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default route on layer 3 switch

you need to understand it at its simplest form.

routerB = B
switch = C
RouterA = A

From C perspective anything will be destined to A since you have a default route. B pinging C is a layer 2, and on the same subnet.
There's no route explaining how A is supposed to go to B. If C knew about D which is the network behind B than the traffic should be working.

thats the thing, how do i get C to know about D? what command? do i get rid of the ip route to router A and configure something else? like a static to both routers?

router B is running ospf behind to D, and a direct ethernet to layer 3 switch.

router A is running EIGRP to another router behind it and of course ethernet to the layer 3 switch.

only thing i configured on this layer 3 switch is default route to router A, with VLAN interfaces. anything else to do here?

reply to kracksmith

reply to kracksmith
oh ok,

well i have it configured this way

Layer 3 switch (E) -- routerD -- routerB -- layer3 (c) -- router A

layer3 switch (E) ip is 172.16.201.2
routerD ip is 172.16.201.1 to E, and 192.168.201.0/30 network running ospf to router B, router B then is on the same subnet of layer 3 C switch.

router A is running eigrp to another router and that router connects to a layer 2 switch that connects to many other switches on trunks of course.

reply to kracksmith
ok i expanded my network by adding router B to layer 3 switch C and anything beyond router b can't see router A.
with this said, i can't make it a default route anymore, not a stub network anymore. have to use static routes to see beyond router B and router A as you mentioned.

reply to kracksmith
This a production thing you're testing here kracksmith, or are you just looking to drive
yourself (and possibly us as well) batty?

If it's the latter, it's too close to friday for deep thinking on my part, so I'd just say drop
the static route and go all dynamic routing, and redistribute between OSPF and EIGRP
accordingly

Regards

reply to kracksmith
just a play thing, haha.

yea i think what makes sense is just run all dynamic protocol and just call it the day. running static would be insane as i have 5-6 different networks all router and layer 3 switch has to be mapped.

reply to HELLFIRE
I got your problem. just need your ip scheme to tell you the exact solution. i also can give you working solution on GNS

reply to kracksmith
So on the layer 3 switch you need to add a route pointing the subnet behind router B to router B.

If you do a "show ip route x.x.x.x" on the layer 3 switch where x.x.x.x is an IP sitting behind router B, youll soon find out where it thinks it should send packets (which would probably be to router A if it doesnt have a more explicit instruction due to the deault route). You then fix it by adding routes to point traffic in the right direction.

Likewise youd need to add a similar route on router A so that router A sends traffic for that subnet to the layer 3 switch, which then sends it to router B.

Of course, a dynamic routing protocol takes care of all this for you. You then just configure router A to originate a default route which will make its way to all other routers.

Seems simple?

reply to kracksmith
A routing protocol is definitely the way to go if you're going to be running multiple subnets. However, to get a full understanding, it's always a good to do the "long division" first (a.k.a. "static routing") to better understand where the "short cut" (a.k.a. "routing protocols") takes over.

Referring to your example, is the layer3 switch running routed ports or just access ports? "If" both ports on layer 3 were routed ports (meaning the "no switchport" command was used), and provided routers a and b both had address schemes that correlated with the layer3 switch, I'd use "ip route 0.0.0.0 0.0.0.0 [add ip address of next-hop rtr here] on the port connecting to the layer3 switch from each router as a start. Example:

---------------------------------------------------------------

Host1-----RtrB---------------L3_Sw------------RtrA

1) L3_Sw-to-RtrB = 192.168.2.1/30

RtrB-to-L3_Sw = 192.168.2.2/30

2) L3_Sw-to-RtrA = 192.168.1.5/30

RtrA-to-L3_Sw = 192.168.1.6/30

3) Host1-RtrB = 192.168.2.3

So, for "host 1" to ping "RtrA," on "RtrB," enter:

ip route 0.0.0.0 0.0.0.0 192.168.2.1

For "RtrA" to ping "Host1," enter on "RtrA:"

ip route 0.0.0.0 0.0.0.0 192.168.1.5

Once I'm able to ping that way, I'd start adding ip addresses to become more specific...

----------------------------------------------------------------

Based on this quick config, Host1 should be able to hit RtrA and vice-versa.

Let me know if I'm off on what's being spoken about

Jay

reply to kracksmith
ok thanks you guys for at least taking the interest to help me out.

Here is my original one that works, all VLANS can ping all VLANS running eigrp between 2 routers. »sendshack.com/download/w7rc8tb layer 3 switch C has an ip route to router A, it's a stub network, one way in, one way out. so IP route is possible here.

Here is my expanded network which i'm having a bit of problem but fixed it somewhat from your help. »sendshack.com/download/zud0d0g again layer 3 is a stub network with IP route to router A

now i'm adding router B running OSPF to another network with Vlans. this 2nd network wasn't able to ping layer 3 switch C until i added the Left VLANs static subnets to the layer 3 switch C, now these left VLANS can now ping layer 3 switch C but can't ping router A.

i would imagine if the static i did on layer 3 switch C is able to ping the left VLANs and the left VLANs can ping layer 3 switch C then the IP route to Router A would work, but it doesn't.

question, do i need to just go dynamic on the layer 3 switch C? also why isn't ip route to router A work if left VLANs can ping layer 3 switch C??

i have a feeling you guys are going to say router a doesn't know these left VLANs but i think it shouldn't matter as the layer 3 switch C forwards any and everything to router A anyways.

oh, password is cisco and enable is class

reply to kracksmith
another thing, i have to run eigrp on router A and have to run ospf on router B. so i need a solution to make it work but run these 2 wan protocols at it's destination.

If that's the case, it sounds like you're going to need to treat your L3 switch as an ASBR and then redistribute the routes between rtrA and rtrB..

Staying with my earlier scheme but with minor change of IP's:

RtrA-to-L3
int f0/0 = 172.16.1.2/32
- router eigrp 100
-- network 172.16.1.0
-- no auto

L3-to-RtrA:
int f0/1 = 172.16.1.1/32
- router eigrp 100
-- no auto
-- network 172.6.1.0
-- redistribute ospf 1
--- redistribute default-metric 100000 100 255 1 15000
--- default-information originate always (ensures default route is always available when peforming route redistribution)

L3-to-RtrB
int f0/0 = 192.168.1.1/32
-router ospf 1
-- network 192.168.1.0 0.0.0.3 area 0
-- redistribute eigrp 100 subnets (defines all "classful" and "classless"; very important)
--- redistribute eigrop 100 connected (advertises subnets "not" directly advertised

RtrB
int f0/0 = 192.168.1.2/30
- router ospf 1
- network 192.168.1.0 0.0.0.3 area 0

As you can see, all the work is going to be done by L3 because it's the distribution point between the other two routes. A keything when doing redistribution with eigrp is to do a "show interface" out of the port of the ASBR that's connected to the EIGRP route to get your stats for BW (100000), Delay (10), Reliability (255), Load (1), and MTU (1500). Additionally, you'll need to devide the delay by "10" before you input your redistribution command.

Granted I'm still making my way through the CCNP curriculum, this should be it.

Here's a link from the CISCO site to help as well:

»www.cisco.com/en/US/tech/tk365/t···7e.shtml

Jay