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show serial interface - explanation


I have T1 link to internet on my 3640 route. It is configured with all time slots 1-24. Upon looking at show interface output, it says the "Available Bandwidth 1152 kilobits/sec". What could be the reason.

My serial interace config and show interface output are as per below.

I am curious to know the reason and want to make sure if I have full T1.

thanks and regards



EG624BGR#sh inter ser 0/0

Serial0/0 is up, line protocol is up

Hardware is QUICC with integrated T1 CSU/DSU

Description: Internet connection to AT&T - ckt id xxxx

Internet address is xx.xx.xx.xx/30

MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,

reliability 255/255, txload 15/255, rxload 184/255

Encapsulation PPP, loopback not set

Keepalive set (10 sec)

LCP Open

Open: IPCP

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

Last clearing of "show interface" counters 6d23h

Input queue: 0/75/1738/0 (size/max/drops/flushes); Total output drops: 315

Queueing strategy: weighted fair

Output queue: 0/1000/64/315 (size/max total/threshold/drops)

Conversations 0/158/256 (active/max active/max total)

Reserved Conversations 0/0 (allocated/max allocated)

**** Available Bandwidth 1152 kilobits/sec ****

5 minute input rate 1111000 bits/sec, 136 packets/sec

5 minute output rate 92000 bits/sec, 88 packets/sec

40097316 packets input, 3009557303 bytes, 0 no buffer

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

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

39033933 packets output, 726165775 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=up DSR=up DTR=up RTS=up CTS=up


interface Serial0/0

description Internet connection to AT&T - ckt id DHEC538546

ip address xx.xx.xx.xx

ip access-group worm in

no ip redirects

ip accounting output-packets

encapsulation ppp

no ip mroute-cache

service-module t1 timeslots 1-24

no cdp enable


Accepted Solutions
New Member

Re: show serial interface - explanation

as per bandwidth calculations you are getting same bandwidth what you have taken..

184*1536/255 = 5 minute input rate 1111000 bits/sec

15*1536/255 = 5 minute output rate 92000 bits/sec

New Member

Re: show serial interface - explanation

Thanks for responding.

I think, your calulation translates the two different type of same value. And that matches as expected. What i am thinking is, why it says "Available Bandwidth 1152 kilobits/sec" instead of T1 bw i.e.1536kb.

The no. 1152 translates to 18 timeslots (64 x 18 = 1152). So i am thinking if the provider has only configured 18 timeslots instead of 24 at their end.




New Member

Re: show serial interface - explanation

thanks for the post. This explains and clears my question exactly.




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