C819G-4G-VZ-K9 Verizon 4G LTE Flapping

[fdiedrich]

Hi there,

We try to use a Cisco 819G 4G LTE ISR with a Verizon sim card. The 819G should be the backup for an existing cable connection. We configured it and are able to ping to the internet from the 819G. If we now try to use the backup from the internal LAN, the connection starts to flap about every minute or even seconds. Attached is the log when flapping and the current config.

We assume the connection could be dropped by Verizon because of sending packets they don't like (referring to this document, page 3, 7.a., Document). Maybe someone can help to figure out how to reconfigure the 819G as we don't know what to do next.

Thank you

Florian

Log

*Jan 23 09:21:44: %CELLWAN-2-BEARER_UP: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now UP
*Jan 23 09:21:46: %LINK-3-UPDOWN: Interface Cellular0, changed state to up
*Jan 23 09:22:11: %CELLWAN-2-BEARER_DELETED: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now deleted.
*Jan 23 09:22:18: %LINK-3-UPDOWN: Interface Cellular0, changed state to down
*Jan 23 09:22:29: %CELLWAN-2-BEARER_UP: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now UP
*Jan 23 09:22:31: %LINK-3-UPDOWN: Interface Cellular0, changed state to up
*Jan 23 09:22:37: %CELLWAN-2-BEARER_DELETED: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now deleted.
*Jan 23 09:22:44: %LINK-3-UPDOWN: Interface Cellular0, changed state to down
*Jan 23 09:22:55: %CELLWAN-2-BEARER_UP: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now UP
*Jan 23 09:22:58: %LINK-3-UPDOWN: Interface Cellular0, changed state to up
*Jan 23 09:23:36: %CELLWAN-2-BEARER_DELETED: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now deleted.
*Jan 23 09:23:43: %LINK-3-UPDOWN: Interface Cellular0, changed state to down
*Jan 23 09:23:54: %CELLWAN-2-BEARER_UP: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now UP
*Jan 23 09:23:56: %LINK-3-UPDOWN: Interface Cellular0, changed state to up
*Jan 23 09:23:58: %CELLWAN-2-BEARER_DELETED: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now deleted.
*Jan 23 09:24:05: %LINK-3-UPDOWN: Interface Cellular0, changed state to down
*Jan 23 09:24:16: %CELLWAN-2-BEARER_UP: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now UP
*Jan 23 09:24:18: %LINK-3-UPDOWN: Interface Cellular0, changed state to up
*Jan 23 09:24:51: %CELLWAN-2-BEARER_DELETED: Instance id=0, Default bearer (bearer_id=6) in Cellular0 is now deleted.
*Jan 23 09:24:58: %LINK-3-UPDOWN: Interface Cellular0, changed state to down
...

Config

Current configuration : 5331 bytes
!
! Last configuration change at 10:08:30 EST Mon Jan 23 2017 by admin
!
version 15.5
service timestamps debug datetime msec
service timestamps log datetime localtime
no service password-encryption
!
hostname C819G4G
!
boot-start-marker
boot-end-marker
!
!
logging buffered 51200 warnings
!
no aaa new-model
ethernet lmi ce
clock timezone EST -5 0
clock summer-time EDT recurring
!
crypto pki trustpoint TP-self-signed-1113351855
 enrollment selfsigned
 subject-name cn=IOS-Self-Signed-Certificate-1113351855
 revocation-check none
 rsakeypair TP-self-signed-1113351855
!
!
crypto pki certificate chain TP-self-signed-1113351855
 certificate self-signed 01
 ...
 quit
!
!
!
!
!
!
!
!
!
!
!
!
!
!
!


!
!
!
!
no ip domain lookup
ip domain name ...
ip cef
no ipv6 cef
!
!
!
!
!
multilink bundle-name authenticated
!
!
chat-script lte "" "AT!CALL" TIMEOUT 20 "OK"
!
!
!
!
!
license udi pid C819G-4G-VZ-K9 sn ...
!
!
object-group network net-3.238-ltetransfer
 10.3.238.0 255.255.255.0
!
vtp mode client
username admin privilege 15 password 7 ...
!
!
!
!
!
controller Cellular 0
 lte modem link-recovery rssi onset-threshold -110
 lte modem link-recovery monitor-timer 20
 lte modem link-recovery wait-timer 10
 lte modem link-recovery debounce-count 6
no cdp run
!
!
!
!
!
!
!
!
!
!
!
!
interface Cellular0
 ip address negotiated
 ip nat outside
 ip virtual-reassembly in
 encapsulation slip
 dialer in-band
 dialer pool-member 1
 dialer-group 1
 async mode interactive
 routing dynamic
!
interface FastEthernet0
 switchport mode trunk
 no ip address
!
interface FastEthernet1
 description UPLINK to SWITCH
 switchport access vlan 238
 no ip address
!
interface FastEthernet2
 switchport mode trunk
 no ip address
!
interface FastEthernet3
 switchport mode trunk
 no ip address
!
interface GigabitEthernet0
 no ip address
 shutdown
 duplex auto
 speed auto
!
interface Serial0
 no ip address
 shutdown
 clock rate 2000000
!
interface Vlan1
 no ip address
!
interface Vlan238
 ip address 10.3.238.254 255.255.255.0
 ip nat inside
 ip virtual-reassembly in
!
interface Dialer1
 ip address negotiated
 ip nat outside
 ip virtual-reassembly in
 encapsulation slip
 dialer pool 1
 dialer idle-timeout 0
 dialer string lte
 dialer persistent
 dialer-group 1
!
ip forward-protocol nd
no ip http server
ip http access-class 23
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
!
!
ip dns server
ip nat inside source list nat-list interface Dialer1 overload
ip route 0.0.0.0 0.0.0.0 Dialer1
ip ssh version 2
!
ip access-list extended nat-list
 permit ip host 10.3.238.253 any
 deny ip any any
!
dialer-list 1 protocol ip permit
!
!
control-plane
!
!
!
mgcp behavior rsip-range tgcp-only
mgcp behavior comedia-role none
mgcp behavior comedia-check-media-src disable
mgcp behavior comedia-sdp-force disable
!
mgcp profile default
!
!
!
!
!
!
line con 0
 login local
 no modem enable
line aux 0
line 2
 no activation-character
 no exec
 transport preferred none
 transport input all
 stopbits 1
line 3
 script dialer lte
 modem InOut
 no exec
 rxspeed 100000000
 txspeed 50000000
line vty 0 4
 access-class 23 in
 privilege level 15
 login local
 transport input telnet ssh
line vty 5 15
 access-class 23 in
 privilege level 15
 login local
 transport input telnet ssh
!
scheduler allocate 20000 1000
ntp server 10.3.254.254
!
!
!
end

[Georg Pauwen]

Hello,

how is the 819 cellular backup triggered ? With the current configuration, the link would always be up.

What is your primary link and how is it connected to the 819 ?

[fdiedrich]

Hi Georg,

We use a Sophos UTM,  the cable uplink is the preferred one, if it fails/disconnects, the UTM switches to the 819G uplink automaticly. Switching to the other uplink works like a charm on the UTM, but as soon as traffic occurs on the 819G it starts to flap.

Regards

[Georg Pauwen · Accepted solution]

Hello,

I made a few changes to your config (marked in bold), give it a try and check if the link stops flapping.

I also took out the 'routing dynamic' from the cellular interface.

Current configuration : 5331 bytes
!
! Last configuration change at 10:08:30 EST Mon Jan 23 2017 by admin
!
version 15.5
service timestamps debug datetime msec
service timestamps log datetime localtime
no service password-encryption
!
hostname C819G4G
!
boot-start-marker
boot-end-marker
!
logging buffered 51200 warnings
!
no aaa new-model
ethernet lmi ce
clock timezone EST -5 0
clock summer-time EDT recurring
!
crypto pki trustpoint TP-self-signed-1113351855
enrollment selfsigned
subject-name cn=IOS-Self-Signed-Certificate-1113351855
revocation-check none
rsakeypair TP-self-signed-1113351855
!
crypto pki certificate chain TP-self-signed-1113351855
certificate self-signed 01
...
quit
!
no ip domain lookup
ip domain name ...
ip cef
no ipv6 cef
!
multilink bundle-name authenticated
!
chat-script lte "" "AT!CALL" TIMEOUT 20 "OK"
!
license udi pid C819G-4G-VZ-K9 sn ...
!
object-group network net-3.238-ltetransfer
10.3.238.0 255.255.255.0
!
vtp mode client
username admin privilege 15 password 7 ...
!
controller Cellular 0
lte modem link-recovery rssi onset-threshold -110
lte modem link-recovery monitor-timer 20
lte modem link-recovery wait-timer 10
lte modem link-recovery debounce-count 6
no cdp run
!
interface Cellular0
ip address negotiated
ip nat outside
ip virtual-reassembly in
encapsulation slip
dialer in-band
dialer pool-member 1
dialer-group 1
async mode interactive
!
interface FastEthernet0
switchport mode trunk
no ip address
!
interface FastEthernet1
description UPLINK to SWITCH
switchport access vlan 238
no ip address
!
interface FastEthernet2
switchport mode trunk
no ip address
!
interface FastEthernet3
switchport mode trunk
no ip address
!
interface GigabitEthernet0
no ip address
shutdown
duplex auto
speed auto
!
interface Serial0
no ip address
shutdown
clock rate 2000000
!
interface Vlan1
no ip address
!
interface Vlan238
ip address 10.3.238.254 255.255.255.0
ip nat inside
ip virtual-reassembly in
!
interface Dialer1
ip address negotiated
ip nat outside
ip virtual-reassembly in
encapsulation slip
dialer pool 1
dialer idle-timeout 0
dialer string lte
dialer persistent
dialer-group 1
!
ip forward-protocol nd
no ip http server
ip http access-class 23
ip http authentication local
ip http secure-server
ip http timeout-policy idle 60 life 86400 requests 10000
!
ip dns server
ip nat inside source route-map BACKUP interface Dialer1 overload
ip route 0.0.0.0 0.0.0.0 Dialer1
ip ssh version 2
!
access-list 1 permit 10.3.238.0 0.0.0.255
!
dialer-list 1 protocol ip permit
!
route-map BACKUP permit 10
match ip address 1
match interface Dialer1
!
control-plane
!
mgcp behavior rsip-range tgcp-only
mgcp behavior comedia-role none
mgcp behavior comedia-check-media-src disable
mgcp behavior comedia-sdp-force disable
!
mgcp profile default
!
line con 0
login local
no modem enable
line aux 0
line 2
no activation-character
no exec
transport preferred none
transport input all
stopbits 1
line 3
script dialer lte
modem InOut
no exec
rxspeed 100000000
txspeed 50000000
line vty 0 4
access-class 23 in
privilege level 15
login local
transport input telnet ssh
line vty 5 15
access-class 23 in
privilege level 15
login local
transport input telnet ssh
!
scheduler allocate 20000 1000
ntp server 10.3.254.254
!
end

[fdiedrich]

Thank you for your help, I'll reconfigure the 819G with your suggested lines. As I configure it remotely, it will need some time to test it again.

Anyhow, I'll let you know the result as soon as possible.

Regards

[fdiedrich]

We did a test last friday and it seemed like it fixed our issues. A stable connection was established for over 15 minutes.

Again, thank you for your help!

[Rami Al Helou]

you can try this command under Interface cellular0:
(config-if)# dialer idle-timeout 0

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