Dear All,
I have seen an error in GRE configured between two routers over WAN. i am monitoring the WAN link and GRe tunnel via WhatsupGold NMS and it reported that Gre tunnel having packet loss sometimes and this time it affects the services and traffic passing over tunnel.
sh int t101 shows output drops . is that the problem ? i have read that i have to adjust MTC size but i tried to change the tunnel MTU to 1400 but still sh int t101 shows MTU as 1514 ? What could be the problem of output drops in my tunnel link. this is only error i am seeing .
SiteA #sh int t101
Tunnel101 is up, line protocol is up
Hardware is Tunnel
Description: Internet address is 172.18.1.1/30
MTU 1514 bytes, BW 2048 Kbit/sec, DLY 500000 usec,
reliability 255/255, txload 1/255, rxload 5/255
Encapsulation TUNNEL, loopback not set
Keepalive set (60 sec), retries 2
Tunnel source 172.16.172.82, destination 172.31.186.254
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255
Fast tunneling enabled
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 1w4d
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 179
Queueing strategy: fifo
Output queue: 0/0 (size/max)
5 minute input rate 48000 bits/sec, 13 packets/sec
5 minute output rate 0 bits/sec, 1 packets/sec
11172631 packets input, 2233002357 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
1663202 packets output, 148126571 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
SiteB#sh int t101
Tunnel101 is up, line protocol is up
Hardware is Tunnel
Description: Internet address is 172.18.1.2/30
MTU 1514 bytes, BW 2048 Kbit/sec, DLY 500000 usec,
reliability 255/255, txload 5/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive set (60 sec), retries 2
Tunnel source 172.31.186.254, destination 172.16.172.82
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255
Fast tunneling enabled
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input 00:00:02, output 00:00:02, output hang never
Last clearing of "show interface" counters 7w6d
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/0 (size/max)
5 minute input rate 1000 bits/sec, 1 packets/sec
5 minute output rate 46000 bits/sec, 19 packets/sec
31399204 packets input, 2675546039 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
347796910 packets output, 1364546113 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
