Frame-Relay

1
Frame-Relay

• Layer 2 technology
• Leased line to Frame-Relay network a telco
  provided cloud
• Frame-Relay is the technology deployed between
  the router and the Frame-Relay switch
• Used for one connection to a mesh network per
  site

2
Frame Relay

• Data Link Connection Identifier (DCLI) is the
  Layer 2 address
• A number used to identify the end point in a
  frame relay network.
• DLCI 1023 is reserved for LMI updates
• Committed Information Rate (CIR) bandwidth
  which has been purchased from supplier
• Burst Rate Additional bandwidth utilised, is
  not guaranteed and has the DE bit set

3
Resolving IP/DLCI

• Inverse ARP
• An automatic system that enables a router to link
  an IP address to a DCLI
• Determines the IP address of a distant host
• Resolves IP addresses to DLCI
• A Frame-Relay map is a manual configuration,
  mapping IP and DLCI number
• frame-relay map ip 200.10.10.2 22

4
Types

• Point to point - like a standard serial line
  (each sub-interface on its own subnet)
• Multi point all sub-interfaces are on the same
  subnet
• Multi point is often used to create an OSPF
  network. Causes problems with split horizon for
  dv routing protocols

5
Configuration Commands

• Router (config)int s0/0
• encapsulation frame-relay
• int s0/0.1 point to point
• ip address 200.10.10.1 255.255.255.0
• Frame-relay interface-dlci 22

6
LMI

• Layer Management Interface
• Informs routers of the dcli numbers that are
  relevant and pvc status
• Status values-
• Active end to end connectivity
• Inactive other end wants response
• Deleted - our end is down