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ipv4: allow warming up the ARP cache with request type gratuitous ARP

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If the per device ARP_ACCEPT option is enable, currently we only allow
creating new ARP cache entries for response type gratuitous ARP.

Allowing gratuitous ARP to create new ARP entries (not only to update
existing ones) is useful when we want to avoid unnecessary delays for
the first packet of a stream.

This patch allows request type gratuitous ARP to create new ARP cache
entries as well. This is useful when we want to populate the ARP cache
entries for a large number of hosts on the same LAN.

Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Octavian Purdila 2010-01-18 12:58:44 +00:00 committed by David S. Miller
parent fa44a73cc7
commit 6d955180b2
2 changed files with 14 additions and 4 deletions
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15
Documentation/networking/ip-sysctl.txt
View file

@ -852,9 +852,18 @@ arp_notify - BOOLEAN
or hardware address changes.
arp_accept - BOOLEAN
Define behavior when gratuitous arp replies are received:
0 - drop gratuitous arp frames
1 - accept gratuitous arp frames
Define behavior for gratuitous ARP frames who's IP is not
already present in the ARP table:
0 - don't create new entries in the ARP table
1 - create new entries in the ARP table
Both replies and requests type gratuitous arp will trigger the
ARP table to be updated, if this setting is on.
If the ARP table already contains the IP address of the
gratuitous arp frame, the arp table will be updated regardless
if this setting is on or off.
app_solicit - INTEGER
The maximum number of probes to send to the user space ARP daemon

3
net/ipv4/arp.c
View file

@ -907,7 +907,8 @@ static int arp_process(struct sk_buff *skb)
devices (strip is candidate)
*/
if (n == NULL &&
arp->ar_op == htons(ARPOP_REPLY) &&
(arp->ar_op == htons(ARPOP_REPLY) ||
(arp->ar_op == htons(ARPOP_REQUEST) && tip == sip)) &&
inet_addr_type(net, sip) == RTN_UNICAST)
n = __neigh_lookup(&arp_tbl, &sip, dev, 1);
}