Messages in this thread | | | Date | Mon, 5 May 2003 11:35:23 +0200 | From | Christian Hammers <> | Subject | icmp_ratelimit seems to be too low (related to NAT?) |
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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.
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.
bye,
-christian-
-- Christian Hammers WESTEND GmbH | Internet-Business-Provider Technik CISCO Systems Partner - Authorized Reseller Lütticher Straße 10 Tel 0241/701333-11 ch@westend.com D-52064 Aachen Fax 0241/911879
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