GT 70 Series FAQ
This document provides answers to the most frequently asked questions about OpenROUTE Networks GT 70 Series routers.
Note: OpenROUTE Networks updates Frequently Asked Questions (FAQ) periodically. Check our Web site at http://www.openroute.com for the latest information.
This document has the following sections:
Questions
Answers
Interoperability
Questions
General
1. Who is calling me, or who did I call?
2. Why does my PPP interface keep going up and down?
3. Why does my router not place a call?
4. What does the ELS message `NULL dial key' mean?
5. When I have multiple ISDN circuits configured on my GT 70 Series router, why does a remote router connect to the wrong circuit when it dials in?
6. How can I tell if caller ID is provided by the switch variant?
7. Why does the PPP link keep resetting when there are high traffic loads between my GT 70 Series router and another router?
8. Why am I seeing garbled data on my console screen when I power up the GT 70 Series router?
9. Why does the Voice call fail, even though I enabled Data Over Speech Bearer Service (DOSBS) to make Voice calls over ISDN?
10. What is the difference between ANI, CLIP, and Caller ID?
Interoperability with a Motorola BitSURFR Pro(TM)
11. Can my Motorola BitSURFR Pro dial into a GT 70 Series router?
12. Why does PPP drop the link before the negotiation is completed when I dial into a GT 70 Series router with a Motorola BitSURFR Pro?
Interoperability with a Cisco® Router
13. Why can I not get Multilink PPP (MP) working with a Cisco router?
14. When I enable PAP between my GT70 Series router and a Cisco, why is my router able to call the Cisco, but when the Cisco calls my router, the connection fails?
15. Why can a Cisco router call into my GT 70 Series router, but the GT 70 Series router cannot call the Cisco?
16. Why does the link come up, but I cannot send IP traffic through it, when I enable Stac compression between the GT 70 Series router and a Cisco router?
17. Why do I only get an initial RIP update over ISDN from a remote Cisco router, and then all the learned routes end up timing out?
Interoperability with an Ascend(TM) Router
18. What is the maximum PPP MRU size that the GT 70 Series router and an Ascend router can negotiate?
19. Why is my GT 70 Series router not making a Multilink PPP (MP) connection to an Ascend router?
20. Does RIP work between the Ascend router and the GT 70 Series router with the configuration in Question 18?
21. How is IP configured between the GT 70 Series router and an Ascend router?
22. What does ELS message `lcp unk 0' mean when connecting to an Ascend router?
23. Why does the PPP link not come up when I enable Stac compression between my GT 70 Series router and an Ascend router?
24. Can the Ascend MAX Multilink PPP do Short Sequence Number Length?
25. What should I check for if I get "Protocol Reject" messages from an Ascend 400 (running Release 4.5B+ Firmware) when my GT 70 Series router attempts to negotiate the PPP IP or Compression Control protocols?
Answers
General
1. Who is calling me, or who did I call?
If the switch provides caller ID, you can find the name of the calling router by using the call command at the BRI> monitoring prompt, if the caller's name and address are configured in the ISDN phone book. If the switch does not provide caller ID, enable PAP or CHAP at the PPP Config> prompt for the specific interface and configure the name and password/secret of the remote router.
2. Why does my PPP interface keep going up and down?
You must assign an IP address to the ISDN dial circuit, or you must enable unnumbered IP on the dial circuit. You can do this with Quick Config or by using the add address command at the IP Config> prompt.
3. Why does my router not place a call?
You must assign an IP address to the ISDN dial circuit or you must enable unnumbered IP on the dial circuit. You can do this with Quick Config or by using the add address command at the IP Config> prompt.
4. What does the ELS message `NULL dial key' mean?
The destination is missing from the WAN configuration for the interface. Add a destination at the WAN Config> prompt.
5. When I have multiple ISDN circuits configured on my GT 70
Series router, why does a remote router connect to the wrong
circuit when it dials in?
At the WAN Config> prompt, use the list command to check the access list. It should be set for the name of the remote router that is connecting to this specific circuit.
If you do not have CHAP enabled, the access list should include the remote router's name as configured in the ISDN address list.
If you have CHAP enabled, the access list must also include the remote router's name as configured in the CHAP secret table.
6. How can I tell if caller ID is provided by the switch variant?
When you receive a call, use MONITOR and the ISDN ELS messages. If the switch does not provide caller ID, the following message displays:
ISDN.045: Calling address NOT PROVIDED by the ISDN switch
If the switch provides caller ID, the following message displays:
ISDN.004: ConnID 0x0 Q.931 Display Info Element "Calling# 5088982800" (cause 0x6:0x4) on nt 1 int PPP/0
where 5088982800 is the caller ID.
7. Why does the PPP link keep resetting when there are high traffic
loads between my GT 70 Series router and another router?
At the Config> prompt, check the PPP configuration for the interface to see if LCP echo is enabled. If echo is already enabled, use the disable echo command to disable it.
8. Why am I seeing garbled data on my console screen when I
power up the GT 70 Series router?
Check the console port settings on your terminal or terminal emulator for the following required settings: 9600 baud, 8 bits, no parity, 1 stop bit.
9. Why does the Voice call fail, even though I enabled Data Over
Speech Bearer Service (DOSBS) to make Voice calls over
ISDN?
If you want the GT 70 Series router to make a Voice call first but will accept its making a Data call when the Voice call fails, change the destination address entry in the ISDN phone book to Voice_data when you enable DOSBS.
10. What is the difference between ANI, CLIP, and Caller ID?
These terms are synonymous. They describe the feature that enables your router to identify who is the caller.
Interoperability With a Motorola BitSURFR Pro
11. Can my Motorola BitSURFR Pro dial into a GT 70 Series router?
Yes. The BitSURFR Pro can connect to the GT 70 Series router either at 64 Kbps via a single ISDN B channel or at 128 Kbps using Multilink PPP (MP).
Note: Stac compression is not supported on the BitSURFR Pro.
12. Why does PPP drop the link before the negotiation is completed when I dial into a GT 70 Series router with a Motorola
BitSURFR Pro?
On the GT 70 Series router, under PPP LCP options, change the Config NAK Tries counter to 5 (default is 10), using the set lcp parameters command at the PPP Config> prompt. Otherwise, the BitSURFR Pro times out the link before PPP negotiates its options.
Be aware that Motorola supplies NetManage(TM) Chameleon(TM) software as the IP stack for the PC. Chameleon insists on doing PPP PAP authentication, so you have to enable PAP on the GT 70 Series router and configure a name and password. On the PC, configure the name and password by clicking the Chameleon icon; then use the following menu items:
Setup - Communications - Login.
Interoperability With a Cisco Router
13. Why can I not get Multilink PPP (MP) working with a Cisco
router?
Make sure that the following configuration line is in the interface BRI0 section on the Cisco router:
dialer load-threshold 1
Otherwise, the Cisco does not try to join a second circuit to the bundle until the first one reaches full capacity.
14. When I enable PAP between my GT70 Series router and a
Cisco, why is my router able to call the Cisco, but when the
Cisco calls my router, the connection fails?
If PAP is enabled on the Cisco, the Cisco tries to authenticate the remote system regardless of which side made the call. If the Cisco called into the GT Series 70 router and tried to initiate the PAP authentication, the GT 70 Series router refuses the call. To set the Cisco to authenticate PAP only when the remote router is the caller, the Cisco configuration line should be:
ppp authentication pap callin
15. Why can a Cisco router call into my GT 70 Series router, but
the GT 70 Series router cannot call the Cisco?
The Cisco router's configuration line may not be set correctly for caller ID to work. The dialer map line in the Cisco router's configuration should look like this:
dialer map ip 128.185.33.2 name 5088982200 98982200
where the IP address matches the GT 70 Series router's ISDN interface address, 9898200 matches the number the Cisco router uses to call the GT 70 Series router, and 5088982200 matches the incoming number (caller ID) presented to the Cisco router when the remote GT 70 Series router calls into it.
16. Why does the link come up, but I cannot send IP traffic through
it, when I enable Stac compression between the GT 70 Series
router and a Cisco router?
Stac compression negotiates with the Cisco router, but the header format used by Cisco for the compressed packets is incompatible with the format used by the GT 70 Series router, due to Cisco following an older version of the Stac standard. Cisco is correcting the problem in an upcoming release.
17. Why do I only get an initial RIP update over ISDN from a remote
Cisco router, and then all the learned routes end up timing out?
The Cisco router sends a directed RIP update on the initial connection. From then on all the RIP updates are sent as subnet broadcasts. The Cisco router does not send these updates out on the ISDN interface unless either the broadcast option is added to the dialer map configuration line, or a neighbor statement is added to the Cisco router's RIP section pointing to the GT 70 Series router ISDN IP interface address.
Interoperability With an Ascend Router
18. What is the maximum PPP MRU size that the GT 70 Series
router and an Ascend router can negotiate?
You can configure the Ascend router for a Maximum Receive Unit (MRU) of 1524 (the default). To speed up PPP negotiation slightly between the GT 70 Series router and the Ascend router, you can configure the GT 70 Series router's MRU to 1524 by using the set lcp options command at the PPP Config> prompt.
19. Why is my GT 70 Series router not making a Multilink PPP (MP)
connection to an Ascend router?
Make sure the Base Ch Count is set to a value of 2 in the Ascend router's configuration in the Connection Profile. Also, be sure to set the Min Ch Count to a value of 2.
In the GT 70 Series router's configuration, at the PPP Config> prompt, enable MP, set MP discriminator generate, set MP max-bundle-size = 2, and set MP initial-bundle-size = 2.
20. Does RIP work between the Ascend router and the GT 70 Series
router with the configuration in Question 18?
Yes. RIP works as if the GT 70 Series router were directly on the same Ethernet as the Ascend router. If you are setting up the GT 70 Series router for dial-on-demand connections, you do not want to use RIP, since it keeps the line up. Configure static routes on the GT 70 Series router instead.
21. How is IP configured between the GT 70 Series router and an
Ascend router?
Ascend uses a single box-level IP address, rather than one address per interface. Configure the GT 70 Series router ISDN interface with an IP address that is part of the same subnet that the Ascend Ethernet port is on.
22. What does ELS message `lcp unk 0' mean when connecting to
an Ascend router?
The Ascend router is trying to make an unknown option 0 with the GT 70 Series router, which simply acknowledges by also making an unknown option 0. Option 0 is an unknown option to the GT 70 Series router. The ELS messages are as follows:
23. Why does the PPP link not come up when I enable Stac
compression between my GT 70 Series router and an Ascend
router?
Ascend has multiple selections for Stac PPP compression. Select the Stac-v9 option. This option is compatible with the GT 70 Series routers. The other two compression options (Stac and MS-Stac) are not compatible with GT 70 Series routers.
24. Can the Ascend MAX Multilink PPP do Short Sequence Number
Length?
The Ascend MAX only negotiates a Long Sequence Number Length. If your GT 70 Series router is configured for a Short Sequence Number Length, then the Ascend MAX sends an LCP reject to the GT 70 Series router, and both routers negotiate a Long Sequence Number Length.
25. What should I check for if I get "Protocol Reject" messages from
an Ascend 400 (running Release 4.5B+ Firmware) when my GT
70 Series router attempts to negotiate the PPP IP or
Compression Control protocols?
There are two known workarounds. For the first workaround,
- 1. Make sure the Ascend router has PPP Recv Auth=CHAP in the PPP Options menu under the Answers menu. (Of course, make sure the Ascend router and your GT 70 Series router are configured with CHAP secrets).
- 2. Make sure the Ascend router has CLID Auth=Ignore in the Answers menu. This prevents the Ascend router from using Caller ID if it is offerred with an incoming call.
Both of these properties must be true if your GT 70 Series router is to successfully call into the Ascend 400.
For the second workaround,
- 1. Make sure the Ascend router has PPP Recv Auth=CHAP in the PPP Options menu under the Answers menu.
- 2. Make sure the Ascend router has CLID Auth=Preferred under the Answers menu.
- 3. Set the Calling # in the Connections menu for your GT 70 Series router's incoming circuit to a null (empty) number. This guarantees that the Ascend router, even if caller ID is present, does not match the caller ID with this circuit.
Once again, all of these items must be true to assure a GT 70 Series router to Ascend router interoperability.
Interoperability
The following sections provide current information on the interoperability between OpenROUTE Networks GT 70 Series routers and other vendors' routers.
Interoperability Matrix
Interoperability Legends
X Passed the test.
N/A Not Applicable.
N/T Should work but was not covered during the qualification effort.
S/T Tested as part of an earlier GT 70 release, but not retested with the GT 72.
* For security reasons, many routers do not let the remote (calling) router initiate PAP.
Notes:
- 1. When running software load 11.1 or below on the 2500 Series CCP, the Cisco would not interoperate with the GT 70 Series router. Beta load 11.2 that was generated as a result of the California ISDN Users Group (CIUG) ISDN PPP Interoperability Workshop in May 1996 corrected this problem. Contact Cisco for additional information.
- 2. The BAY AN does not support STAC compression.
- 3. The current revision of the CCP draft is 9. The GT 70 Series routers are compatible with STAC-9 compression in release 4.6C-i2 for both the Ascend MAX and Pipeline 400. To set STAC-9 compression on the Ascend, under the Encapsulation menu select Link Compression and then select Stac-9.
Interoperability Problems and Solutions
Interoperating With Ascend
- Calls from the GT 70 Series router to the Ascend 400, with 4.5B+ firmware, fail to negotiate PPP successfully when Multilink PPP is enabled on both routers. To work around this problem, make sure that the Ascend 400 has the following configured:
- Ascend routers do not use an IP network address on ISDN ports. When configuring the GT 70 Series router to dial into the Ascend router, you should set the router's ISDN interface IP address to be on the same IP subnet as the Ascend Ethernet interface. Also, at the PPP Config> prompt on the router, use the set IPCP command to set Send our IP address and Request their IP address to no. If you're configuring a static gateway route, use the same gateway that the Ascend uses to get to remote networks. In addition, make sure the Ascend's Ethernet profile has proxy ARP enabled.
- When connecting the GT 72 to an Ascend MAX or Ascend Pipeline, the Ascend routers have shown some problems in negotiating certain IPXCP options in PPP. Therefore, there are problems bringing up an IPX WAN link or receiving IPX RIP routes from the Ascend. Ascend Communication has been notified of the issue and a solution is being sought.
To work around this problem, use the IPX configuration commands to configure the following on the PPP interface that connects to Ascend.
- a. Set the IPX circuit type to broadcast and increase the SAP aging multiplier on the circuit to the maximum (133 hours). (Ascend only sends a full SAP update at the time of the initial connection, after that it sends delta updates.)
To do so, use the add bcastcircuit command and answer yes to the prompt that asks if you want to continue with expert config questions.
- b. Add an IPX static RIP route with a value of FFFFFFFE, pointing at the PPP interface as the route using the add route-static command.
An alternative to increasing the SAP aging multiplier is to add a static SAP route using the add sap-static command. This way, the SAP route never ages out.
- In interoperability tests between the GT 70 Series routers and the Ascend MAX 1800 configured for a two link Multilink PPP connection (S/W release +4.6Ai12, BRI ports configured for USNI-1 Multipoint), testers found that two links of a Multilink PPP connection come up and pass traffic, but the link goes down after a few minutes. A Q931 analyzer reports "Normal Call Clearing" and the MAX 1800 reports "Call Cleared/L1 Change." If you reconfigure the MAX 1800 for AT&T 5ESS Point-to-Point and reprovision the switch for the same, both links of the Multilink PPP connection come up and stay up. Ascend Communication has been notified of the issue and a solution is being sought.
- When the Ascend MAX 1800 or Pipeline 400 with release 4.6a or 4.6c is configured for either PAP or CHAP authentication and calls a GT 70 Series router not configured for authentication, the Ascend system hangs. During LCP negotiation, the Ascend does not negotiate the authentication option. However, at the end of LCP negotiation, the Ascend product hangs, appearing to wait for authentication and does not enter the NCP negotiation phase. There are three workarounds for this problem:
Interoperating with Cisco
Interoperating with Motorola BitSURFR Pro
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