From: Adel Abouchaev (adel@netmasterclass.net)
Date: Sat Aug 28 2004 - 09:28:16 GMT-3
Tom:
If you have connected the same server to both switches using separate
NIC cards then
you're ok, no need to switch off anything there, MAC addresses are
different. If you have managed
to connect your server to both switches using the same NIC card (which
involves a hub in between,
as Alexey mentioned already),
then you will announce your mac address to both switches and that's a
design flaw,
it will replicate traffic to/from destinations twice. There will be
nothing wrong with switch, it will keep
seeing your MAC address thru 2 ports and each packet will reset timers
on these ports at the same time.
If this is a redundancy scenario, then you are having a single point of
failure on the interface in the second case.
Or a hub can fail. The problem with MAC caching and interconnected
devices appears in a clustered environment,
when multiple hosts share a virtual IP which is advertised from one
particular node or from both nodes, depending
on the task. Then you need to failover within the time specified by your
client's SLA.
Cheers,
Adel Abouchaev, CCIE# 12037
asadovnikov wrote:
>Tom,
>
>Device which does not do 'cache' is named a hub. Although hubs have a lot
>of drawbacks they are available. In almost any case a switch can do the
>work for a particular application.
>
>And I do not know to switch off 'cache' or MAC address learning on a switch.
>
>Best Regards,
>Alexei
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Tom
>Young
>Sent: Friday, August 27, 2004 2:41 PM
>To: Hale, Wendy
>Cc: ccielab@groupstudy.com
>Subject: RE: catalyst's MAC address cache
>
>Infact, I connect to a server named Regatte with two
>cat3550, and one of my friend said if I don't close the
>MAC cache function, the server will not work fine. So I
>really want to know how to close it, I think it wasn't
>refered the aging-time.
>
>Thanks alot
>
>--- "Hale, Wendy" <wrhale@necunified.com> $B$+$i$N%a%C%;!<(B
>$B%8!'(B
>
>
>>I don't believe you can stop the caching of
>>addresses, but you set the age down to 10 seconds.
>>Default aging time is 5 minutes. I assume you are
>>using IOS, not CatOS.
>>
>>
>>
>>
>http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12119ea1/3550cr/cl
>i1.htm#1862251
>
>
>>mac address-table aging-time
>>Use the mac address-table aging-time global
>>configuration command to set the length of time that
>>a dynamic entry remains in the MAC address table
>>after the entry is used or updated. Use the no form
>>of this command to return to the default setting.
>>The aging time applies to all VLANs or a specified
>>VLAN.
>>
>>mac address-table aging-time {0 | 10-1000000} [vlan
>>vlan-id]
>>no mac address-table aging-time {0 | 10-1000000}
>>[vlan vlan-id]
>>
>>
>>-----Original Message-----
>>From: nobody@groupstudy.com
>>[mailto:nobody@groupstudy.com] On Behalf Of Tom
>>Young
>>Sent: Thursday, August 26, 2004 8:47 AM
>>To: ccielab@groupstudy.com
>>Subject: catalyst's MAC address cache
>>
>>
>>Hi, group
>>
>> A simple question, how to close the MAC address
>>cache function on a catalyst. What the default
>>seting about MAC address cache ? And which command
>>could confirm it?
>>
>>Thanks alot
>>
>>
>>__________________________________________________
>>GANBARE! NIPPON!
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>>
>>
>>
>>
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>>
>
>__________________________________________________
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