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ISDN BRI: Multilink PPP Not Working

Hardware: two Cisco 1760 routers.

Software on both: IOS 12.2(11)T8.

I'm having problems getting multilink ppp to work on a single ISDN BRI connection between a main site and a remote site. My objective is for the full 128K bandwidth to be available as soon as a connection is made. There are no problems making the connection from either site; however, the multilink capability does not seem to be working.

Below are configurations of each router and some interface information during a session that should bring up the second B channel.

Any ideas as to why the multilink capabiliby is not working?

Thanks.

--------------------------------------------

Main-site Router Configuration

!

isdn switch-type basic-ni

!

interface BRI0/0

description ISDN Circuit: ...

ip unnumbered FastEthernet0/0

encapsulation ppp

dialer string 913136784329

dialer load-threshold 1 either

dialer-group 1

isdn switch-type basic-ni

isdn spid1 313678543500 6785435

isdn spid2 313678543600 6785436

no fair-queue

ppp multilink

!

-------------------------------------------

Remote-site Router Configuration

!

isdn switch-type basic-ni

!

interface BRI0/0

description ISDN Circuit: ...

ip unnumbered FastEthernet0/0

encapsulation ppp

dialer string 913136785435

dialer-group 1

isdn switch-type basic-ni

isdn spid1 31367843290101 6784329

isdn spid2 31367843300101 6784330

no fair-queue

ppp multilink

!

--------------------------------------------------------

IT-1760-MDF#sh ip int brief

Interface IP-Address OK? Method Status Prot

ocol

FastEthernet0/0 10.0.0.8 YES NVRAM up up

BRI0/0 10.0.0.8 YES unset up up

BRI0/0:1 unassigned YES unset up up

BRI0/0:2 unassigned YES unset down down

Virtual-Access1 unassigned YES unset up up

Loopback0 unassigned YES NVRAM administratively down down

IT-1760-MDF#sh int bri 0/0

BRI0/0 is up, line protocol is up (spoofing)

Hardware is PQUICC BRI with U interface (Infenion)

Description: ISDN Circuit: 34ibdc379351-000pt

Interface is unnumbered. Using address of FastEthernet0/0 (10.0.0.8)

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, loopback not set

Last input 00:00:03, output never, output hang never

Last clearing of "show interface" counters 00:21:50

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue :0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

129 packets input, 872 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

144 packets output, 951 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 output buffer failures, 0 output buffers swapped out

1 carrier transitions

IT-1760-MDF#sh int bri 0/0 1

BRI0/0:1 is up, line protocol is up

Hardware is PQUICC BRI with U interface (Infenion)

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 79/255, rxload 79/255

Encapsulation PPP, loopback not set

LCP Open, multilink Open

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue :0/40 (size/max)

5 minute input rate 20000 bits/sec, 6 packets/sec

5 minute output rate 20000 bits/sec, 6 packets/sec

456 packets input, 458812 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

458 packets output, 462451 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

1 carrier transitions

IT-1760-MDF#sh int bri 0/0 2

BRI0/0:2 is down, line protocol is down

Hardware is PQUICC BRI with U interface (Infenion)

MTU 1500 bytes, BW 64 Kbit, DLY 20000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation PPP, loopback not set

LCP Closed, multilink Closed

Closed: BRIDGECP, IPCP, CCP, CDPCP, LLC2, BACP

Last input never, output never, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue :0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

8 carrier transitions

IT-1760-MDF#sh int virtual-access 1

Virtual-Access1 is up, line protocol is up

Hardware is Virtual Access interface

MTU 1500 bytes, BW 64 Kbit, DLY 100000 usec,

reliability 255/255, txload 87/255, rxload 87/255

Encapsulation PPP, loopback not set

DTR is pulsed for 5 seconds on reset

Time to interface disconnect: idle 00:01:59

LCP Open, multilink Open

Open: IPCP, CDPCP

Last input 00:00:08, output never, output hang never

Last clearing of "show interface" counters 00:01:50

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue :0/40 (size/max)

5 minute input rate 22000 bits/sec, 6 packets/sec

5 minute output rate 22000 bits/sec, 6 packets/sec

520 packets input, 528382 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

522 packets output, 529432 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

IT-1760-MDF#sh ppp multilink

Virtual-Access1, bundle name is RH-1760-MDF

Bundle up for 00:03:55

Dialer interface is BRI0/0

0 lost fragments, 0 reordered, 0 unassigned

0 discarded, 0 lost received, 187/255 load

0x0 received sequence, 0x0 sent sequence

Member links: 1 (max not set, min not set)

BRI0/0:1, since 00:03:55, no frags rcvd

3 REPLIES
Silver

Re: ISDN BRI: Multilink PPP Not Working

Hi Larry

Acoording to:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1831/products_configuration_guide_chapter09186a00800d9845.html#1001636

I would use "dialer idle-timeout" command under interface BRI0/0 configuration at main site router, and set a very high idle timer.

That document says:

"When MLP is configured and you want a multilink bundle to be connected indefinitely, use the dialer idle-timeout command to set a very high idle timer. (The dialer-load threshold 1 command no longer keeps a multilink bundle of n links connected indefinitely, and the dialer-load threshold 2 command no longer keeps a multilink bundle of two links connected indefinitely.)"

Please, try it and let us know

HTH

New Member

Re: ISDN BRI: Multilink PPP Not Working

Dear Jose: Thanks for the information. I have made some progress: the second link attempts to come up, but the interface dials the first number--which is in use--and gets a busy signal. Attached are the changes I made to the bri 0/0 interface and the output of a debug session.

interface BRI0/0

description ISDN Circuit: ...

ip unnumbered FastEthernet0/0

encapsulation ppp

dialer idle-timeout 300

dialer map ip 10.69.0.1 broadcast 913136784330

dialer map ip 10.69.0.1 broadcast 913136784329

dialer load-threshold 1 either

dialer-group 1

isdn switch-type basic-ni

isdn spid1 313678482500 6784825

isdn spid2 313678482600 6784826

no fair-queue

ppp multilink

!

*** BEGIN DEBUG OUTPUT ***

IT-1760-MDF#

Oct 17 15:12:52.164: ISDN BR0/0 Q931: TX -> SETUP pd = 8 callref = 0x45

Bearer Capability i = 0x8890

Standard = CCITT

Transer Capability = Unrestricted Digital

Transfer Mode = Circuit

Transfer Rate = 64 kbit/s

Channel ID i = 0x83

Keypad Facility i = '913136784330'

Oct 17 15:12:52.312: ISDN BR0/0 Q931: RX <- CALL_PROC pd = 8 callref = 0xC5

Channel ID i = 0x89

Locking Shift to Codeset 5

Codeset 5 IE 0x2A i = 0x80880C, '913136784330', 0x800108800114800114800

114

Oct 17 15:12:52.593: ISDN BR0/0 Q931: RX <- CONNECT pd = 8 callref = 0xC5

Oct 17 15:12:52.593: %LINK-3-UPDOWN: Interface BRI0/0:1, changed state to up

Oct 17 15:12:52.597: ISDN BR0/0 Q931: TX -> CONNECT_ACK pd = 8 callref = 0x45

Oct 17 15:12:52.621: BR0/0:1 MLP: Request add link to bundle

Oct 17 15:12:52.621: BR0/0:1 MLP: Adding link to bundle

Oct 17 15:12:52.621: Vi1 MLP: Added to huntgroup BR0/0

Oct 17 15:12:52.621: Vi1 MLP: Clone from BR0/0

Oct 17 15:12:52.625: %LINK-3-UPDOWN: Interface Virtual-Access1, changed state to

up

IT-1760-MDF#

Oct 17 15:12:52.625: Vi1 MLP: Added first link BR0/0:1 to bundle RH-1760-MDF

IT-1760-MDF#

Oct 17 15:12:53.623: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0/0:1, c

hanged state to up

Oct 17 15:12:53.627: %LINEPROTO-5-UPDOWN: Line protocol on Interface Virtual-Acc

ess1, changed state to up

IT-1760-MDF#

Oct 17 15:12:58.599: %ISDN-6-CONNECT: Interface BRI0/0:1 is now connected to 917

076784330 RH-1760-MDF

IT-1760-MDF#

Oct 17 15:13:03.226: Vi1 MLP: Load (7) above threshold in bundle RH-1760-MDF

Oct 17 15:13:03.226: ISDN BR0/0 Q931: TX -> SETUP pd = 8 callref = 0x46

Bearer Capability i = 0x8890

Standard = CCITT

Transer Capability = Unrestricted Digital

Transfer Mode = Circuit

Transfer Rate = 64 kbit/s

Channel ID i = 0x83

Keypad Facility i = '913136784330'

Oct 17 15:13:03.411: ISDN BR0/0 Q931: RX <- CALL_PROC pd = 8 callref = 0xC6

Channel ID i = 0x8A

Locking Shift to Codeset 5

Codeset 5 IE 0x2A i = 0x808308, '96784330', 0x80010C800114800114800114

IT-1760-MDF#

Oct 17 15:13:03.447: ISDN BR0/0 Q931: RX <- DISCONNECT pd = 8 callref = 0xC6

Cause i = 0x8291 - User busy

Signal i = 0x04 - Busy tone on

Oct 17 15:13:03.455: ISDN BR0/0 Q931: TX -> RELEASE pd = 8 callref = 0x46

Oct 17 15:13:03.547: ISDN BR0/0 Q931: RX <- RELEASE_COMP pd = 8 callref = 0xC6

Signal i = 0x3F - Tones off

IT-1760-MDF#

*** END DEBUG OUTPUT ***

New Member

Re: ISDN BRI: Multilink PPP Not Working

Isn't it amazing how obvious the solution is after it is found?

Here's the solution to my problem:

interface BRI0/0

description ISDN Circuit:

ip unnumbered FastEthernet0/0

encapsulation ppp

dialer order round-robin

dialer idle-timeout 300

dialer map ip 10.69.0.1 broadcast 913136784329

dialer map ip 10.69.0.1 broadcast 913136784330

dialer load-threshold 5 either

dialer-group 1

isdn switch-type basic-ni

isdn spid1 313678482500 6784825

isdn spid2 313678482600 6784826

no fair-queue

ppp multilink

Now, on to compression...

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