From: Karelis, Pete (2507) (Pete.Karelis@xxxxxxxxxx)
Date: Mon Aug 20 2001 - 14:45:04 GMT-3
The low order bit of the first octet in an ethernet mac address sets weather
it is a Layer 2 Multicast or not.
Any MAC address that has an odd number in the first octet is indeed A
multicast MAC address, it's just not THE Multicast MAC Addresses used by
IP....
-Pete Karelis
-----Original Message-----
From: Chuck Church [mailto:cchurch@MAGNACOM.com]
Sent: Monday, August 20, 2001 1:35 PM
To: 'BRZYSKI, ADAM E (SWBT) '; 'Bob Chahal '; 'Daniel C. Young '; Chuck
Church; 'ccielab@groupstudy.com '
Subject: RE: ipx routing 1111.1111.1111
Those are the ones that make a valid translation to a class D IP address.
Notice that they all start with 01:, indicating the group bit is set. As
long as the group address bit is set, devices will see the frame as a
non-unicast.
Chuck
-----Original Message-----
From: BRZYSKI, ADAM E (SWBT)
To: Bob Chahal; Daniel C. Young; 'Chuck Church'; ccielab@groupstudy.com
Sent: 8/20/01 10:33 AM
Subject: RE: ipx routing 1111.1111.1111
I though that the range of mac's reserved for multicasts falls in the
following range:
01:00:5e:00:00:00 - 01:00:5e:7f:ff:ff
that would not explain why 1111.1111.1111 would not work on a loopback
interface.
Adam Brzyski
Design Engineer II
CCNP, CCDP, NNCDE
-----Original Message-----
From: Bob Chahal [mailto:bob.chahal@ntlworld.com]
Sent: Monday, August 20, 2001 3:54 AM
To: Daniel C. Young; 'Chuck Church'; ccielab@groupstudy.com
Subject: Re: ipx routing 1111.1111.1111
Chuck, thanks for the reminder. I keep forgetting about this.
Daniel, in a lab scenario you are very likely to be asked to configure
an
IPX network on a loopback.
Thanks for the replies.
Bob
----- Original Message -----
From: "Daniel C. Young" <danyoung99@mediaone.net>
To: "'Chuck Church'" <cchurch@MAGNACOM.com>; "'Bob Chahal'"
<bob.chahal@ntlworld.com>; <ccielab@groupstudy.com>
Sent: Monday, August 20, 2001 5:26 AM
Subject: RE: ipx routing 1111.1111.1111
> Also Bob,
>
> With IPX, you don't need to worry about putting networks on loopbacks.
Think
> about it, IPX is a desktop protocol for connecting LANs. I've never
had a
> problem with using the 'ipx routing 1.1.1' convention.
>
> Regards,
> Daniel
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Chuck Church
> Sent: Sunday, 19 August 2001 4:01 PM
> To: 'Bob Chahal'; 'ccielab@groupstudy.com'
> Subject: RE: ipx routing 1111.1111.1111
>
>
> Bob,
>
> You're defining a multicast address. This is from
> http://www.cisco.com/warp/customer/473/85.shtml#multicast :
>
> Note: Recall that the least significant bit of the most significant
octet
of
> an Ethernet or FDDI MAC address is the "group bit." If the bit is set
(1),
> the MAC address is a
> multicast (or broadcast). If the bit is not set (0), the MAC address
is a
> unicast. The MAC address 0900.3333.4444 has the group bit set, and is
> therefore a multicast
> MAC (09 hex = 00001001; the last bit, the group bit, is set).
>
> Chuck
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
> Bob Chahal
> Sent: Sunday, August 19, 2001 5:16 PM
> To: ccielab@groupstudy.com
> Subject: ipx routing 1111.1111.1111
>
>
> When I configure a router with
>
> ipx routing 1111.1111.1111
>
> and then configure a loopback
>
> int lo0
> ipx netw 10
>
> if I do a show ipx int lo0 the ipx address is 10.1111.1111.1111
>
> if I then ping this address from the same router (i.e the router on
which
> this is configured) my pings timeout.
>
> If I do not configure an address with the ipx routing command the ipx
add
of
> the lo0
> uses tha mac address of the ethernet interface on the router and when
I
now
> ping the lo0 it works
>
> p 10.0010.7bfe.6cc1
> Translating "10.0010.7bfe.6cc1"
>
> Type escape sequence to abort.
> Sending 5, 100-byte IPX cisco Echoes to 10.0010.7bfe.6cc1, timeout is
2
> seconds:
>
> !!!!!
> Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
>
>
> Can anyone explain why this happens. I was thinking of configuring my
ipx
> routers like the first method above as it makes configuring
frame-relay
> maps easier to configure and troubleshoot but the side-effect is what
I
just
> described.
>
> Thanks
>
> Bob
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