iPXE
dhcp.h
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1 #ifndef CONFIG_DHCP_H
2 #define CONFIG_DHCP_H
3 
4 /** @file
5  *
6  * DHCP configuration
7  *
8  */
9 
10 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
11 
12 #include <config/defaults.h>
13 
14 /*
15  * DHCP and PXE Boot Server timeout parameters
16  *
17  * Initial and final timeout for DHCP discovery
18  *
19  * The PXE spec indicates discover request are sent 4 times, with
20  * timeouts of 4, 8, 16, 32 seconds. iPXE by default uses 1, 2, 4, 8.
21  */
22 #define DHCP_DISC_START_TIMEOUT_SEC 1
23 #define DHCP_DISC_END_TIMEOUT_SEC 10
24 //#define DHCP_DISC_START_TIMEOUT_SEC 4 /* as per PXE spec */
25 //#define DHCP_DISC_END_TIMEOUT_SEC 32 /* as per PXE spec */
26 
27 /*
28  * Maximum number of discovery deferrals due to blocked links
29  * (e.g. from non-forwarding STP ports)
30  */
31 #define DHCP_DISC_MAX_DEFERRALS 60
32 
33 /*
34  * ProxyDHCP offers are given precedence by continue to wait for them
35  * after a valid DHCPOFFER is received. We'll wait through this
36  * timeout for it. The PXE spec indicates waiting through the 4 & 8
37  * second timeouts, iPXE by default stops after 2.
38  */
39 #define DHCP_DISC_PROXY_TIMEOUT_SEC 2
40 //#define DHCP_DISC_PROXY_TIMEOUT_SEC 11 /* as per PXE spec */
41 
42 /*
43  * Per the PXE spec, requests are also tried 4 times, but at timeout
44  * intervals of 1, 2, 3, 4 seconds. To adapt this to an exponential
45  * backoff timer, we can either do 1, 2, 4, 8, ie. 4 retires with a
46  * longer interval or start at 0 (0.25s) for 0.25, 0.5, 1, 2, 4,
47  * ie. one extra try and shorter initial timeouts. iPXE by default
48  * does a combination of both, starting at 0 and going through the 8
49  * second timeout.
50  */
51 #define DHCP_REQ_START_TIMEOUT_SEC 0
52 #define DHCP_REQ_END_TIMEOUT_SEC 10
53 //#define DHCP_REQ_END_TIMEOUT_SEC 4 /* as per PXE spec */
54 
55 /*
56  * A ProxyDHCP offer without PXE options also goes through a request
57  * phase using these same parameters, but note the early break below.
58  */
59 #define DHCP_PROXY_START_TIMEOUT_SEC 0
60 #define DHCP_PROXY_END_TIMEOUT_SEC 10
61 //#define DHCP_PROXY_END_TIMEOUT_SEC 8 /* as per PXE spec */
62 
63 /*
64  * A ProxyDHCP request timeout should not induce a failure condition,
65  * so we always want to break before the above set of timers expire.
66  * The iPXE default value of 2 breaks at the first timeout after 2
67  * seconds, which will be after the 2 second timeout.
68  */
69 #define DHCP_REQ_PROXY_TIMEOUT_SEC 2
70 //#define DHCP_REQ_PROXY_TIMEOUT_SEC 7 /* as per PXE spec */
71 
72 /*
73  * Per the PXE spec, a PXE boot server request is also be retried 4
74  * times at timeouts of 1, 2, 3, 4. iPXE uses the same timeouts as
75  * discovery, 1, 2, 4, 8, but will move on to the next server if
76  * available after an elapsed time greater than 3 seconds, therefore
77  * effectively only sending 3 tries at timeouts of 1, 2, 4.
78  */
79 #define PXEBS_START_TIMEOUT_SEC 1
80 #define PXEBS_END_TIMEOUT_SEC 10
81 //#define PXEBS_START_TIMEOUT_SEC 0 /* as per PXE spec */
82 //#define PXEBS_END_TIMEOUT_SEC 8 /* as per PXE spec */
83 
84 /*
85  * Increment to the next PXE Boot server, if available, after this
86  * this much time has elapsed.
87  */
88 #define PXEBS_MAX_TIMEOUT_SEC 3
89 //#define PXEBS_MAX_TIMEOUT_SEC 7 /* as per PXE spec */
90 
91 #include <config/local/dhcp.h>
92 
93 #endif /* CONFIG_DHCP_H */
FILE_LICENCE(GPL2_OR_LATER_OR_UBDL)