IBM Networking

Document ID: 12254

Contents

Introduction
Prerequisites
      Requirements
      Conventions
Configure
      Configuration Notes
      Network Diagram
      Network Diagram Notes
      Configurations
Verify
      Debug and Verification Tips
      Show Command Output
Troubleshoot
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Introduction

In this sample configuration, a Cisco router configured for Frame Relay Access Support (FRAS) boundary network node (BNN) is connected to Ethernet devices that communicate with a FRAS host configured router; the FRAS host configured router is connected to a Token Ring-attached host.

The BNN support in this sample configuration is based on Cisco IOS^® Software Release 11.2 and earlier versions in which you need to define each of the end stations attached to the LAN with the fras map command.

Note: If needed, the FRAS host router can be replaced with a Network Control Program (NCP) Frame Relay connection. If you use that scenario, there is no need to change the configuration of the FRAS BNN router from what is presented in the Network Diagram.

Prerequisites

Requirements

There are no specific requirements for this document.

Conventions

Refer to Cisco Technical Tips Conventions for more information on document conventions.

Configure

Configuration Notes

In this section, you are presented with the information to configure the features described in this document.

• The FRAS BNN router (Turbo) e0 MAC address is the same as the destination MAC (DMAC) configured in all the end devices (0200.2222.0000).

• The FRAS BNN router configuration contains the fras map llc 0000.2222.0000 4 8 Serial 1 frame-relay dlci 20 4 4 command. This command accepts inbound requests from 0000.2222.0000 with SAP 0x08 that try to connect to 0200.2222.0000 with SAP 0x04. On the Frame Relay side, the router sends data over DLCI 20, with a destination SAP (DSAP) of 0x04 and a SSAP of 0x04.

• The FRAS Host router configuration contains the fras-host bnn Serial1 fr-lsap 04 vmac 4000.2222.0000 hmac 4000.3745.0000 command. This command enables the FRAS Host function for the BNN router to accept inbound BNN frames that arrive at Serial 1 with a DSAP of 0x04. The router sends Logical Link Control (LLC) frames to the MAC addresses specified in the HMAC parameter. The HMAC parameter must match the MAC address of the CIP adapter or LAN-attached host. By default, the router uses DSAP = 0x04. The VMAC parameter is used in combination with the DLCI number to form a unique source MAC address that the router uses to communicate with the host. The DLCI number is appended to the last two bytes of the VMAC parameter, which is visible in the show fras-host command output.

• Cisco IOS Software Release 11.2 and earlier support for BNN requires you to map every single end station in the segment/ring with the fras map command. The MAC address in the fras map command represents the end station source MAC (SMAC).

• In this example scenario, the Frame Relay connection is back-to-back with no Frame Relay switch in the middle; there is no Local Management Interface (LMI) or keepalives. In a real situation, you have a Frame Relay switch in the middle.

Note: Use the Command Lookup Tool ( registered customers only) to find more information on the commands used in this document.

Network Diagram

This document uses this network setup.

Network Diagram Notes

• The SNA Gateway is configured with these Media Access Control (MAC) addresses:

  smac = 0000.2222.0000 (canonical), dmac = 0200.2222.0000 (canonical)
  lsap = 0x08 and dsap = 0x04
  

  For easy reference, these are the bit swap values of the MAC addresses:

  smac = 0000.4444.0000 (non-canonical), dmac = 4000.4444.0000
  (non-canonical)
  

• The Host uses this MAC value on to0:

  smac = 4000.3745.0000 (non-canonical)
  

Configurations

This document uses these configurations:

turbo#show running-config

 Building configuration...
 !
 hostname turbo
 !
 !
 interface Ethernet0
  !This MAC is the DMAC of all the Ethernet stations.
   mac-address 0200.2222.0000
   ip address 5.5.5.1 255.255.255.0
   no ip directed-broadcast
   fras map llc 0000.2222.0000 4 8 Serial 1 frame-relay dlci 20 4 4
 !
 interface Serial1
  ip address 2.2.2.1 255.255.255.0
  no ip directed-broadcast
  encapsulation frame-relay IETF
  no keepalive
  frame-relay map llc2 20
  frame-relay interface-dlci 20
 !
 end

limno#show running-config

 Building configuration...
 !
 hostname limno
 !
 source-bridge ring-group 500
 !
 interface Serial1
  ip address 2.2.2.2 255.255.255.0
  no ip directed-broadcast
  encapsulation frame-relay IETF
  no keepalive
  clockrate 4000000
  frame-relay map llc2 20
  frame-relay interface-dlci 20
 !
 interface TokenRing0
  ip address 4.4.4.2 255.255.255.0
  no ip directed-broadcast
  ring-speed 16
  source-bridge 10 1 500
 !
 interface Virtual-TokenRing0
  no ip address
  no ip directed-broadcast
  ring-speed 16
  source-bridge 400 1 500
  source-bridge spanning
  fras-host bnn Serial1 fr-lsap 04 vmac 4000.2222.0000 hmac 4000.3745.0000
 !
 end

Verify

Debug and Verification Tips

You can turn on these debugs in the FRAS BNN router:

• debug fras error - Displays information about FRAS protocol errors.

• debug fras state - Displays information about FRAS data link control link state changes. These are the possible states: reset, request open station is sent, exchange xid, connection request is sent, signal station wait, connection response wait, connection response sent, connection established, disconnect wait, and number of link states.

• debug fras message - Displays general information about FRAS messages.

You can turn on these debugs in the FRAS HOST router:

• debug fras-host packet - Sees what LLC2 session frames are handled by FRAS Host. Use this command with great care. If many LLC2 sessions are active and passing data, this command can generate a tremendous amount of output to the console and impact performance.

• debug fras-host error - Enables FRAS Host to send error messages to the console.

• debug fras-host activation - Displays the LLC2 session activation and deactivation frames (such as XID, SABME, DISC, UA) that are handled by FRAS Host. If many LLC2 sessions are activated or deactivated at any time, this command can generate large amounts of output to the console.

Show Command Output

You can use the show commands to verify the configuration.

The Output Interpreter Tool ( registered customers only) (OIT) supports certain show commands. Use the OIT to view an analysis of show command output.

turbo#show fras

 Boundary Network Node (BNN): 

 DLCI: 20
 Type Destination    Int LSap RSap Role State
 llc  0000.2222.0000 Et0 4    8    P    ls_Contacted 
 fr   -              Se1 4    4    S    ls_Contacted 
 Boundary Access Node (BAN): 

turbo#show llc
LLC2 Connections: total of 2 connections
Serial1 DTE: 20 04 04 state NORMAL
V(S)=1, V(R)=1, Last N(R)=1, Local window=7, Remote Window=127
akmax=3, n2=10, 
xid-retry timer 0/0 ack timer 0/1000 
p timer 0/1000 idle timer 9400/10000 
rej timer 0/3200 busy timer 0/9600 
akdelay timer 0/100 txQ count 0/200 

Ethernet0 DTE: 0000.2222.0000 0200.2222.0000 04 08 state NORMAL
V(S)=1, V(R)=1, Last N(R)=1, Local window=7, Remote Window=127
akmax=3, n2=10, 
xid-retry timer 0/0 ack timer 0/1000 
p timer 0/1000 idle timer 8480/10000 
rej timer 0/3200 busy timer 0/9600 
akdelay timer 0/100 txQ count 0/200 

limno#show fras-host

 Number of Active Control Blocks = 1
 Number of Available Control Blocks in Pool = 127

 Port Dlci Type FrRsap FrLsap HostSap FrMac / VMac    HostMac
 Se1  20   BNN  04     04     04      4000.2222.0014  4000.3745.0000


limno#show fras-host detail

 Number of Active Control Blocks = 1
 Number of Available Control Blocks in Pool = 127

 Port = Se1, Dlci = 20, Type = BNN, FrRsap = 04, FrLsap = 04, HostSap = 04
 Host Mac = 4000.3745.0000, Rif = 0810.1901.1F41.00A0
 Frames Fwd to Host = 110, Last Rcvd From Frad = 0 sec
 Fr Mac = 4000.2222.0014, Rif = NONE
 Frames Fwd to Frad = 111, Last Rcvd from Host = 0 sec


limno#show fras-host serial 1

 Number of Active Control Blocks = 1
 Number of Available Control Blocks in Pool = 127

 Port Dlci Type FrRsap FrLsap HostSap FrMac / VMac    HostMac
 Se1  20   BNN  04     04     04      4000.2222.0014  4000.3745.0000


limno#show fras-host dlci 20

 Number of Active Control Blocks = 1
 Number of Available Control Blocks in Pool = 127

 Port Dlci Type FrRsap FrLsap HostSap FrMac / VMac    HostMac
 Se1  20   BNN  04     04     04      4000.2222.0014  4000.3745.0000


limno#show llc

No LLC2 connections.

Troubleshoot

There is currently no specific troubleshooting information available for this configuration.

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