Cisco Compatible Micro Router Series

This document answers frequently asked questions about Compatible Systems - dialing in and dialing out.

A. Yes. Make sure that if you use RIP on the WAN port, it is set to "triggered" and not "periodic." If you use RIP over sub-divided Class C subnets, RIP version 2 must be used since RIP Version 1 does not recognize the Class C subnets.

A. The router dials out initially and then stores the network number and server information. Any access to the remote network causes it to dial. At this time, it checks the SAP and routing tables to determine if there are any changes that need to be made to these tables. For IPX WAN routing, you must use the "triggered," not "periodic," update method.

A. Any Compatible Systems router with multiple WAN ports and no internal CSU, which includes the 2600i, 2800i, 2900i, 3400R, 3500R, and 3800R can be configured for such a scenario. Each WAN port can only be configured to dial-up to one remote network. All other Compatible Systems routers can dial-up to just one remote network.

A. Yes. This also works for single protocol routers.

Use CompatiView:

Set the "Optional Remote End Node Information" on the TCP/IP configuration screen for the applicable WAN port to an unused IP address on your local (Ethernet) IP network. Use this IP address in the MacPPP configuration when you dial in. For the PC, set the host to pick up an IP address dynamically from a server.

Use Command Line:

• Router Code 3.x.x and earlier

  int wan x (where x is the applicable WAN port)
  set ip wan remote a.b.c.d (where a.b.c.d is the unused address on your LAN) 

• Router Code 4.x.x and later

  config IP wan x (where x is the applicable WAN port)
  remote address = a.b.c.d (where a.b.c.d is the unused address on your LAN) 

A. Dynamic IP assignment is not supported on Compatible Systems products. The router dials up to make a PPP connection, but, because of the dynamic IP assignment, it probably never actually makes the PPP connection. You must use a static IP address on the Linux box for the port to which the router dials in.

A. You go through a 28.8K modem. In order to allow for compression, you must set the modem speed to 115200 and turn on Hardware Flow Control for your router. This gives you the maximum data rate between the router and the modem.

A. This is an issue unrelated to the routers. Use the DIP switch on the USR Sportster modem to set Auto Answer on both modems. The MicroRouter sends a string to enable auto answer on the modem, but, if the modem is unstable or gets reset, they do not answer. If you set the DIP switch, it ensures that the modem answers all inbound calls.

A. The modem does not get a dial tone from the phone line. Try this in your chat script:

send atdt 9,1-703-749-0973

The comma causes a pause while the PBX switches to an outside line.

A. For IP networks:

In the log, after initialization, this message appears:

Wan A: wait for dialin/dialout

After this line, when the link is brought up, this appears:

Wan A: start link due to ip activity
Debug +0.0: Wan A: 45000049 44010000 1f113143 cc0d4844 cb0d4801 00890035 
Debug +0.0: Wan A: 0035d81f 01680100 00010000 00000000 05465241 4e4b0373 

The IP address of the source machine is encoded in the fourth hexadecimal number in the log message while the IP address of the destination machine is located in the fifth hexdecimal number:

Debug +0.0: Wan A: 45000049 44010000 1f113143 cc0d4844 cb0d4801 00890035
cc=204
0d =13
48 =72
44=68

source IP address = 204.13.72.68

cb=203
0d=13
48=72
01=1

destination IP address = 203.13.72.1

For IPX networks:

In the log, after initialization, this message appears:

Wan A: wait for dialin/dialout

After this line, when the link is brought up, this appears:

Wan A: start link due to ipx activity
Wan A: ffff0024 02000000 0205ffff ffffffff 84140000 02000000
Wan A: c0fc17c3 84131b00 03000000 6c7e7e7e 7e7e7e7e 7e7e7428

This hexadecimal data is the IPX header. You can find descriptions of this in NetWare Unleashed by Rick Sant'Angelo (page 883) or in NetWare LAN Analysis by Laura Chappell and Dan E. Hakes (page 272).

Here are the packet header fields:

|destination
|ffff      |0024    |02   |00   |0000 0205  |ffff ffff ffff   |8414
|checksum  |length  |hops |type |net number |node (broadcast) |socket
|source
|00   |0000 0200  |0000 c0fc 17c3   |8413    |1b00
|type |net number |node             |socket  |data

What happens is that source net number 200 (hex), node 0000c0fc17c3 sends out a packet broadcast to all nodes on net 205 (hex).

The source node number here is the Ethernet hardware address of the originating device. If this is a server, its address displays in the SAP table.

For AppleTalk networks:

In the log, after initialization, this message appears:

Wan0: wait for dialin/dialout

After this line, when the link is brought up, this appears:

Wan0: start link due to atalk activity
Wan0: 002e0000 006e0002 002c0202 02412100 026efe00 013d0c51
Wan0: 7561726b 58507265 73733c0a 41425420 5379646e 65797665

This hexadecimal data consists of AppleTalk packet header bytes. You can find descriptions of these in Inside AppleTalk, Second Edition, by Gursharan S. Sidhu et al, Addison Wesley, 1990.

The first 13 bytes of the packet header contain the same fields:

|002e   |0000  |006e  |0002   |  
|packet |check |dest. |source ||length |sum   |net   |net    |
                                                             
|00    |2c     |02     |02     |02   |
|dest. |source |dest.  |source |DDP  |
|node  |node   |socket |socket |type |
                               |(NBP)|

These bytes are specific to the DDP type. This one is NBP.

Name Binding Protocol (NBP)

|4        |1     |21  |00 02  |6e   |
|function |tuple |NBP |Net    |node |
|(FwdReq) |count |ID  |number |ID   |
                                     
                                     

|fe     |00         |01     |3d     |0c     |
|socket |enumerator |object |object |type   |
|number |           |field  |       |field  |
                    |length |       |length |
                                    |(12)   |

|517561726b 58507265 73733c |0a     |
|Q u a r k  X P r e  s s <  |zone   |
|type                       |field  |
                            |length |
                            |(10)   |

|41425420 5379646e 6579 |7665 |
|A B T SP S y d n  e y  |old  |
|zone                   |data |

This example is from Australia. Quark XPress caused the router to dial. Quark periodically sends packets as a copyright measure. A Quark software mod prevents this.

In addition to NBP, there can be any of these DDP types:

01 RTMP response or data packet
02 NBP packet
03 ATP packet
04 AEP packet
05 RTMP request packet
06 ZIP packet
07 ADSP packet

RTMP response or data packet, DDP type 01:

Wan0: 00200000 00000000 ff000101 01000008 00000082 00068000
Wan0: 08820032 81003c82 21970007 7cfe000d 506c6174 654d616b

The first 13 bytes:

|0020   |0000  |0000  |0000   |  
|packet |check |dest. |source |
|length |sum   |net   |net    |   

|ff    |00     |01     |01     |01     |
|dest. |source |dest.  |source |DDP    |
|node  |node   |socket |socket |type   |
                               |(RTMP) |

The RTMP portion:

|0000   |08     |00     |0000  |82   |
|router |id     |router |two   |flag |
|net    |length |node   |zero  |
|number |= 8    |id     |bytes |
|0006  |8     |0    |0008  |82   |
|range |range |hops |range |flag |
|start |flag  |     |end   |
|0032  |8     |1    |003c  |82   |
|range |range |hops |range |flag |
|start |flag  |     |end   |