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Verify Interfaces
Purpose
From your network topology, determine the adjacent interfaces through which the LSP is meant to traverse, and examine the output for the encapsulation type, PPP options, FCS size, and whether keepalive frames are enabled or disabled
 | Note: Before you proceed with this step, check the physical layer to ensure that the problem is not in the physical layer. |
Action
To verify the functioning of adjacent interfaces, enter the following commands from the relevant routers:
user@host> show interfaces type-fpc/pic/port extensive user@host> show interfaces type-fpc/pic/port
Sample Output 1
user@R6> show interfaces so-0/0/3 extensive
Physical interface: so-0/0/3, Enabled, Physical link is Up
Interface index: 131, SNMP ifIndex: 27, Generation: 14
Link-level type: Cisco-HDLC , MTU: 4474, Clocking: Internal, SONET mode, Speed: OC3, Loopback: None,
FCS: 16 , Payload scrambler: Enabled
Device flags : Present Running
Interface flags: Link-Layer-Down Point-To-Point SNMP-Traps 16384
Link flags : Keepalives
Hold-times : Up 0 ms, Down 0 ms
Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3
Keepalive statistics:
Input : 0 (last seen: never)
Output: 357 (last sent 00:00:04 ago)
CoS queues : 4 supported
Last flapped : 2004-07-21 16:03:49 PDT (10w0d 07:01 ago)
Statistics last cleared: Never
Traffic statistics:
Input bytes : 203368873 0 bps
Output bytes : 186714992 88 bps
Input packets: 3641808 0 pps
Output packets: 3297569 0 pps
Input errors:
Errors: 0, Drops: 0, Framing errors: 0, Runts: 0, Giants: 0, Bucket drops: 0,
Policed discards: 1770, L3 incompletes: 0, L2 channel errors: 0, L2 mismatch timeouts: 0,
HS link CRC errors: 0, HS link FIFO overflows: 0
Output errors:
Carrier transitions: 1, Errors: 0, Drops: 0, Aged packets: 0, HS link FIFO underflows: 0,
MTU errors: 0
Queue counters: Queued packets Transmitted packets Dropped packets
0 best-effort 197012 197012 0
1 expedited-fo 0 0 0
2 assured-forw 0 0 0
3 network-cont 3100557 3100557 0
SONET alarms : None
SONET defects : None
SONET PHY: Seconds Count State
PLL Lock 0 0 OK
PHY Light 0 0 OK
SONET section:
BIP-B1 0 0
SEF 1 3 OK
LOS 1 1 OK
LOF 1 1 OK
ES-S 1
SES-S 1
SEFS-S 1
SONET line:
BIP-B2 0 0
REI-L 0 0
RDI-L 0 0 OK
AIS-L 0 0 OK
BERR-SF 0 0 OK
BERR-SD 0 0 OK
ES-L 1
SES-L 1
UAS-L 0
ES-LFE 0
SES-LFE 0
UAS-LFE 0
SONET path:
BIP-B3 0 0
REI-P 0 0
LOP-P 0 0 OK
AIS-P 0 0 OK
RDI-P 0 0 OK
UNEQ-P 0 0 OK
PLM-P 0 0 OK
ES-P 1
SES-P 1
UAS-P 0
ES-PFE 0
SES-PFE 0
UAS-PFE 0
Received SONET overhead:
F1 : 0x00, J0 : 0x00, K1 : 0x00, K2 : 0x00
S1 : 0x00, C2 : 0xcf, C2(cmp) : 0xcf, F2 : 0x00
Z3 : 0x00, Z4 : 0x00, S1(cmp) : 0x00
Transmitted SONET overhead:
F1 : 0x00, J0 : 0x01, K1 : 0x00, K2 : 0x00
S1 : 0x00, C2 : 0xcf, F2 : 0x00, Z3 : 0x00
Z4 : 0x00
Received path trace: R3 so-0/0/3
52 33 20 73 6f 2d 30 2f 30 2f 33 00 00 00 00 00 R3 so-0/0/3.. ...
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 0d 0a ................
Transmitted path trace: R6 so-0/0/3
52 36 20 73 6f 2d 30 2f 30 2f 33 00 00 00 00 00 R6 so-0/0/3 .....
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
HDLC configuration:
Policing bucket: Disabled
Shaping bucket : Disabled
Giant threshold: 4484, Runt threshold: 3
Packet Forwarding Engine configuration:
Destination slot: 0, PLP byte: 1 (0x00)
CoS transmit queue Bandwidth Buffer Priority Limit
% bps % bytes
0 best-effort 95 147744000 95 0 low none
3 network-control 5 7776000 5 0 low none
Logical interface so-0/0/3.0 (Index 71) (SNMP ifIndex 28) (Generation 16)
Flags: Device-Down Point-To-Point SNMP-Traps Encapsulation: Cisco-HDLC
Traffic statistics:
Input bytes : 406737746
Output bytes : 186714992
Input packets: 7283616
Output packets: 3297569
Local statistics:
Input bytes : 203368873
Output bytes : 186714992
Input packets: 3641808
Output packets: 3297569
Transit statistics:
Input bytes : 203368873 0 bps
Output bytes : 0 0 bps
Input packets: 3641808 0 pps
Output packets: 0 0 pps
Protocol inet, MTU: 4470, Generation: 46, Route table: 0
Flags: None
Addresses, Flags: Dest-route-down Is-Preferred Is-Primary
Destination: 10.1.36.0/30, Local: 10.1.36.2, Broadcast: 10.1.36.3, Generation: 38
Protocol iso, MTU: 4469, Generation: 47, Route table: 0
Flags: None
Protocol mpls, MTU: 4458, Generation: 48, Route table: 0
Flags: None
Sample Output 2
user@R3> show interfaces so-0/0/3
Physical interface: so-0/0/3, Enabled, Physical link is Up
Interface index: 131, SNMP ifIndex: 24
Link-level type: PPP , MTU: 4474, Clocking: Internal, SONET mode, Speed: OC3, Loopback: None, FCS: 16 ,
Payload scrambler: Enabled
Device flags : Present Running
Interface flags: Point-To-Point SNMP-Traps
Link flags : Keepalives
Keepalive settings: Interval 10 seconds, Up-count 1, Down-count 3
Keepalive: Input: 736827 (00:00:03 ago), Output: 736972 (00:00:05 ago)
LCP state: Opened
NCP state: inet: Opened, inet6: Not-configured, iso: Opened, mpls: Opened
CHAP state: Not-configured
CoS queues : 4 supported
Last flapped : 2004-07-21 16:08:01 PDT (10w5d 19:57 ago)
Input rate : 40 bps (0 pps)
Output rate : 48 bps (0 pps)
SONET alarms : None
SONET defects : None
Logical interface so-0/0/3.0 (Index 70) (SNMP ifIndex 51)
Flags: Point-To-Point SNMP-Traps Encapsulation: PPP
Protocol inet, MTU: 4470
Flags: None
Addresses, Flags: Is-Preferred Is-Primary
Destination: 10.1.36.0/30, Local: 10.1.36.1, Broadcast: 10.1.36.3
Protocol iso, MTU: 4470
Flags: None
Protocol mpls, MTU: 4458
Flags: None
Meaning
Sample Output 1 from egress router R6 shows that there are no SONET alarms or defects (none), the states are all OK, and the path trace shows the distant end (R3 so-0.0.0), indicating that the physical link is up. However, the logical link is down, and the link-level type is Cisco HDLC.
Sample Output 2 from transit router R3 shows that the link-level type is PPP, indicating that the encapsulation types are mismatched, resulting in the LSP going down.
