Building a Compound Frame Relay Switch

Introduction:

The following document describes how to build a compound high density Frame Relay switch by cascading multiple routers which have a low density of interfaces. This is accomplished by connecting the routers together with a rollover cable between their AUX ports and configuring a GRE tunnel over this asynchronous connection.

Hardware Used:

• 2 Cisco Routers with DB-60 Serial Interfaces for Frame Relay Cloud
• 1 Rollover (Console) Cable
• 5 DB-60 DTE/DCE Serial Cables

Configuration:

The above 2501 and 2520 routers have been connected with a rollover (console) cable between their AUX ports. The resulting effect is a 6 port Frame Relay cloud that is transparently one device from the perspective of the CPE devices, R1 through R5.

interface Serial0
 description To R1
 clock rate 2000000
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 102 interface Serial1 201
 frame-relay route 103 interface Tunnel0 103
 frame-relay route 113 interface Tunnel0 113
 frame-relay route 104 interface Tunnel0 104
 frame-relay route 105 interface Tunnel0 105
!
interface Serial1
 description To R2
 clock rate 2000000
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 201 interface Serial0 102
 frame-relay route 203 interface Tunnel0 203
 frame-relay route 213 interface Tunnel0 213
 frame-relay route 204 interface Tunnel0 204
 frame-relay route 205 interface Tunnel0 205
!
interface Async4
 ip address 12.0.0.1 255.0.0.0
 async dynamic routing
 async mode dedicated
!
interface Tunnel0
 tunnel source Async4
 tunnel destination 12.0.0.2
!
line aux 0
 modem InOut
 transport input all
 speed 38400
 flowcontrol hardware

2520:
interface Serial0
 description To R3-1
 clock rate 2000000
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 301 interface Tunnel0 103
 frame-relay route 302 interface Tunnel0 203
 frame-relay route 304 interface Serial2 403
 frame-relay route 305 interface Serial3 504
!
interface Serial1
 description To R3-2
 clock rate 2000000
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 311 interface Tunnel0 113
 frame-relay route 312 interface Tunnel0 213
 frame-relay route 314 interface Serial2 413
 frame-relay route 315 interface Serial3 514
!
interface Serial2
 description To R4
 clock rate 2000000
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 401 interface Tunnel0 104
 frame-relay route 402 interface Tunnel0 204
 frame-relay route 403 interface Serial0 403
 frame-relay route 413 interface Serial1 413
 frame-relay route 405 interface Serial3 504
!
interface Serial3
 description To R5
 clock rate 2000000
 encapsulation frame-relay
 frame-relay intf-type dce
 frame-relay route 501 interface Tunnel0 105
 frame-relay route 502 interface Tunnel0 205
 frame-relay route 503 interface Serial0 305
 frame-relay route 513 interface Serial1 315
 frame-relay route 504 interface Serial2 405
!
interface Async4
 ip address 12.0.0.2 255.0.0.0
 async dynamic routing
 async mode dedicated
!
interface Tunnel0
 tunnel source Async4
 tunnel destination 12.0.0.1
!
line aux 0
 modem InOut
 transport input all
 speed 38400
 flowcontrol hardware

© 2006 Internetwork Expert, Inc.