From: xander (xander@xxxxxx)
Date: Wed May 09 2001 - 05:53:33 GMT-3
Hello Devender,
Multicast addresses begin from bit 1, but in the canonical
(Token-Ring) notation, so, in Ethernet notation, it will be the last
bit. Therefore, any kind of MAC that finishes by bit=1 in Ethernet
notation will be multicast.
Cisco's methos to convert multicast addresses from 23 bits to 32 bits
is the add 01-00-5e to the begining of 23 bits got from converting
multicast ip address to hexidecimal notation.
DS> Fred,
DS> I thought the mac addresses for multicast is 01-00-5e-xx-xx-xx. But
DS> obviously it seems like I am wrong.
DS> But Tariq's email and your response it seems like multicast mac addresses
DS> mostly are
DS> 1) 01-00-xx-xx-xx-xx
DS> 2) but some protocols can also have first octet to be XXXXXXX1- and the
DS> second octet to XXXXXXXX
DS> Will you be kind enough to clarify this for me.
DS> Devender Singh
DS> BE(Hons), CCNP
DS> IP Solution Specialist
DS> -----Original Message-----
DS> From: Fred Ingham [mailto:fningham@worldnet.att.net]
DS> Sent: Wednesday, 11 April 2001 5:51
DS> To: Tariq Sharif; Ccielab@Groupstudy. Com
DS> Subject: Re: MAC Address Filter Examples
DS> Tariq: feff will catch any odd number in the second nibble. There are
DS> protocols that use multicast with an address other than 01 but they are
DS> all odd.
DS> Cheers, Fred
DS> Tariq Sharif wrote:
>>
>> Sorry guys, I was after generic MAC filtering. e.g. with IRB etc not DLSw+
>>
>> Ok, here is the question I have:
>>
>> R2 has IRB running with 1 Ethernet interface, serial & 1 BVI. Configure an
>> MAC Address filter on R2 so that it will block broadcast and multicast
>> packets for a host on its Ethernet Bridge segment. The filter is shown
>> below. Now why is 1st line in the filter with mask of "feff". I know we
DS> need
>> to match multicasts which start with "0100" but shouldn't the mask for
DS> this
>> portion be "f0ff" rather than "feff"?
>>
>> hostname R2
>> bridge irb
>> interface Ethernet1/0
>> no ip address
>> bridge-group 1
>> bridge-group 1 input-pattern-list 1100
>> !
>> interface Serial1/0
>> ip address 140.1.5.2 255.255.255.0
>> interface BVI1
>> ip address 140.1.3.2 255.255.255.240
>> !
>> bridge 1 protocol ieee
>> bridge 1 route ip
>> !
>> access-list 1100 deny 0000.0000.0000 ffff.ffff.ffff 0100.0000.0000
>> feff.ffff.ffff
>> access-list 1100 deny 0000.0000.0000 ffff.ffff.ffff ffff.ffff.ffff
>> 0000.0000.0000
>> access-list 1100 permit 0000.0000.0000 ffff.ffff.ffff 0000.0000.0000
>> ffff.ffff.ffff
>>
>> -----Original Message-----
>> From: Patrick Murphy [mailto:pjm@roadrunner.nf.net]
>> Sent: 10 April 2001 16:04
>> To: Tariq Sharif; Ccielab@Groupstudy. Com
>> Subject: Re: MAC Address Filter Examples
>>
>> http://www.cisco.com/warp/public/697/dlswfilter.shtml
>>
>> The best I have seen yet!
>>
>> Patrick
>>
>> ----- Original Message -----
>> From: "Tariq Sharif" <tariq_sharif@yahoo.com>
>> To: "Ccielab@Groupstudy. Com" <ccielab@groupstudy.com>
>> Sent: Tuesday, April 10, 2001 11:49 AM
>> Subject: MAC Address Filter Examples
>>
>> > Does anyone know where I can get MAC Address Filter Examples or info?
>> >
>> > Many thanks & regards.
>> >
>> > Tariq Sharif
>> >
>> > [GroupStudy.com removed an attachment of type application/ms-tnef which
>> had a name of winmail.dat]
DS> **Please read:http://www.groupstudy.com/list/posting.html
-- WBW, xander mailto:xander@adt.ru CCNA, CCNP+VoiceAccess, CCIE second attempt in Brussels 9-10, July, 2001... **Please read:http://www.groupstudy.com/list/posting.html
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