[c-nsp] Runts in the network

[Antonio Soares]

Thank you for your feedback. This is actually frame-relay. But your post made me think and i found this interesting statement:

"There is no commonly implemented minimum or maximum frame size for Frame Relay, although a network must support at least a
262-octet. Generally, each Frame Relay provider specifies an appropriate value for its network. Frame Relay DTE must allow the
maximum acceptable frame size to be configurable. The minimum frame size allowed for Frame Relay is five octets between the opening
and closing flags, assuming a two-octet Q.922 address field. This minimum increases to six octets for a three-octet Q.922 address
and to seven octets for a four-octet Q.922 address format." 

Source:

http://www.informit.com/library/content.aspx?b=Troubleshooting_Remote_Access&seqNum=119

Anynone knows what is the minimum frame size implemented by Cisco (cisco and ietf encapsulations) ?

Thanks.

Regards,
 
Antonio Soares, CCIE #18473 (R&S)
amsoares at netcabo.pt

-----Original Message-----
From: masood at nexlinx.net.pk [mailto:masood at nexlinx.net.pk] 
Sent: quarta-feira, 25 de Novembro de 2009 12:03
To: Antonio Soares
Cc: cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] Runts in the network

you know these are frames with a frame size between 8 and 63 bytes with a
valid CRC and no alignment errors. if this is the case, you may or may not
have a problem. depending on the type of equipment, the vendor maybe using
nonstandard frames. these frames are interpreted as runts. however, runts
may be caused by a malfunctioning interface.

in ATM cells have a 48 byte information field and a 5 byte header. This 53
byte cell falls within the definition of a under size packet and may be
counted as a runt.

find out what you have "a bad ethernet card or atm" :)

Regards,
Masood
Blog: http://weblog.com.pk/jahil/


>
> Any ideas how to troubleshoot this ?
>
> Thanks.
>
> Regards,
>
> Antonio Soares, CCIE #18473 (R&S)
> amsoares at netcabo.pt
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Antonio Soares
> Sent: terça-feira, 24 de Novembro de 2009 11:46
> To: cisco-nsp at puck.nether.net
> Subject: [c-nsp] Runts in the network
>
> Hello Group,
>
> I have 7200's acting as PE's and running 12.4.23 that show an abnormal
> numbers of runts. The interfaces where this can be seen are
> E1 channel-groups configured for frame-relay. This is the typical
> configuration:
>
> !
> frame-relay switching
> !
> controller E1 x/y
>  channel-group 0 timeslots 1-31
> !
> interface Serialx/y:0
>  encapsulation frame-relay
>  frame-relay traffic-shaping
>  frame-relay lmi-type ansi
>  frame-relay ip rtp header-compression
>  frame-relay intf-type dce
> !
> interface Serialx/y:0.100 point-to-point
>  ip vrf forwarding MY-VRF
>  ip address x.x.x.x x.x.x.x
>  ip rip advertise 10
>  frame-relay interface-dlci 100
>   class MY-CLASS
>  frame-relay ip rtp header-compression
> !
>
> The E1 is completely clean but the serial interface shows runts:
>
> ROUTER#sh int sx/y:0
> Serialx/y:0 is up, line protocol is up
> (...)
>      Received 0 broadcasts, 12 runts, 0 giants, 0 throttles
>      12 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
> (...)
> ROUTER#
>
> This happens everywhere in the network and there are many 7200's. The PA
> is the PA-MC-8TE1+.
>
> What could be the source of the problem ? I know what a runt is but i
> would like to understand why i have it all over the network.
>
>
>
> Thanks.
>
> Regards,
>
> Antonio Soares, CCIE #18473 (R&S)
> amsoares at netcabo.pt
>
>
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