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Ask All Knowledge Base Sites All Knowledge Base Sites JunosE Defect (KA)Knowledge BaseSecurity AdvisoriesTechnical BulletinsTechnotes Sign in to display secure content and recently viewed articles[EX] Hash-Table collision occurs even with lookup-length increased to 8
Hash-table collision failure occurs when hash buckets are full. Any mac that hash to an already full bucket causes collision. The existing work-around is to increase the mac-lookup length to 8 or 12. However, when increasing the lookup length to 8, which scans two consecutive buckets (4 entries each), and when the consecutive buckets are also full, hash-table collision is still observed.
Even though the ethernet-switching table capacity is not reached, continuous add/delete is seen happening for the mac:
Mon Sep 24 11:38:19 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:38:19 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:38:21 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:38:21 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:38:23 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0
Consider 4 MACs which hash to the same hash bucket index:
00:00:00:33:69:70 00:00:00:33:89:4c 00:00:00:33:b1:43 00:00:00:33:c1:5d
The four MACs are learned in the ethernet-switching-table and PFE:
root@bng-5konadev> show ethernet-switching table Ethernet-switching table: 6 entries, 4 learned, 0 persistent entries VLAN MAC address Type Age Interfaces vlan22 2c:21:72:8f:50:c1 Static - Router vlan100 * Flood - All-members vlan100 00:00:00:33:69:70 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:89:4c Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:b1:43 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:c1:5d Learn 0 ge-0/0/21.0
FDB table for VlanIdx: 6, VlanTag: 100, HwToken: 100
Legend: SP - Storm Prevention, V - Valid, s - Skip,
R - Refresh, S - Static, Vl - VlanId, Vx - Vidx
Dev Core HwTkn UCast-Mac/MCast-G;S Dest SP|V|s|R|S Cmd Rt Mir SId Dev QoS Sec Idx/Offset
--- ---- ----- --------------------- ------- ---------- --- -- --- --- --- --- --- ----------
0 0 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 1 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 2 100 00:00:00:33:69:70 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 3 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 0 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 1 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 2 100 00:00:00:33:89:4C 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 3 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 0 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 1 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 2 100 00:00:00:33:B1:43 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 3 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 0 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 1 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 2 100 00:00:00:33:C1:5D 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 3 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
All of these four macs are hashed to the same bucket 0x0000.
We tried to add a fifth MAC 00:00:00:22:45:ed which also hash to same bucket (0x0000).
We see that the fifth MAC 00:00:00:22:45:ed is continuously added / deleted from the logs:
Mon Sep 24 11:38:19 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:38:19 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:38:21 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:38:21 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:38:23 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:38:23 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:38:25 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:38:25 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0
Increase the lookup length to 8:
master:0}[edit]
root@bng-5konadev# set ethernet-switching-options mac-lookup-length 8
{master:0}[edit]
root@bng-5konadev# commit
configuration check succeeds
commit complete
The mac entry 00:00:00:22:45:ed was added:
[master:0][edit]
root@bng-5konadev# run show ethernet-switching table
Ethernet-switching table: 7 entries, 5 learned, 0 persistent entries
VLAN MAC address Type Age Interfaces
vlan22 2c:21:72:8f:50:c1 Static - Router
vlan100 * Flood - All-members
vlan100 00:00:00:22:45:ed Learn 0 ge-0/0/21.0 <-- 5th mac
vlan100 00:00:00:33:69:70 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:89:4c Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:b1:43 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:c1:5d Learn 0 ge-0/0/21.0
[master:0][edit]
% cprod -A fpc0 -c "show shim bridge fdb"
FDB table for VlanIdx: 6, VlanTag: 100, HwToken: 100
Legend: SP - Storm Prevention, V - Valid, s - Skip,
R - Refresh, S - Static, Vl - VlanId, Vx - Vidx
Dev Core HwTkn UCast-Mac/MCast-G;S Dest SP|V|s|R|S Cmd Rt Mir SId Dev QoS Sec Idx/Offset
--- ---- ----- --------------------- ------- ---------- --- -- --- --- --- --- --- ----------
0 0 100 00:00:00:22:45:ED 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 1 100 00:00:00:22:45:ED 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 2 100 00:00:00:22:45:ED 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 3 100 00:00:00:22:45:ED 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0 <--Was added in the subsequent bucket
0 0 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 1 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 2 100 00:00:00:33:69:70 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 3 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 0 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 1 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 2 100 00:00:00:33:89:4C 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 3 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 0 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 1 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 2 100 00:00:00:33:B1:43 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 3 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 0 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 1 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 2 100 00:00:00:33:C1:5D 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 3 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
Same test when the subsequent buckets are full.
Clearing ethernet-switching-table:
[master:0][edit]
root@bng-5konadev# run show ethernet-switching table
Ethernet-switching table: 2 entries, 0 learned, 0 persistent entries
VLAN MAC address Type Age Interfaces
vlan22 2c:21:72:8f:50:c1 Static - Router
vlan100 * Flood - All-members
[master:0][edit]
root@bng-5konadev# run show configuration ethernet-switching-options
inactive: traceoptions {
file eswd.log size 10m;
flag all;
}
mac-lookup-length 8;
mac-table-aging-time 60;
Sent streams with 8 MAC address, which will fill up 0x0000 and 0x0004 buckets:
[master:0][edit] root@bng-5konadev# run show ethernet-switching table Ethernet-switching table: 10 entries, 8 learned, 0 persistent entries VLAN MAC address Type Age Interfaces vlan22 2c:21:72:8f:50:c1 Static - Router vlan100 * Flood - All-members vlan100 00:00:00:33:3e:28 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:69:70 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:76:39 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:89:4c Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:96:05 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:ae:0a Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:b1:43 Learn 0 ge-0/0/21.0 vlan100 00:00:00:33:c1:5d Learn 0 ge-0/0/21.0
[master:0][edit]
FDB table for VlanIdx: 6, VlanTag: 100, HwToken: 100
Legend: SP - Storm Prevention, V - Valid, s - Skip,
R - Refresh, S - Static, Vl - VlanId, Vx - Vidx
Dev Core HwTkn UCast-Mac/MCast-G;S Dest SP|V|s|R|S Cmd Rt Mir SId Dev QoS Sec Idx/Offset
--- ---- ----- --------------------- ------- ---------- --- -- --- --- --- --- --- ----------
0 0 100 00:00:00:33:3E:28 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 1 100 00:00:00:33:3E:28 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 2 100 00:00:00:33:3E:28 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 3 100 00:00:00:33:3E:28 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 0 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 1 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 2 100 00:00:00:33:69:70 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 3 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 0 100 00:00:00:33:76:39 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 1 100 00:00:00:33:76:39 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 2 100 00:00:00:33:76:39 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 3 100 00:00:00:33:76:39 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 0 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 1 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 2 100 00:00:00:33:89:4C 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 3 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 0 100 00:00:00:33:96:05 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 1 100 00:00:00:33:96:05 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 2 100 00:00:00:33:96:05 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 3 100 00:00:00:33:96:05 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 0 100 00:00:00:33:AE:0A 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 1 100 00:00:00:33:AE:0A 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 2 100 00:00:00:33:AE:0A 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 3 100 00:00:00:33:AE:0A 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 0 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 1 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 2 100 00:00:00:33:B1:43 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 3 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 0 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 1 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 2 100 00:00:00:33:C1:5D 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 3 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
We see that the fifth MAC 00:00:00:22:45:ed is continuously added / deleted from the logs:
[master:0][edit] root@bng-5konadev# run show ethernet-switching mac-learning-log Mon Sep 24 11:53:08 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:53:08 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:53:10 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:53:10 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:53:12 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:53:12 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:53:14 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:53:14 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0 Mon Sep 24 11:53:16 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was learned on ge-0/0/21.0 Mon Sep 24 11:53:16 2018 vlan_name vlan100 mac 00:00:00:22:45:ed was deleted on ge-0/0/21.0
MAC 00:00:00:22:45:ed can't be added, as the adjacent buckets are full.
Attempted to increase mac lookup length to 12:
[master:0][edit] root@bng-5konadev# set ethernet-switching-options mac-lookup-length 12 [master:0][edit] root@bng-5konadev# commit configuration check succeeds commit complete
Mac addition for 00:00:00:22:45:ed is successful:
root@bng-5konadev# run show ethernet-switching table
Ethernet-switching table: 11 entries, 9 learned, 0 persistent entries
VLAN MAC address Type Age Interfaces
vlan22 2c:21:72:8f:50:c1 Static - Router
vlan100 * Flood - All-members
vlan100 00:00:00:22:45:ed Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:3e:28 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:69:70 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:76:39 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:89:4c Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:96:05 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:ae:0a Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:b1:43 Learn 0 ge-0/0/21.0
vlan100 00:00:00:33:c1:5d Learn 0 ge-0/0/21.0
[master:0][edit]
root@bng-5konadev#
FDB table for VlanIdx: 6, VlanTag: 100, HwToken: 100
Legend: SP - Storm Prevention, V - Valid, s - Skip,
R - Refresh, S - Static, Vl - VlanId, Vx - Vidx
Dev Core HwTkn UCast-Mac/MCast-G;S Dest SP|V|s|R|S Cmd Rt Mir SId Dev QoS Sec Idx/Offset
--- ---- ----- --------------------- ------- ---------- --- -- --- --- --- --- --- ----------
0 0 100 00:00:00:22:45:ED 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0008/0x0 <-- New bucket
0 1 100 00:00:00:22:45:ED 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0008/0x0
0 2 100 00:00:00:22:45:ED 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0008/0x0
0 3 100 00:00:00:22:45:ED 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0008/0x0
0 0 100 00:00:00:33:3E:28 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 1 100 00:00:00:33:3E:28 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 2 100 00:00:00:33:3E:28 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 3 100 00:00:00:33:3E:28 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x1
0 0 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 1 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 2 100 00:00:00:33:69:70 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 3 100 00:00:00:33:69:70 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x3
0 0 100 00:00:00:33:76:39 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 1 100 00:00:00:33:76:39 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 2 100 00:00:00:33:76:39 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 3 100 00:00:00:33:76:39 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x0
0 0 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 1 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 2 100 00:00:00:33:89:4C 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 3 100 00:00:00:33:89:4C 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x0
0 0 100 00:00:00:33:96:05 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 1 100 00:00:00:33:96:05 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 2 100 00:00:00:33:96:05 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 3 100 00:00:00:33:96:05 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x2
0 0 100 00:00:00:33:AE:0A 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 1 100 00:00:00:33:AE:0A 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 2 100 00:00:00:33:AE:0A 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 3 100 00:00:00:33:AE:0A 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0004/0x3
0 0 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 1 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 2 100 00:00:00:33:B1:43 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 3 100 00:00:00:33:B1:43 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x1
0 0 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 1 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 2 100 00:00:00:33:C1:5D 0/37 F|1|0|1|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
0 3 100 00:00:00:33:C1:5D 0/37 F|1|0|0|0 0|0 0 0 0 0 0|0 0|0 0x0000/0x2
It is possible that even when the mac lookup length was increased to 8, and the buckets are full, it would result in MAC not being able to get added.
In the above test, we did not see hash collision prints in PFE, but there is a collision occurring.
Increasing the mac lookup length to 8 does not guarantee non-collisions.
The reason we see this specific issue is because the major part of the mac address is the same 00:00:00:33. Hence, when the hashing is done, the macs are getting hashed to the same bucket.
This issue will not be seen if the macs are different.
This is as per Marvel design.
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