From: Edwards, Andrew M (andrew.m.edwards@boeing.com)
Date: Tue Aug 03 2004 - 21:02:35 GMT-3
Yes it is one of those contrived and weird situations.... But my point
was that, although R1 should see R3 as on its local Layer2 segment (e.g.
ARP resolvable), the truth is that they are on two separate L2 segments
(e.g. VLANS). The ARP debug should prove that to you...
My suggestion to get around it was essentially fooling R6 into thinking
it was a proxy-arp server for R1 to reach R3. The classic problem where
the SA inputs the wrong subnet mask so R6 fixes that problem for them...
Yes, magic to the SA, but makes my skin crawl. 8)
HTH,
Andy
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Tuesday, August 03, 2004 4:24 PM
To: Group Study; Edwards, Andrew M
Subject: Re: IRB question
Hi Andy,
Thanks for your response. This is certainly an interesting problem,
don't ya think?
I will try those things you suggested and see what happens. But, you
confirmed for me the biggest question I had which was should R1 be able
to ping R3. I wasn't 100% sure that it should, so I didn't try to debug
this problem before knowing that in fact this was a problem.
Thanks for getting back to me on this.
Tim
----- Original Message -----
From: "Edwards, Andrew M" <andrew.m.edwards@boeing.com>
To: "ccie2be" <ccie2be@nyc.rr.com>
Sent: Tuesday, August 03, 2004 6:51 PM
Subject: RE: IRB question
I think the problem is that the switch you are trunked to does not
forward between VLANS. So, do the debug arp and you should see that R1
sees R3 as directly connected, but it doesn't get ARP resolution because
the only way to get ARP resolution from the local subnet is via R6
(because the switch wont forward between vlans).
Possible resolution, place R3 into a subnet that is LARGER than /24 and
enable Proxy arp on R6!!!!
Andy
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Tuesday, August 03, 2004 11:20 AM
To: Group Study
Subject: IRB question
Hi guys,
Here's the scenario.
R1 <--> R6 <-->R3
R6 has a BVI 1 configured and R6's fa1/0/0 is trunking. Here's the
config:
bridge irb
interface FastEthernet1/0/0
no ip address
half-duplex
!
interface FastEthernet1/0/0.16
encapsulation dot1Q 16
bridge-group 1
!
interface FastEthernet1/0/0.36
encapsulation dot1Q 36
bridge-group 1
interface BVI1
ip address 136.7.136.6 255.255.255.0
bridge 1 protocol ieee
bridge 1 route ip
R6 can ping both R1 and R3, but R1 can't ping R3. There are no acl's or
any other obvious (at least to me) reasons for this. I assume R1 should
be able to ping R3. Can someone help me out?
Thanks in advanced, Tim
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