Mailing List Archive

Problems with multilink PPP/ISDN
Hi,

I am experiencing problems that I can't understand.

I have a Cisco 3600 with an ISDN PRI and I can't get ISDN-2 Multilink PPP
(128K) to work and I really don't know why.

Everything works fine with a single 64K ISDN channel. Also, multilink PPP
with one ISDN channel and an analog modem connection works fine.

Clients are various Windows Workstations with Lasat and Zyxel ISDN modems.

Radius server is MS IAS with the following parameters set:
Framed-Protocol: PPP
Service-type: Framed
Filter-Id: depending on profile

The following is debug output (I would like to know what the "Ignoring bad
ACK!" message means):

00:13:14: %LINK-3-UPDOWN: Interface Serial3/0:0, changed state to up
00:13:15: %LINK-3-UPDOWN: Interface Serial3/0:1, changed state to up
00:13:15: %ISDN-6-CONNECT: Interface Serial3/0:0 is now connected to 443
00:13:17: Se3/0:0 LCP: Ignoring bad ACK!
00:13:19: Se3/0:0 EVT: Packet suspended unexpectedly
00:13:21: %ISDN-6-CONNECT: Interface Serial3/0:1 is now connected to 443
00:13:22: Se3/0:0 LCP: Ignoring bad ACK!
00:13:25: %ISDN-6-DISCONNECT: Interface Serial3/0:1 disconnected from 443
, call lasted 10 seconds
00:13:25: %LINK-3-UPDOWN: Interface Serial3/0:1, changed state to down
00:13:25: %ISDN-6-DISCONNECT: Interface Serial3/0:0 disconnected from 443
071f1c, call lasted 10 seconds
00:13:25: %LINK-3-UPDOWN: Interface Serial3/0:0, changed state to down

Configuration:
!RANCID-CONTENT-TYPE: cisco
!
!Chassis type: 3640 - a 3600 router
!CPU: R4700
!
!Memory: main 93184K/5120K
!Memory: nvram 125K
!Memory: flash partition 24576K
!Memory: flash partition 8192K
!
!Power: Redundant Power System is not present.
!
!Image: Software: C3640-IS-M, 12.2(13)T, RELEASE SOFTWARE (fc1)
!Image: Compiled: Fri 15-Nov-02 23:41 by ccai
!Image: flash:c3640-is-mz.122-13.T.bin
!
!ROM Bootstrap: Version 11.1(17)AA, EARLY DEPLOYMENT RELEASE SOFTWARE (fc2)
!
!
!Flash: System flash directory, partition 1:
!Flash: File Length Name/status
!Flash: 1 16705296 c3640-is-mz.122-13.T.bin
!Flash: [16705360 bytes used, 8460464 available, 25165824 total]
!Flash: 24576K bytes of processor board System flash (Read/Write)
!Flash: System flash directory, partition 2:
!Flash: File Length Name/status
!Flash: 1 468529 mica-modem-pw.2.9.4.0.bin
!Flash: [468596 bytes used, 7920012 available, 8388608 total]
!Flash: 8192K bytes of processor board System flash (Read/Write)
!
!Flash: nvram: Directory of nvram:/
!Flash: nvram: 121 -rw- 5503 <no date>
startup-config
!Flash: nvram: 122 ---- 27 <no date>
private-config
!Flash: nvram: 1 -rw- 0 <no date>
ifIndex-table
!Flash: nvram: 129016 bytes total (122410 bytes free)
!
!Interface: FastEthernet0/0, AMD Am79c971
!Interface: Ethernet1/0, AMD Unknown
!
!Slot 0: hvers 1.0 rev B0
!Slot 0: part 800-03490-01, serial 7719046
!
!Slot 1: type Combo 1E, 1R, 2W, 4 ports
!Slot 1: hvers 1.0 rev A0
!Slot 1: part 800-01223-02, serial 7858403
!
!Slot 2: type Digital Modems, 12 ports
!Slot 2: hvers 0.2 rev A0
!Slot 2: part 800-02316-03, serial 12886220
!
!Slot 3: type CE1 Balanced, 1 ports
!Slot 3: hvers 1.1 rev A0
!Slot 3: part 800-01234-04, serial 11306628
!
!VTP: VTP Version : 2
!VTP: Configuration Revision : 0
!VTP: Maximum VLANs supported locally : 256
!VTP: Number of existing VLANs : 5
!VTP: VTP Operating Mode : Server
!VTP: VTP Domain Name :
!VTP: VTP Pruning Mode : Disabled
!VTP: VTP V2 Mode : Disabled
!VTP: VTP Traps Generation : Disabled
!VTP: MD5 digest : 0xBF 0x86 0x94 0x45 0xFC 0xDF 0xB5
0x70
!VTP: Local updater ID is 192.168.1.181 on interface Fa0/0 (first interface
found)
!
!VLAN: % Ambiguous command: "show vlan"
!
!
config-register 0x101
This command has no effect on this line; use modem AT commands instead

!
config-register 0x101
version 12.2
service timestamps debug uptime
service timestamps log uptime
service password-encryption
!
hostname "ao-srv01-dia01"
!
logging buffered 4096 debugging
enable secret 5 <removed>
!
!username admin password <removed>
!username ao password <removed>
!username dialin password <removed>
modem country mica denmark
aaa new-model
!
!
aaa group server radius AO
!
aaa authentication login NO_AUTHEN local
aaa authentication ppp default group radius
aaa session-id common
ip subnet-zero
!
!
no ip dhcp conflict logging
ip dhcp excluded-address 192.168.187.1
ip dhcp excluded-address 192.168.187.254
!
ip dhcp pool 0
network 192.168.187.0 255.255.255.0
domain-name NTDOMAIN1
dns-server 192.168.1.15
netbios-name-server 192.168.1.15
netbios-node-type h-node
default-router 192.168.187.254
!
ip dhcp-server 192.168.187.254
virtual-profile virtual-template 1
multilink virtual-template 1
isdn switch-type primary-net5
!
!
!
!
!
!
!
!
!
!
!
mta receive maximum-recipients 0
partition flash 2 24 8
!
!
controller E1 3/0
pri-group timeslots 1-30
!
!
!
!
interface Loopback0
ip address 192.168.187.254 255.255.255.0
!
interface FastEthernet0/0
ip address 192.168.1.181 255.255.255.0
duplex auto
speed auto
!
interface Ethernet1/0
no ip address
shutdown
half-duplex
no cdp enable
!
interface TokenRing1/0
no ip address
shutdown
ring-speed 16
no cdp enable
!
interface Serial3/0:15
no ip address
encapsulation ppp
ip mroute-cache
dialer rotary-group 1
dialer-group 1
autodetect encapsulation ppp v120
isdn switch-type primary-net5
isdn incoming-voice modem
peer default ip address dhcp
no cdp enable
ppp authentication ms-chap-v2 chap pap ms-chap
ppp multilink
!
interface Virtual-Template1
ip unnumbered Loopback0
peer default ip address dhcp
ppp authentication ms-chap-v2 chap pap ms-chap
ppp multilink
!
interface Group-Async1
ip unnumbered Loopback0
encapsulation ppp
ip tcp header-compression
async mode dedicated
peer default ip address dhcp
no keepalive
ppp authentication ms-chap-v2 chap pap ms-chap
ppp multilink
group-range 65 76
!
interface Dialer1
ip unnumbered Loopback0
encapsulation ppp
dialer in-band
dialer idle-timeout 3600
dialer-group 1
peer default ip address dhcp
no cdp enable
ppp authentication ms-chap-v2 chap pap ms-chap
ppp multilink
!
ip classless
ip route 0.0.0.0 0.0.0.0 192.168.1.250
no ip http server
!
!
!
logging history debugging
logging source-interface Loopback0
logging 192.168.1.18
access-list 101 blah blah
access-list 102 blah blah
access-list 103 blah blah
access-list 104 blah blah
dialer-list 1 protocol ip permit
!
snmp-server community <skipped> RW
snmp-server community <skipped> RO
snmp-server location "AUDK M.P. Bruuns Gade 27, Serverrum 1"
snmp-server contact "Network Administrator @ AUDK +45 87 30 60 00"
snmp-server enable traps tty
radius-server host 192.168.1.26 auth-port 1645 acct-port 1646
!radius-server key <removed>
radius-server authorization permit missing Service-Type
call rsvp-sync
!
!
mgcp profile default
!
!
!
dial-peer cor custom
!
!
!
!
line con 0
login authentication NO_AUTHEN
line 65 76
flush-at-activation
modem InOut
autoselect during-login
autoselect ppp
line aux 0
line vty 0 4
! password <removed>
!
!
end


Regards
--
Regnar Bang Lyngsø, Network Administrator
Aarhus United Denmark
M.P. Bruuns Gade 27, DK-8100 Århus C, Denmark
Email: mailto:regnar.lyngso@aarhusunited.com
Phone: +45 87 30 61 65 Mobile: +45 40 45 08 89
Re: Problems with multilink PPP/ISDN [ In reply to ]
At 11:47 AM 1/9/2004 +0100, Regnar Bang Lyngsø wrote:
>Hi,
>
>I am experiencing problems that I can't understand.
>
>I have a Cisco 3600 with an ISDN PRI and I can't get ISDN-2 Multilink PPP
>(128K) to work and I really don't know why.
>
>Everything works fine with a single 64K ISDN channel. Also, multilink PPP
>with one ISDN channel and an analog modem connection works fine.
>
>Clients are various Windows Workstations with Lasat and Zyxel ISDN modems.
>
>Radius server is MS IAS with the following parameters set:
>Framed-Protocol: PPP
>Service-type: Framed
>Filter-Id: depending on profile
>
>The following is debug output (I would like to know what the "Ignoring bad
>ACK!" message means):

Each PPP Control Protocol packet has an ID associated with it, along with
the different options being requested; the response (ACK) to this packet
must have the same ID and the options can't be reordered or modified in
any way. If this is not the case, we will print out this message.

It typically indicates some sort of delay or processing error on the
part of the PPP peer.

>00:13:14: %LINK-3-UPDOWN: Interface Serial3/0:0, changed state to up
>00:13:15: %LINK-3-UPDOWN: Interface Serial3/0:1, changed state to up
>00:13:15: %ISDN-6-CONNECT: Interface Serial3/0:0 is now connected to 443
>00:13:17: Se3/0:0 LCP: Ignoring bad ACK!

<debug ppp neg> would indicate what's happening here, but I suspect
the clients are having issues.

>00:13:19: Se3/0:0 EVT: Packet suspended unexpectedly
>00:13:21: %ISDN-6-CONNECT: Interface Serial3/0:1 is now connected to 443
>00:13:22: Se3/0:0 LCP: Ignoring bad ACK!
>00:13:25: %ISDN-6-DISCONNECT: Interface Serial3/0:1 disconnected from 443
>, call lasted 10 seconds
>00:13:25: %LINK-3-UPDOWN: Interface Serial3/0:1, changed state to down
>00:13:25: %ISDN-6-DISCONNECT: Interface Serial3/0:0 disconnected from 443
>071f1c, call lasted 10 seconds
>00:13:25: %LINK-3-UPDOWN: Interface Serial3/0:0, changed state to down

>interface Serial3/0:15
> no ip address
> encapsulation ppp
> ip mroute-cache
> dialer rotary-group 1
> dialer-group 1
> autodetect encapsulation ppp v120
> isdn switch-type primary-net5
> isdn incoming-voice modem
> peer default ip address dhcp
> no cdp enable
> ppp authentication ms-chap-v2 chap pap ms-chap
> ppp multilink
>!
>interface Virtual-Template1
> ip unnumbered Loopback0
> peer default ip address dhcp
> ppp authentication ms-chap-v2 chap pap ms-chap
> ppp multilink
>!
>interface Dialer1
> ip unnumbered Loopback0
> encapsulation ppp
> dialer in-band
> dialer idle-timeout 3600
> dialer-group 1
> peer default ip address dhcp
> no cdp enable
> ppp authentication ms-chap-v2 chap pap ms-chap
> ppp multilink

Again, <debug ppp neg> would confirm what's going on with negotiations,
but I suspect you'll have to take a closer look at the ISDN modems.

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