RE: MAC addresses on switches [7:60807]
Every port on a Layer 2 switch has its own MAC address, per IEEE 802.1D. ira wrote: > > hallo, > I have a q regarding switches. > > Does any interf have a separate MAC address ? > Is there a diff betw managed / unmanaged switches Those are marketing terms. You have to get the tech specs to know what "unmanaged switch" really means to the particular vendor. It might actually mean a hub, in which case MAC addresses are irrelevanat as a hub is just a physical-layer device. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com > regarding mac addrsses and interfaces ? > > thanks > > __ > Do you Yahoo!? > Yahoo! Mail Plus - Powerful. Affordable. Sign up now. > http://mailplus.yahoo.com > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=60844&t=60807 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: MAC Addresses
This is how many MAC addresses the switch can hold in its cache DUCK - Original Message - From: Howard C. Berkowitz <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, July 24, 2000 3:25 PM Subject: Re: MAC Addresses > >What does it mean to say that the Catalyst 1912 has 1024 MAC Addresses, > >while the Catalyst 2828 has 8192 MAC Addresses. > >Can anyone please explain? > >Thanks in advance. > >Reply to, > >[EMAIL PROTECTED] > > > > You touch on what is an interesting problem in product design, which > shows why products differentiate. > > Specifically, this refers to the size of the MAC address lookup table > on the bridge. It doesn't mean that there can only be 1024 or 8192 > MAC addresses defined, only that many that the switch will handle > quickly by knowing immediately whether to block or forward the frame. > > Cisco and Bay(Nortel) have taken different approaches to MAC tables. > Neither one is best under all circumstances. Cisco defines a table > for the entire switch, which is used by all broadcast domains. > Nortel defines a separate 1K table to each port. > > Let's say you are brought in to fix a horribly performing campus > network that has 1000 active hosts in a broadcast domain. Fits easily > into 1K. In a calm, rational way, you split that single domain into > four subnets. 250 each. No problem. > > But each subnet then goes through 20% growth, giving 300 hosts per > domain. Weird and unpredictable performance starts occurring, as the > four subnets compete for slots in the cache. In this case, if you > know the subnets will individually have no more than 1K MAC > addresses, the guaranteed 1K of the Bay switch is much more > predictable. Do you have a sane, managed policy about growth? To > coin a phrase, It Depends. > > Return to the problem of a horribly performing campus network, but > assume this time that it has 4000 hosts -- quite possible with FDDI. > Connect a Bay switch to this, and it will be in immediate trouble. So > will a Cat 1912. But a 2828 will handle the total number of hosts in > a reasonably predictable manner. > > "What Problem are you trying to solve?" > ***send Cisco questions to the list, so all can benefit -- not > directly to me*** > > Howard C. Berkowitz [EMAIL PROTECTED] > Technical Director, CertificationZone.com > Senior Product Manager, Carrier Packet Solutions, NortelNetworks (for ID only) >but Cisco stockholder! > "retired" Certified Cisco Systems Instructor (CID) #93005 > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: MAC Addresses
>What does it mean to say that the Catalyst 1912 has 1024 MAC Addresses, >while the Catalyst 2828 has 8192 MAC Addresses. >Can anyone please explain? >Thanks in advance. >Reply to, >[EMAIL PROTECTED] > You touch on what is an interesting problem in product design, which shows why products differentiate. Specifically, this refers to the size of the MAC address lookup table on the bridge. It doesn't mean that there can only be 1024 or 8192 MAC addresses defined, only that many that the switch will handle quickly by knowing immediately whether to block or forward the frame. Cisco and Bay(Nortel) have taken different approaches to MAC tables. Neither one is best under all circumstances. Cisco defines a table for the entire switch, which is used by all broadcast domains. Nortel defines a separate 1K table to each port. Let's say you are brought in to fix a horribly performing campus network that has 1000 active hosts in a broadcast domain. Fits easily into 1K. In a calm, rational way, you split that single domain into four subnets. 250 each. No problem. But each subnet then goes through 20% growth, giving 300 hosts per domain. Weird and unpredictable performance starts occurring, as the four subnets compete for slots in the cache. In this case, if you know the subnets will individually have no more than 1K MAC addresses, the guaranteed 1K of the Bay switch is much more predictable. Do you have a sane, managed policy about growth? To coin a phrase, It Depends. Return to the problem of a horribly performing campus network, but assume this time that it has 4000 hosts -- quite possible with FDDI. Connect a Bay switch to this, and it will be in immediate trouble. So will a Cat 1912. But a 2828 will handle the total number of hosts in a reasonably predictable manner. "What Problem are you trying to solve?" ***send Cisco questions to the list, so all can benefit -- not directly to me*** Howard C. Berkowitz [EMAIL PROTECTED] Technical Director, CertificationZone.com Senior Product Manager, Carrier Packet Solutions, NortelNetworks (for ID only) but Cisco stockholder! "retired" Certified Cisco Systems Instructor (CID) #93005 ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: MAC Addresses
That is how many MAC addresses it can store in its tables On Mon, 24 Jul 2000, Nasser N Khwaja wrote: > What does it mean to say that the Catalyst 1912 has 1024 MAC Addresses, > while the Catalyst 2828 has 8192 MAC Addresses. > Can anyone please explain? > Thanks in advance. > Reply to, > [EMAIL PROTECTED] > > > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > -- - Brian Feeny, CCNA [EMAIL PROTECTED] 318-222-2638 x 109 http://www.shreve.net/~signal Network Administrator ShreveNet Inc. (ASN 11881) ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: MAC Addresses
Nasser N Khwaja wrote: > What does it mean to say that the Catalyst 1912 has 1024 MAC Addresses, > while the Catalyst 2828 has 8192 MAC Addresses. > Can anyone please explain? > Thanks in advance. > Reply to, > [EMAIL PROTECTED] > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] That number refers to the size of the MAC Address table... basically, how many nodes can be hooked up to the switch (directly, via cascaded hub, multilayer switches, etc) and remember what port every station is on. For best performance, a switch should be able to remember every MAC Address on it's side of the router, and therefor after recieving a packet from every station, no longer have to flood all segments to locate a station. This is optimum use. If you were to purchase a switch that can hold 1024 MAC Addresses in it's table, and attach 1100 stations, the switch will function, it will only be less efficient. For example, MAC Address #1 isn't used for a long time, and 1024 other stations "talk" since... SwitchA will remove the entry for Station1, since "it must be turned off, and this will free room in the table". Suddenly, a packet for Station1 comes into the switch... it doesn't have an entry in the MAC Table, so it floods all ports. This flooding causes excess traffic on all other ports. Same scenario, but the switch has a 2048 entry MAC Address Table. Station1's MAC is never removed, because there is still room in the table after everyone on the network has talked. The same packet comes in for Station1, the switch looks up the MAC, and sends it out the appropriate port. The 1099 other stations don't have to process that packet to layer 2 and drop it. Regards, Trevor Corness, CCNA+ACRC ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Mac addresses
Check the "Vendor/Ethernet MAC Address Lookup" site here: http://coffer.com/mac_find/ Priscilla At 07:43 AM 5/23/2000 -0700, George Dodds wrote: >Does any know if there is a website where you can >search for the make of a peice of hardware from the >mac address? > >Cheers > >George > >= >George Dodds > >CCNA, MCP > >__ >Do You Yahoo!? >Send instant messages & get email alerts with Yahoo! Messenger. > >http://im.yahoo.com/ > >___ >UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html >FAQ, list archives, and subscription info: http://www.groupstudy.com >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > __ Priscilla Oppenheimer Phone 541-482-5685 Fax 541-488-1708 Web http://www.priscilla.com ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Mac addresses
http://www.shmoo.com/tools/mac/ Rog > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of > George Dodds > Sent: Tuesday, May 23, 2000 10:43 AM > To: [EMAIL PROTECTED] > Subject: Mac addresses > > > Does any know if there is a website where you can > search for the make of a peice of hardware from the > mac address? > > Cheers > > George > > = > George Dodds > > CCNA, MCP > > __ > Do You Yahoo!? > Send instant messages & get email alerts with Yahoo! Messenger. > http://im.yahoo.com/ > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Mac addresses
Try this: http://standards.ieee.org/regauth/oui/index.shtml -Andrew -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of George Dodds Sent: Tuesday, May 23, 2000 10:43 AM To: [EMAIL PROTECTED] Subject: Mac addresses Does any know if there is a website where you can search for the make of a peice of hardware from the mac address? Cheers George = George Dodds CCNA, MCP __ Do You Yahoo!? Send instant messages & get email alerts with Yahoo! Messenger. http://im.yahoo.com/ ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Mac addresses
You can use Sniffer device or software to identify Make. The other method is on NT box run Network Monitor and capture the data and look for the name conversions for mac part. Rgds Sridhar - Original Message - From: "George Dodds" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, May 23, 2000 9:43 AM Subject: Mac addresses > Does any know if there is a website where you can > search for the make of a peice of hardware from the > mac address? > > Cheers > > George > > = > George Dodds > > CCNA, MCP > > __ > Do You Yahoo!? > Send instant messages & get email alerts with Yahoo! Messenger. > http://im.yahoo.com/ > > ___ > UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html > FAQ, list archives, and subscription info: http://www.groupstudy.com > Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] > ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Mac addresses
http://standards.ieee.org/regauth/oui/index.shtml -Original Message- From: George Dodds [mailto:[EMAIL PROTECTED]] Sent: Tuesday, May 23, 2000 9:43 AM To: [EMAIL PROTECTED] Subject: Mac addresses Does any know if there is a website where you can search for the make of a peice of hardware from the mac address? Cheers George = George Dodds CCNA, MCP __ Do You Yahoo!? Send instant messages & get email alerts with Yahoo! Messenger. http://im.yahoo.com/ ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
