R2511-HP MSR Router Series Layer 3 - IP Routing Configuration Guide(V5)

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Limiting LSP flooding
In well-connected ATM, FR and NBMA networks, many P2P links exist. Figure 41 shows a fully meshed
network, where Routers A, B, C and 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 receiving 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. LSP flooding consumes extra bandwidth.
Figure 41 Network diagram of a fully meshed network
To avoid this, configure some interfaces as a mesh group, configure the blocked interfaces, or both.
• After receiving an LSP, a member interface in a mesh group floods it out of the interfaces that do not
belong to the mesh group.
• If an interface is blocked, it does not send LSPs unless the neighbor sends LSP requests to it.
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