8371 Interface Configuration

Self Learning IP

Self Learning IP is a feature that enables a LAN switch that is inserted between routers and their associated LANs to dynamically determine IP routing information. Once the LAN switch determines routing information, it assumes responsibility for routing all local IP unicast data and transparently passes data it cannot route to the attached router.

Self Learning IP works by snooping on the contents of ARP packets, identifying adjacent routers and building an IP forwarding table. The forwarding table includes the following information:

• IP address of the station
• MAC address of the station
• Interface through which the station can be accessed
• Type of LAN encapsulation used by the station
• MAC address of the station's default router
• Timeout value indicating when the IP forwarding table entry is to be aged-out

The Self Learning IP function does not rely on any routing protocol, so it works seamlessly in networks that use RIP, OSPF, or IGRP.

Note:

The Self Learning IP and routing functions are mutually exclusive since only one of these functions may be enabled at any given time.

Accessing the Self Learning IP Configuration Environment

Use the following procedure to access the Self Learning IP configuration process.

1. At the OPCON prompt, enter talk 6. For example:

       * talk 6
       Config>
    
   

   After you enter the talk 6 command, the CONFIG prompt (Config>) displays on the terminal. If the prompt does not appear when you first enter configuration, press Return again.

2. At the CONFIG prompt, enter the feature self command to get to the Self Learning IP Config> prompt.

Self Learning IP Configuration Commands

Table 47. Self Learning IP Configuration Command Summary

Command	Function
? (Help)	Displays all the commands available for this command level or lists the options for specific commands (if available). See "Getting Help".
Disable	Disables Self Learning IP.
Enable	Enables Self Learning IP in default mode.
One_to_one	Enables Self Learning IP in one-to-one mode.
Exit	Returns you to the previous command level. See "Exiting a Lower Level Environment".

Disable

Use the disable command to disable Self Learning IP.

Syntax:

disable

Enable

Use the enable command to enable Self Learning IP in default mode.

Syntax:

enable

One-to-one

When this mode is enabled, the ports on the IBM 8371 are paired. Either of the ports of the dedicated pair may then be connected to a router port and the other port of the dedicated pair is connected to the router's LAN interface. In this mode, broadcast frames received at one port will be transmitted only on the other port of the pair.

To disable One-to-one mode, use the enable command to enable Self Learning IP in default mode.

Syntax:

one-to-one

Accessing the Self Learning IP Monitoring Environment

Use the following procedure to access the Self Learning IP monitoring process.

1. At the OPCON prompt, enter talk 5. For example:

       * talk 5
    
       CGW Operator Console
    
       +
    
   

   After you enter the talk 5 command, the GWCON prompt (+) displays on the terminal. If the prompt does not appear when you first enter the monitoring environment, press Return again.

2. At the + prompt, enter the feature self learning ip command to get to the Self Learning IP Console> prompt.

Self Learning IP Monitoring Commands

Table 48. Self Learning IP Monitoring Command Summary

Command	Function
? (Help)	Displays all the commands available for this command level or lists the options for specific commands (if available). See "Getting Help".
Disable	Dynamically disables Self Learning IP.
Enable	Dynamically enables Self Learning IP.
Hosts	Views the discovered hosts.
Routers	Views the discovered routers.
State	Displays the state of Self Learning IP.
Exit	Returns you to the previous command level. See "Exiting a Lower Level Environment".

Disable

Use the disable command to dynamically disable Self Learning IP.

Syntax:

disable

Enable

Use the enable command to dynamically enable Self Learning IP.

Syntax:

enable

Hosts

Use the hosts command to display discovered hosts.

Syntax:

hosts

Self Learning IP Console> hosts
 
 
Host IP Addr. | Host MAC Address  | IF | EN |    Router MAC     | Ttl
--------------+-------------------+----+----+-------------------+-----
1.1.1.10      | 00:00:00:00:6E:00 | 00 | DX | 00:00:00:00:82:00 | 56 *
2.2.2.20      | 00:00:00:00:78:00 | 01 | SN | 00:00:00:00:82:01 | 56 *
 

Host IP Addr

Specifies the Host IP address.

Host MAC Address

Specifies the Host MAC address

IF

Specifies the interface number on which the host has been found.

EN

Specifies the encapsulation type. The encapsulation types are SN-LLC/SNAP and DX-DIX.

Router MAC

Specifies the MAC address of this host's router.

Ttl

Specifies the Time to Live for this host entry in this table.

*

Indicates that this entry has an active shortcut.

Routers

Use the routers command to display discovered routers.

Syntax:

routers

Self Learning IP Console> routers
 
 
IF | Router MAC Address    | State      | Ttl
---+-----------------------+------------+-----
01 | 00:00:00:00:78:00     |RESOLVED    | 198 
00 | 00:00:00:00:6E:00     |RESOLVED    | 199 
03 | 00:00:00:00:82:01     |RESOLVED    | 199 
02 | 00:00:00:00:82:00     |RESOLVED    | 199 
 

IF

Specifies the interface to which the router is attached.

Router MAC

Specifies the router MAC address.

State

Specifies the interface state.

Ttl

Specifies the Time to Live for this router entry in this table.

State

Use the state command to display the current state of Self Learning IP.

Syntax:

state

Example:

Self Learning IP Console> state
Self Learning IP Enabled Flag is ON 
Current Microcode load           Self Learning IP
Self Learning IP Flag in SRAM is ON 
Self Learning IP Operation Mode  Default
Number of Routers found          4
Number of Hosts found            10
Memory blocks allocated          32
Memory blocks freed              12
Self Learning IP Console>