H3C Technologies H3C S12500 Series Switches - Manual (Page 361)

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Configuring IPv6 IS-IS MTR
On a network comprising both IPv4 and IPv6 topologies, the IPv4 and IPv6 topologies must be consistent
so that both IPv6 IS-IS and IPv4 IS-IS can use the Shortest Path First (SPF) algorithm to perform route
calculation. If they are different, routers supporting both IPv4 and IPv6 send IPv6 packets to routers that
do not support IPv6, and thus packet loss occurs.
To solve the problem, you can configure IPv6 IS-IS Multi-Topology Routing (MTR) to perform route
calculation separately in IPv4 and IPv6 topologies.
Figure 114 Network diagram
In Figure 114 , the numbers refer to the link costs. Router A, Router B, and Router D support both IPv4 and
IPv6. Router C supports only IPv4 and cannot forward IPv6 packets.
Enable IPv6 IS-IS MTR on Router A, Router B, Router C, and Router D to make them perform route
calculation separately in IPv4 and IPv6 topologies. In this way, Router A will not forward IPv6 packets
destined to Router D through Router B to avoid packet loss.
Configuration prerequisites
Before you configure IPv6 IS-IS MTR, complete the following tasks:
• Configure basic IS-IS and IPv6 IS-IS.
• Establish IS-IS neighbors.
Configuration procedure
To configure IPv6 IS-IS MTR:
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. Specify the cost style for IS-IS.
cost-style { narrow | wide |
wide-compatible | { compatible |
narrow-compatible }
[ relax-spf-limit ] }
By default, narrow is adopted.
4. Enable IPv6 IS-IS MTR. multiple-topology ipv6-unicast Disabled by default.
Router A Router B
Router D Router C
IPv4
IPv4
36
5
4
3
IPv6
IPv6
IPv4
IPv4
IPv6 IPv6