Tunnel Interface

[ajf303]

                   Hi,

Any one will explain brief about the following tunnel interface conf.

interface Tunnel0

  bandwidth 6144

ip address XX.XX.XX.XX XX.XX.XX.XX

ip mtu 1514

ip load-sharing per-packet

delay 3

keepalive 3 3

tunnel source XX.XX.XX.XX

tunnel destination XX.XX.XX.XX

Thx.

Franco

[paul driver]

Hello

interface Tunnel0- This is a logical GRE interface  -  ( used to encrypt specific traffic over ip network)

bandwidth 6144-  Sets the BW value for route metric calculations for dynamic routing protocols

ip address XX.XX.XX.XX XX.XX.XX. -  ip address of the tunnel

ip mtu 1514- set maximum transmission value to accommodate the extra over head of the gre tunnel- this should be a lower value of 1500 ( 1400 is preferred) so not to produce fragmentation

ip load-sharing per-packet -ip cef per-packet load-sharing -- usually default is per destination

delay 3 -applicable for eigrp which is used to calculate a composite metric for best path

keepalive 3 3-  keepalives are sent every 3 seconds to check if the destination address is active, with a value to check 3 times if any of the hellos are missed.

tunnel source XX.XX.XX.XX - physical interface of the source address -- this should have connectivity to the destination address

tunnel destination XX.XX.XX.XX - physical interface of the destination address -- this should have connectivity to the source address

res

Paul

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Thanks.

[ajf303]

Thanks.

few question about that,

      1,in case if there in no  bandwidth command (default) what will be the calculation for dynamic routing protocol.Is it must for all routing protocols?

     2. would you explain with one example for "ip mtu"

     3. if there is no tunnel source and distination configuration in tunnel interface. will tunnel establish and how the date flow would be..?

[paul driver · Accepted solution]

Hello

1 No, you can leave it to the default which is (8mbps) this command is solely used for route metric calculation with dynamic routing protocols it has no effect on the actual BW that traverses the physical links.

  2.  Please look at this url -http://www.cisco.com/en/US/tech/tk827/tk369/technologies_tech_note09186a0080093f1f.shtml

3. No  src/dest addresses or interfaces means there will be no tunnel for the specific traffic to be encrypted, it will just be a logical interface on the router/switch.

res

Paul

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Thanks.