[j-nsp] equal-cost, multi-next-hop static routes

[Nilesh Khambal]

Hi,

You should really do

"show route forwarding-table destination 69.165.166.240/28 detail|extensive"


"show route" only shows the RPD's (routing process) view of the route. 
Load balancing policy is applied when the routes are installed in the 
kernel forwarding-table (same as PFE forwarding-table). Only there you 
can see the 2 next-hops for the route.

The other problem of router using only one agg ethernet link while 
forwarding traffic is related to load balance hash calculation which in 
turn depends on the traffic type. If source/destination pairs are not 
varying much, router may not yield good hash values.

Another thing to add is, if you are using multiple agg ethernet links 
for load balancing, you might want to try this knob.

"set forwarding-options load-balance indexed-next-hop"

Depending upon the release this knob may or may not be hidden. This knob 
produces better hashing results for load balancing over multiple agg 
ethernet links.

Thanks,
Nilesh.

Joe Abley wrote:
> A router of my acquaintance in Toronto has:
> 
> jabley at agg01.tor-Switch> show version | grep Base
> JUNOS Base OS boot [8.5R4.3]
> JUNOS Base OS Software Suite [8.5R4.3]
> 
> jabley at agg01.tor-Switch>
> 
> and also
> 
> routing-options {
>      static {
>          route 69.165.166.240/28 next-hop [ 69.165.167.156  
> 69.165.167.20 ];
>      }
>      forwarding-table {
>          export load-balancing-policy;
>      }
> }
> policy-options {
>      policy-statement load-balancing-policy {
>          then {
>              load-balance per-packet;
>          }
>      }
> }
> 
> The idea is to do some crude load-sharing of outbound traffic from  
> this router towards 69.165.166.240/28. Both 69.165.167.156  
> 69.165.167.20 are reachable via interface/connected routes.
> 
> The router only ever seems to select one next-hop. Interface counters  
> elsewhere confirm that only one path is being used for traffic towards  
> the customer.
> 
> jabley at agg01.tor-Switch> show route 69.165.166.240/28 detail
> 
> inet.0: 326067 destinations, 886829 routes (325604 active, 70  
> holddown, 453765 hidden)
> 69.165.166.240/28 (1 entry, 1 announced)
>          *Static Preference: 5
>                  Next hop type: Router, Next hop index: 262255
>                  Next-hop reference count: 3
>                  Next hop: 69.165.167.20 via ae0.146
>                  Next hop: 69.165.167.156 via ae0.115, selected
>                  State: <Active Int Ext>
>                  Local AS:  5645
>                  Age: 4d 18:54:21
>                  Task: RT
>                  Announcement bits (4): 0-KRT 2-RT 5-BGP RT Background  
> 6-Resolve tree 1
>                  AS path: I
>                  AS path: Recorded
> 
> jabley at agg01.tor-Switch>
> 
> jabley at agg01.tor-Switch> show route 69.165.167.20 detail
> 
> inet.0: 326088 destinations, 886857 routes (325655 active, 47  
> holddown, 453807 hidden)
> 69.165.167.16/29 (1 entry, 1 announced)
>          *Direct Preference: 0
>                  Next hop type: Interface
>                  Next-hop reference count: 2
>                  Next hop: via ae0.146, selected
>                  State: <Active Int>
>                  Local AS:  5645
>                  Age: 4d 19:09:55
>                  Task: IF
>                  Announcement bits (3): 2-RT 5-BGP RT Background 6- 
> Resolve tree 1
>                  AS path: I
>                  AS path: Recorded
> 
> jabley at agg01.tor-Switch> show route 69.165.167.156 detail
> 
> inet.0: 326096 destinations, 886861 routes (325655 active, 55  
> holddown, 453813 hidden)
> 69.165.167.152/29 (1 entry, 1 announced)
>          *Direct Preference: 0
>                  Next hop type: Interface
>                  Next-hop reference count: 2
>                  Next hop: via ae0.115, selected
>                  State: <Active Int>
>                  Local AS:  5645
>                  Age: 4d 19:06:28
>                  Task: IF
>                  Announcement bits (3): 2-RT 5-BGP RT Background 6- 
> Resolve tree 1
>                  AS path: I
>                  AS path: Recorded
> 
> jabley at agg01.tor-Switch>
> 
> What am I missing?
> 
> 
> Joe
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