Reference Guide

510 | Intermediate System to Intermediate System
www.dell.com | support.dell.com
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.
Use this command the following command in ROUTER ISIS mode to set the overload bit manually.
Enter
no set-overload-bit to remove the overload bit.
When the bit is set, a 1 is placed in the OL column in the show isis database command output. In
Figure 26-9, 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
Figure 26-9. Command Example: show isis database
Debugging IS-IS
Enter the debug isis command in EXEC Privilege mode to debug all IS-IS processes.
Use the following commands for specific IS-IS debugging.
Command Syntax Command Mode Purpose
set-overload-bit
ROUTER ISIS Set the overload bit in LSPs. This prevents other routers from
using it as an intermediate hop in their shortest path first (SPF)
calculations.
Command Syntax Command Mode Purpose
debug isis
EXEC Privilege View all IS-IS information.
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
Dell.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
Dell.00-00 0x00000004 0xCDA9 1093 0/0/0
Dell#
when overload bit
is set, 1 is listed in
the OL column.