From: Joseph Brunner (joe@affirmedsystems.com)
Date: Mon Jan 07 2008 - 21:10:19 ARST
R4 and R5 should ONLY be connected to a switch (it doesn't matter which
one). Look at the diagram all those sub-interfaces on the routers (including
E0/0.45 on R4 and E0/1.45 on R5) are not physical but VIRTUAL connections.
The routers simply connect to the switch fabric (the associated group of
switches and their vlans) via one physical port to the switches. From there
we make virtual sub-interfaces that terminate vlan's onto the routers,
making the router's "trunk routers" where they have a trunk to a switch port
(configured also a trunk). They receive frames on the wire, with a dot1q tag
and process the layer3 ip portion of that frame. All this is done over 1
physical link to switch.
>how am I supposed to
>determine which switchports are connected to which routers?
You can use
A) show cdp neighbor from R4 or R5 if you are internetworkexpert's rented
racks
b)if you are using your own rack's you can make your's like their's
http://www.internetworkexpert.com/resources/ccierack.htm#cabling
Of course I recommend you get used to just doing show cdp nei. You will need
to learn to quickly play in and figure out any sandbox at any dojo you fight
at.
The switchports you need to configure are the ones connected to physical
(e0/0 R4, E0/1 R5) ports of the routers. Those switchports again become
trunks, and the router's are simply configured as router's on a sticks
(802.1q interface sub-if tagged trunks).
Have you worked with router on a stick before? This is the same thing, its
just used to make a logical topology using virtual links between devices
over one physical connection.
Whew! I feel like Writing the last secret Harry Potter book after this post!
"Harry Potter and the Kraken Tentacled dot1q Sticked Router"
LOL
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of John
Sent: Monday, January 07, 2008 1:41 PM
To: ccielab@groupstudy.com
Subject: Re: IWEB vol4 lab 6 task 1.5 trunking
1. As you noted R4 has a connection through e0/0's subinterfaces to R5, SW4,
and SW3. R4's e0/0 is one physical connection. how is it possible to have
3 physical connections terminate at one physical interface. I'm missing
some logic there.(yes, I'm looking in the switching guide right now, haven't
found it yet.)
2. Looking at the diagram and at the running configs how am I supposed to
determine which switchports are connected to which routers? Once I've
determined that I can config them as l3trunks. Again the only clue I get
from the diagram is the vlan interface ID. Although I can now see that by
IWEB's logic I can guess that for R4 it's f0/4 on SW3 and SW4 and f0/5 on
SW4 and SW3 for R5. The solution only has one port on each switch being
configured (I'm missing logic and it's probably the same thing thats giving
me a headache on issue 1). There has to be a better way to determine which
switchports I need to configure.
----- Original Message -----
From: "Joseph Brunner" <joe@affirmedsystems.com>
To: "'John'" <jgarrison1@austin.rr.com>; <ccielab@groupstudy.com>
Sent: Monday, January 07, 2008 11:27 AM
Subject: RE: IWEB vol4 lab 6 task 1.5 trunking
> >How am I supposed to determine which switch interfaces to use in a
>>situation like this and if someone can please explain how three devices
>>each with a separate physical connection can attach to a single physical
>>interface on another device I would appreciate it
>
> Looking at the diagram, its clear
> 1. R4 & R5 are trunked to each other on vlan 45
> 2. R5 is trunked to switch4's vlan 50 svi on vlan 50
> 3. R5 is trunked to switch3's vlan 59 svi on vlan 59
> 4. R4 is trunked to switch4's vlan 40 svi on vlan 40
> 5. R4 is trunked to switch3's vlan 49 svi on vlan 49
>
> So yes indeed each router has 3 sub-interfaces running dot1q trunk
> encapsulation. So you are using (and "supposed to determine")
>
> 1. Use any physical interface that the routers in the diagrams physically
> are connected to
> 2. make those interfaces dot1q trunks on the adjacent switches
> 3. make sure the vlans in question are allowed on those trunks on switch
> to
> the routers "switchport trunk allowed vlan x,x,x"
>
> Once those vlans are active between switches 3,4 it doesn't matter which
> interfaces on the switch fabric connect to those routers, so long as you
> have the switch trunks, switch svi's and router sub-interfaces configured
> it
> will work.
>
> -Joe
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> John
> Sent: Monday, January 07, 2008 11:05 AM
> To: ccielab@groupstudy.com
> Subject: IWEB vol4 lab 6 task 1.5 trunking
>
> I am tasked with configuring dot1q trunking between R4, R5, SW3, and SW4.
> R4
> is trunking to R5 via e0/0.45. R4 is trunking to SW3 via e0/0.49. R5 is
> trunking to SW4 via e0/0.40. R5 is trunking to R4 via e0/1.45. R5 is
> trunking to SW3 via e0/1.59. R5 is trunking to SW4 via e0/1.50.
>
> I'm having problems understanding a couple of things. first how R4 and R5
> for example can have trunks to three different devices coming into a
> single
> interface. second in the diagram it has the interfaces for the trunks on
> the
> switches as vlan40 and vlan50 on SW4 and vlan49 on SW3. Those are not
> physical interfaces. The solution says that I should be configuring SW2
> f0/4
> and SW3 f0/5. I'll assume that SW2 is supposed to be SW4 it's still short
> one
> trunk port.
>
> How am I supposed to determine which switch interfaces to use in a
> situation
> like this and if someone can please explain how three devices each with a
> seperate physical connection can attatch to a single physical interface on
> another device I would appreciate it
>
> thanks
>
> JG
>
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