Static Routes on the NE5000E Cannot Take Effect Due to the Iteration Depth

Publication Date:  2012-07-27 Views:  202 Downloads:  0
Issue Description
1. Networking: The NE5000E is connected to Router C through two upstream POS links.
loopback 222.83.16.19 loopback 202.97.32.243
NE5000E pos 1/0/0 (222.83.25.50)---------------------(.49) Router C
pos 9/0/0 (222.83.25.222)------------------(.221)
2. The NE5000E has established the EBGP neighbor relationship with the peer router.
<NE5000E>display bgp peer
BGP local router ID : 222.83.16.19
Local AS number : 65338
Total number of peers : 5 Peers in established state : 5
Peer V AS MsgRcvd MsgSent OutQ Up/Down State
202.97.32.243 4 4134 51037 24806 0 0171h03m Established
3. Two static routes are configured on the NE5000E.
ip route-static 202.97.32.243 255.255.255.255 Pos1/0/0 222.83.25.49
ip route-static 202.97.32.243 255.255.255.255 222.83.25.221
On the routing table, all the routes to Router C have the same next hop, POS 1/0/0.
<XJ-KS-28-A-1.163>dis ip rout
Routing Tables: Public
Destinations : 21160 Routes : 21176
Destination/Mask Proto Pre Cost NextHop Interface
0.0.0.0/0 BGP 100 0 202.97.32.243 Pos1/0/0
12.163.89.0/24 BGP 255 0 202.97.32.243 Pos1/0/0
12.163.90.0/23 BGP 255 0 202.97.32.243 Pos1/0/0
12.163.92.0/23 BGP 255 0 202.97.32.243 Pos1/0/0
12.163.94.0/24 BGP 255 0 202.97.32.243 Pos1/0/0
12.167.159.0/24 BGP 255 0 202.97.32.243 Pos1/0/0
24.96.0.0/17 BGP 255 0 202.97.32.243 Pos1/0/0 
 
Alarm Information
Null
Handling Process
 1. Configure the static routes as follows:
ip route-static 202.97.32.243 255.255.255.255 Pos1/0/0 222.83.25.49
ip route-static 202.97.32.243 255.255.255.255 Pos9/0/0 222.83.25.221 //Add an outbound interface.
Then all the routes to Router C in the routing table have two next hops as follows:
Destination/Mask Proto Pre Cost NextHop Interface
0.0.0.0/0 BGP 100 0 202.97.32.243 Pos1/0/0
BGP 100 0 202.97.32.243 Pos9/0/0
12.163.89.0/24 BGP 255 0 202.97.32.243 Pos1/0/0
BGP 255 0 202.97.32.243 Pos9/0/0
12.163.90.0/23 BGP 255 0 202.97.32.243 Pos1/0/0
BGP 255 0 202.97.32.243 Pos9/0/0
12.163.92.0/23 BGP 255 0 202.97.32.243 Pos1/0/0
BGP 255 0 202.97.32.243 Pos9/0/0
12.163.94.0/24 BGP 255 0 202.97.32.243 Pos1/0/0
BGP 255 0 202.97.32.243 Pos9/0/0
12.167.159.0/24 BGP 255 0 202.97.32.243 Pos1/0/0
BGP 255 0 202.97.32.243 Pos9/0/0
24.96.0.0/17 BGP 255 0 202.97.32.243 Pos1/0/0
BGP 255 0 202.97.32.243 Pos9/0/0
2. Cause analysis:
Configure two static routes on the NE5000E.
ip route-static 202.97.32.243 255.255.255.255 Pos1/0/0 222.83.25.49 //An outbound interface is specified for the static route and no iteration is required; therefore, the iteration depth is 0.
ip route-static 202.97.32.243 255.255.255.255 222.83.25.221//No outbound interface is specified for this static route and one iteration is required; therefore, the iteration depth is 1.
BGP then selects the static route with the smallest iteration depth for the next hop. Therefore, the outbound interface for BGP routes is POS 1/0/0.
3. Change the static routes as follows:
ip route-static 202.97.32.243 255.255.255.255 Pos1/0/0 222.83.25.49
ip route-static 202.97.32.243 255.255.255.255 Pos9/0/0 222.83.25.221 //An outbound interface is specified for the static route and no iteration is required; therefore, the iteration depth is 0.
BGP selects the static route with the smallest iteration depth for the next hop. Both the preceding static routes match the criteria, and therefore two outbound interfaces ― POS 1/0/0 and POS 9/0/0 ― are available. 
 
Root Cause
Static routes cannot take effect due to the iteration depth caused by configuration. 
Suggestions
Null

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