I've created a Tunnel between a Cisco 2811 router and a Switch 6509, the tunnel works fine. However, I would like to run Multicast down this tunnel to avoid using a non-supported 3rd party network device that doesn't support multicast. Some of the multicast packets are above 1500 bytes. I would like figure out why the 6509 tunnel does not support frame sizes over 1500 bytes and the 2811 router does. I have applied ip mtu 1576 but this does not really come into play as the packets are UDP. problems seen below:
See the difference with MTU sh int tunnel1 - why is this
Switch config (s72033_rp-IPSERVICESK9-M), Version 12.2(18)SXF13)
interface Tunnel1
ip address 10.210.183.14 255.255.255.252
ip mtu 1576
ip pim sparse-mode
keepalive 2 3
tunnel source Loopback2
tunnel destination 10.210.183.254
end
Routers config (C2800NM-IPBASEK9-M), Version 12.4(24)T3)
interface Tunnel1
ip address 10.210.183.13 255.255.255.252
ip mtu 1576
ip pim sparse-mode
keepalive 2 3
tunnel source Loopback2
tunnel destination 10.210.183.250
end
SWITCH TUNNEL#sh int tun1
Tunnel1 is up, line protocol is up
Hardware is Tunnel
Internet address is 10.210.183.14/30
MTU 1514 bytes, BW 9 Kbit, DLY 500000 usec,
reliability 255/255, txload 1/255, rxload 28/255
Encapsulation TUNNEL, loopback not set
Keepalive set (2 sec), retries 3
Tunnel source 10.210.183.250 (Loopback2), destination 10.210.183.254, fastswitch TTL 255
Tunnel protocol/transport GRE/IP, key disabled, sequencing disabled
Tunnel TTL 255
Checksumming of packets disabled, fast tunneling enabled
Last input 00:00:10, output 00:00:00, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1
Queueing strategy: fifo
Output queue: 0/0 (size/max)
5 minute input rate 1000 bits/sec, 1 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
L2 Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes
L3 in Switched: ucast: 0 pkt, 0 bytes - mcast: 0 pkt, 0 bytes mcast
L3 out Switched: ucast: 0 pkt, 0 bytes mcast: 17786 pkt, 1386206 bytes
459623 packets input, 40759994 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
287693 packets output, 77721813 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
ROUTER TUNNEL#sh int tun0
Tunnel0 is up, line protocol is up
Hardware is Tunnel
Internet address is 10.210.183.5/30
MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation TUNNEL, loopback not set
Keepalive set (2 sec), retries 3
Tunnel source 10.210.183.254 (Loopback2), destination 10.210.183.249
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255
Fast tunneling enabled
Tunnel transport MTU 1576 bytes
Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)
Last input 00:00:06, output 00:00:01, output hang never
Last clearing of "show interface" counters never
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 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
12914 packets input, 704198 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
12981 packets output, 728594 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
