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New Member

T1 encapsulation

Hi, I have T1 connected to the internet, but for some reason the encapsulation is set for frame relay. I find this unusual since it is not connecting to any other branches. I am asking this because I find this T1 connection kind of slow and I wonder if this T1 is dropping frames due to the CIR. I am new to the company so I don't know the history why was it done that way. Shouldn't I switch this T1 to PPP or HDLC? Any help would be appriciated. Thanks

Hall of Fame Super Gold

Re: T1 encapsulation


likely you can't just switch switch to PPP or HDLC.

This is because you ISP is giving you service over FR, they do so for saving on both leased circuits, and router ports (they are aggregating multiple customers over a single router interface).

You may find that using a dedicated line may have you incur in higher charges.

Hall of Fame Super Silver

Re: T1 encapsulation


Am I correct in understanding your message that traffic is flowing over this link - but slowly? If so then whatever is connected to the other end of the link is running Frame Relay encapsulation. If you change your end to HDLC or to PPP and the other end does not change then there will be NO traffic flowing over the link.

It might be interesting to see the output of show frame pvc so we could understand better what is running on the link.



New Member

Re: T1 encapsulation

Yes I do understand that the link will go down if the encap. does not match at the other side. This T1 is connected to the internet and not to any of my other branches.

Here are the outputs: Thanks again!!!!

show frame relay pvc

PVC Statistics for interface Serial0/3/0 (Frame Relay DTE)

Active Inactive Deleted Static

Local 1 0 0 0

Switched 0 0 0 0

Unused 0 0 0 0


input pkts 6520966 output pkts 8058527 in bytes 3510575659

out bytes 2545960682 dropped pkts 0 in pkts dropped 0

out pkts dropped 0 out bytes dropped 0

in FECN pkts 589681 in BECN pkts 0 out FECN pkts 0

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

out bcast pkts 0 out bcast bytes 0

5 minute input rate 399000 bits/sec, 42 packets/sec

5 minute output rate 35000 bits/sec, 27 packets/sec

pvc create time 18w3d, last time pvc status changed 18w3d


show frame relay traffic

VSA-2851-13#show frame-relay traffic

Frame Relay statistics:

ARP requests sent 0, ARP replies sent 0

ARP request recvd 0, ARP replies recvd 0

VSA-2851-13#show int s 0/0/0

Serial0/0/0 is up, line protocol is up

Hardware is GT96K with integrated T1 CSU/DSU

MTU 4470 bytes, BW 1544 Kbit, DLY 20000 usec,

reliability 255/255, txload 192/255, rxload 237/255

Encapsulation FRAME-RELAY IETF, loopback not set

Keepalive set (10 sec)

LMI enq sent 51036, LMI stat recvd 51036, LMI upd recvd 0, DTE LMI up

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

LMI DLCI 1023 LMI type is CISCO frame relay DTE

FR SVC disabled, LAPF state down

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

Last input 00:00:08, output 00:00:08, output hang never

Last clearing of "show interface" counters 5d21h

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 8

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 1437000 bits/sec, 172 packets/sec

5 minute output rate 1168000 bits/sec, 195 packets/sec

20788541 packets input, 18595317 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

18408432 packets output, 3368921077 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

Hall of Fame Super Silver

Re: T1 encapsulation


Thanks for posting the additional output. This clearly shows an active Frame Relay link, with 1 active PVC, and 1 active subinterface (which was not mentioned in previous posts). As currently configured it is working. and the receive load

reliability 255/255, txload 192/255, rxload 237/255

may help explain why it is a bit slow. It appeaers to be getting close to being saturated.

If you want to change it from Frame Relay to HDLC or PPP then you would need to request from whoever provides the line that they change their end. You might find that the pricing for an HDLC service or a PPP service would be different from the pricing of the Frame Relay service.



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