Hitachi GR2000 Series - Manual (Page 243)

Troubleshooting
GR2K-GA-0015 7-77
Ver. 07-02
7.8.4.7 Confirmation of configuration definition NAT-PT MTU
Packets are discarded in an IPv6 network when the packet size after IPv6 translation
is larger than PathMTU. Confirm the MTU size using a configuration definition
command (CLI type 1) (show natpt) and set the value lower than PathMTU. If
PathMTU is not found, delete the MTU setting and return to the default value (1280
bytes). See steps (Subsection 7.8.4.8, “Confirmation of statistics related to
DNS-ALG”) and (Subsection 7.8.4.9, “Confirmation of relay network”) when no
communication is possible even if MTU is set correctly.
7.8.4.8 Confirmation of statistics related to DNS-ALG
Display DNS-ALG statistical information using a show dns-relay command when
name resolution cannot be performed during communication from IPv6 to IPv4. A
DNS query or DNS response is not translated by DNS-ALG when both AAAA->A and
A->AAAA do not increase. In this case, there may be a problem in a DNS relay. See
Section 7.5.5 for resolution of the problem in a DNS relay.
7.8.4.9 Confirmation of relay network
Communication is considered to be impossible due to failure in a relay network. See
Subsection 7.5.1 (IPv4 network) and Subsection 7.8.1" (IPv6 network) for the
procedure.
See Subsection 7.5.3 when PPPoe is used in the interface adjacent to an IPv4
network. See Subsection 7.5.2.3 when a DHCP client is used.
(config)# show natpt
natpt yes {
mtu 1500;
rule {
napt any 10.20.30.100;
};
interface {
IPv6-net;
IPv4-net;
};
};
Confirm this content.
> show dns-relay
[Omitted halfway]
DNS-ALG Statistics:
AAAA -> A : 0
A -> AAAA : 0
>
Does not increase when translation
is not performed.