FrameRelay (PVC) Interfaces

Document revision 1.3 (30-Jun-2003)
This document applies to MikroTik RouterOS v2.7

Table of Contents

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 : synchronous
Home menu 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:

Configuring Frame Relay Interface

Submenu level : /interface pvc

Description

To configure frame relay, you should first 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

  • Cyclades
    • [admin@MikroTik] interface cyclades> print
Flags: X - disabled, R - running
  0  R name="cyclades1" mtu=1500 line-protocol=frame-relay media-type=V35
       clock-rate=64000 clock-source=external line-code=B8ZS framing-mode=ESF
       line-build-out=0dB rx-sensitivity=short-haul frame-relay-lmi-type=ansi
       frame-relay-dce=no chdlc-keepalive=10s

[admin@MikroTik] interface cyclades>
  • PVC
    • [admin@MikroTik] interface pvc> print
Flags: X - disabled, R - running
  #    NAME                 MTU  DLCI INTERFACE
  0  R pvc1                 1500 42   cyclades1
[admin@MikroTik] interface pvc>
  • CISCO router setup

    • CISCO# show running-config

    Building configuration...

    Current configuration...

    ...
!
ip subnet-zero
no ip domain-lookup
frame-relay switching
!
interface Ethernet0
 description connected to EthernetLAN
 ip address 10.0.0.254 255.255.255.0
!
interface Serial0
 description connected to Internet
 no ip address
 encapsulation frame-relay IETF
 serial restart-delay 1
 frame-relay lmi-type ansi
 frame-relay intf-type dce
!
interface Serial0.1 point-to-point
 ip address 1.1.1.2 255.255.255.0
 no arp frame-relay
 frame-relay interface-dlci 42
!
...
end.

    Send ping to MikroTik router

    CISCO#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/31/32 ms
CISCO#

    Frame Relay 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

  • Moxa
    • [admin@MikroTik] interface moxa-c502> print
Flags: X - disabled, R - running
  0  R name="moxa1" mtu=1500 line-protocol=frame-relay clock-rate=64000
       clock-source=external frame-relay-lmi-type=ansi frame-relay-dce=no
       cisco-hdlc-keepalive-interval=10s

  1 X  name="moxa-c502-2" mtu=1500 line-protocol=sync-ppp clock-rate=64000
       clock-source=external frame-relay-lmi-type=ansi frame-relay-dce=no
       cisco-hdlc-keepalive-interval=10s

[admin@MikroTik] interface moxa-c502>
  • PVC
    • [admin@MikroTik] interface pvc> print
Flags: X - disabled, R - running
  #    NAME                 MTU  DLCI INTERFACE
  0  R pvc1                 1500 42   moxa1
[admin@MikroTik] interface pvc>

    CISCO router setup

    CISCO# show running-config

    Building configuration...

    Current configuration...

    ...
!
ip subnet-zero
no ip domain-lookup
frame-relay switching
!
interface Ethernet0
 description connected to EthernetLAN
 ip address 10.0.0.254 255.255.255.0
!
interface Serial0
 description connected to Internet
 no ip address
 encapsulation frame-relay IETF
 serial restart-delay 1
 frame-relay lmi-type ansi
 frame-relay intf-type dce
!
interface Serial0.1 point-to-point
 ip address 1.1.1.2 255.255.255.0
 no arp frame-relay
 frame-relay interface-dlci 42
!
...
end.

    Send ping to MikroTik router

    CISCO#ping 1.1.1.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/31/32 ms
CISCO#

    MikroTik Router to MikroTik Router

    Let us consider the following example:

    In this example we will use two Moxa C101 syncronous 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>

    Frame Relay Troubleshooting

    Additional Resources

    Frame Relay forum
    www2.rad.com/networks/1994/fram_rel/frame.htm
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