Relationship between xmit/255 and tmit/255 on sub-interfaces

Unanswered Question
Aug 6th, 2007
User Badges:

Can someone help me interpret the "txload" and "rxload" values for sub-interfaces in the "show interface x/y.z CLI output?

In this example below we have a main interface frame circuit with 256K of bandwidth and then a sub-interface with a 16K PVC. I'm pretty sure that I need to look at the "txload" and "rxload" from the sub-interface output and correlate that to the main interface, not the sub-interface? As I recall, the sub-iface output can deceive the unwary.


Router#show int Serial3/3.131

Serial3/3.131 is up, line protocol is up

Hardware is M8T-V.35


Internet address is x.x.x.x/30

MTU 1500 bytes, BW 16 Kbit, DLY 20000 usec,

reliability 255/255, txload 8/255, rxload 6/255

Encapsulation FRAME-RELAY IETF


Router#show int s3/3

Serial3/3 is up, line protocol is up

Hardware is M8T-V.35

Description: 256K Circuit

MTU 1500 bytes, BW 256 Kbit, DLY 20000 usec,

reliability 255/255, txload 8/255, rxload 6/255

Encapsulation FRAME-RELAY IETF, crc 16, loopback not set

Keepalive set (10 sec)

Restart-Delay is 0 secs

LMI enq sent 512784, LMI stat recvd 512782, LMI upd recvd 0, DTE LMI up

LMI enq recvd 0, LMI stat sent 0, LMI upd sent 0

LMI DLCI 0 LMI type is ANSI Annex D frame relay DTE

FR SVC disabled, LAPF state down

Broadcast queue 0/64, broadcasts sent/dropped 1364392/0, interface broadcasts 1108253

Last input 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 8w3d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 104

Queueing strategy: weighted fair

Output queue: 0/1000/64/91 (size/max total/threshold/drops)

Conversations 0/254/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

Available Bandwidth 192 kilobits/sec

5 minute input rate 7000 bits/sec, 10 packets/sec

5 minute output rate 9000 bits/sec, 10 packets/sec

32559938 packets input, 3385652823 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

1495 input errors, 1476 CRC, 0 frame, 11 overrun, 0 ignored, 8 abort

33710499 packets output, 1912238829 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

74 carrier transitions DCD=up DSR=up DTR=up RTS=up CTS=up


  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
wochanda Mon, 08/06/2007 - 16:56
User Badges:
  • Silver, 250 points or more

The txload and rxload under the subinterface simply copies the information from the main interface. There isn't any real straightforward way to calculate these values relevant to only the subinterface.

These aren't exactly the numbers you want to look at to figure out how loaded your FR interface is. If you want to look at rates, you can do a 'show frame-relay pvc ', which will show you 5-minute input and output rates for that VC.

By default, the txload and rxload aren't used for anything. They are calculated and put in the 'show interface' output in the event you choose to use them in your EIGRP calculations by changing the defaults for your K values.

spremkumar Mon, 08/06/2007 - 19:48
User Badges:
  • Red, 2250 points or more


In addition to William's comments the bandwidth parameter under the interface in general is being used by OSPF to calculate its metric or cost.


Nova Tue, 08/07/2007 - 04:50
User Badges:

Well that's disappointing as I'd have to believe that there is a way to get a snapshot of PVC utiliz at the CLI. From my output I get a byte count but not any rate information.

show frame-relay pvc 131

PVC Statistics for interface Serial3/3 (Frame Relay DTE)


input pkts 78504 output pkts 117458 in bytes 6594630

out bytes 52920843 dropped pkts 0 in pkts dropped 0

out pkts dropped 0 out bytes dropped 0

in FECN pkts 0 in BECN pkts 0 out FECN pkts 0

out BECN pkts 0 in DE pkts 112 out DE pkts 0

out bcast pkts 0 out bcast bytes 0

pvc create time 20w5d, last time pvc status changed 12w5d


This Discussion