Fix on howto increase the number of IPv6 (BGP) route entries in HW LPM

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Create Date: Mar 10 2013 1:44PM

Hi, 

As some of you may have seen, the current IPv6 BGP Tablesize is growing quickly currently. 

That might give messages in your LOG on the switch stating that it can't download a route into HW LPM. ( HW LPM table full ) 

In the latest 15.2.2.7 releases (and up), there is a fix to make a change in the distribution of the current hw entries between IPv4 and IPv6 L3 entries. 


The command : configure forwarding external-tables l3-only ipv4-and-ipv6  (*reboot required to activate) 


This will provide more room for IPv6 prefixes (upto 47.5k routes) by lowering the IPv4 HW LPM to 475k entries. 

To state the obvious, you should always have both IPv4 and IPv6 route compression enabled.  

enable iproute ipv4 compression

enable iproute ipv6 compression

This will result in a similar route stat (If you have both IPv4 and IPv6 running on BGP on an X480)

sho iproute reserved-entries statistics

                       |-----In HW Route Table----|   |--In HW L3 Hash Table--|

                       # Used Routes   # IPv4 Hosts   IPv4   IPv4   IPv6  IPv4

Slot  Type              IPv4   IPv6    Local Remote   Local  Rem.   Loc.  MCast

----  ---------------- ------ ------  ------ ------   -----  -----  ----  -----

1     X480-24x         242489   5794>     41      0       0      0     4     22

sho iproute summary

=================ROUTE SUMMARY=================

Mask distribution:

       2 default routes               17 routes at length  8

      13 routes at length  9          29 routes at length 10

      88 routes at length 11         247 routes at length 12

     481 routes at length 13         863 routes at length 14

    1554 routes at length 15       12517 routes at length 16

    6568 routes at length 17       10920 routes at length 18

   21563 routes at length 19       31024 routes at length 20

   33172 routes at length 21       45101 routes at length 22

   40705 routes at length 23      231077 routes at length 24

      81 routes at length 25          75 routes at length 26

      74 routes at length 27          85 routes at length 28

      75 routes at length 29         158 routes at length 30

     159 routes at length 32

Route origin distribution:

436181 IBGP          450  OSPFExt1      1    OSPFInter 

8    OSPFIntra     2    Blackhole     3    Static    

3    Direct       

Total number of routes = 436648

Total number of compressed routes = 194052



For IPv6:  



sho bgp rou address-family ipv6-unicast summary

Flags: (*) Preferred BGP route, (>) Active, (d) Suppressed, (h) History

       (s) Stale, (m) Multipath, (u) Unfeasible

Origin: (?) Incomplete, (e) EGP, (i) IGP

BGP Route Statistics

  Total Rxed Routes : 11667

  Feasible Routes   : 11667

  Active Routes     : 11667

  Rejected Routes   : 0

  Unfeasible Routes : 0

  Advertised Routes : 5

Route Statistics on Session Type

  Routes from Int Peer: 0

  Routes from Ext Peer: 11667

For IPv4 : 
sho bgp rou sum

Flags: (*) Preferred BGP route, (>) Active, (d) Suppressed, (h) History

       (s) Stale, (m) Multipath, (u) Unfeasible

Origin: (?) Incomplete, (e) EGP, (i) IGP

BGP Route Statistics

  Total Rxed Routes : 489325

  Feasible Routes   : 489325

  Active Routes     : 436125

  Rejected Routes   : 0

  Unfeasible Routes : 0

  Advertised Routes : 48

Route Statistics on Session Type

  Routes from Int Peer: 489325

  Routes from Ext Peer: 0 

GL,
Erik Bais
A2B Internet 

(from Erik_Bais)
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Posted 4 years ago

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Create Date: Mar 11 2013 12:07AM

Pretty cool - I hadn't seen that in the release notes, great find! Thanks!

(from Ansley_Barnes)

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