From: BRZYSKI, ADAM E (SWBT) (ab1723@xxxxxxx)
Date: Wed Aug 22 2001 - 12:02:51 GMT-3
Consider the following topology:
| |
H-|-R1-----R2-|-H = MAC --> 00:23:45:67:89:12
| |
Both of the routers have an attached Ethernet segment as well as a serial
point-to-point interface.
Transparent bridging is enabled on both routers.
Filtering on source MAC:
Router 2
interface ethernet 0
bridge-group 1 input-address-list 750
access-list 750 permit 0023.4567.8912 0000.0000.0000
Filtering on destination MAC:
interface ethernet 0
bridge-group 1 input-address-list 750
access-list 750 permit 0023.4567.8912 0000.0000.0000
access-list 750 permit FFFF.FFFF.FFFF 0000.0000.0000
access-list 750 permit 0100.0000.0000 FEFF.FFFF.FFFF
the last two entries allowing for broadcasts and multicasts.
Is this correct?
The other question I had concerns token ring.
The RII bit is defined as the high order bit of the source mac address. It
indicates the presence of a RIF field. Is this definition referencing
non-canonical representation. I am guessing it is.
Finally in a token ring environment would access-list 750 would look as
follows
-o-R1-o-R2-o-H = MAC --> 00:23:45:67:89:12
Filtering on source MAC:
Router 2
interface tokenring 0
source-bridge input-address-list 750
access-list 750 permit 0023.4567.8912 8000.0000.0000
Filtering on destination MAC:
Router 2
interface tokenring 0
source-bridge output-address-list 750
access-list 750 permit 0023.4567.8912 0000.0000.0000
access-list 750 permit FFFF.FFFF.FFFF 0000.0000.0000
access-list 750 permit 8000.0000.0000 7FFF.FFFF.FFFF
once again the last two entries allowing broadcasts and multicasts.
I think that this is all correct but I need for somebody to give me a sanity
check.
Thanks! for the help.
Adam Brzyski
Design Engineer II
CCNP, CCDP, NNCDE
-----Original Message-----
From: Boris Bertelsons [mailto:info@bertelsons.de]
Sent: Monday, August 20, 2001 10:00 AM
To: BRZYSKI, ADAM E (SWBT)
Cc: ccielab@groupstudy.com
Subject: RE: ipx routing 1111.1111.1111
Hey Adam !
Please check the link below provided by Chuck and the explaining
text :
"Note: Recall that the least significant bit of the most significant octet
of an Ethernet is the "group bit." "
This means that this bit in the MAC address decides if the address
is handled as a multicast or a unicast address. If set to 1, the
address will be handled as an multicast (or broadcast) regardingless of the
rest of the address.
You see, in 01:00:5e:00:00:00 this bit is also set.
(BTW: You are right with your official multicast defenition :) ).
I hope this brings a little light into the darkness !?
Kind regards,
Boris
-- Boris Bertelsons CCIE #6373, CCDP, CCNP Security Specialist---------- Original Message ---------------------------------- From: "BRZYSKI, ADAM E (SWBT)" <ab1723@sbc.com> Reply-To: "BRZYSKI, ADAM E (SWBT)" <ab1723@sbc.com> Date: Mon, 20 Aug 2001 09:33:38 -0500
>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 >> **Please read:http://www.groupstudy.com/list/posting.html >> **Please read:http://www.groupstudy.com/list/posting.html >> **Please read:http://www.groupstudy.com/list/posting.html >**Please read:http://www.groupstudy.com/list/posting.html >**Please read:http://www.groupstudy.com/list/posting.html **Please read:http://www.groupstudy.com/list/posting.html **Please read:http://www.groupstudy.com/list/posting.html
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