08-24-2007 02:41 AM - edited 03-05-2019 06:05 PM
Hi all, can anyone tell me about typical encapsulation, say ppp, does it only encapsualtion the ip header and data within the ethernet frame, or does it encapsulate the ethernet frame ?
08-24-2007 03:15 AM
PPP encapsulation is defined in RFC 1661; please check that for all the information
08-24-2007 03:37 AM
Hi Carl,
The router adds the appropriate layer 2 header to encapsulate the IP packet before it is sent out of the appropriate interface according to the encapsulation of the outgoing interface with no relation to the input interface (if the routers is running CEF the adjacency table should be responsible about this).
Cisco-2821#sh adjacency detail
Protocol Interface Address
IP Serial0/1/0 point2point(7)
0 packets, 0 bytes
FF030021
CEF expires: 00:02:39
refresh: 00:00:39
Epoch: 0
IP GigabitEthernet0/0 192.168.99.1(9)
28 packets, 3555 bytes
000D28C783750019E771F5F80800
ARP 04:02:22
Epoch: 0
IP GigabitEthernet0/1 192.168.13.2(5)
0 packets, 0 bytes
00055E124F820019E771F5F90800
ARP 00:52:40
Epoch: 0
HTH,
Mohammed Mahmoud.
08-24-2007 03:46 AM
Hi, carl
Normally ppp only encapsulate Layer3 packets (like ip packets). Unless you are doing some advanced feature like l2tpv3 tunnel, ppp won't encapsulte the whole ethernet frames because they are in the same layer.
HTH
SSLIN
09-06-2007 08:52 AM
so over ppp serial link, what is the frame type changed too ? is the layer 2 properties now a ppp frame and not ethernet ?
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