Hi All,
I've 2 gre tunnels connectivity between 3 system
Internal ----linux1(greA)-----(greB)linux2(greC)------(greD)cisco-router ---
-Internet
In this setup i cannot access few of sites. These sites seems DF bit set.
Following is dump on gre tunnel(greA) on my linux1 box. Same data can be
seen on greB on linux2. If I replace linux2 with cisco router then
everything works fine.
Is it something to do with MTU or any other setting? Strange point to me is
I can access that site from linux1(with lynx) only and only if I set greA
MTU to 1476(or lower)and greB MTU to 1500(or lower), but not from any client
on my Internal network. I randomly tried with many different MTU settings
and its combinations. At GreD MTU is 1514, and its my ISP so i cannot have
anything to do there.
I'm helpless, please get time to write in.
Thanks,
--Sumit
------------------- tcpdump ------------------------
19:26:31.372493 > 203.195.174.121.45244 > 202.54.21.184.www: S
1680594:1680594(0) win 8192 <mss 1460,nop,nop,sackOK>
4500 0030 7a0c 0000 7f06 6790 cbc3 ae79
ca36 15b8 b0bc 0050 0019 a4d2 0000 0000
7002 2000 b2fb 0000 0204 05b4 0101 0402
19:26:31.435508 < 202.54.21.184.www > 203.195.174.121.45244: S
2455708745:2455708745(0) ack 1680595 win 17520 <mss 1460,nop,nop,sackOK>
(DF)
4500 0030 9f81 4000 7706 0a1b ca36 15b8
cbc3 ae79 0050 b0bc 925f 2449 0019 a4d3
7012 4470 d7d1 0000 0204 05b4 0101 0402
19:26:31.436599 > 203.195.174.121.45244 > 202.54.21.184.www: . 1:1(0) ack 1
win 8760
4500 0028 7c0c 0000 7f06 6598 cbc3 ae79
ca36 15b8 b0bc 0050 0019 a4d3 925f 244a
5010 2238 26ce 0000
19:26:31.441460 > 203.195.174.121.45244 > 202.54.21.184.www: P 1:352(351)
ack 1 win 8760
4500 0187 7d0c 0000 7f06 6339 cbc3 ae79
ca36 15b8 b0bc 0050 0019 a4d3 925f 244a
5018 2238 8fb9 0000 4745 5420 2f20 4854
5450 2f31 2e31 0d0a 4163 6365 7074 3a20
696d 6167 652f 6769 662c 2069 6d61 6765
2f78 2d78 6269 746d 6170 2c20 696d 6167
652f 6a70 6567 2c20 696d 6167 652f 706a
7065 672c 2061 7070 6c69 6361 7469 6f6e
2f76 6e64 2e6d 732d 706f 7765 7270 6f69
19:26:34.404329 > 203.195.174.121.45244 > 202.54.21.184.www: P 1:352(351)
ack 1 win 8760
4500 0187 830c 0000 7f06 5d39 cbc3 ae79
ca36 15b8 b0bc 0050 0019 a4d3 925f 244a
5018 2238 8fb9 0000 4745 5420 2f20 4854
5450 2f31 2e31 0d0a 4163 6365 7074 3a20
696d 6167 652f 6769 662c 2069 6d61 6765
2f78 2d78 6269 746d 6170 2c20 696d 6167
652f 6a70 6567 2c20 696d 6167 652f 706a
7065 672c 2061 7070 6c69 6361 7469 6f6e
2f76 6e64 2e6d 732d 706f 7765 7270 6f69
19:26:34.426319 < 202.54.21.184.www > 203.195.174.121.45244: . 2921:2921(0)
ack 352 win 17169 (DF)
4500 0028 a0ad 4000 7706 08f7 ca36 15b8
cbc3 ae79 0050 b0bc 925f 2fb2 0019 a632
5010 4311 f92d 0000
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