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This configuration describes a
simple point-to-point fractional DS3 connection from
an ImageStream 530 series DS3/E3 (531-DE, 532-DE)
port to a Cisco PA-T3 port in a 7xxx series router.
On both WAN ports, the address of the WAN port is
set to an IP address on a common IP network, and the
destination addresses are set to the IP address of
WAN port of the unit on the far side of the link.
====ETHERNET===================== 192.168.1.0/24 ===
|
| LAN IP: 192.168.1.100
+-------+--------+
| |
| ImageStream |
| Serial0 |
+-------+--------+
| WAN IP: 192.168.54.1/30 (255.255.255.252)
|
[-] CSU/DSU (integrated on WAN card)
|
| DS3 WAN with 6 Mbps
|
[-] CSU/DSU (integrated on WAN card)
|
| WAN IP: 192.168.54.2/30 (255.255.255.252)
+-------+--------+
| Serial0 |
| Cisco |
| |
+-------+--------+
| LAN IP: 192.168.2.200
|
====ETHERNET===================== 192.168.2.0/24 ===
Before You Start
Be sure to have three separate IP
subnets, one for the WAN network and two for the Ethernets
connected to the routers. Each WAN port connected to
the point-to-point WAN must have it's own IP address
from the same IP network. Since they are on the same
IP network, they will have the same netmask.
These IP network addresses are given to you by your
Internet Service Provider, your leased line carrier,
or by ARIN. If you
do not plan to connect you network to the Internet,
you can use an IP network address set aside for private
use. The IP network address for private use can be found
in RFC 1597. Most people will use 192.168.0.0 as we
have in this example.
Configuring The WAN Ports
In this example, we are going to
assume the following:
- The ImageStream
router has an Ethernet IP address of 192.168.1.100
with a netmask of 255.255.255.0
- The ImageStream
router has a WAN IP address of 192.168.54.1 with
a netmask of 255.255.255.252
- The Cisco
router has an Ethernet IP address of 192.168.2.200
with a netmask of 255.255.255.0
- The Cisco
router has a WAN IP address of 192.168.54.2 with
a netmask of 255.255.255.252
- The ImageStream
router is providing Internet access to the Cisco
router.
- The WAN port
on both routers is Serial0.
The IP addresses used in this Technical
Note are examples only, you will need to use an IP network
given to you by your Internet Service Provider.
ImageStream router
!
version 2.00
!
interface Ethernet0
ip address 192.168.1.100 255.255.255.0
!
interface Serial0
description Connection to Cisco router
encapsulation ppp
ip address 192.168.54.1 255.255.255.252
transport ds3
service-module ds3 timeslots 1-4
service-module ds3 clock source external
dsu mode digital-link
crc 16
!
ip route 0.0.0.0 0.0.0.0 192.168.1.1
!
end
Cisco router
!
version 12.1
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname Router
!
ip subnet-zero
!
controller T3 2/0
cablelength 10
!
interface FastEthernet0/0
ip address 192.168.2.200 255.255.255.0
duplex auto
speed auto
!
interface Serial2/0
bandwidth 6144
ip address 192.168.54.2 255.255.255.252
encapsulation ppp
dsu mode digital-link
crc 16
dsu bandwidth 6144
no scramble
!
ip route 0.0.0.0 0.0.0.0 192.168.54.1
!
ip classless
no ip http server
!
line con 0
line aux 0
line vty 5 15
!
end
Troubleshooting
If the port does not have an "up"
status for both hardware and protocol in the interface
statistics output (Option 2 from the Main menu) do the
following:
If hardware shows "down", check your cable connections
and ensure that you have connected to the correct port.
If you have connected to the correct port, double-check
the telephone company smart jack or other telephone
company-installed equipment for your circuit. The smart
jack should show no red alarms if the cables are connected.
If, after connecting the cables correctly, you have
errors on the telephone company equipment, contact your
line provider for assistance.
If hardware shows "up", but protocol shows "down", you
should see the PPP negotiation and see the status of
the WAN port change to up. At this point you should
be able to ping the other side.
If you have an external CSU/DSU, put the CSU/DSU into
a local loopback. This will cause each packet sent to
the CSU/DSU to reflect back to the WAN port. This is
for testing only, the line will not function while the
CSU/DSU is in a local loopback. If, in the interface
statistics detail output for the port, you see transmitted
packets immediately received on the same port, then
you can determine the following facts:
- The WAN port
on the router is sending and receiving data.
- The cable
and connectors between the router and the CSU/DSU
are functioning.
- The DTE port
on the CSU/DSU is functioning.
- THE ROUTER
IS FUNCTIONING AS IT SHOULD.
If you don't get your packets back
immediately on the same interface:
- For cards
with a software-selectable serial interface, check
that you have specified the correct wiring specification
(V.35, RS232, RS422/X.21). The "dctype" command
is typically set to V.35 (the default) in North
America and RS422 in Europe and Asia.
- That all
cables are securely connected.
- Begin swapping
hardware, cables, CSU/DSU, etc.
If you get your packets back immediately,
but the line protocol status is not "up":
- Check the
CSU/DSU settings such as clocking, etc. Almost always
the CSU/DSU should be set for external clocking.
Your line provider typically provides the clock.
It's not a bad idea to verify any external CSU/DSU
settings with the manufacturer.
- Have their
telephone carrier test the line. Requesting a hard
copy of the test results will often get you a better
test.
If the line protocol status is "up"
but you can't ping the other side:
- Double check
settings. Make sure that the IP address for the
WAN port on both sides are in the same subnet.
- Do a traceroute
from your workstation through the local (to you)
router to the router in trouble. Then do a traceroute
from the router in trouble (assuming you can get
to it) back to your workstation. The problem will
lie in the gap between the two traceroutes.
- Make sure
the default gateway is set to the upstream router
or the serial device used for the upstream connection,
as in our example above on Cisco router.
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