap local-sap] | Enables local SAP for DSPUs. |
The network configuration shown in Figure 208 includes NCIA clients that connect to a FEP on a Token Ring through a remote router. Figure 209 shows a logical view of the NCIA Server session with RSRB (to a remote Token Ring). Because DLSw+ is the latest technology provided by Cisco, Cisco does not encourage using the NCIA Server feature with RSRB. If the router on the host side is running DLSw+, then RSRB should not be used. Support for the NCIA Server feature with RSRB is provided to encourage RSRB users to migrate to DLSw+.
For a configuration example, see "NCIA Server Session with DLSw+ Example" section".
The source-bridge virtual ring can be shared between DLSw+ and SRB/RSRB. In DLSw+, the source-bridge ring group specifies the virtual ring that will appear to be the last ring in the RIF. Because RIFs are terminated at the router, the ring group numbers specified in commands to set up DLSw+ peers can be different. The ring group numbers can be the same for management simplicity, but they do not have to be.
To define a source-bridge ring group for DLSw+, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
source -bridge ring-group ring-group [virtual-mac-address] | Defines a ring group. |
In our implementation, whenever you connect Token Rings using non-Token Ring media, you must treat that non-Token Ring media as a virtual ring by assigning it to a ring group. Every router with which you want to exchange Token Ring traffic must be a member of this same ring group. For more information about defining a ring group, see the "Define a Ring Group in SRB Context" section of the "Configuring Source-Route Bridging" chapter of this document.
To identify the remote peers, use the following command in global configuration mode:
Specify one source-bridge remote-peer command for each peer router that is part of the virtual ring. Also specify one source-bridge remote-peer command to identify the IP address of the local router.
NCIA server supports only RSRB pass-through mode. Local acknowledgment is not supported.
| Command | Purpose |
|---|---|
dlsw local-peer [peer-id ip-address] [group group] [border] [cost cost] [lf size] [keepalive seconds] [passive] [promiscuous] [biu-segment] | Defines the DLSw+ local peer. |
Configuring an NCIA server on a router enables the router to perform two roles:
To configure an NCIA server, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
ncia server server-number server-ip-address server-virtual-mac-address virtual-mac-address virtual-mac-range [inbound-only] [keepalive seconds] [tcp_keepalive minutes] | Configures the NCIA server. |
To configure an RSRB ring for the NCIA server on the local router, use the following command in global configuration mode:
| Command | Purpose |
|---|---|
ncia rsrb virtual-ring local-bridge local-ring ncia-bridge ncia-ring virtual-mac-address | Defines the NCIA/RSRB interface. |
You can monitor and maintain the operation of an NCIA server network. To display information about the state of the NCIA server feature and perform maintenance tasks, use the following commands in EXEC mode:
| Command | Purpose |
|---|---|
show ncia server [server-number] | Shows the status of the NCIA server. |
show ncia client [sap-list] [ip-address] | Shows the status of the NCIA client. |
clear ncia client [ip-address] | Terminates an NCIA client connection. |
show ncia circuits [id-number] | Shows the status of an NCIA circuit. |
clear ncia circuit [id-number] | Drops an NCIA circuit. |
clear ncia client registered [ip-address] | Terminates the active connection to the specified client and release all control blocks of the registered client. |
ncia stop | Stops an NCIA server. |
ncia start | Restarts an NCIA server. |
The following sections provide NCIA server configuration examples:
Figure 210 illustrates the use of DLSw+ local peer with an NCIA server session to a local Token Ring.
The following is a configuration file for the network example shown in Figure 210:
source-bridge ring-group 44 dlsw local-peer ncia server 1 10.2.20.4 4000.3174.0001 4000.0000.0001 128 ! interface token ring 0 ring-speed 16 source-bridge 21 3 44
Figure 211 illustrates the use of DLSw+ with an NCIA server session.
The following is a configuration file for the network example shown in Figure 211:
source-bridge ring-group 44 dlsw local-peer peer-id 10.2.20.4 dlsw remote-peer 0 tcp 10.2.20.3 ncia server 1 10.2.20.4 4000.3174.0001 4000.0000.0001 128
Figure 212 illustrates an NCIA server session with RSRB/DLSw+ and DSPU.
The following is a configuration file for the network example shown in Figure 212:
ncia server 1 10.2.20.4 4000.3745.0001 4000.0000.0001 128 ! dspu ncia 1 dspu ncia enable-pu lsap 8 ! dspu host HOST-9370 xid-snd 11100001 rmac 4000.1060.1000 rsap 4 lsap 4 ! dspu pu CISCOPU-A xid-rcv 01700001 dspu lu 2 6 host HOST-9370 2 ! interface TokenRing 0 ring-speed 16 llc2 xid-retry-time 0 dspu enable-host lsap 4 dspu start HOST-9370
Figure 213 illustrates the use of RSRB with an NCIA server session.
The following is a configuration file for router Cisco 2 for the network example shown in Figure 213:
source-bridge ring-group 44 source-bridge ring-group 22 source-bridge remote-peer 22 tcp 10.2.20.3 source-bridge remote-peer 22 tcp 10.2.20.4 dlsw local-peer ncia server 1 10.2.20.4 4000.3174.0001 4000.0000.0001 128 ncia rsrb 22 2 33 4 44 1111.1111.2222
Posted: Thu Jul 20 10:29:26 PDT 2000
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