CCNA: HDLC and GRE

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Description:

Remember that clock rates are set on the DTE side and you must set them to match!

Setup Default Serial Connection:

   Router#config t
   Router(config)#interface Serial0
   Router(config-if)#ip address 192.168.1.1 255.255.255.0
   Router(config-if)#encapsulation hdlc
   Router(config-if)#clock rate 64000
   Router(config-if)#no shutdown
   Router(config-if)#^Z
   Router#

Show Commands:

   show controllers serial 0
   show ip interface brief
   show interface Serial0

Description:

  • PP IP tunnel. Stateless (no flow control), no security, additional overhead. Supports multiple protocols, multicast, ipv6. IP in IP does not support it.

To configure GRE Tunneling:

   R1#config t
   R1(config)#int tunnel 21
   R1(config-if)#ip address 21.0.0.1 255.255.255.0
   R1(config-if)#tunnel source s0/0/0
   R1(config-if)#tunnel destination 10.1.1.6 # the destination router's IP
   R1(config-if)#tunnel mode gre ip
   R1(config-if)#end
   R1#copy run start

On the other side (R2):

   R2#config t
   R2(config)#int tunnel 21
   R2(config-if)#ip address 21.0.0.2 255.255.255.0
   R2(config-if)#tunnel source s0/0/1
   R2(config-if)#tunnel destination 10.1.1.5 # the source router's IP
   R2(config-if)#tunnel mode gre ip
   R2(config-if)#end
   R2#copy run start

Show Commands:

   show interface tunnel

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