[c-nsp] Adding a second switch for redundancy

[Eric Kagan]

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> Eric Kagan wrote:
> >> Eric Kagan wrote:
> >>> I am trying to lab the following - Several routers plugged
> >> in to two
> >>> seperate switches for redundancy.  Catalyst 3524XL/3550.  
> 7200/7500
> >>> routers
> >>> - 
> >>>
> >>>
> >>> Design A (works fine - diagram below)
> >>>
> >>> 5 routers plugged in to a 3550 (configured as Layer 2
> >> ports).  We are
> >>> running EIGRP on the routers.
> >>>
> >>>
> >>>
> >>> Design B (EIGRP Errors - diagram below)
> >>>
> >>> We added 2nd FE cards to the routers
> >>> We plugged them in to the new switch
> >>> We assigned a new / separate subnet for the interfaces.
> >>>
> >>> When we bring them up, we get EIGRP flaps. (log clip below)
> >> Are there
> >>> EIGRP settings that need to be changed for having 2 FE's
> >> from the same
> >>> routers in different switches ?  Do the switches need to be
> >> trunked ?
> >>> Thanks
> >>> Eric
> >>>
> >>>
> >>>
> >>> Design A: (working - single switch, multiple routers)
> >>>
> >>>
> >>> -----------------
> >>> |  Cat 3550-A   |
> >>> -----------------
> >>>   |   |   |   | ----- 1.1.1.0 /24 (EIGRP)
> >>>   R   R   R   R
> >>>
> >>>
> >>> Design B: (problem)
> >>>
> >>>
> >>> -----------------
> >>> |  Cat 3550-A   |
> >>> -----------------
> >>>   |   |   |   | ----- 1.1.1.0 /24 (EIGRP)
> >>>   R   R   R   R
> >>>   |   |   |   | ----- 2.1.1.0 /24 (EIGRP)
> >>> -----------------
> >>> |  Cat 3550-B   |
> >>> -----------------
> >>>
> >> Well, assuming that 3550-A and 3550-B are not connected in
> >> any way, I wouldn't think there would be any problem.
> > 
> > The 2 switches are not directly connected in any way.  They are 
> > completely separate from each other.
> >  
> >> Is there more info here than is implied in simple ASCII art?
> > 
> > Not really - its pretty simple.  The routers do have HSRP and MPLS 
> > running since I am using our actual production configs on the lab 
> > routers.
> > 
> >> Config snippet would be helpful...
> > 
> > Clips from 2 routers and both switches for those router -
> > 
> > Thanks
> > Eric
> > 
> > R1 - (BGP Border router)
> > 
> > interface FastEthernet0/0
> >  ip address 2.1.1.12 255.255.255.0
> >  no ip unreachables
> >  ip flow ingress
> >  load-interval 30
> >  duplex full
> >  no clns route-cache
> > !
> > interface GigabitEthernet4/0
> >  ip address 1.1.1.1.12 255.255.255.0
>               ^^^^^^^^^^^
> Is this a cut and paste or typo???

Typo.  Should be 1.1.1.12. I didn't have access to the lab so I pulled the
data off the routers and modified them.

> 
> >  no ip redirects
> >  negotiation auto
> >  no clns route-cache
> >  standby 2 ip 1.1.1.1
> >  standby 2 priority 105
> >  standby 2 preempt
> > !
> > router eigrp 65555
> >  redistribute connected
> >  redistribute static metric 10000 100 255 1 1500
> >  network 1.1.1.0 0.0.0.255
> >  network 2.1.1.0 0.0.0.255
> >  no auto-summary
> > 
> > 
> > R2 - (PE/VPN Agg)
> > 
> > interface FastEthernet0/0
> >  ip address 1.1.1.10 255.255.255.0
> >  no ip unreachables
> >  ip flow ingress
> >  load-interval 30
> >  duplex full
> >  tag-switching mtu 1524
> >  tag-switching ip
> >  no clns route-cache
> >  standby 2 ip 1.1.1.1
> >  standby 2 preempt
> > !
> > interface FastEthernet6/0
> >  ip address 2.1.1.10 255.255.255.0
> >  ip flow ingress
> >  duplex full
> >  mpls label protocol ldp
> >  tag-switching mtu 1524
> >  tag-switching ip
> >  no clns route-cache
> > !
> > router eigrp 65555
> >  redistribute connected
> >  redistribute static
> >  network 1.1.1.0 0.0.0.255
> >  network 2.1.1.0 0.0.0.255
> >  no auto-summary
> > 
> > 
> > Sw1 -
> > 
> > interface FastEthernet0/13
> >  description connected to R2
> >  switchport mode dynamic desirable
> >  no ip address
> >  duplex full
> >  speed 100
> > !
> > interface GigabitEthernet0/1
> >  description connected to R1 PA-GE (G4/0)
> >  switchport mode dynamic desirable
> >  no ip address
> > !
> 
> Hmm, on Switch 2 you have access vlan set on the two 
> interfaces.  Not on switch 1 though.

On Sw1 they are both in default VLAN1

> 
> Are you using these switches as L2 devices or L3?  On switch 
> 1 with "switchport mode dynamic" you are saying these are 
> tagged trunk interfaces.

Sw 1 is a c3550 with L3 capability but for these routers it should be L2
only.  There are a few ports configured as L3 but they are different subnets
/ purposes completely.

>   The router interfaces aren't configured as trunks.  On 
> switch 2 with "switchport access vlan2" you are saying these 
> are nontagged access interfaces.

Yes, no trunking from any of the routers on these FE's

> 
> > interface Vlan1
> >  ip address 1.1.1.4 255.255.255.0
> > !
> 
> Do you have these SVIs configured with IP addresses for mgmt 
> purposes or something else?

Mgt only

> 
> > router eigrp 65555
> >  network 1.1.1.0 0.0.0.255
> >  network 2.1.1.0 0.0.0.255
> >  no auto-summary
> >  eigrp log-neighbor-changes
> > 
> 
> Looks like this switch is supposed to be running EIGRP too?

Yes, since there are a few L3 ports on the switch.  Could this be causing
the problem ?

> 
> > 
> > sw2 -
> > 
> > !
> > interface FastEthernet0/1
> >  description connected to R1 (F0/0)
> >  duplex full
> >  switchport access vlan 2
> > !
> > interface FastEthernet0/5
> >  description connected to R2-f6/0
> >  mtu 1548
> >  duplex full
> >  switchport access vlan 2
> > !
> > interface VLAN1
> >  no ip address
> >  no ip directed-broadcast
> >  no ip route-cache
> >  shutdown
> > !
> > interface VLAN2
> >  ip address 2.1.1.4 255.255.255.0
> >  no ip directed-broadcast
> >  no ip route-cache
> > 
> > 
> 
> This switch looks more like I would expect out of a basic L2 device.

Yes, it's a 3500XL L2 only switch.  If the 3550 switch with L3 and EIGRP is
causing the issue I could move to a true L2 core and move the 3550 out as an
edge device.

>From the responses so far, it seems the design "concept" is okay and no
EIGRP commands have to be changed or modified - is that correct ?

Thanks
Eric