lhecking@xxxxxxxxxxxxxxxxxxxxx wrote:
>>According to the Linux bonding docs, xmit_hash_policy=layer3+4 uses:
>>
>> ((source port XOR dest port) XOR
>> ((source IP XOR dest IP) AND 0xffff)
>> modulo slave count
>>
>>So I guess you could plug in in the above IP addresses and port numbers
>>and see if you get 3 unique results?
>
>
> That's an interesting point - how exactly do you XOR these numbers?
> Bit by bit? And does 0xffff really mean 0xffffffff in this context?
I guess you need to look at the bonding src code - looks like it is in
drivers/net/bonding/bond_main.c - for CentOS 5 it is:
/*
* Hash for the output device based upon layer 3 and layer 4 data. If
* the packet is a frag or not TCP or UDP, just use layer 3 data. If it is
* altogether not IP, mimic bond_xmit_hash_policy_l2()
*/
static int bond_xmit_hash_policy_l34(struct sk_buff *skb,
struct net_device *bond_dev, int count)
{
struct ethhdr *data = (struct ethhdr *)skb->data;
struct iphdr *iph = ip_hdr(skb);
__be16 *layer4hdr = (__be16 *)((u32 *)iph + iph->ihl);
int layer4_xor = 0;
if (skb->protocol == htons(ETH_P_IP)) {
if (!(iph->frag_off & htons(IP_MF|IP_OFFSET)) &&
(iph->protocol == IPPROTO_TCP ||
iph->protocol == IPPROTO_UDP)) {
layer4_xor = ntohs((*layer4hdr ^ *(layer4hdr +
1)));
}
return (layer4_xor ^
((ntohl(iph->saddr ^ iph->daddr)) & 0xffff)) %
count;
}
return (data->h_dest[5] ^ bond_dev->dev_addr[5]) % count;
}
James Pearson
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