Hi all !
I'm trying to work out what's wrong with my 3CCFE575BT cardbus
3Com network adapter. Things don't really work right, and I'm
trying to figure out what goes wrong, but I know jack about driving
nics... If anyone has suggestions to things I could try, based
on the info below, I'd much appreciate it.
Situation: Laptop (with 3c575), Node0 (with 3c905), and
Node1 (with Tulip)
Node0 <-> Node1 has always worked, and they connect perfectly with
all other machines. They are not the problem.
When I ping from the laptop to to either node0 or node1, this is what
happens:
Ping with n byte packets, where n < 1475 : All is fine
Ping with n byte packets, where n >= 1475 : ICMP echo request reaches
node[01], but a reply is never returned. The ICMP echo reply packet is
simply never sent from node[01] back to the laptop. The nodes can ping
each other fine using packets of any size.
Ofcourse, at 1475 bytes, the packet gets fragmented. So I suspect that
something goes wrong there. But why is the reply never sent from the
nodes ?
tcpdump on a node, when pinging from laptop to node with 1475 byte packets:
(request)
01:45:14.440681 0:10:4b:f9:37:3b 0:60:8:29:93:72 ip 60: laptop > node: (frag
35032:3@1480) (ttl 64)
01:45:14.441040 0:10:4b:f9:37:3b 0:60:8:29:93:72 ip 1514: laptop > node: icmp: echo
request (frag 35032:1480@0+) (ttl 64)
(request)
01:45:15.437247 0:10:4b:f9:37:3b 0:60:8:29:93:72 ip 60: laptop > node: (frag
35033:3@1480) (ttl 64)
01:45:15.437626 0:10:4b:f9:37:3b 0:60:8:29:93:72 ip 1514: laptop > node: icmp: echo
request (frag 35033:1480@0+) (ttl 64)
(request)
01:45:16.437230 0:10:4b:f9:37:3b 0:60:8:29:93:72 ip 60: laptop > node: (frag
35034:3@1480) (ttl 64)
01:45:16.437598 0:10:4b:f9:37:3b 0:60:8:29:93:72 ip 1514: laptop > node: icmp: echo
request (frag 35034:1480@0+) (ttl 64)
This looks fine in my eyes. The offsets seem right. But there is no echo reply.
tcpdump on a node, when pinging from the other node to this node with 1475 byte
packets:
(request)
01:55:28.861364 0:0:e8:24:52:17 0:60:8:29:93:72 ip 60: node1 > node2: (frag
22505:3@1480) (ttl 64)
01:55:28.861704 0:0:e8:24:52:17 0:60:8:29:93:72 ip 1514: node1 > node2: icmp: echo
request (frag 22505:1480@0+) (ttl 64)
(*reply*)
01:55:28.861900 0:60:8:29:93:72 0:0:e8:24:52:17 ip 37: node2 > node1: (frag
56171:3@1480) (ttl 255)
01:55:28.862003 0:60:8:29:93:72 0:0:e8:24:52:17 ip 1514: node2 > node1: icmp: echo
reply (frag 56171:1480@0+) (ttl 255)
(request)
01:55:29.861466 0:0:e8:24:52:17 0:60:8:29:93:72 ip 60: node1 > node2: (frag
22946:3@1480) (ttl 64)
01:55:29.861921 0:0:e8:24:52:17 0:60:8:29:93:72 ip 1514: node1 > node2: icmp: echo
request (frag 22946:1480@0+) (ttl 64)
Same offsets. But now there's echo reply...
As far as I can read from the driver, the packet fragmentation does not happen in the
ethernet driver, (I could well be mistaken here), so I guess it happens at the IP
layer. But
the IP layer ought to be the same... Same kernels out there...
Oh, I shouldn't forget: Kernel is 2.2.9 with pcmcia-3.0.12, but 2.2.5 had similar
problems.
By the way, the laptop can do NFS transfers fine, but it stalls as soon as I hit it
with
FTP or rcp etc. (even scp). I guess it's only happy with smaller packets.
Suggestions will be much appreciated,
thanks,
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