6513 Sup720 & load sharing per-destination CEF

Unanswered Question
Mar 21st, 2008

I read that per-destination load-sharing via CEF is enabled by default on the Sup720.

I have a few equal-cost static routes and figured that per-destination load-sharing would take place over the equal-cost routes However, when I run the command 'show ip cef 192.168.133.0', There's no mention of load-sharing in the output. Is there something else that needs to be configured ?

Thanks for your help.

Mike

NWQ6513#sh ip cef 192.168.133.254

192.168.133.0/24, version 12849, epoch 0

0 packets, 0 bytes

Flow: AS 0, mask 24

via 172.25.0.3, 0 dependencies, recursive

traffic share 1

next hop 172.25.0.3, Vlan901 via 172.25.0.3/32

valid adjacency

via 172.25.0.5, 0 dependencies, recursive

traffic share 1

next hop 172.25.0.5, Vlan901 via 172.25.0.5/32

valid adjacency

0 packets, 0 bytes switched through the prefix

tmstats: external 0 packets, 0 bytes

internal 0 packets, 0 bytes

NWQ6513#sh ip route 192.168.133.0

Routing entry for 192.168.133.0/24

Known via "static", distance 1, metric 0

Routing Descriptor Blocks:

* 172.25.0.3

Route metric is 0, traffic share count is 1

172.25.0.5

Route metric is 0, traffic share count is 1

NWQ6513#sh ip arp 172.25.0.3

Protocol Address Age (min) Hardware Addr Type Interface

Internet 172.25.0.3 42 001b.d494.cb30 ARPA Vlan901

NWQ6513#sh ip arp 172.25.0.5

Protocol Address Age (min) Hardware Addr Type Interface

Internet 172.25.0.5 42 001b.d4a9.d650 ARPA Vlan901

NWQ6513#sh ip cef detail

IP Distributed CEF with switching (Table Version 12850), flags=0x0

841 routes, 0 reresolve, 0 unresolved (0 old, 0 new), peak 44

71 instant recursive resolutions, 0 used background process

841 leaves, 108 nodes, 226808 bytes, 12862 inserts, 12021 invalidations

2 load sharing elements, 672 bytes, 2 references

universal per-destination load sharing algorithm, id FDDB7516

3(0) CEF resets, 2 revisions of existing leaves

Resolution Timer: Exponential (currently 1s, peak 2s)

0 in-place/0 aborted modifications

refcounts: 29479 leaf, 27904 node

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Edison Ortiz Sat, 03/22/2008 - 09:09

It is load-sharing as both next-hops are listed in CEF and the IP Route output.

__

Edison.

msrohman Sat, 03/22/2008 - 11:12

Thanks Edison, I appreciate your input.

I just thought that the output of the command would specifically state that the network traffic was getting load balanced via per destination.

-MIke

Edison Ortiz Sat, 03/22/2008 - 11:43

Hi Mike,

It does. Look at the show ip cef detail output more closely.

NWQ6513#sh ip cef detail

IP Distributed CEF with switching (Table Version 12850), flags=0x0

841 routes, 0 reresolve, 0 unresolved (0 old, 0 new), peak 44

71 instant recursive resolutions, 0 used background process

841 leaves, 108 nodes, 226808 bytes, 12862 inserts, 12021 invalidations

2 load sharing elements, 672 bytes, 2 references

universal per-destination load sharing algorithm, id FDDB7516

3(0) CEF resets, 2 revisions of existing leaves

Resolution Timer: Exponential (currently 1s, peak 2s)

0 in-place/0 aborted modifications

refcounts: 29479 leaf, 27904 node

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