Cisco ICND2 – Configure and verify Frame Relay on Cisco routers

  • Packet-switching protocol
  • DCLI’s are local – layer 2 addressing. Not advertised to other routers
  • Permanent virtual circuit (PVC) – Dedicated circuit always up
  • Switched virtual circuit (SVC) – Temporary circuit that is only up for example during a data transfer session
  • Three LMI types cisoc, ansi and q933a
  • Local Management Interface (LMI) – passes information about the status of the circuit. Must match on the DCE (Provider) and DTE end
  • non-broadcast multi-access (NBMA) – broadcasts are not sent over frame-relay by default
  • inverse ARP – Used to allow dynamic mapping. On by default can be turned off using no frame-relay inverse-arp
  • Split horizon – Stops rouging updates such as RIP from being sent out of the same interface it was received on. Turning off split horizon may cause routing loops
  • Sub-interfaces can overcome the split horizon by creating sub interfaces out of a serial interface. This gets around the problem of a routing update being sent and received out of the same interface. Sub-interfaces can either be point-to-point or multipoint

Show commands:

  • show frame-relay map – Table of frame maps, shows dlci and lmi information
  • show frame-relay lmi – Shows configured LMI type, if timeouts occur and increase could indiciate a lmi mis-match
  • show frame-relay pvc – Shows BECN and FECN information

Debug commands:

  • debug frame-relay lmi – myseq increments but yourseen doesn’t indicates lmi mismatch

Frame relay point-to-point

Frame_Relay_P2P

R1:

interface Serial2/0
no ip address
encapsulation frame-relay

interface Serial2/0.301 point-to-point
ip address 10.0.1.1 255.255.255.0
frame-relay interface-dlci 301

interface Serial2/0.302 point-to-point
ip address 10.0.3.1 255.255.255.0
frame-relay interface-dlci 302

router rip
network 10.0.0.0

R2:

interface Serial2/0
no ip address
encapsulation frame-relay

interface Serial2/0.102 point-to-point
ip address 10.0.2.2 255.255.255.0
frame-relay interface-dlci 102

interface Serial2/0.103 point-to-point
ip address 10.0.1.2 255.255.255.0
frame-relay interface-dlci 103

router rip
network 10.0.0.0
network 192.168.0.0

R3:

interface Serial2/0
no ip address
encapsulation frame-relay

interface Serial2/0.201 point-to-point
ip address 10.0.2.1 255.255.255.0
frame-relay interface-dlci 201

interface Serial2/0.203 point-to-point
ip address 10.0.3.2 255.255.255.0
frame-relay interface-dlci 203

router rip
network 10.0.0.0
network 172.16.0.0

Frame relay multipoint

Frame_Relay_Multipoint

R1:

interface Serial2/0
ip address 10.0.1.1 255.255.255.0
encapsulation frame-relay
frame-relay map ip 10.0.1.2 301 broadcast

router rip
network 10.0.0.0

R2:

interface Serial2/0
ip address 10.0.1.2 255.255.255.0
encapsulation frame-relay

router rip
network 10.0.0.0
network 192.168.0.0

R3:

interface Serial2/0
ip address 10.0.1.2 255.255.255.0
encapsulation frame-relay

network 10.0.0.0
network 172.16.0.0