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bonding: document the new xmit policy modes and update the changed ones

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Add new documentation for encap2+3 and encap3+4, also update the formula
for the old modes due to the changes.

Signed-off-by: Nikolay Aleksandrov <nikolay@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nikolay Aleksandrov 2013-10-02 13:39:26 +02:00 committed by David S. Miller
parent 32819dc183
commit 7a6afab1de
1 changed files with 36 additions and 30 deletions
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66
Documentation/networking/bonding.txt
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@ -743,21 +743,16 @@ xmit_hash_policy
protocol information to generate the hash.
Uses XOR of hardware MAC addresses and IP addresses to
generate the hash. The IPv4 formula is
generate the hash. The formula is
(((source IP XOR dest IP) AND 0xffff) XOR
( source MAC XOR destination MAC ))
modulo slave count
hash = source MAC XOR destination MAC
hash = hash XOR source IP XOR destination IP
hash = hash XOR (hash RSHIFT 16)
hash = hash XOR (hash RSHIFT 8)
And then hash is reduced modulo slave count.
The IPv6 formula is
hash = (source ip quad 2 XOR dest IP quad 2) XOR
(source ip quad 3 XOR dest IP quad 3) XOR
(source ip quad 4 XOR dest IP quad 4)
(((hash >> 24) XOR (hash >> 16) XOR (hash >> 8) XOR hash)
XOR (source MAC XOR destination MAC))
modulo slave count
If the protocol is IPv6 then the source and destination
addresses are first hashed using ipv6_addr_hash.
This algorithm will place all traffic to a particular
network peer on the same slave. For non-IP traffic,
@ -779,21 +774,16 @@ xmit_hash_policy
slaves, although a single connection will not span
multiple slaves.
The formula for unfragmented IPv4 TCP and UDP packets is
The formula for unfragmented TCP and UDP packets is
((source port XOR dest port) XOR
((source IP XOR dest IP) AND 0xffff)
modulo slave count
hash = source port, destination port (as in the header)
hash = hash XOR source IP XOR destination IP
hash = hash XOR (hash RSHIFT 16)
hash = hash XOR (hash RSHIFT 8)
And then hash is reduced modulo slave count.
The formula for unfragmented IPv6 TCP and UDP packets is
hash = (source port XOR dest port) XOR
((source ip quad 2 XOR dest IP quad 2) XOR
(source ip quad 3 XOR dest IP quad 3) XOR
(source ip quad 4 XOR dest IP quad 4))
((hash >> 24) XOR (hash >> 16) XOR (hash >> 8) XOR hash)
modulo slave count
If the protocol is IPv6 then the source and destination
addresses are first hashed using ipv6_addr_hash.
For fragmented TCP or UDP packets and all other IPv4 and
IPv6 protocol traffic, the source and destination port
@ -801,10 +791,6 @@ xmit_hash_policy
formula is the same as for the layer2 transmit hash
policy.
The IPv4 policy is intended to mimic the behavior of
certain switches, notably Cisco switches with PFC2 as
well as some Foundry and IBM products.
This algorithm is not fully 802.3ad compliant. A
single TCP or UDP conversation containing both
fragmented and unfragmented packets will see packets
@ -815,6 +801,26 @@ xmit_hash_policy
conversations. Other implementations of 802.3ad may
or may not tolerate this noncompliance.
encap2+3
This policy uses the same formula as layer2+3 but it
relies on skb_flow_dissect to obtain the header fields
which might result in the use of inner headers if an
encapsulation protocol is used. For example this will
improve the performance for tunnel users because the
packets will be distributed according to the encapsulated
flows.
encap3+4
This policy uses the same formula as layer3+4 but it
relies on skb_flow_dissect to obtain the header fields
which might result in the use of inner headers if an
encapsulation protocol is used. For example this will
improve the performance for tunnel users because the
packets will be distributed according to the encapsulated
flows.
The default value is layer2. This option was added in bonding
version 2.6.3. In earlier versions of bonding, this parameter
does not exist, and the layer2 policy is the only policy. The