* Re: route cache flush??
2012-02-03 15:05 ` Eric Dumazet
@ 2012-02-03 15:48 ` Stephen Clark
0 siblings, 0 replies; 3+ messages in thread
From: Stephen Clark @ 2012-02-03 15:48 UTC (permalink / raw)
To: Eric Dumazet; +Cc: Linux Kernel Network Developers
On 02/03/2012 10:05 AM, Eric Dumazet wrote:
> Le vendredi 03 février 2012 à 09:59 -0500, Stephen Clark a écrit :
>
>> Hello,
>>
>> I have been beating my head against the wall for 2 days trying to
>> figure why when I change a route and do a "ip route flush cache"
>> it still takes up to a minute for packets to start using the new
>> route.
>>
>> Is there a step I am missing?
>>
>> kernel is 2.6.32
>>
>>
> Nothing comes to mind, please share more information ?
>
>
Sure
I have a box "A" with 2 interfaces ips 2.2.2.1 and 3.3.3.1 going to
another box "B" that has 3 nics 2.2.2.254
3.3.3.254 and 1.1.1.254 there is a third box "C" with ip 1.1.1.1. Box B
is to simulate the net.
I have 2 vpns on box A going to box C. The default rt on A is
2.2.2.254. If I don't do anything else routing wise
esp packet originated on 1.1.1.1 come 3.3.3.1 on box A but the response
packet from 3.3.3.1 goes out the
default route. This works OK in the lab but in the field the isps
generally drop packet that have a source address
that doesn't match their subnet.
So I have found on the net how to set up a simple rule to route packets
with src address 3.3.3.1 back out that interface.
$ ip r s
2.2.2.0/24 dev eth1 proto kernel scope link src 2.2.2.1
3.3.3.0/24 dev eth2 proto kernel scope link src 3.3.3.1
10.0.128.0/17 dev eth0 proto kernel scope link src 10.0.133.22
default via 2.2.2.254 dev eth1
L703103:~
$ ip r s table second
default via 3.3.3.254 dev eth2 src 3.3.3.1
L703103:~
$ ip rule list
0: from all lookup local
200: from 3.3.3.1 lookup second
32766: from all lookup main
32767: from all lookup default
So I run a script to disable the src route an flush the cache.$
date;sudo /usr/local/pgsql/storeproc/programs/src_rt_off.sh
Fri Feb 3 10:20:16 EST 2012 --- notice the time.
++ id -un
+ '[' root '!=' root ']'
+ /sbin/ip route delete default table second
+ /sbin/ip rule delete table second
+ /sbin/ip route flush cache
+ /sbin/ip rule list
0: from all lookup local
32766: from all lookup main
32767: from all lookup default
This is a tcpdump of the interface with 3.3.3.1 ip address - I ran the
script at 10:20:16
Notice how long before response quit going out this interface and switch
to the default
route. I see similar behavior when I reinstall the src route and flush
the cache.
10:20:19.102448 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x24e),
length 116
10:20:19.103221 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x24e),
length 116
10:20:19.498523 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x24f),
length 116
10:20:19.498701 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x24f),
length 116
10:20:30.704175 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x250),
length 116
10:20:30.704357 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x250),
length 116
10:20:34.217349 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x251),
length 116
10:20:34.218150 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x251),
length 116
10:20:34.333011 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x252),
length 116
10:20:34.333795 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x252),
length 116
10:20:40.826996 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x253),
length 116
10:20:40.827775 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x253),
length 116
10:20:41.412308 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x254),
length 116
10:20:41.413081 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x254),
length 116
10:20:41.910528 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x255),
length 116
10:20:41.910711 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x255),
length 116
10:20:42.413504 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x256),
length 116
10:20:42.414260 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x256),
length 116
10:20:43.413755 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x257),
length 116
10:20:43.414510 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x257),
length 116
10:20:44.413807 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x258),
length 116
10:20:44.414560 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x258),
length 116
10:20:49.468466 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x259),
length 116
10:20:49.469267 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x259),
length 116
10:20:49.576539 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x25a),
length 116
10:20:49.577318 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x25a),
length 116
10:20:53.116021 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x25b),
length 116
10:20:53.116196 IP 3.3.3.1 > 1.1.1.1: ESP(spi=0x05690af9,seq=0x25b),
length 116
10:21:04.320972 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x25c),
length 116<<<<<<<
10:21:04.720342 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x25d),
length 116
10:21:04.808653 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x25e),
length 116
10:21:08.422372 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x25f),
length 116
10:21:09.423730 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x260),
length 116
10:21:10.424971 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x261),
length 116
10:21:11.425469 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x262),
length 116
10:21:15.525572 IP 1.1.1.1 > 3.3.3.1: ESP(spi=0x021bd1a9,seq=0x263),
length 116
--
"They that give up essential liberty to obtain temporary safety,
deserve neither liberty nor safety." (Ben Franklin)
"The course of history shows that as a government grows, liberty
decreases." (Thomas Jefferson)
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