dslreports logo
    All Forums Hot Topics Gallery
spc
Search Topic:
uniqs
13
share rss forum feed

cramer
Premium
join:2007-04-10
Raleigh, NC
kudos:9

1 recommendation

reply to flq06

Re: Cisco switch into non-cisco switch, unknown initial lag

said by flq06:

layer 2 (only) switches doesn't keep any ARP info.

Yes they do; you just cannot see it on an unmanaged switch. Unless it's flooding every packet to every port all the time (which would make it a HUB), it does have tables of MAC's known to be on each port.

flq06

join:2009-08-06
Verdun, QC
Of course, basic layer 2 mechanism. I was talking about ARP. Only a layer 3 switch, router, host know about ARP bindings.

aryoba
Premium,MVM
join:2002-08-22
kudos:6
reply to cramer
said by cramer:

said by flq06:

layer 2 (only) switches doesn't keep any ARP info.

Yes they do; you just cannot see it on an unmanaged switch.

Layer-2 switch has no knowledge of IP address or anything concerning Layer-3 and up since Layer-2 switch deals with only MAC addresses. Therefore Layer-2 switch maintains CAM or MAC address table which correlate between MAC address and certain switch port. ARP Table keeps correlation between IP address and MAC address which typically Layer-3 capable devices maintain such as Layer-3 switch and router.

An exception is IGMP snooping feature where Layer-2 switch is capable to snoop Layer-3 info of Multicast group in order to associate the Multicast MAC address (as a result of the Multicast group translation from Layer-3 IP address to Layer-2 MAC address) with certain switch ports where the Multicast subscribers connect.

said by cramer:

Unless it's flooding every packet to every port all the time (which would make it a HUB), it does have tables of MAC's known to be on each port.

Layer-2 switches typically do not flood packets, however they flood frames since the switches only talk Layer-2.