H3C Technologies H3C SecPath F1000-E - Manual (Page 720)

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Because Host A considers that Host B is on the same network, it directly sends an NS message to obtain
the hardware address of Host B. Host B, however, cannot receive this message because it locates in a
different broadcast domain.
You can solve the problem by enabling ND proxy on Ethernet 1/1 and Ethernet 1/2 of Router. After that,
Router can search the forwarding entries according to the IPv6 address of the NS message, obtain the
outgoing interface and forward the NS message through that interface. In this case, Host B receives the
NS message and responds with an NA message, and the NA message is then forwarded by Router to
Host A. Thus, Router allows communications between Host A and Host B.
Configuration procedure
You can enable ND proxy in Layer 3 Ethernet interface view, or Layer 3 Ethernet subinterface view.
To enable ND proxy:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view. interface interface-type interface-number N/A
3. Enable ND proxy. ipv6 nd proxy enable Disabled by default
Configuring path MTU discovery
Configuring the interface MTU
IPv6 routers do not support packet fragmentation. After an IPv6 router receives an IPv6 packet, if the
packet size is greater than the MTU of the forwarding interface, the router will discard the packet.
Meanwhile, the router sends the MTU to the source host through an ICMPv6 packet — Packet Too Big
message. The source host fragments the packet according to the MTU and resends it. To reduce the extra
flow overhead resulting from packets being discarded, a proper interface MTU should be configured
according to the actual networking environment.
To configure the interface MTU:
Step Command Remarks
1. Enter system view. system-view N/A
2. Enter interface view. interface interface-type interface-number N/A
3. Configure the interface MTU. ipv6 mtu mtu-size Optional
Configuring a static path MTU for a specific IPv6 address
You can configure a static path MTU for a specified destination IPv6 address. When a source host sends
a packet through an interface, it compares the interface MTU with the static path MTU of the specified
destination IPv6 address. If the packet size is larger than the smaller one of the two values, the host
fragments the packet according to the smaller value.
To configure a static path MTU for a specified IPv6 address: