Messages in this thread | | | Date | Mon, 5 May 2003 07:53:58 -0700 | From | "Randy.Dunlap" <> | Subject | Re: icmp_ratelimit seems to be too low (related to NAT?) |
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On Mon, 5 May 2003 11:35:23 +0200 Christian Hammers <ch@westend.com> wrote:
| Hello | | icmp_ratelimit has, as of kernel 2.4.20, a default of 100 (which unit | btw?). This seems to be too low as I have packet loss when doing two | "mtr" to the same 4 hops away host simultaneously. As this suggerates | packet loss on the network to the administrator, a too low limit will | certainly annoy network admins as it gives wrong information.
icmp_ratelimit is init to 1 * HZ (where HZ == 100 most likely), so I'll guess that unit is jiffies (100ths of a second).
| My tests gave the following results: | | src. linux --> SNAT'ing linux router --> cisco1 --> cisco2 --> dst. linux | | On the src linux host I opened _two_ mtr at the same time and watched | the packet loss at the first host after 30 rounds (seconds). | | icmp_ratelimit | loss at hop1 for both mtr | 0 0 | 10 0 | 20 0 | 40 0 | 80 34% and 37% | 100 44% and 57% (default) | 160 64% and 75% | 320 87% and 83% | 999 100% and 100% | | For 2*(4*icmp_request + 4*icmp_timeexceeded/reply) = 16 packets per | second the loss seems to be a bit high at the default value of 100. | | Is this related to any other setting? Maybe NAT? | My /proc/net/ip_conntrack only has 1200 lines and the max in | /proc/sys/net/ipv4/ip_conntrack_max is 32767.
Only other value that I see related to it is icmp_ratemask, which has a default value of 0x1818. From net/ipv4/icmp.c:
/* * Configurable global rate limit. * * ratelimit defines tokens/packet consumed for dst->rate_token bucket * ratemask defines which icmp types are ratelimited by setting * it's bit position. * * default: [for ratemask -RDD] * dest unreachable (3), source quench (4), * time exceeded (11), parameter problem (12) */
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