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ServerIron ADX NAT64 Configuration Guide 17
53-1002288-02
High availability for NAT64
2
DRAFT: BROCADE CONFIDENTIAL
Regular packets – IP total length greater than 1480 bytes
Fragmented packets – IP total length greater than 1480 + 8 bytes
If the packets exceed these limitations, one of the following actions will be taken:
1. If the frag-664-reverse-full-sized-pkt command is configured, the packet will be split and no
further actions will be performed.
2. If the condition in step 1 isn’t met, and the DF bit is set at the server, the “frag needed” ICMP
error message will be sent.
3. If the conditions in steps 1 and 2 aren’t met, the packet will be split.
The frag-664-reverse-full-sized-pkt command is configured as shown in the following.
ServerIronADX(config)# frag-664-reverse-full-sized-pkt
Syntax: [no] frag-664-reverse-full-sized-pkt
For more information about NAT64 fragmentation support see “NAT64 fragmentation support” on
page 5.
NOTE
If the IPv4 host sends out UDP Fragmented packets with checksum 0, we do not support it.
High availability for NAT64
The only high availability mode currently supported with NAT64 feature is the Active-Active HA. In
the Active-Active HA mode, the NAT64 IPv4 NAT pool ports are divided equally among ServerIron
ADXs. Upstream and Downstream routers use ECMP to distribute the load equally among the
ServerIron ADXs. This ensures that there is no port starvation. This feature is available only for a
ServerIron ADX running router code.
Each ServerIron ADX is configured with a NAT64 prefix, specifying the IPv6 address range and a
NAT pool that specifies the IPv4 address pool. Sessions are synchronized periodically between the
ServerIron ADXs. These sessions are synchronized using a separate link as shown. As long as a
ServerIron ADX receives packets on a given flow or session, the age of the session is updated to
keep the session alive. The age of the session is also synchronized periodically which maintains the
session as alive on both ServerIron ADXs.
FIGURE 8 NAT64 active-active HA configuration
Active
ADX - 1
Data
Upstream Router
Downstream Router
NAT64
Active
ADX - 2
Session - Sync
NAT64