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ISR 4331 -> dialer stay's up but no IP traffic



I've a ISR 4331 running 15.5(3)S4b. Once in a while we loose the uplink connection. The dialer stays up but IP doesn't work anymore. Does anyone have a clue? I did search the bug database but found nothing.




4 Replies 4

Giuseppe Larosa
Hall of Fame
Hall of Fame

Hello @Peter Spekreijse (keps) ,

please post the configuration to see how you have configured DDR Dial on Demand Routing.


For new IOS releses the use of dialer watch and a watch-list is the recommended workaround.

With dialer watch the router checks the routing table to see if routes to be watched disappears.


In the classic DDR setup you use a floating static default route to trigger routing over the dialer interface.


ip route Dialer1 220

this acts as a backup default route to be used.

do the dialer interface get an IP address ?

show interface dialer x

when it is up provides you an IP address ?

if using PPP looks for state OPEN for IPCP



Hope to help





The relevant portion of the config follows:


interface Dialer1
  mtu 1492
  ip address negotiated
  no ip redirects
  no ip unreachables
  no ip proxy-arp
  encapsulation ppp
  dialer pool 1
  dialer-group 1
  ppp authentication pap callin
  ppp pap sent-username <removed> password <removed>
  no cdp enable
  ip virtual-reassembly


ip route Dialer1


dialer-list 1 protocol ip permit is the BGP  neighbor we get a default route from.


Now and then the IP connectivity over the dialer stops. We can't ping our BGP neighbor. A shut / no shut on the dialer solves the problem.


I think it's a bug. But how do I find it in the database?





Hello @Peter Spekreijse (keps) ,

I don't understand your network scenario.


1) The dialer interface is used as a backup path or it is your primary path because you have a PPPoE connection to the internet?


2) the BGP peer has a fixed IP address, normally BGP allows sessions with static IP address, is your dialer interface getting always the same IP addres from the provider ?


3) >> Now and then the IP connectivity over the dialer stops. We can't ping our BGP neighbor. A shut / no shut on the dialer solves the problem.


I agree this looks like a SW issue unless the session is timed out by the ISP when you shut/unshut a new PPP session is started.

Contact the ISP and ask about their policies for this kind of service.


Hope to help




Hi Giuseppe,


1. Its the primary connection. Its a private network. We've a 4G backup link.


2. We're always getting the same IP address from the provider (private space).


3. I already contacted the ISP.  No answers there.


Thanks for the reply.





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