Redundant Core switches and Single Router Design

[Fazal E Rasool Khan]

Hello Everyone,

I am working on one design and need support for connectivity between two core switches and router.

As shown in the attached diagram, it has two 4506E core switches and 2921 router which is connected to the internet. I need idea how the configuration between core switches and router.

On the LAN side i have 10+ floors and on each floor i have two access switches stacked together, by using HSRP i load balance 50% access switches on core 1 andother 50% access switches on core 2.

Right now i have connected only core 1 to the router and its working fine but i want to connect core 2 also to the router.

i am using the similar config for LAN VLANs

core 1

======

interface Vlan10

ip address 192.168.10.252 255.255.255.0

standby 10 ip 192.168.10.254

standby 10 preempt

Standby 4 timers mes 200 msec 750

interface Vlan10

ip address 192.168.10.253 255.255.255.0

standby 10 ip 192.168.10.254

Standby 4 timers mes 200 msec 750

I tried this thread https://supportforums.cisco.com/thread/2183460 solution but it did not work for me.

Please advise

Thanks in advance.

[daniel.dib]

Yes, you could run EIGRP there as well or just announce that subnet from the core if that is where the SVI is.

Daniel Dib
CCIE #37149

[Fazal E Rasool Khan]

Hi Daniel,

Yes i advertise the voice gateway subnets in eigrp ex: 192.168.200.0. Due to the redistribute static command in internet router its generating default router on voice gateway pointing to core switch.

When i put the static default route on voice gateway using the ip route command pointing to SIP server this default router pointing to core switch disappear. But when the Link connecting to PSTN (SIP server) will be down than again all the traffic will point to core switch from default gateway.

Can we filter the default route which is pointing to core switch on voice gateway.

Thanks for continues support.

[daniel.dib]

Hi,

That is one of the positive things about EIGRP since it is distance vector. Filtering is easy to do. Either you could use ACL or prefix-list and tie that to a distribute-list.

I made a quick lab to show you. Here R1 is receiving a default from R2:

R1#sh ip route eigrp

D*   0.0.0.0/0 [90/409600] via 10.0.0.2, 00:00:03, FastEthernet0/0

D       2.2.2.2 [90/409600] via 10.0.0.2, 00:00:02, FastEthernet0/0

Then I create ACL and filter it.

R1(config)#ip access-list standard NO_DEFAULT

R1(config-std-nacl)#deny 0.0.0.0

R1(config-std-nacl)#permit any

R1(config-std-nacl)#router eigrp 1

R1(config-router)#distribute-list NO_DEFAULT in

R1#sh ip route eigrp

     2.0.0.0/32 is subnetted, 1 subnets

D       2.2.2.2 [90/409600] via 10.0.0.2, 00:00:31, FastEthernet0/0

R1#

The default is now gone.

Daniel Dib
CCIE #37149

[Fazal E Rasool Khan]

Hi Daniel,

Thanks for the reply, i applied the distribute list and it worked fine. default router pointing to core switches disappear. i will implement the full solution at site and i will give you a feedback.

Many Thanks.