Dell S4820T, Configuration Manual

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Setting the Overload Bit
Another use for the overload bit is to prevent other routers from using this router as an intermediate hop
in their shortest path first (SPF) calculations. For example, if the IS-IS routing database is out of memory
and cannot accept new LSPs, Dell Networking OS sets the overload bit and IS-IS traffic continues to
transit the system.
To set or remove the overload bit manually, use the following commands.
• Set the overload bit in LSPs.
ROUTER ISIS mode
set-overload-bit
This setting prevents other routers from using it as an intermediate hop in their shortest path first (SPF)
calculations.
• Remove the overload bit.
ROUTER ISIS mode
no set-overload-bit
Example of Viewing the Overload Bit Setting
When the bit is set, a 1 is placed in the OL column in the
show isis database
command output. The
overload bit is set in both the Level-1 and Level-2 database because the IS type for the router is
Level-1-2.
Dell#show isis database
IS-IS Level-1 Link State Database
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/ OL
B233.00-00 0x00000003 0x07BF 1074 0/0/0
eljefe.00-00 * 0x0000000A 0xF963 1196 0/0/ 1
eljefe.01-00 * 0x00000001 0x68DF 1108 0/0/0
eljefe.02-00 * 0x00000001 0x2E7F 1099 0/0/0
Force10.00-00 0x00000002 0xD1A7 1088 0/0/0
IS-IS Level-2 Link State Database
LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/ OL
B233.00-00 0x00000006 0xC38A 1110 0/0/0
eljefe.00-00 * 0x0000000E 0x53BF 1196 0/0/ 1
eljefe.01-00 * 0x00000001 0x68DF 1108 0/0/0
eljefe.02-00 * 0x00000001 0x2E7F 1099 0/0/0
Force10.00-00 0x00000004 0xCDA9 1093 0/0/0
Dell#
Debugging IS-IS
To debug IS-IS processes, use the following commands.
• View all IS-IS information.
EXEC Privilege mode
debug isis
• View information on all adjacency-related activity (for example, hello packets that are sent and
received).
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Intermediate System to Intermediate System