WAN Configuration for Numbered Point to Point

UPDATED: August 26, 1999

PortMaster (TM) Models

Each of the following models are equipped with synchronous ports that can be used as WAN interfaces. The synchronous ports for each unit are listed as follows:
 

  • PM-4, W59
  • PM-3, W0-W24 (W48 if using T1 card)
  • PM-2R, W1
  • PM-2ER, W1
  • IRX-211, S1
  • IRX-111, S1
  • IRX-112, S1,S2
  • IRX-114, S1,S2,S3,S4
  • OR-LS, W1
  • OR-HS, W1

Summary

Point-to-point numbered refers to connections where the interfaces connecting the routers to the WAN have IP addresses. 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 ===
        |
        | E0 ip: 192.168.1.100
+-------+--------+
|      E0        |
|  LUCENT A      |
|      W1        |
+-------+--------+
        | W1 ip: 192.168.54.1 / 255.255.255.252
        |
       [-] CSU/DSU
        |
        | PTP WAN
        |
        [-] CSU/DSU
        |
        | W1 ip: 192.168.54.2 / 255.255.255.252
+-------+--------+
|      W1        |
|  LUCENT B      |
|      E0        |
+-------+--------+
        | 192.168.2.200
        |
====ETHERNET===================== 192.168.2.0/24 ===

Before You Start

  1. 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. 


    2. These IP network addresses are given to you by your Internet Service Provider, your leased line carrier, or by the Internic http://www.internic.net/

    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 RFC1597. Most people will use 192.168.0.0. 

    For all products except the PortMaster 3 which has built in CSU/DSUs:

  2. V.35 cable to connect the PortMaster's synchronous port to the CSU/DSU
  3. CSU/DSU configured for external clock.
  4. Point-to-point line.

Configuring The WAN Ports

In this example, we are going to assume the following:

  • PortMaster A has an Ethernet IP address of 192.168.1.100 with a netmask of 255.255.255.0
  • PortMaster A has a WAN IP address of 192.168.54.1 with a netmask of 255.255.255.252
  • PortMaster B has an Ethernet IP address of 192.168.2.200 with a netmask of 255.255.255.0
  • PortMaster B has a WAN IP address of 192.168.54.2 with a netmask of 255.255.255.252
  • PortMaster A is providing Internet access to PortMaster B.
  • The WAN ports on both PortMaster's is represented by W1.

The IP addresses used in this Technical Note are example only, you will need to use an IP network given to you by your Internet Service Provider. 

# PortMaster A

set address 192.168.1.100
# set ethernet IP address
set netmask 255.255.255.0
 
set w1 network hardwire
set w1 address 192.168.54.1
# IP address required for local wan port
set w1 destination 192.168.54.2
# IP address of the router WAN port at opposite end
set w1 netmask 255.255.255.252
set w1 modem on
# This can be off if circuit flaps too much
set w1 protocol ppp
set w1 rip on
# This sets IP Routing Information Protocol on
set w1 mtu 1500
# Maximum Transfer Unit

save all
reset w1 

# PortMaster B

set address 192.168.2.200
# set ethernet IP address
set netmask 255.255.255.0
set gateway 192.168.54.1
# IP address of upstream router
 
set w1 network hardwire
set w1 address 192.168.54.2
# IP address required for local wan port
set w1 destination 192.168.54.1
# IP address of the router wan port at opposite end
set w1 netmask 255.255.255.0
set w1 modem on
# This can be off if circuit flaps too much
set w1 protocol ppp
set w1 routing on
# This sets IP Routing Information Protocol on
set w1 mtu 1500
# Maximum Transfer Unit

save all
reset w1 

Troubleshooting

If the port does not have an "ESTABLISHED" status do the following:

You should see the PPP negotiation and see the status of the WAN port change to established. At this point you should be able to ping the other side.  

 
set console
set debug 0x51

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 you see "LCP: Apparent Loop", then you can determine the following facts:

  1. The WAN port on the PortMaster is sending and receiving data.
  2. The cable and connectors between the PortMaster and the CSU/DSU are functioning.
  3. The DTE port on the CSU/DSU is functioning.
  4. THE PortMaster IS FUNCTIONING AS IT SHOULD.

If you don't get apparent loops:

  1. Check that the RS232-V.35 dip switch next to the WAN port is set correctly, (usually V.35)
  2. That all cables are securely connected.
  3. Check that they are using the V.35 cable that came with the unit.
  4. Start swapping hardware, cables, CSU/DSU, etc.

If you get apparent loops and the status is not established:

  1. Check the CSU/DSU settings such as clocking, etc. Almost always the CSU/DSU should be set for external clocking. The Telco provides the clock. It's not a bad idea to verify your CSU/DSU settings with the manufacturer.
  2. Have their telephone carrier test the line. Requesting a hard copy of the test results will often get you a better test.

If the port status is "ESTABLISHED" but you can't ping the other side.

  1. Double check settings. Make sure that the IP address for the WAN ports on both sides are in the same subnet.
  2. Do a traceroute from your workstation at PortMaster 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.
  3. Make sure the "set gateway" is set to the upstream router.

A powerful trouble-shooting tool is the packet filter

This packet filter will show all pings passing through the PortMaster on which  packet filter is located. It will NOT show pings originating from the PortMaster.  

add filter p
set filter p 1 permit icmp
 
To enable ptrace, enter the following commands:
 
reset console 
# Turns off any output of packet headers the ptrace filter denies from
coming to the screen

ptrace p ext
 
To disable ptrace, enter the following command:
 
ptrace