[j-nsp] GigE: M10 <-> Cisco Catalyst 6509: oversized and corrupted frames

Josef Buchsteiner josefb at juniper.net
Mon Mar 24 15:47:14 EST 2003

At 03:29 PM 3/24/2003, Matti Saarinen wrote:

>I've connected Juniper M10 (JUNOS 5.6R2.4) and Cisco Catalyst 6509
>(IOS 12.1(13)E4) to each other via gigabit ethernet using multimode
>fibre. Both ends complain about the packets they are seeing. On M10,
>the number in oversized frames counter increases.

this might be normal if you use tagged interface connections
and the frame is longer then 1518 including FCS. Although all
works perfect the counter is increasing as oversized frames.
So you would get a frame of 1522 including FCS in this case which
will increase the oversize counter.

>  The 6509 complains
>about corrupted IP packets, too.

so you get checksum error when you ping the interface address
of the cisco ?  is this consistent ?
you can run one test on the juniper where you perform an external
loopback between TX and RX and you ping your local interface
address with the bypass routing knob. This way you check if the
local PIC and/or forwarding path is working correct.


>I did check the MTUs but they are the same on the both ends. There are
>no other errors which could be the cause of this beaviour.
>The relevant counters on M10 look like this:
> > show interfaces ge-0/1/0 extensive
>Physical interface: ge-0/1/0, Enabled, Physical link is Up
>   Interface index: 14, SNMP ifIndex: 17, Generation: 13
>   Link-level type: Ethernet, MTU: 1518, Speed: 1000mbps, Loopback: Disabled,
>   MAC statistics:                      Receive         Transmit
>     Total octets                   49678735078      23364511178
>     Total packets                    264424668        266312599
>     Unicast packets                  259715065        265837157
>     Broadcast packets                      242            17960
>     Multicast packets                  4362526           457482
>     CRC/Align errors                         0                0
>     FIFO errors                              0                0
>     MAC control frames                       0                0
>     MAC pause frames                         0                0
>     Oversized frames                    346835
>     Jabber frames                            0
>     Fragment frames                          0
>     VLAN tagged frames               263506071
>     Code violations                          0
>Cisco just logs this:
>%MLS_STAT-SP-4-IP_CSUM_ERR: IP checksum errors
>The local Cisco support informed me that sometimes Juniper sends GigE
>packets too rapidly. I understood this so that sometimes the interval
>between two frames Juniper sends is shorter than the GigE specs allow.
>Is anyone able to confirm that information? I've no reason not to
>believe that, but I'm curious whether anyone else has encountered the
>same problem. Also, I'm very interested in finding a workaround.
>- Matti -
>juniper-nsp mailing list juniper-nsp at puck.nether.net

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