* checksum calculation in ip packet forwarding
@ 2005-01-30 13:09 cranium 2003
0 siblings, 0 replies; only message in thread
From: cranium 2003 @ 2005-01-30 13:09 UTC (permalink / raw)
To: netdev
Hello,
1) How Router knows destinations mtu. In IP forwarding case following
function is used that checks pmtu value to decide whether outgoing
packet is required to fragment a packet or not?
static inline int ip_send(struct sk_buff *skb)
{
if (skb->len > skb->dst->pmtu)
return ip_fragment(skb, ip_finish_output);
else
return ip_finish_output(skb);
}
2) Can anybody help me how following function works in calcualting checksum?
static inline int ip_decrease_ttl(struct iphdr *iph)
{
u32 check = iph->check;
check += __constant_htons(0x0100);
iph->check = check + (check>=0xFFFF);
return --iph->ttl;
}
regards,
cranium
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2005-01-30 13:09 UTC | newest]
Thread overview: (only message) (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2005-01-30 13:09 checksum calculation in ip packet forwarding cranium 2003
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).