Setting the lsdb overload bit – H3C Technologies H3C S5560 Series Switches User Manual

Page 169

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Step Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter IS-IS view.

isis [ process-id ] [ vpn-instance
vpn-instance-name ]

N/A

3.

Configure the SPF
calculation interval.

timer spf maximum-interval
[ minimum-interval [ incremental-interval ] ]

By default:

The maximum interval is 5

seconds.

The minimum interval is 50

milliseconds.

The incremental interval is

200 milliseconds.

Configuring convergence priorities for specific routes

A topology change causes IS-IS routing convergence. To improve convergence speed, you can assign

convergence priorities to IS-IS routes. Convergence priority levels are critical, high, medium, and low. The

higher the convergence priority, the faster the convergence speed.
By default, IS-IS host routes have medium convergence priority, and other IS-IS routes have low

convergence priority.
To assign convergence priorities to specific IS-IS routes:

Step Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter IS-IS view.

isis [ process-id ] [ vpn-instance
vpn-instance-name ]

N/A

3.

Assign convergence priorities
to specific IS-IS routes.

priority { critical | high | medium }
{ prefix-list prefix-list-name | tag

tag-value }

By default, IS-IS routes, except IS-IS
host routes, have the low

convergence priority.

Setting the LSDB overload bit

By setting the overload bit in sent LSPs, a router informs other routers of failures that make it unable to

select routes and forward packets.
When an IS-IS router cannot record the complete LSDB, for example, because of memory insufficiency,
it will calculate wrong routes. To make troubleshooting easier, temporarily isolate the router from the IS-IS

network by setting the overload bit.
To set the LSDB overload bit:

Step Command

Remarks

1.

Enter system view.

system-view

N/A

2.

Enter IS-IS view.

isis [ process-id ] [ vpn-instance vpn-instance-name ]

N/A

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