Brocade Communications Systems 12.4.00 manual Hash-based persistence for IPv6

Advanced GSLB configuration for IPv6 2

High availability considerations for IPv6 sticky persistence

Sticky GSLB enables the GSLB controller to return the same IP address if a client sends multiple DNS requests within a configurable period of time.

Controllers, when configured in HA scenarios, will need to sync their sticky sessions in order to maintain persistence across the controllers. This is similar to the IPV4 sticky persistence behavior.

IPV4 and IPV6 sticky sessions will share the same special signature. All sticky GSLB ipv6 sessions are identified by the client IP and the following three tuples that remain the same for all sticky sessions:

•Dst-IP - 255.0.255.0

•S-port – 7

•D-port – 8

ServerIronADX(config)# show session all 0 Session Info:

Flags - 0:UDP, 1:TCP, 2:IP, 3:INT, 4:INVD, H: sessInHash, N: sessInNextEntry

Index Src-IP		Age	Dst-IP	Serv	Flags	S-port
D-port			Next			======
===== ======		====	======	======	======
===	0.0.0.5		====		5	80
0		000000	100.1.1.10	SLB1 H
0	0.0.0.5		n/a		5	80
1		000000	100.1.1.30	SLB1 H
0			n/a		7	8
2	2001:0DB8::78 255.0.255.0			SLB3 H
57		000000	n/a		7	8
3	100.1.1.0		255.0.255.0	SLB3 H
57		000000	n/a

In the example, the second and third rows show IPV6 and IPV4 sticky sessions.

Hash-based persistence for IPv6

GSLB ServerIron ADX offers two methods for site persistence: sticky persistence and hash-based persistence.

Hash-based persistence is the best solution for site persistence in environments that utilize two GSLB controllers (not in an HA configuration) for the same domain and where site persistence is needed for a single client that is directed to those GSLB controllers. When users query for a host name, they receive the same IP address for that domain regardless of which GSLB controller is contacted.

Sticky persistence alone is sufficient for single-box and High Availability (hot standby, symmetric active-standby, symmetric active-active) topologies. For more information, see “Sticky persistence for IPv6” on page 222.

Specifying hash-based persistence prefix lengths

By default, the ServerIron ADX does hash-based GSLB persistence for every IPv6 DNS client with a prefix length of 128 bits. The ipv6-prefix-len-hash-persistparameter enables you to specify an alternative prefix length.

ServerIron ADX Global Server Load Balancing Guide	225
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