Hello,
I do "ping XXX -l 1600" from ubuntu to VPP.
It looks like that 2 part of icmp have been reassembled .
But,
when the VPP-intfc's MTU is 9216 by default, it would not split the response
ICMP pkt,so the ubuntu receive nothing.
set MTU to be 1500, it don't split response ICMP pkt too, only notice 'ICMP
destination_unreachable fragmentation_needed_and_dont_fragment_set'
Help please!
trace info:
MTU：9216
Packet 1
00:03:52:633983: dpdk-input
GigabitEthernet2/0/0 rx queue 0
buffer 0x2a5d: current data 14, length 1500, free-list 0, clone-count 0,
totlen-nifb 0, trace 0x0
ext-hdr-valid
l4-cksum-computed l4-cksum-correct l2-hdr-offset 0
l3-hdr-offset 14
PKT MBUF: port 1, nb_segs 1, pkt_len 1514
buf_len 2176, data_len 1514, ol_flags 0x0, data_off 128, phys_addr
0x5dea97c0
packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0
IP4: 28:d2:44:0d:45:c1 -> 68:05:ca:47:2b:9e
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1500, checksum 0xb43e
fragment id 0x56be, flags MORE_FRAGMENTS
ICMP echo_request checksum 0x3622
00:03:52:633989: ip4-input
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1500, checksum 0xb43e
fragment id 0x56be, flags MORE_FRAGMENTS
ICMP echo_request checksum 0x3622
00:03:52:633992: ip4-reassembly-feature
reass id: 1, op id: 0 first bi: 10845, data len: 1480, ip/fragment[0, 1479]
new range: [0, 1479], off 0, len 1480, bi 10845
reass id: 1, op id: 2 first bi: 10845, data len: 1608, ip/fragment[0, 1479]
finalize reassembly
00:03:52:633998: ip4-lookup
fib 0 dpo-idx 7 flow hash: 0x00000000
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd3be
fragment id 0x56be
ICMP echo_request checksum 0x3622
00:03:52:634000: ip4-local
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd3be
fragment id 0x56be
ICMP echo_request checksum 0x3622
00:03:52:634002: ip4-icmp-input
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd3be
fragment id 0x56be
ICMP echo_request checksum 0x3622
00:03:52:634002: ip4-icmp-echo-request
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd3be
fragment id 0x56be
ICMP echo_request checksum 0x3622
00:03:52:634003: ip4-load-balance
fib 0 dpo-idx 13 flow hash: 0x00000000
ICMP: 192.168.100.100 -> 192.168.100.111
tos 0x00, ttl 64, length 1628, checksum 0x259e
fragment id 0x04df
ICMP echo_reply checksum 0x3e22
00:03:52:634003: ip4-rewrite
tx_sw_if_index 2 dpo-idx 1 : ipv4 via 192.168.100.111 GigabitEthernet2/0/0:
mtu:9202 28d2440d45c16805ca472b9e0800 flow hash: 0x00000000
00000000: 28d2440d45c16805ca472b9e08004500065c04df00004001259ec0a86464c0a8
00000020: 646f00003e2200010d2d6162636465666768696a6b6c6d6e6f707172
00:03:52:634004: GigabitEthernet2/0/0-output
GigabitEthernet2/0/0
IP4: 68:05:ca:47:2b:9e -> 28:d2:44:0d:45:c1
ICMP: 192.168.100.100 -> 192.168.100.111
tos 0x00, ttl 64, length 1628, checksum 0x259e
fragment id 0x04df
ICMP echo_reply checksum 0x3e22
00:03:52:634005: GigabitEthernet2/0/0-tx
GigabitEthernet2/0/0 tx queue 0
buffer 0x2a5d: current data 0, length 1514, free-list 0, clone-count 0,
totlen-nifb 128, trace 0x0
ext-hdr-valid
next-buffer 0x2a36, segment length 128, clone-count 0
l4-cksum-computed l4-cksum-correct l2-hdr-offset 0
l3-hdr-offset 14
PKT MBUF: port 1, nb_segs 2, pkt_len 1642
buf_len 2176, data_len 1514, ol_flags 0x0, data_off 128, phys_addr
0x5dea97c0
packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0
IP4: 68:05:ca:47:2b:9e -> 28:d2:44:0d:45:c1
ICMP: 192.168.100.100 -> 192.168.100.111
tos 0x00, ttl 64, length 1628, checksum 0x259e
fragment id 0x04df
ICMP echo_reply checksum 0x3e22
Packet 2
00:03:52:633995: dpdk-input
GigabitEthernet2/0/0 rx queue 0
buffer 0x2a36: current data 14, length 148, free-list 0, clone-count 0,
totlen-nifb 0, trace 0x1
ext-hdr-valid
l4-cksum-computed l4-cksum-correct l2-hdr-offset 0
l3-hdr-offset 14
PKT MBUF: port 1, nb_segs 1, pkt_len 162
buf_len 2176, data_len 162, ol_flags 0x0, data_off 128, phys_addr 0x5dea8e00
packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0
IP4: 28:d2:44:0d:45:c1 -> 68:05:ca:47:2b:9e
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 148, checksum 0xd8cd
fragment id 0x56be offset 1480, flags
ICMP unknown 0x61 checksum 0x6364
00:03:52:633995: ip4-input
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 148, checksum 0xd8cd
fragment id 0x56be offset 1480, flags
ICMP unknown 0x61 checksum 0x6364
00:03:52:633997: ip4-reassembly-feature
reass id: 1, op id: 1 first bi: 10845, data len: 1608, ip/fragment[1480, 1607]
new range: [1480, 1607], off 0, len 128, bi 10806
//////////////////////////////////////////////////////////////////////////////////////////
MTU：1500
Packet 1
00:07:19:687235: dpdk-input
GigabitEthernet2/0/0 rx queue 0
buffer 0xc248: current data 14, length 1500, free-list 0, clone-count 0,
totlen-nifb 0, trace 0x0
ext-hdr-valid
l4-cksum-computed l4-cksum-correct l2-hdr-offset 0
l3-hdr-offset 14
PKT MBUF: port 1, nb_segs 1, pkt_len 1514
buf_len 2176, data_len 1514, ol_flags 0x0, data_off 128, phys_addr
0x5db09280
packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0
IP4: 28:d2:44:0d:45:c1 -> 68:05:ca:47:2b:9e
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1500, checksum 0xb3fe
fragment id 0x56fe, flags MORE_FRAGMENTS
ICMP echo_request checksum 0x3616
00:07:19:687239: ip4-input
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1500, checksum 0xb3fe
fragment id 0x56fe, flags MORE_FRAGMENTS
ICMP echo_request checksum 0x3616
00:07:19:687243: ip4-reassembly-feature
reass id: 9, op id: 0 first bi: 49736, data len: 1480, ip/fragment[0, 1479]
new range: [0, 1479], off 0, len 1480, bi 49736
reass id: 9, op id: 2 first bi: 49736, data len: 1608, ip/fragment[0, 1479]
finalize reassembly
00:07:19:687249: ip4-lookup
fib 0 dpo-idx 7 flow hash: 0x00000000
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd37e
fragment id 0x56fe
ICMP echo_request checksum 0x3616
00:07:19:687251: ip4-local
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd37e
fragment id 0x56fe
ICMP echo_request checksum 0x3616
00:07:19:687253: ip4-icmp-input
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd37e
fragment id 0x56fe
ICMP echo_request checksum 0x3616
00:07:19:687254: ip4-icmp-echo-request
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 1628, checksum 0xd37e
fragment id 0x56fe
ICMP echo_request checksum 0x3616
00:07:19:687255: ip4-load-balance
fib 0 dpo-idx 13 flow hash: 0x00000000
ICMP: 192.168.100.100 -> 192.168.100.111
tos 0x00, ttl 64, length 1628, checksum 0xae8d
fragment id 0x7bef
ICMP echo_reply checksum 0x3e16
00:07:19:687255: ip4-rewrite
tx_sw_if_index 0 dpo-idx 1 : ipv4 via 192.168.100.111 GigabitEthernet2/0/0:
mtu:1486 28d2440d45c16805ca472b9e0800 flow hash: 0x00000403
00000000: 4500065c7bef00004001ae8dc0a86464c0a8646f00003e1600010d3961626364
00000020: 65666768696a6b6c6d6e6f7071727374757677616263646566676869
00:07:19:687256: ip4-icmp-error
ICMP: 192.168.100.100 -> 192.168.100.111
tos 0x00, ttl 64, length 1628, checksum 0xae8d
fragment id 0x7bef
ICMP echo_reply checksum 0x3e16
00:07:19:687257: ip4-drop
ICMP: 0.0.40.210 -> 192.168.100.100
tos 0x00, ttl 255, length 604, checksum 0x6bc2
fragment id 0x0000
ICMP destination_unreachable fragmentation_needed_and_dont_fragment_set
checksum 0xb7b3
00:07:19:687258: error-drop
ip4-input: ip4 MTU exceeded and DF set
Packet 2
00:07:19:687245: dpdk-input
GigabitEthernet2/0/0 rx queue 0
buffer 0xc221: current data 14, length 148, free-list 0, clone-count 0,
totlen-nifb 0, trace 0x1
ext-hdr-valid
l4-cksum-computed l4-cksum-correct l2-hdr-offset 0
l3-hdr-offset 14
PKT MBUF: port 1, nb_segs 1, pkt_len 162
buf_len 2176, data_len 162, ol_flags 0x0, data_off 128, phys_addr 0x5db088c0
packet_type 0x0 l2_len 0 l3_len 0 outer_l2_len 0 outer_l3_len 0
IP4: 28:d2:44:0d:45:c1 -> 68:05:ca:47:2b:9e
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 148, checksum 0xd88d
fragment id 0x56fe offset 1480, flags
ICMP unknown 0x61 checksum 0x6364
00:07:19:687247: ip4-input
ICMP: 192.168.100.111 -> 192.168.100.100
tos 0x00, ttl 64, length 148, checksum 0xd88d
fragment id 0x56fe offset 1480, flags
ICMP unknown 0x61 checksum 0x6364
00:07:19:687248: ip4-reassembly-feature
reass id: 9, op id: 1 first bi: 49736, data len: 1608, ip/fragment[1480, 1607]
new range: [1480, 1607], off 0, len 128, bi 49697
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