Frame
Relay Configuration
A Frame Relay network represents two or more
routers interconnected by a Frame Relay cloud. Each router on the Frame Relay
cloud is connected to the Frame Relay network that has a Permanent Virtual Circuit
(PVC). The Frame Relay network is connected to a Frame Relay switch that in turn
connects to the Frame Relay cloud. The interface or port used to connect
the router to the Frame Relay network is called a Frame Relay interface and each
Frame Relay interface must have an IP address. - Each router is a node
on the Frame Relay network.
- The Frame Relay network has its own IP network
number that is normally a class C or a subnet of a class C that is unique from
other subnets on the system.
- Each router Frame Relay interface (port)
is assigned an IP address from the Frame Relay network's subnet, thus the netmask
for each Frame interface on each router of the Frame Relay network is the same.
- Data Link Connector Identifier (DLCI) numbers are used to point from
the Frame Relay switch located at the telephone company central office, to the
PVC of a router(s) on the other side of the Frame cloud.
- The router communicates
with the switch by polling the switch at a manually configured polling interval.
The default value is 10 seconds.
- The router can communicate with the
switch using Local Management Interface (LMI) or Annex-d signaling. If the
router receives 3 LMI packets back from the switch the connection is established,
and the interface statistics (stats) will show the protocol status as "up". If
LMI packets are not present the connection (protocol in the stats interface)
will go down.
- When using LMI the switch will respond with a full DLCI
list after a few exchanges of LMI packets. The router can use this information
to build a dynamic DLCI list or the DLCI list can be set up statically.
====ETHERNET===================== 192.168.100.0/24 ===
|
| LAN IP: 192.168.100.100
+-------+--------+
| |
| Router A |
| Serial0 |
+-------+--------+
| WAN IP: 192.168.1.1
|
[-] CSU/DSU
|
|Frame Relay Cloud WAN 192.168.1.0 255.255.255.0
+----------------------------+
| |
[-] CSU/DSU | WAN IP: 192.168.1.3
| +-------+-------+
| WAN IP: 192.168.1.2| Serial0 |
+-------+--------+ | Router C |
| Serial0 | | |
| Router B | +-------+-------+
| | | LAN IP: 192.168.300.300
+-------+--------+ ===ETHERNET======= 192.168.200.0/24===
| LAN IP: 192.168.200.200
|
====ETHERNET===================== 192.168.200.0/24 ===
Configuring IP Over Frame Relay The following
is a sample of a port configuration: - For this example: The Frame
Relay interface on the router is Serial0
- For this example: The IP address
of the Frame Relay connection on the router is 192.168.1.1
!
# Comments (denoted by a hash mark at the beginning of the line)
# are permitted anywhere in the file
# See the Command Reference for more information on the
# commands below
version 2.00
!
interface Serial0
description Port 0
encapsulation frame-relay ietf
frame-relay lmi-type ansi
# frame-relay lmi-type ccitt
# frame-relay lmi-type cisco
!
interface Serial0.1
description UUNet T1
encapsulation frame-relay ietf
frame-relay interface-dlci 500
ip address 192.168.1.1 255.255.255.0
!
ip route 0.0.0.0 0.0.0.0 Serial0.1
!
end
At this point, LMI packets
should be being transmitted and received. The status of the WAN port should change
to up. It should now be possible to ping the other
side. The interface statistics (Option 2 from the Main menu) should show:
19:03:17 Interface Summary Router A
# Port Description Encaps Bandwidth HW Proto In Out
0 Ethernet0 100Mb Ethernet Ethernet 100.00 Mbit up up 0% 0%
1 Serial0 Port 0 Frame Relay 1.54 Mbit up up 0% 0%
2 Serial0.1 UUNet T1 1.54 Mbit up up 0% 0%
-----------------------------------------------------------------------------
d - Detail s - Sleep interval q - Quit
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