From: Gerard Robinson (gerardrobinson@xxxxxxxxxxxxxx)
Date: Tue Jun 27 2000 - 19:35:44 GMT-3
Brian,
I am pretty sure to bridge IP you must turn off ip routing
globally whether IP addresses are configured or not, IP won't get bridged
otherwise. CRB/IRB will allow IP bridging without turning off ip routing
globally but I think that's the only way to do it. That has been my
experience anyway but I may be mistaken, it wouldn't be the first time.
----- Original Message -----
From: Brian Hescock <bhescock@cisco.com>
To: Gerard Robinson <gerardrobinson@dial.pipex.com>
Cc: <ccielab@groupstudy.com>
Sent: Tuesday, June 27, 2000 8:04 PM
Subject: Re: IRB and DLSW+
Gerard,
Just a quick clarification, are you saying you must turn off ip routing
at the global level, or if you're running IRB / CRB to use "bridge 1 no ip
routing"? The reason I ask is because you can have two interfaces with no
ip addresses at all and bridge between them even if "ip
routing" (global) is turned on. Unless I'm recalling incorrectly, of
course.
R1 with IRB configured ------- E0 [R2] E1 -------- R3 with IRB configured
In the example above R2 doesn't have any ip address on E0 nor E1, only
bridge-group 1. But ip routing (global command) is turned on.
Brian
On Tue, 27 Jun 2000, Gerard Robinson wrote:
>
> IP is always routed unless you issue the command 'no ip routing'
or you run CRB so putting an interface into a bridge-group will not bridge
IP unless you have specifically turned off IP routing by issuing the
aforementioned command. If you do a 'sh int irb' you can see which protocols
are bridged and which are routed. Once you turn on routing for a protocol
and then put a layer 3 address on an interface then all traffic for that
protocol is routed and not bridged. So on a interface with an IP address and
ip routing enabled all IP traffic is always routed and non-routable traffic
like NetBIOS/SNA is bridged to DLSW and then encapsulated to IP.
>
> One thing that confuses me is why all example configs for DLSW
from a Token Ring interface are always using source-route bridging, you can
use normal transparent bridging on Token Ring interface and it works fine so
source-route bridging is not a necessity. I think it must be that
source-route bridging is very popular in Token Ring environments and is the
bridging of choice for Token Ring.
>
>
> ----- Original Message -----
> From: Earl Aboytes
> To: ccielab@groupstudy.com
> Sent: Monday, June 26, 2000 9:35 AM
> Subject: IRB and DLSW+
>
>
> Here is a question that I thought I had resolved until I started reading
the doc CD
>
> Assumptions:
>
> When you turn on dlsw in a router you have to bridge from Ethernet to
dlsw. When you turn on dlsw on a router you have to source-route bridge
from token ring to dlsw.
>
> Question:
>
> Did you just ruin routing of IP over the Ethernet and Token if you put
it a bridge group or turn on source route bridging?
>
> Possible answer:
>
> My guess is no. It seems that dlsw turns on IRB automatically. I
thought this was the answer for both token and Ethernet until I read the
following passage on the Doc CD.
>
>
>
> "Integrated routing and bridging is supported for transparent bridging,
but not for source-route bridging (SRB)."
>
>
>
> So what is the real answer? Did I lose routing of IP on my token
interface when I turned on SRB? I would guess that dlsw takes care of this.
Any thoughts on this?
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> Earl Aboytes
>
> Senior Technical Conultant
>
> GTE Managed Solutions
>
> 805-381-8817
>
> earl.aboytes@telops.gte.com
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
>
>
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