HP VPN Firewall Appliances Network Management Configuration Guide

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Limiting LSP flooding
In NBMA networks such as ATM, FR, many P2P links exist. As shown in Figure 279, Router A, Router B,
Router C and Router D run IS-IS. When Router A generates an LSP, it floods the LSP out of Ethernet 1/1,
Ethernet 1/2 and Ethernet 1/3. After Router D receives the LSP from Ethernet 1/3, Router D floods it out
of Ethernet 1/1 and Ethernet 1/2 to Router B and Router C. However, Router B and Router C have
already received the LSP from Router A. Repeated LSP flooding consumes extra bandwidth.
Figure 279 Network diagram of a fully meshed network
To avoid this problem, you can add some interfaces to a mesh group or block some interfaces.
• An interface in a mesh group floods a received LSP only to interfaces not in the mesh group.
• A blocked interface sends LSPs only after receiving LSP requests.
Before you configure this task, you must consider redundancy for interfaces in case that LSP packets
cannot be flooded due to link failures.
To add an interface into a mesh group and block an interface:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter interface view.
interface interface-type
interface-number
N/A
3. Add the interface to a mesh
group or block the interface.
• Add the interface to a mesh
group:
isis mesh-group
mesh-group-number
• Block the interface:
isis mesh-group mesh-blocked
Use either method.
By default, the interface neither
belongs to any mesh group nor is it
blocked.
The mesh group feature takes effect
only on P2P interfaces.
Configuring SPF parameters
When the LSDB changes on a router, a route calculation starts. Frequent route calculations consume a lot
of system resources. You can set an appropriate interval for SPF calculations to improve efficiency.
To configure the SPF parameters:
Eth1/1
Eth1/2
Eth1/3
Eth1/1
Eth1/1
Eth1/2
Eth1/3
Eth1/1
Eth1/2
Eth1/3
Eth1/2
Eth1/3
Router A
Router B Router C
Router D