Re: [c-nsp] Why only 10 has buckets?

Sat, 16 May 2015 18:45:49 -0700

There are 16 buckets on the sup720, i am not positive about the sup2t. If you were to go over 16 paths it would cut them in half (like using 10 buckets for 20 paths) because that's how it has to assign it in the hardware.
The hardware is limited to using (i believe) a maximum of 16 paths per prefix 'route' so anything over 16 would be pointless. I think some of the newer hardware has been changed to 32 or 64 but as far as I know the s720 and most likely the s2t is limited to 16 (and it is i just edited my email lol) 

Browsing a sup2t white paper while typing this out.. I see:

Load sharing at the FIB levels occurs when a single prefix possesses 
multiple adjacencies. This is usually achieved by using multiple equal 
cost paths to the destination. This situation is highly desirable for 
redundancy purposes. The Supervisor 2T is capable of load-balancing 
traffic for up to 16 paths for each single prefix (IPv4 or IPv6). Load 
balancing is performed on a per-flow basis and the following 
configuration can be used to program the load-balancing hash:



So I suppose the new question is, why when using more than 16 paths does 
it cut it in half instead of using the first 16 and using the remaining 
as backups in case one of the 16 are deleted..


My suggestion would be to use 16 and no more per destination prefix



On 5/15/2015 6:02 PM, Peter Kranz wrote:

C6506-E running Sup2T.. I was under the impression there were more than 10
hash buckets available? I can't seem to generate anycast load balancing over
10 destinations.. Here is an example with 20 paths where CEF only inserts
10..


  


rtr-sungard#sho ip cef 208.76.31.254 internal

208.76.31.254/32, epoch 8, flags rib only nolabel, rib defined all labels,
RIB[B], refcount 6, per-destination sharing

   sources: RIB, Adj

   feature space:

    Broker: linked

    NetFlow: Origin AS 65009, Peer AS 0, Mask Bits 0

    IPRM: 0x00018000

   subblocks:

    Adj source: IP adj out of Vlan10, addr 208.76.31.254 2C4D49E0

     Dependent covered prefix type adjfib cover 208.76.31.0/24

   ifnums:

    Vlan10(20): 162.244.60.50, 162.244.60.51, 162.244.60.52, 162.244.60.53

                162.244.60.54, 162.244.60.55, 162.244.60.56, 162.244.60.57

                162.244.60.58, 162.244.60.59, 162.244.60.60, 162.244.60.61

                162.244.60.62, 162.244.60.63, 162.244.60.64, 162.244.60.65

                162.244.60.66, 162.244.60.67, 162.244.60.68, 162.244.60.69

   path 675395F4, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.50[IPv4:Default], fib 6C189DF4, 1 terminal fib

     path 6753A644, path list 27D808D8, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.50
2C4D5880

   path 67539A7C, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.51[IPv4:Default], fib 6C184B44, 1 terminal fib

     path 67539254, path list 27D80390, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.51
2C4D5A20

   path 675398AC, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.52[IPv4:Default], fib 5C1EC38C, 1 terminal fib

     path 6753B280, path list 27D807A0, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.52
2C4D5BC0

   path 67539F04, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.53[IPv4:Default], fib 5C1EC23C, 1 terminal fib

     path 6753A400, path list 27D809A8, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.53
2C4D5D60

   path 67538C70, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.54[IPv4:Default], fib 2B7C0DCC, 1 terminal fib

     path 6753A970, path list 27D80B48, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.54
2C4D5F00

   path 675391E0, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.55[IPv4:Default], fib 2AD09878, 1 terminal fib

     path 6753A888, path list 27D80D50, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.55
2C4D60A0

   path 675397C4, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.56[IPv4:Default], fib 5F228B64, 1 terminal fib

     path 6753A1BC, path list 27D80EF0, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.56
2C4D6240

   path 67539B64, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.57[IPv4:Default], fib 1D623CC8, 1 terminal fib

     path 6753A4E8, path list 27D80C18, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.57
2C4D63E0

   path 6753A318, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.58[IPv4:Default], fib 5837CE50, 1 terminal fib

     path 6753AA58, path list 27D80AE0, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.58
2C4D7420

   path 6753933C, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.59[IPv4:Default], fib 1BD00500, 1 terminal fib

     path 6753AD84, path list 27D80600, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.59
2C4D6580

   path 675390F8, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.60[IPv4:Default], fib 243196A4, 1 terminal fib

     path 53BC20CC, path list 14C36BD0, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.60
2C4D6720

   path 6753AD10, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.61[IPv4:Default], fib 6C187A84, 1 terminal fib

     path 67539CC0, path list 27D80DB8, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.61
2C4D56E0

   path 6753A230, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.62[IPv4:Default], fib 5D3616C8, 1 terminal fib

     path 6753AB40, path list 27D80CE8, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.62
2C4D5540

   path 6753A2A4, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.63[IPv4:Default], fib 6306FA24, 1 terminal fib

     path 6753A55C, path list 27D80A10, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.63
2C4D53A0

   path 67539FEC, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.64[IPv4:Default], fib 1F8877F0, 1 terminal fib

     path 6753ADF8, path list 27D80940, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.64
2C4D5200

   path 6753B4C4, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.65[IPv4:Default], fib 58D55638, 1 terminal fib

     path 6753A9E4, path list 27D80668, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.65
2C4D5060

   path 6753B9C0, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.66[IPv4:Default], fib 5D3694C8, 1 terminal fib

     path 6753A6B8, path list 27D80FC0, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.66
2C4D4EC0

   path 28011AAC, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.67[IPv4:Default], fib 1DFD3BD8, 1 terminal fib

     path 6753B694, path list 27D80188, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.67
2C4D4D20

   path 28010DFC, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.68[IPv4:Default], fib 6C18A1E4, 1 terminal fib

     path 675393B0, path list 27D80120, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.68
2C4D4B80

   path 28011B20, path list 27D7F6F8, share 1/1, type recursive nexthop, for
IPv4, flags resolved

   recursive via 162.244.60.69[IPv4:Default], fib 22BAB6E8, 1 terminal fib

     path 67539920, path list 27D80E20, share 1/1, type adjacency prefix, for
IPv4

     attached to Vlan10, adjacency IP adj out of Vlan10, addr 162.244.60.69
2C4D4840

   output chain:

     loadinfo 53BB6B24, per-session, 10 choices, flags 0003, 5 locks

     flags: Per-session, for-rx-IPv4

     10 hash buckets

       < 0 > IP adj out of Vlan10, addr 162.244.60.50 2C4D5880

       < 1 > IP adj out of Vlan10, addr 162.244.60.51 2C4D5A20

       < 2 > IP adj out of Vlan10, addr 162.244.60.52 2C4D5BC0

       < 3 > IP adj out of Vlan10, addr 162.244.60.53 2C4D5D60

       < 4 > IP adj out of Vlan10, addr 162.244.60.54 2C4D5F00

       < 5 > IP adj out of Vlan10, addr 162.244.60.55 2C4D60A0

       < 6 > IP adj out of Vlan10, addr 162.244.60.56 2C4D6240

       < 7 > IP adj out of Vlan10, addr 162.244.60.57 2C4D63E0

       < 8 > IP adj out of Vlan10, addr 162.244.60.58 2C4D7420

       < 9 > IP adj out of Vlan10, addr 162.244.60.59 2C4D6580

     Subblocks:

      None


  


Peter Kranz
www.UnwiredLtd.com <http://www.unwiredltd.com/>
Desk: 510-868-1614 x100
Mobile: 510-207-0000
[email protected] <mailto:[email protected]>


  


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