CBS220: Reporting Oversized Packets on all Trunk ports

[dialsc]

Hi

I just got this CBS220-24T-4G V02 a hand full of weeks ago and I'm struggling a bit with this device. My today's topic is the Oversized Packets reported under "Status and Statistics/Etherlike".

I got a couple of interfaces configured in VLAN trunk mode. These are individuals/physicals as well as one link aggregation of two physical ports. All these ports, the ones having the vlan trunk configured directly on them, the link aggregation being configured in VLAN trunk mode, even the "raw" physical ports being part of the link aggregation reporting Oversized Packets.

This happens if a package is being forwarded which has a length of 1514 byte, e.g. by sending pings filling the whole MTU of 1500.

These packages are not getting dropped and it looks like everything is working fine beside the fact of seeing them being reported as oversized.

On the other hand, running the same tests with e.g. ping on ports in VLAN access mode, not a single Oversize Packets entry gets reported there.

It very well might be that I just do not understand the whole thing but this looks very strange to me. I investigated deeply, even tracing the network traffic with WireShark, comparing the tests agains trunk and access mode ports. I did not find any differences in those test because, of course, there aren't any. I somehow have the feeling that there is a bug in the firmware. BTW: Im running the latest one on this switch which is 2.0.1.9.

So, anybody out there being able to tell me about the missing link or maybe from Cisco if this acctually might be a bug?

Best,

dialsc

[nashkaminski]

Yes, I see this exact same behavior. Sending full-size (1514 byte) frames which ingress the switch with a 802.1Q VLAN tag present appear to be counted as oversize but are forwarded without any loss.

Hardware is a CBS220-24FP-4X V01 in my case running the same 2.0.1.9 firmware

Seems like a (cosmetic) bug in the CBS220 software to me as I would expect the oversize check to be applied after removal of the VLAN tag.

[Jitendra Kumar]

Here is the troubleshooting Guide.

https://gzhls.at/blob/ldb/7/b/a/d/1a91d8f5204aaaff39026d9ed3a2178cba63.pdf

[Jitendra Kumar]

below make sense for you ?

Etherlike
The Etherlike page displays statistics per port according to the Etherlike MIB standard definition. The refresh
rate of the information can be selected. This page provides more detailed information regarding errors in the
physical layer (Layer 1) that might disrupt traffic.
To view Etherlike Statistics and/or set the refresh rate follow these steps:
Step 1 Click Status and Statistics > Etherlike.
Step 2 Enter the parameters.
• Interface-Select the specific interface for which Ethernet statistics are to be displayed.
• Refresh Rate-Select the amount of time that passes before the Etherlike statistics are refreshed.
The fields are displayed for the selected interface.
• Frame Check Sequence (FCS) Errors - Received frames that failed the CRC (cyclic redundancy checks).
• Single Collision Frames- Frames that involved in a single collision, but successfully transmitted.
• Late Collisions - Collisions that have been detected after the first 512 bits of data.
• Excessive Collisions - TRansmissions rejected due to excessive collisions.
• Oversize Packets - Packets greater than 2000 octets received.
• Internal MAC Receive Errors - Frames rejected because of receiver errors.
• Pause Frames Received - Received flow control pause frames. This field is only supported XG ports. When the port
speedis 1 G, the received pause frames counter is not operational.
Note If one of the fields listed above shows a number of errors (not 0), a Last Up time is displayed.
Step 3 To view statistics counters in table view, click View All Interfaces Statistics to see all ports in table view. You can also
click Refresh to refresh the stats or click Clear Interface Counters to clear the counters.

[nashkaminski]

I proceeded to raise a support case regarding this and this has been confirmed to be a bug and is assigned Cisco bug ID CSCwc58954.

[nattawat1]

i have problem about packete loss on trunk port. CBS220-24FP-4G firmware to 2.0.1.9 

i'am try check error but not show .

[schuladmin]

Hello,

got a bunch of CBS220-24P-4X switches an all Trunk-Ports do count giants packages. Same like DIALSC mentioned.
My switches are on 2.0.2.14 firmware. Can someone help to get around this?

There is a Bug-Report CSCwc58954 but there is no fix for it.
Any help is welcome

Regards Schuladmin