[c-nsp] Giants and input errors but no MTU mismatch 7600-to-4948
Brian Turnbow
b.turnbow at twt.it
Thu Sep 20 03:28:01 EDT 2012
Hi,
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of John Neiberger
> Sent: mercoledì 19 settembre 2012 21:07
> To: Aaron
> Cc: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] Giants and input errors but no MTU mismatch 7600-to-
> 4948
>
> We're not doing any q-in-q or mpls. There is nothing unusual about this
> config at all. I'm stumped! To make matters even more entertaining, I just
> checked the other switch in this pair of
> switches:
>
> 0 runts, 1894463 giants, 0 throttles
> 1894463 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
>
> That switch has the exact same trunk connection to a different 7600 and it
> is also seeing input errors. I'm starting to think it's a bug in the 4948
> code and maybe it's just misreporting somehow. It's very strange.
Actually it is a recurring "feature" that shows up from time to time in various platforms/versions. Years ago it was fairly common.
Since you are tagging on the interface you are exceeding the 1518 ethernet mtu hence it reports an error.
As you are not dropping (except for the overruns) It is just cosmetic.
You can try and raise the MTU settings, or look to see if there is a bug on bug tracker matching your version.
Regards
Brian
>
>
> On Wed, Sep 19, 2012 at 12:30 PM, Aaron <aaron1 at gvtc.com> wrote:
> > Would double tagging (qnq) sitting atop g3/3 (service instances or
> > svi's) cause this? Or mpls-enabled svi's sitting on top of g3/3 perhaps
> ?
> > (brainstorming as I'm not sure what to make of it)
> >
> > Aaron
> >
> >
> > -----Original Message-----
> > From: cisco-nsp-bounces at puck.nether.net
> > [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of John Neiberger
> > Sent: Wednesday, September 19, 2012 12:20 PM
> > To: cisco-nsp at puck.nether.net
> > Subject: [c-nsp] Giants and input errors but no MTU mismatch
> > 7600-to-4948
> >
> > I have an interface on a 4948 that is reporting increasing giants and
> > input errors. The MTU is the default 1500 and so is the interface on
> > the other side of the link. This is a dot1q trunk, if that is relevant.
> >
> > 7600 Side:
> >
> > GigabitEthernet3/3 is up, line protocol is up (connected)
> > Hardware is C6k 1000Mb 802.3, address is 7081.058f.471e (bia
> > 7081.058f.471e)
> > MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
> > reliability 255/255, txload 6/255, rxload 6/255
> > Input queue: 0/2000/15/0 (size/max/drops/flushes); Total output drops:
> > 52636
> > Queueing strategy: fifo
> > Output queue: 0/40 (size/max)
> > 30 second input rate 25560000 bits/sec, 3911 packets/sec
> > 30 second output rate 25889000 bits/sec, 2481 packets/sec
> > 103422624782 packets input, 96894603872012 bytes, 0 no buffer
> > Received 421340 broadcasts (390040 multicasts)
> > 0 runts, 0 giants, 0 throttles
> > 0 input errors, 0 CRC, 0 frame, 15 overrun, 0 ignored
> > 0 watchdog, 0 multicast, 0 pause input
> > 0 input packets with dribble condition detected
> >
> > 4948 Side:
> >
> > GigabitEthernet1/46 is up, line protocol is up (connected)
> > Hardware is Gigabit Ethernet Port, address is e05f.b919.522d (bia
> > e05f.b919.522d)
> > MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
> > reliability 255/255, txload 6/255, rxload 7/255
> > Last input 00:00:00, output never, output hang never
> > Last clearing of "show interface" counters never
> > Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops:
> 0
> > Queueing strategy: fifo
> > Output queue: 0/40 (size/max)
> > 5 minute input rate 27555000 bits/sec, 2622 packets/sec
> > 5 minute output rate 25030000 bits/sec, 3827 packets/sec
> > 103432206170 packets input, 100545576069607 bytes, 0 no buffer
> > Received 401659764 broadcasts (377463573 multicasts)
> > 0 runts, 1892602 giants, 0 throttles
> > 1892602 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
> > 0 input packets with dribble condition detected
> >
> > Any idea how I could be getting giants inbound to the 4948 when the
> > interface on the 7600 is set to 1500? I could see it if both sides
> > were not set to dot1q, but they are:
> >
> > Gi3/3 on 802.1q trunking 1
> >
> > Gi1/46 on 802.1q trunking 1
> >
> > What in the world is going on here?
> > _______________________________________________
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> >
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