Configuring the Hash Algorithm Seed
Deterministic ECMP sorts ECMPs in order even though RTM provides them in a random order. However, the hash algorithm uses as a seed
the lower 12 bits of the chassis MAC, which yields a different hash result for every chassis.
This behavior means that for a given flow, even though the prefixes are sorted, two unrelated chassis can select different hops.
Dell Networking OS provides a command line interface (CLI)-based solution for modifying the hash seed to ensure that on each configured
system, the ECMP selection is same. When configured, the same seed is set for ECMP, LAG, and NH, and is used for incoming traffic only.
NOTE:
While the seed is stored separately on each port-pipe, the same seed is used across all CAMs.
NOTE:
You cannot separate LAG and ECMP, but you can use different algorithms across the chassis with the same seed. If LAG
member ports span multiple port-pipes and line cards, set the seed to the same value on each port-pipe to achieve deterministic
behavior.
NOTE:
If you remove the hash algorithm configuration, the hash seed does not return to the original factory default
setting.
To configure the hash algorithm seed, use the following command.
•
Specify the hash algorithm seed.
CONFIGURATION mode.
hash-algorithm seed
value
[stack—unit
stack—unit-number
] [port-set
number
]
The range is from 0 to 4095.
Link Bundle Monitoring
Link bundle monitoring allows the system to monitor the use of multiple links for an uneven distribution.
Monitoring linked ECMP bundles allows traffic distribution amounts in a link to be monitored for unfair distribution at any given time. A
global default threshold of 60% is Link bundle monitoring allows the system to monitor the use of multiple links for an uneven distribution. .
Links are monitored in 15-second intervals for three consecutive instances. Any deviation within that time causes a syslog to be sent and an
alarm event generate. When the deviation clears, another syslog is sent and a clear alarm event generates. For example, link bundle
monitoring percent threshold:
%STKUNIT0-M:CP %IFMGR-5-BUNDLE_UNEVEN_DISTRIBUTION: Found uneven
distribution in LAG bundle 11.
Link bundle utilization is calculated as the total bandwidth of all links divided by the total bytes-per-second of all links. Within each ECMP
group, you can specify interfaces. If you enable monitoring for the ECMP group, utilization calculation performs when the utilization of the
link-bundle (not a link within a bundle) exceeds 60%.
Enable link bundle monitoring using the
ecmp-group
command.
NOTE:
An ecmp-group index is generated automatically for each unique ecmp-group when you configure multipath routes to the
same network. The system can generate a maximum of 512 unique ecmp-groups. The ecmp-group indexes are generated in even
numbers (0, 2, 4, 6... 1022) and are for information only.
For link bundle monitoring with ECMP, to enable the link bundle monitoring feature, use the
ecmp-group
command. In the following
example, the ecmp-group with id 2, enabled for link bundle monitoring is user configured. This is different from the ecmp-group index 2 that
is created by configuring routes and is automatically generated.
These two ecmp-groups are not related in any way.
Example of Viewing Link Bundle Monitoring
Dell# show link-bundle-distribution ecmp-group 1
Link-bundle trigger threshold - 60
ECMP bundle - 1 Utilization[In Percent] - 44 Alarm State - Active
Equal Cost Multi-Path (ECMP)
265
Содержание S3048-ON
Страница 1: ...Dell Configuration Guide for the S3048 ON System 9 11 2 5 ...
Страница 137: ...0 Gi 1 1 Gi 1 2 rx Flow N A N A 0 0 No N A N A yes Access Control Lists ACLs 137 ...
Страница 142: ...Figure 10 BFD Three Way Handshake State Changes 142 Bidirectional Forwarding Detection BFD ...
Страница 241: ...Dell Control Plane Policing CoPP 241 ...
Страница 287: ... RPM Synchronization GARP VLAN Registration Protocol GVRP 287 ...
Страница 428: ...Figure 53 Inspecting the LAG Configuration 428 Link Aggregation Control Protocol LACP ...
Страница 429: ...Figure 54 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 429 ...
Страница 432: ...Figure 56 Inspecting a LAG Port on BRAVO Using the show interface Command 432 Link Aggregation Control Protocol LACP ...
Страница 433: ...Figure 57 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 433 ...
Страница 477: ...Figure 73 Configuring Interfaces for MSDP Multicast Source Discovery Protocol MSDP 477 ...
Страница 478: ...Figure 74 Configuring OSPF and BGP for MSDP 478 Multicast Source Discovery Protocol MSDP ...
Страница 479: ...Figure 75 Configuring PIM in Multiple Routing Domains Multicast Source Discovery Protocol MSDP 479 ...
Страница 483: ...Figure 77 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 483 ...
Страница 484: ...Figure 78 MSDP Default Peer Scenario 3 484 Multicast Source Discovery Protocol MSDP ...
Страница 634: ...protocol spanning tree pvst no disable vlan 300 bridge priority 4096 634 Per VLAN Spanning Tree Plus PVST ...
Страница 745: ...Figure 104 Single and Double Tag TPID Match Service Provider Bridging 745 ...
Страница 746: ...Figure 105 Single and Double Tag First byte TPID Match 746 Service Provider Bridging ...