Quick-Config: Frame-Relay

Aus NetWiki
Wechseln zu: Navigation, Suche


Frame-Relay (v4)

L1 and Frame-Relay Terminology

  • L1 DTE = Data Termination Equipment
  • L1 DCE = Data Communication Equipment
  • Frame-Relay switch is called the DTE, endpoints are called DCE. This is unrelated to L1 DCE/DTE.
  • FR DCE responds to LMI inquiries by sending LMI status, never sends LMI inquiries.
  • FR DTE sends LMI inquiries, never sends LMI status.
  • DLCIs are only locally significant.



Inverse ARP

  • Because serial interfaces and FR are NBMA networks, there is no ARP flooding to discover neighbor addresses.
  • Instead FR relies on inverse ARP to allow clients to notify neighbors of their presence and reply to requests.
  • Disabling inverse ARP will disable the notification, these are called dynamic mappings.
  • Has to be disabled on all routers to disable automatic learning of mappings.
  • Inverse-ARP does not allow self-ping.


int s1/0
 encapsulation frame-relay 
 no frame-relay inverse-arp

clear frame inarp


Frame-Relay Mappings

  • If dynamic mappings have been disabled, static ones need to be created on the clients (R1,R3).
  • The broadcast keyword allows broadcast packets over NBMA.
  • Only configure broadcast on one statement, preferably the statement that configures the router to ping itself.


int se1/0
 ip address 10.0.13.1 255.255.255.0
 frame-relay map ip 10.0.13.1 103 broadcast
 frame-relay map ip 10.0.13.3 103

int se1/0
 ip address 10.0.13.3 255.255.255.0
 frame-relay map ip 10.0.13.1 301
 frame-relay map ip 10.0.13.3 301 broadcast

show frame pvc show frame map


Frame-Relay Switch

  • Set encapsulation to frame-relay.
  • Configure DCE on interfaces
  • Create FR PVCs using either frame routes (FR switching framework) or connections (L2VPN framework).



Create FR PVCs using frame routes on FR Switch:

int se1/0
 encapsulation frame-relay 
 frame-relay intf-type dce
 frame route 103 interface se1/1 301

int se1/1
 encapsulation frame-relay 
 frame-relay intf-type dce
 frame route 301 interface se1/0 103

show frame route show frame pvc

Create FR PVCs using connections on FR Switch:

connect R1-R3 se1/0 103 se1/1 301
show connection all


Frame-Relay with Sub-interfaces

  • If sub-interfaces are being used, the DLCI needs to be linked to the sub-interface.
  • Inverse ARP configuration is not inherited by sub-interfaces.
  • With PTP mode sub-interfaces are configured on the hub, each to single location.
  • With PTMP mode a single interface is configured on the hub to multiple locations. Disable split-horizon if using EIGRP.
  • The no inverse-arp configuration on the physical interface is not inherit by the sub-interface.


int se1/0.123 point-to-multipoint 
 frame-relay interface-dlci 123

int se1/0.102 point-to-point 
 frame-relay interface-dlci 102 
int se1/0.103 point-to-point 
 frame-relay interface-dlci 103


Frame-Relay Authentication

  • Use point-to-point sub-interfaces configured with PPP encapsulation.
  • Use ip unnumbered in order to enable self-ping.



R1 configuration:

username R3 password cisco 
int se1/0.103 point-to-point
 frame-relay interface-dlci 103 ppp virtual-template 1
interface virtual-template 1
 ip address 10.0.13.1 255.255.255.0
 encapsulation ppp
 ppp authentication chap
 ppp pap sent-username R1 password cisco


R3 configuration:

username R1 password cisco 
int s1/1.301 point-to-point
 frame-relay interface-dlci 301 ppp virtual-template 1

interface virtual-template 1
 ip address 10.0.13.3 255.255.255.0
 encapsulation ppp 
 ppp chap hostname R2
 ppp chap password cisco 
 ppp authentication pap