I was doing a lab last weekend and sniffed packets coming from a 2500's e0 interface. The packet was an 802.3 and the 'show int e0' showed the ethernet encapsulation as being ARPA.
Then, I turned on CDP and captured another set of packets. The sniffer showed that the e0 packets contained a SNAP header.
So, apparently, a Cisco is capable of processing multiple ethernet encapsulation types. Why then, is there one specific one configured?
I'm confused by this because I remember from my CCNA exam, that there were multiple types to be configured (i.e, novell-ether, snap, and a few others).
I was under the assumption that if a host sends an ethernet frame in a format that differes from the one configured on the router, that the router wouldn't be able to process it.
It looks like this is not true in the case of ethernet.
Any comments?
BTW, does anyone have an overview of the various ethernet encapsulations (Ethernet II, 802.3 and 802.3/SNAP (did I miss anything?))and the corresponding Cisco ios config names?
Thanks!
