About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog

Documentation / networking / ipvs-sysctl.txt




Custom Search

Based on kernel version 2.6.34. Page generated on 2010-05-31 16:03 EST.

1	/proc/sys/net/ipv4/vs/* Variables:
2	
3	am_droprate - INTEGER
4	        default 10
5	
6	        It sets the always mode drop rate, which is used in the mode 3
7	        of the drop_rate defense.
8	
9	amemthresh - INTEGER
10	        default 1024
11	
12	        It sets the available memory threshold (in pages), which is
13	        used in the automatic modes of defense. When there is no
14	        enough available memory, the respective strategy will be
15	        enabled and the variable is automatically set to 2, otherwise
16	        the strategy is disabled and the variable is  set  to 1.
17	
18	cache_bypass - BOOLEAN
19	        0 - disabled (default)
20	        not 0 - enabled
21	
22	        If it is enabled, forward packets to the original destination
23	        directly when no cache server is available and destination
24	        address is not local (iph->daddr is RTN_UNICAST). It is mostly
25	        used in transparent web cache cluster.
26	
27	debug_level - INTEGER
28		0          - transmission error messages (default)
29		1          - non-fatal error messages
30		2          - configuration
31		3          - destination trash
32		4          - drop entry
33		5          - service lookup
34		6          - scheduling
35		7          - connection new/expire, lookup and synchronization
36		8          - state transition
37		9          - binding destination, template checks and applications
38		10         - IPVS packet transmission
39		11         - IPVS packet handling (ip_vs_in/ip_vs_out)
40		12 or more - packet traversal
41	
42		Only available when IPVS is compiled with the CONFIG_IPVS_DEBUG
43	
44		Higher debugging levels include the messages for lower debugging
45		levels, so setting debug level 2, includes level 0, 1 and 2
46		messages. Thus, logging becomes more and more verbose the higher
47		the level.
48	
49	drop_entry - INTEGER
50	        0  - disabled (default)
51	
52	        The drop_entry defense is to randomly drop entries in the
53	        connection hash table, just in order to collect back some
54	        memory for new connections. In the current code, the
55	        drop_entry procedure can be activated every second, then it
56	        randomly scans 1/32 of the whole and drops entries that are in
57	        the SYN-RECV/SYNACK state, which should be effective against
58	        syn-flooding attack.
59	
60	        The valid values of drop_entry are from 0 to 3, where 0 means
61	        that this strategy is always disabled, 1 and 2 mean automatic
62	        modes (when there is no enough available memory, the strategy
63	        is enabled and the variable is automatically set to 2,
64	        otherwise the strategy is disabled and the variable is set to
65	        1), and 3 means that that the strategy is always enabled.
66	
67	drop_packet - INTEGER
68	        0  - disabled (default)
69	
70	        The drop_packet defense is designed to drop 1/rate packets
71	        before forwarding them to real servers. If the rate is 1, then
72	        drop all the incoming packets.
73	
74	        The value definition is the same as that of the drop_entry. In
75	        the automatic mode, the rate is determined by the follow
76	        formula: rate = amemthresh / (amemthresh - available_memory)
77	        when available memory is less than the available memory
78	        threshold. When the mode 3 is set, the always mode drop rate
79	        is controlled by the /proc/sys/net/ipv4/vs/am_droprate.
80	
81	expire_nodest_conn - BOOLEAN
82	        0 - disabled (default)
83	        not 0 - enabled
84	
85	        The default value is 0, the load balancer will silently drop
86	        packets when its destination server is not available. It may
87	        be useful, when user-space monitoring program deletes the
88	        destination server (because of server overload or wrong
89	        detection) and add back the server later, and the connections
90	        to the server can continue.
91	
92	        If this feature is enabled, the load balancer will expire the
93	        connection immediately when a packet arrives and its
94	        destination server is not available, then the client program
95	        will be notified that the connection is closed. This is
96	        equivalent to the feature some people requires to flush
97	        connections when its destination is not available.
98	
99	expire_quiescent_template - BOOLEAN
100		0 - disabled (default)
101		not 0 - enabled
102	
103		When set to a non-zero value, the load balancer will expire
104		persistent templates when the destination server is quiescent.
105		This may be useful, when a user makes a destination server
106		quiescent by setting its weight to 0 and it is desired that
107		subsequent otherwise persistent connections are sent to a
108		different destination server.  By default new persistent
109		connections are allowed to quiescent destination servers.
110	
111		If this feature is enabled, the load balancer will expire the
112		persistence template if it is to be used to schedule a new
113		connection and the destination server is quiescent.
114	
115	nat_icmp_send - BOOLEAN
116	        0 - disabled (default)
117	        not 0 - enabled
118	
119	        It controls sending icmp error messages (ICMP_DEST_UNREACH)
120	        for VS/NAT when the load balancer receives packets from real
121	        servers but the connection entries don't exist.
122	
123	secure_tcp - INTEGER
124	        0  - disabled (default)
125	
126	        The secure_tcp defense is to use a more complicated state
127	        transition table and some possible short timeouts of each
128	        state. In the VS/NAT, it delays the entering the ESTABLISHED
129	        until the real server starts to send data and ACK packet
130	        (after 3-way handshake).
131	
132	        The value definition is the same as that of drop_entry or
133	        drop_packet.
134	
135	sync_threshold - INTEGER
136	        default 3
137	
138	        It sets synchronization threshold, which is the minimum number
139	        of incoming packets that a connection needs to receive before
140	        the connection will be synchronized. A connection will be
141	        synchronized, every time the number of its incoming packets
142	        modulus 50 equals the threshold. The range of the threshold is
143	        from 0 to 49.
Hide Line Numbers
About Kernel Documentation Linux Kernel Contact Linux Resources Linux Blog
Information is copyright its respective author. All material is available from the Linux Kernel Source distributed under a GPL License. This page is provided as a free service by mjmwired.net.