CCIE - PVC Status

Author

PVC Status

tan.phan

2002-04-04, 1:13 pm

If a sub-interface point-to-point frame relay circuit is administratively shutdown, what should the PVC status be?

Any idea?

I got a live one here...

Yeti-GBR1

2002-04-04, 3:20 pm

This may help: actually this will not help...it's not a sub-int dam

R1>sh frame pvc

PVC Statistics for interface Serial1 (Frame Relay DTE)

Active Inactive Deleted Static
Local 1 0 0 0
Switched 0 0 0 0
Unused 0 0 0 0

DLCI = 150, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1

input pkts 27681 output pkts 27772 in bytes 3194624
out bytes 2102890 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 27762 out bcast bytes 2101850
pvc create time 1w1d, last time pvc status changed 1w1d
R1>en
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int s1
R1(config-if)#shut
R1(config-if)#
1w1d: %LINK-5-CHANGED: Interface Serial1, changed state to administratively down

1w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to
down
R1(config-if)#
R1#
1w1d: %SYS-5-CONFIG_I: Configured from console by console
R1#sh frame pvc

PVC Statistics for interface Serial1 (Frame Relay DTE)

Active Inactive Deleted Static
Local 0 0 1 0
Switched 0 0 0 0
Unused 0 0 0 0

DLCI = 150, DLCI USAGE = LOCAL, PVC STATUS = DELETED, INTERFACE = Serial1

input pkts 27682 output pkts 27773 in bytes 3194740
out bytes 2102966 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 27763 out bcast bytes 2101926
pvc create time 1w1d, last time pvc status changed 00:00:07

R1#sh frame lmi

LMI Statistics for interface Serial1 (Frame Relay DTE) LMI TYPE = CISCO
Invalid Unnumbered info 0 Invalid Prot Disc 0
Invalid dummy Call Ref 0 Invalid Msg Type 0
Invalid Status Message 0 Invalid Lock Shift 0
Invalid Information ID 0 Invalid Report IE Len 0
Invalid Report Request 0 Invalid Keep IE Len 0
Num Status Enq. Sent 76956 Num Status msgs Rcvd 76954
Num Update Status Rcvd 0 Num Status Timeouts 2
R1#
R1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R1(config)#int s1
R1(config-if)#no shut
R1(config-if)#
1w1d: %LINK-3-UPDOWN: Interface Serial1, changed state to up
1w1d: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to
up
R1(config-if)#
R1#conf t
1w1d: %SYS-5-CONFIG_I: Configured from console by console
R1#sh frame lmi

LMI Statistics for interface Serial1 (Frame Relay DTE) LMI TYPE = CISCO
Invalid Unnumbered info 0 Invalid Prot Disc 0
Invalid dummy Call Ref 0 Invalid Msg Type 0
Invalid Status Message 0 Invalid Lock Shift 0
Invalid Information ID 0 Invalid Report IE Len 0
Invalid Report Request 0 Invalid Keep IE Len 0
Num Status Enq. Sent 76957 Num Status msgs Rcvd 76956
Num Update Status Rcvd 0 Num Status Timeouts 2
R1#
R1#sh frame pvc

PVC Statistics for interface Serial1 (Frame Relay DTE)

Active Inactive Deleted Static
Local 1 0 0 0
Switched 0 0 0 0
Unused 0 0 0 0

DLCI = 150, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial1

input pkts 27684 output pkts 27776 in bytes 3194886
out bytes 2103152 dropped pkts 0 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 27766 out bcast bytes 2102112
pvc create time 1w1d, last time pvc status changed 00:00:53
R1#

Yeti-GBR1

2002-04-04, 3:25 pm

I suppose it would make little difference if its an interface or a sub-interface....It would still show it as being deleted in the sh frame pvc command.

tan.phan

2002-04-04, 4:15 pm

Thanks for your insight but I think there are differences between interface and sub interface. Check this out! This config is from a live choke router at my job. The sub interface is shutdown but pvc status shown active.

I wonder because it's dynamically mapped...if so a router reboot should fix it...but I can't just reboot the router...RIGHT?

Another possible explanation is the router doesn't send LMI to the FR switch per sub interface. Therefore even when a sub interface is shutdown, the router still send LMI inquiry to the FR switch via the serial interface. Does this made any sense?

Now sure (I hate that word) if I shutdown the serial interface then every sub interface PVC status should read "Inactive". Right?

interface Serial2/0.4 point-to-point
description xyz
bandwidth 1536
ip address 10.0.0.1 255.255.255.252
no ip directed-broadcast
no ip route-cache
no ip mroute-cache
shutdown
frame-relay interface-dlci 103 IETF

7200#sh frame-relay pvc 103

PVC Statistics for interface Serial2/0 (Frame Relay DTE)

DLCI = 103, DLCI USAGE = LOCAL, PVC STATUS = ACTIVE, INTERFACE = Serial2/0.4

input pkts 714761 output pkts 972 in bytes 66435863
out bytes 58154 dropped pkts 713638 in FECN pkts 0
in BECN pkts 0 out FECN pkts 0 out BECN pkts 0
in DE pkts 0 out DE pkts 0
out bcast pkts 28 out bcast bytes 7630
pvc create time 8w1d, last time pvc status changed 5w2d

7200#sh frame-relay lmi

LMI Statistics for interface Serial2/0 (Frame Relay DTE) LMI TYPE = ANSI
Invalid Unnumbered info 0 Invalid Prot Disc 0
Invalid dummy Call Ref 0 Invalid Msg Type 0
Invalid Status Message 0 Invalid Lock Shift 0
Invalid Information ID 0 Invalid Report IE Len 0
Invalid Report Request 0 Invalid Keep IE Len 0
Num Status Enq. Sent 497952 Num Status msgs Rcvd 497945
Num Update Status Rcvd 0 Num Status Timeouts 7

doctorcisco

2002-04-04, 7:44 pm

If you shut down the subinterface, the PVC status remains active, because "Active, Inactive, Deleted" information comes from the frame relay switch in LMI frames. The router is just repeating what the frame switch tells it. (By contrast, "Local, Switched, Unused" are local to the router.) (In recent IOS's, you can use "frame-relay end-to-end keepalive" to make these status messages less reliant on sometimes false information from the frame switch).

Your PVC shows active because the frame relay switch is sending LMI to the router, and the LMI frames are telling the router that the PVC is up and working.

"Inactive" and "Deleted" mean something is wrong with the PVC itself.

"Inactive" means the frame switch has a PVC with that DLCI configured, but there is some problem with the PVC beyond the local switch.

"Deleted" means the frame relay switch has sent the router has no current information at all about this PVC. This either means the PVC isn't configured on the frame switch, or your physical circuit is down and there's no LMI coming in at all.

Shutting down the physical interface will make all the PVC's go deleted, *because that makes LMI go down.* The remote ends of those PVC's would show inactive, because the frame relay switches know when LMI goes down on their ports.

HTH,
doctorcisco

Yankee

2002-04-05, 5:47 am

Now that's a good answer Doc! Welcome back

Yankee

Yeti-GBR1

2002-04-05, 6:21 am

Cheers Doc for enlightening us...oh my have I got a long long way to go to the CCIE...

Yeti-GBR1

2002-04-05, 6:29 am

Ok then I have some questions:

Assuming that there is something wrong with the PVC i.e its in a deleted or inactive state. What could cause this?

Options (IMHO):

A. Frame Switch is FUBAR'd or someone powered it off

B. The interfaces are FUBAR'd or someones shut it/them down

Other than that what else could there be?

1. DCE clocking at the wrong freq, as long as it has a clocking freq it should make no odds?
2. Wrong DLCI assigned (but this would manifest itself in a different way, since it would not work from the start)?

Any and all thoughts would be appreciated.

tan.phan

2002-04-05, 9:03 am

quote:
Originally posted by doctorcisco

Your PVC shows active because the frame relay switch is sending LMI to the router, and the LMI frames are telling the router that the PVC is up and working.
HTH,
doctorcisco

So what you are saying here is the router send LMI inquiry to frame switch via the serial interface not the sub-interface. This explained why PVC status for shutdown sub-interface shown Active (given that DLCIs in the cloud are mapped to local DLCIs). Another word router doesn't send LMI inquiry on a sub-interface basis.

doctorcisco

2002-04-05, 9:48 pm

quote:
Originally posted by tan.phan

Another word router doesn't send LMI inquiry on a sub-interface basis.

Correct, and more importantly, the frame relay switch has no idea how you configure things on your router. If it sees good LMI from your equipment (which as you note is dependent on the physical interface being up), and believes that the PVC is good at the other end, it doesn't know or care about anything else.

doc

Yankee

2002-04-06, 5:36 am

To further the point just a bit. If you have access to a frame circuit do a "debug frame lmi". You will see the PVCs reported by physical interface and if the frame switch has a PVC configed that your router does not have a subinterface built for. The frame switch will report it going to the physical interface.

If you stop and think it makes sense because those PVCs are built to ride on the T1 connected to that physical interface.

Yankee

doctorcisco

2002-04-07, 8:25 pm

And by the by, good to see ya again, Yankee. The job market has let me down again ... time to get serious about this certification stuff!

doc

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