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VSP 4850 - VOSS switch is receiving BGP default route information but not placing it in the routing table

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TitleVSP 4850 - VOSS switch is receiving BGP default route information but not placing it in the routing table
Symptoms
The core switch (VSP 4850 : v.5.1.1.3.0) which links to WAN and firewall is not populating the route table with default route, even though the routes seen as advertised via the firewall. Also, the same switch is not advertising all routes out to other downstream devices, including route to DNS server or default route for internal VLAN networks. Symptoms reported were no DNS, no ability for users to get to external sites - due to routes not populating from the device to other network devices. In order to mitigate this problem customer added static routes for the default route.

 
Environment
  • VOSS - version 5.1.1.3.0
Cause
The software running on the switch is quite old (v5.1.1.3.0) and there are known issue(s) - sometimes routes that learned from BGP are not reflected in RTM (Routing Manager) - with versions prior VOSS 6.0.
Resolution
Upgrade to one of supported streams  -  higher than v6.0. As requested customer has upgraded their switch to version 7.1.4.0 and the issue has been resolved.
Additional notes
In case the issue manifest the following data collection plan can be executed while the issue is happening before opening case to GTAC :
  • "show fulltech"
  • "show ip route vrfids 1-511"
  • "show io l2-tables"
  • "show io l3-tables
  • in addition BGP related traces could be activated : within the ‘router bgp’ option, BGP event debugging could be enabled with command ‘neighbor <x.x.x.x> neighbor-debug-mask event enable’ and also enable printing to the telnet/SSH session with command ‘debug-screen on’ (‘debug-screen off’ disables this again). There are further debug options such as  ‘none,all,error,packet,event,trace,warning,state,init,filter,update’ but better to start with ‘event’ to see what is captured as regards a potential problem peer with the ‘event’ flag first (the ‘no neighbor <x.x.x.x> neighbor-debug-mask’ format should disable the debug again).

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