FrameRelay (PVC, Private Virtual Circuit) Interface

Document revision:	1.1 (Fri Mar 05 08:14:41 GMT 2004)
Applies to:	V2.8

General Information

Summary

Frame Relay is a multiplexed interface to packet switched network and is a simplified form of Packet Switching similar in principle to X.25 in which synchronous frames of data are routed to different destinations depending on header information. Frame Relay uses the synchronous HDLC frame format.

Specifications

Packages required: synchronous
License required: Level4
Submenu level: /interface pvc
Standards and Technologies: Frame Relay (RFC1490)
Hardware usage: Not significant

Description

To use Frame Relay interface you must have already working synchronous interface. You can read how to set up synchronous boards supported by MikroTik RouterOS:

Additional Resources

Configuring Frame Relay Interface

Submenu level: /interface pvc

Description

To configure frame relay, at first you should set up the synchronous interface, and then the PVC interface.

Property Description

name (name; default: pvcN) - assigned name of the interface

mtu (integer; default: 1500) - Maximum Transmission Unit of an interface

dlci (integer; default: 16) - Data Link Connection Identifier assigned to the PVC interface

interface (name) - Frame Relay interface

Notes

A DLCI is a channel number (Data Link Connection Identifier) which is attached to data frames to tell the network how to route the data. Frame Relay is "statistically multiplexed", which means that only one frame can be transmitted at a time but many logical connections can co-exist on a single physical line. The DLCI allows the data to be logically tied to one of the connections so that once it gets to the network, it knows where to send it.

Frame Relay Configuration

Example with Cyclades Interface

Let us consider the following network setup with MikroTik router with Cyclades PC300 interface connected to a leased line with baseband modems and a Cisco router at the other end.

[admin@MikroTik] ip address> add interface=pvc1 address=1.1.1.1 netmask=255.255.255.0
[admin@MikroTik] ip address> print
Flags: X - disabled, I - invalid, D - dynamic
  #   ADDRESS            NETWORK         BROADCAST       INTERFACE
  0   1.1.1.1/24         1.1.1.0         1.1.1.255       pvc1
[admin@MikroTik] ip address>

PVC and Cyclades interface configuration

Example with MOXA Interface

Let us consider the following network setup with MikroTik router with MOXA C502 synchronous interface connected to a leased line with baseband modems and a Cisco router at the other end.

[admin@MikroTik] ip address> add interface=pvc1 address=1.1.1.1 netmask=255.255.255.0
[admin@MikroTik] ip address> print
Flags: X - disabled, I - invalid, D - dynamic
  #   ADDRESS            NETWORK         BROADCAST       INTERFACE
  0   1.1.1.1/24         1.1.1.0         1.1.1.255       pvc1
[admin@MikroTik] ip address>

PVC and Moxa interface configuration

Example with MikroTik Router to MikroTik Router

Let us consider the following example:

In this example we will use two Moxa C101 synchronous cards.

Do not forget to set line-protocol for synchronous interfaces to frame-relay. To achieve proper result, one of the synchronous interfaces must operate in DCE mode:

[admin@r1] interface moxa-c101> set 0 frame-relay-dce=yes
[admin@r1] interface moxa-c101> print
Flags: X - disabled, R - running
  0  R name="moxa-c101-1" mtu=1500 line-protocol=frame-relay clock-rate=64000
       clock-source=external frame-relay-lmi-type=ansi frame-relay-dce=yes
       cisco-hdlc-keepalive-interval=10s ignore-dcd=no

[admin@r1] interface moxa-c101>

Then we need to add PVC interfaces and IP addresses.

On the R1:

[admin@r1] interface pvc> add dlci=42 interface=moxa-c101-1
[admin@r1] interface pvc> print
Flags: X - disabled, R - running
  #    NAME                                               MTU  DLCI INTERFACE
  0 X  pvc1                                               1500 42   moxa-c101-1

[admin@r1] interface pvc> /ip address add address 4.4.4.1/24 interface pvc1

on the R2:

[admin@r2] interface pvc> add dlci=42 interface=moxa-c101-1
[admin@r2] interface pvc> print
Flags: X - disabled, R - running
  #    NAME                                               MTU  DLCI INTERFACE
  0 X  pvc1                                               1500 42   moxa-c101-1

[admin@r2] interface pvc> /ip address add address 4.4.4.2/24 interface pvc1

Finally, we must enable PVC interfaces:

[admin@r1] interface pvc> enable pvc1
[admin@r1] interface pvc>

[admin@r2] interface pvc> enable pvc1
[admin@r2] interface pvc>

Troubleshooting

Description