Difference between Bandwidth and Tunnel Transmit/Receive Bandwidth

[Jay Joshi]

Hello, 


Can someone please assist me in understanding the difference between Bandwidth of a

GRE/VTI Tunnel vs the tunnel transmit/receive

bandwidth. 

Here is the output for command

show interfaces tunnel1

 

Tunnel1 is up, line protocol is up 
Hardware is Tunnel
Internet address is X
MTU 17916 bytes, BW 100 Kbit/sec, DLY 50000 usec, 
reliability 255/255, txload 255/255, rxload 255/255
Encapsulation TUNNEL, loopback not set
Keepalive set (5 sec), retries 3
Tunnel source X (Loopback0), destination X
Tunnel Subblocks:
src-track:
Tunnel1 source tracking subblock associated with x
Set of tunnels with source x, 2 members (includes iterators), on interface <OK>
Tunnel protocol/transport GRE/IP
Key disabled, sequencing disabled
Checksumming of packets disabled
Tunnel TTL 255, Fast tunneling enabled
Path MTU Discovery, ager 10 mins, min MTU 92
Tunnel transport MTU 1476 bytes
Tunnel transmit bandwidth 8000 (kbps)
 Tunnel receive bandwidth 8000 (kbps)
Last input 4w4d, output never, output hang never
Last clearing of "show interface" counters 40w0d
Input queue: 0/375/0/0 (size/max/drops/flushes); Total output drops: 12894
Queueing strategy: fifo
Output queue: 0/0 (size/max)
30 second input rate 1610000 bits/sec, 1547 packets/sec
30 second output rate 2610000 bits/sec, 1774 packets/sec
26576029373 packets input, 4608367508280 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
34408453207 packets output, 5582525345540 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out

Thanks much in advance

[Julio E. Moisa · Accepted solution]

Hi

These commands: 

Tunnel transmit bandwidth 8000 (kbps)
Tunnel receive bandwidth 8000 (kbps)

Are used to specify the bandwidth value to be used to receive or send packets through the tunnel only. Default is 8000 Kbps.

The bandwidth (BW) command line of a tunnel is not used to allow more bandwidth for packets indeed it is used by protocols like EIGRP, OSPF to calculate metrics. For example interface loopbacks has bandwidth values, If Im not wrong they have 5000 Kbps. 

 :-)

[Jay Joshi]

Thank you Very much for explanation

[Julio E. Moisa]

Hi

It was a pleasure, have a great day!

:-)

[paul driver · Accepted solution]

Hello

Not sure why the tunnel Bw is set so low on these interfaces as the actual BW usage is taken from the physical interfaces the tunnels are tried to.

My understanding of this default value is it can be and is recommended to be change to properly reflect the true BW rate of your physical links so it can be used in-conjunction with dynamic routing protocol metrics such as opsf/eigrp for path calculation

res
Paul

[Jay Joshi]

Thanks very much Paul. This helps