10-15-2012 01:37 AM - edited 03-04-2019 05:51 PM
Hello,
#show adjacency Fastethernet 0/0 detail
above command displays destination MAC,source MAC and Fastethernet interface type value: 0X800, but I wonder what is the type value for Serial interface? and how to find out this?
Can anybody help me out in learning this ?
Regards
Solved! Go to Solution.
10-15-2012 03:29 AM
Hello Suryanarayana,
I beleive that the 0x0800 mainly used for IP, please refer to the following link for more information
http://www.cavebear.com/archive/cavebear/Ethernet/type.html
Also please find below the value when you have serial interface :
Router# show adjacency detail
Protocol Interface Address
IP Serial5/0/0/1:1 point2point(7)
0 packets, 0 bytes
0F000800
CEF expires: 00:02:09
refresh: 00:00:09
Epoch: 14
IP Serial5/0/1/1:1 point2point(7)
0 packets, 0 bytes
0F000800
CEF expires: 00:02:09
refresh: 00:00:09
Epoch: 14
Hope it will help
Ahmed Sonba
10-15-2012 07:50 AM
Hello,
Please allow me to join.
But my doubt is type value s for seriel interfaces are available or not? to identify what type of interface just in case .. I have never tried .. but no idea its a right question or not? sorry if I am wrong anyway..
The type value does not identify the interface type but rather the L3 protocol carried inside a particular frame. You should not try to deduce the interface type by looking at the type value because this value is used for a different purpose - to allow the receiver to know what kind of packet is carried inside the frame.
Now, Ethernet frame format contains an EtherType field. The most common values in this field contain 0x0800 (IPv4), 0x86DD (IPv6), 0x0806 (ARP), 0x8100 (802.1Q tag), 0x8847 (MPLS).
If using Serial interfaces with Cisco HDLC frame format then the modified Cisco HDLC frame uses the EtherType field just like in Ethernet. So here is an example:
R1#show adjacency detail
Protocol Interface Address
IPV6 Serial1/0 point2point(5)
0 packets, 0 bytes
0F0086DD
IPv6 CEF never
Epoch: 0
IP Serial1/0 point2point(7)
0 packets, 0 bytes
0F000800
CEF expires: 00:02:29
refresh: 00:00:26
Epoch: 0
The PPP protocol has its own "Protocol" field that describes the type of packet carried inside a PPP frame. However, the numbering is not identical with EtherType (if you are interested in knowing about PPP protocol numbers see the
http://www.iana.org/assignments/ppp-numbers/ppp-numbers.xml document). In PPP, IPv4 is 0x0021, IPv6 is 0x0057, MPLS would be 0x0281. So if I modify the Serial1/0 interface to PPP, the show adjacency output would be:
R1#show adjacency detail
Protocol Interface Address
IPV6 Serial1/0 point2point(5)
0 packets, 0 bytes
FF030057
IPv6 CEF never
Epoch: 0
IP Serial1/0 point2point(9)
0 packets, 0 bytes
FF030021
CEF expires: 00:02:56
refresh: 00:00:56
Epoch: 0
Therefore, once again, this type field is not describing the type of the interface but rather the kind of L3 packet inside the particular L2 frame that can be sent out this interface.
Best regards,
Peter
10-15-2012 01:56 AM
Hello Suryanarayana,
Serail interface dose not have MAC address , Mac address are addresses that are relevant in Multi-Access networks like Ethernet In such network, you have to do an ARP broadcast to find the MAC address of the host, so you can send packets addressed to it and it only.
While the serial interfaces has two ends, so it dose not need a MAC address to send the packets. and for that serial interfaces doesn't have a MAC address.
Also please refer to the following link for more information about this command
Hope it will help
Ahmed Sonba
10-15-2012 02:51 AM
Hello Ahmed,
Thanks for your reply,
I do agree with you ... We dont need MAC address for Serial interface as encapsulation protocol will handle to send packets.
But my doubt is type values for seriel interfaces are available or not? to identify what type of interface just in case .. I have never tried .. but no idea its a right question or not? sorry if I am wrong anyway..
#show adjacency Fastethernet 0/0 detail
output for this command is
protocol interface Address
IP Fastethernet 0/0 10.1.192.1 (277)
5021 packets , 1062333 Bytes
001EF7BBF7C20019562C8FB40800
As per above output , We can easily identfy : 001EF7BBF7C2 ( Destnation MAC)
0019562C8FB4( Fastethenet 0/0 ie Source MAC Address)
and here is the area where I got doubt:
0800 is the Fastethetnet 0/0 's type value it says and identifying that this is Fastethernet
I'm bit curious to know that is there a type values for serial interfaces just incase if we may need any time to identify whether it is serial or fastethenet interface but I have never come across this... hope you understood ..any guesses..
10-15-2012 03:29 AM
Hello Suryanarayana,
I beleive that the 0x0800 mainly used for IP, please refer to the following link for more information
http://www.cavebear.com/archive/cavebear/Ethernet/type.html
Also please find below the value when you have serial interface :
Router# show adjacency detail
Protocol Interface Address
IP Serial5/0/0/1:1 point2point(7)
0 packets, 0 bytes
0F000800
CEF expires: 00:02:09
refresh: 00:00:09
Epoch: 14
IP Serial5/0/1/1:1 point2point(7)
0 packets, 0 bytes
0F000800
CEF expires: 00:02:09
refresh: 00:00:09
Epoch: 14
Hope it will help
Ahmed Sonba
10-15-2012 03:37 AM
Thanks Ahmed,
Sounds like there is no type values for Serial interfaces...However, Thank you so much for the research.
10-15-2012 07:50 AM
Hello,
Please allow me to join.
But my doubt is type value s for seriel interfaces are available or not? to identify what type of interface just in case .. I have never tried .. but no idea its a right question or not? sorry if I am wrong anyway..
The type value does not identify the interface type but rather the L3 protocol carried inside a particular frame. You should not try to deduce the interface type by looking at the type value because this value is used for a different purpose - to allow the receiver to know what kind of packet is carried inside the frame.
Now, Ethernet frame format contains an EtherType field. The most common values in this field contain 0x0800 (IPv4), 0x86DD (IPv6), 0x0806 (ARP), 0x8100 (802.1Q tag), 0x8847 (MPLS).
If using Serial interfaces with Cisco HDLC frame format then the modified Cisco HDLC frame uses the EtherType field just like in Ethernet. So here is an example:
R1#show adjacency detail
Protocol Interface Address
IPV6 Serial1/0 point2point(5)
0 packets, 0 bytes
0F0086DD
IPv6 CEF never
Epoch: 0
IP Serial1/0 point2point(7)
0 packets, 0 bytes
0F000800
CEF expires: 00:02:29
refresh: 00:00:26
Epoch: 0
The PPP protocol has its own "Protocol" field that describes the type of packet carried inside a PPP frame. However, the numbering is not identical with EtherType (if you are interested in knowing about PPP protocol numbers see the
http://www.iana.org/assignments/ppp-numbers/ppp-numbers.xml document). In PPP, IPv4 is 0x0021, IPv6 is 0x0057, MPLS would be 0x0281. So if I modify the Serial1/0 interface to PPP, the show adjacency output would be:
R1#show adjacency detail
Protocol Interface Address
IPV6 Serial1/0 point2point(5)
0 packets, 0 bytes
FF030057
IPv6 CEF never
Epoch: 0
IP Serial1/0 point2point(9)
0 packets, 0 bytes
FF030021
CEF expires: 00:02:56
refresh: 00:00:56
Epoch: 0
Therefore, once again, this type field is not describing the type of the interface but rather the kind of L3 packet inside the particular L2 frame that can be sent out this interface.
Best regards,
Peter
10-15-2012 08:48 AM
Wow!! Awesome!!!
Yes, Absolutely , after looking at Mr.Ahmed output I did confused and had lot of research on why 0800 is there for type value even for serial interface and then came to the conclusion that, " This value represents the Ethernet type field,which indicates that the frame containing an IP packet,because Ethernet type value 0x800 is registered as the value for IP".
But you have given the right and exact information:
"Therefore, once again, this type field is not describing the type of the interface but rather the kind of L3 packet inside the particular L2 frame that can be sent out this interface."
... Thanks a lot. At atleast, have some satishfaction that I have learned some thing new today.... hope this helps others too..
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