| [CCNA] running EIGRP My eigrp is running fine, when eigrp is configured does it still require the IP ROUTE statement? "ip route 0.0.0.0 0.0.0.0 gateway IP"? |
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aryobaPremium,MVM
join:2002-08-22
kudos:1 | Long Answer:
IGP like EIGRP by design see that in order to have certain network subnets to be within the autonomous system, such subnets must be configured at some EIGRP-speaking router in order to maintain a location integrity. The whole idea is to maintain some kind of full visibility of the entire network within the autonomous system.
Since default gateway (or gateway of last resort) does not maintain specific network subnet location, then you have to introduce the default gateway as external routes.
Short Answer:
If you want machines within EIGRP autonomous system to be able to reach network subnets that are not showing in EIGRP Table (i.e. The Internet), then you have to redistribute default gateway into the EIGRP autonomous system.
In order to redistribute the default gateway, the default gateway route must exist within the routing table by either static route statement (the ip route 0.0.0.0 0.0.0.0 gateway IP), "dynamic" static route from PPP or DHCP, or some dynamic routing protocol such as BGP. |
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| well i have this problem. here is how my topology looks
3500 switch routerA ---serial---routerb2960A2960b
3500 lan has subnet A, 2960 has subnet c, serial has subnet b
3500 switch can ping 2960b, and vise versa 2960b can ping 3500 switch.
routers has Eigrp configured with 2 subnets, the full 10.0.0.0 and 192.168.1.0. subnet a and b are part of the 10.0.0.0 network (10.40.1.0 & 10.30.1.0).
router has no ip route 0.0.0.0 0.0.0.0 gateway ip statement as the pings are working.
switch a has ip default-gateway on router B
routerb can't ping switch b, and switch b can't ping routerb. switch b can ping switch a and vise versa.
how do i get switch b to be able to route over to the 3500 switch on eigrp? |
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aryobaPremium,MVM
join:2002-08-22
kudos:1 | Traceroute is a good friend of any network engineers in regards of troubleshooting. When you see something like incomplete traceroute path, you may want to jump into the last known equipment and verify if the routing needs some kind of manipulation or adjustment. |
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| reply to kracksmith
said by kracksmith:well i have this problem. here is how my topology looks
3500 switch routerA ---serial---routerb2960A2960b
3500 lan has subnet A, 2960 has subnet c, serial has subnet b
3500 switch can ping 2960b, and vise versa 2960b can ping 3500 switch.
routers has Eigrp configured with 2 subnets, the full 10.0.0.0 and 192.168.1.0. subnet a and b are part of the 10.0.0.0 network (10.40.1.0 & 10.30.1.0).
router has no ip route 0.0.0.0 0.0.0.0 gateway ip statement as the pings are working.
switch a has ip default-gateway on router B
routerb can't ping switch b, and switch b can't ping routerb. switch b can ping switch a and vise versa.
how do i get switch b to be able to route over to the 3500 switch on eigrp?
Well you need to get Router B to be able to ping The locally connected 2960B before you worry about anything else. This is a local ping on the same subnet/vlan and doesnt even use eigrp for this since it is a directly connected interface.
So 2960B uses subnet C which is in the 192.168.1.0 i assume?
What is the IP and default-gateway of switch B
What vlan is the IP on switch B? Is this vlan up/up?
Is the default gateway of switch B assigned on an interface on Router B?
You are correct that in your topology you dont need a static route on your routers (unless as was already said you need to access the internet) because as long as eigrp is setup and working correctly the routers will know to go to each other for the given subnets. The switches will need the local default gateway of the given router within their subnet.
If you need more help the configs of each device and a "show ip route" of each router would help a lot. |
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1 edit | reply to kracksmith
thanks guys, i got it done now. i missed switch B default gateway to router b ethernet interface.
Here is the link of my packet tracer if anybody want to see it (password = cisco, enable pw = class) and my configs below:
»sendshack.com/download/keihd2u
so switch 3550 is on subnet A and router serial are on subnet b and switch A and B are on subnet C. pings are able to travel back and forth. switch 3550 has vtp server with it's own vlan DB, so is switch A with switch B being the vtp client. 3550 has ip route enabled for vlans. switch a and B has default gateways. routers are running eigrp with router a being dce. trunking are enabled on switch a and B and lastly router on a stick had to be configured on router b to route switch a and b vlans. one question is it best to trunk router A and switch 3550? currently it's not. 3550 route it's own vlan so is trunking necessary?
En
clock set 09:17:00 03 january 2011
config t
clock timezone pst -5
hostname routerA
banner motd # this is router A #
no ip domain-lookup
enable secret class
service password-encryption
line con 0
password cisco
login
line vty 0 4
password cisco
login
no service password-encryption
int fa0/0
ip address 10.0.0.1 255.255.255.0
no shut
exit
int s0/0/0
ip address 172.16.1.1 255.255.255.252
clock rate 64000
no shut
exit
router eigrp 12
no auto-summary
network 10.0.0.0
network 172.16.0.0
exit
exit
wr
En
clock set 09:17:00 03 january 2011
config t
clock timezone pst -5
hostname routerB
banner motd # this is router B #
no ip domain-lookup
enable secret class
service password-encryption
line con 0
password cisco
login
line vty 0 4
password cisco
login
no service password-encryption
int fa0/0
no ip address
no shut
int fa0/0.1
encapsulation dot1q 1
ip address 192.168.1.1 255.255.255.0
int fa0/0.2
encapsulation dot1q 2
ip address 192.168.2.1 255.255.255.0
int fa0/0.3
encapsulation dot1q 3
ip address 192.168.3.1 255.255.255.0
int fa0/0.4
encapsulation dot1q 4
ip address 192.168.4.1 255.255.255.0
int fa0/0.5
encapsulation dot1q 5
ip address 192.168.5.1 255.255.255.0
exit
int s0/0/0
ip address 172.16.1.2 255.255.255.252
no shut
exit
router eigrp 12
no auto-summary
network 192.168.1.0
network 172.16.0.0
exit
exit
wr
En
clock set 09:17:00 03 january 2011
config t
clock timezone pst -5
hostname 3500
banner motd # this is 3500 #
no ip domain-lookup
enable secret class
service password-encryption
line con 0
password cisco
login
line vty 0 4
password cisco
login
no service password-encryption
ip routing
ip route 0.0.0.0 0.0.0.0 10.0.0.1
vlan 2
name workstation
vlan 3
name printer
vlan 4
name server
vlan 5
name wireless
vtp mode server
vtp domain Domain1.com
vtp password cisco
int vlan 1
ip address 10.0.0.2 255.255.255.0
no shut
exit
int vlan 2
ip address 10.0.2.1 255.255.255.0
no shut
exit
int vlan 3
ip address 10.0.3.1 255.255.255.0
no shut
exit
int vlan 4
ip address 10.0.4.1 255.255.255.0
no shut
exit
int vlan 5
ip address 10.0.5.1 255.255.255.0
no shut
exit
exit
wr
En
clock set 09:17:00 03 january 2011
config t
clock timezone pst -5
hostname 2960A
banner motd # this is 2960A #
no ip domain-lookup
enable secret class
service password-encryption
line con 0
password cisco
login
line vty 0 4
password cisco
login
no service password-encryption
int gi1/1
switchport mode trunk
int fa0/1
switchport mode trunk
vlan 2
name workstation
vlan 3
name printer
vlan 4
name server
vlan 5
name wireless
vtp mode server
vtp domain Domain2.com
vtp password cisco
int vlan 1
ip address 192.168.1.2 255.255.255.0
no shut
exit
int vlan 2
ip address 192.168.2.2 255.255.255.0
no shut
exit
int vlan 3
ip address 192.168.3.2 255.255.255.0
no shut
exit
int vlan 4
ip address 192.168.4.2 255.255.255.0
no shut
exit
int vlan 5
ip address 192.168.5.2 255.255.255.0
no shut
exit
ip default-gateway 192.168.1.1
exit
wr
En
clock set 09:17:00 03 january 2011
config t
clock timezone pst -5
hostname 2960B
banner motd # this is 2960B #
no ip domain-lookup
enable secret class
service password-encryption
line con 0
password cisco
login
line vty 0 4
password cisco
login
no service password-encryption
int gi1/1
switchport mode trunk
no shut
vtp mode client
vtp domain Domain2.com
vtp password cisco
int fa0/1
switchport mode access
switchport access vlan 1
no shut
int vlan 1
ip address 192.168.1.3 255.255.255.0
no shut
exit
ip default-gateway 192.168.1.1
exit
wr |
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1 edit | reply to kracksmith
sorry guys, i ran into a trouble.
switch 3550 can't ping the VLANs on router B and Switch A except for vlan 1 which it can.
switch B can ping all VLANs on router B and Switch A.
with this being said, VLANs on subnet C isn't routing over to switch 3550 correctly. |
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elnino
join:2006-08-27
Akron, OH | said by kracksmith:sorry guys, i ran into a trouble.
switch 3550 can't ping the VLANs on router B and Switch A except for vlan 1 which it can.
switch B can ping all VLANs on router B and Switch A.
with this being said, VLANs on subnet C isn't routing over to switch 3550 correctly.
You need to add wildcard masks to the networks you're advertising in EIGRP. |
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| reply to kracksmith
hmmm, can you explain why it's necessary to use a wild card to make this work correctly?
wildcard 0.0.0.255? |
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| reply to kracksmith
ok by following this theory
0 bit = match
1 bit = ignore
for eigrp 10.0.0.0 network i should use 0.0.0.255 since my subnet mask is a class C, as this states i should match the 1st three octets and ignore the 4th octet
and use 0.0.0.3 for the 172.16.0.0 255.255.255.252 network.
I haven't plugged these in yet so i don't know if it's right or not, also i like to know why this is necessary to make vlans on class C subnets routable to switch 3550. |
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| reply to kracksmith
I came and thought of something, switch B has a default gateway of router B which makes vlan1 work right. How does VLAN 2 through 5 know what their default gateway is?? or how do i configure a GW for VLAN 2 through 5?
i also tried plugging in wildcard mask and it couldn't even ping serials. Since I'm using PT, i believe on a real router if plugging in subnet mask on a network protocol it automatically reverse it to a wildcard mask for you. |
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| reply to kracksmith
You only have 1 default gateway.
You also dont normally need the masks as long as your doing regular subnet stuff it assumes its the native mask. For example 192.168.5.0 would be 0.0.0.255 by default.
Dont have time right now to dig though your configs but i might later. |
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elnino
join:2006-08-27
Akron, OH | reply to kracksmith
said by kracksmith:ok by following this theory
0 bit = match
1 bit = ignore
for eigrp 10.0.0.0 network i should use 0.0.0.255 since my subnet mask is a class C, as this states i should match the 1st three octets and ignore the 4th octet
and use 0.0.0.3 for the 172.16.0.0 255.255.255.252 network. Yep, but you're using 172.16.1.0/24 on RouterA, so the network statement in EIGRP would be 172.16.1.0 0.0.0.3.
Also on RouterB you're only advertising 192.168.1.0/24 in your EIGRP config, so you'd need to advertise the other connected networks too. |
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| well 172.168.1.0 isn't a /24 but /30 instead so 0.0.0.3 is correct. i don't know too much about wildcard but i just subtract 255 from 252 to get 3.
and hmmm, on router B i need to advertise the class 10 network? and advertise class C network on router A? I thought eigrp was to advertise connected networks only? |
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elnino
join:2006-08-27
Akron, OH | said by kracksmith:well 172.168.1.0 isn't a /24 but /30 instead so 0.0.0.3 is correct. i don't know too much about wildcard but i just subtract 255 from 252 to get 3.
Correct, I meant /30, just typed it out wrong. You had the third octet as 0 instead of 1 which is what I was trying to correct.
said by kracksmith:and hmmm, on router B i need to advertise the class 10 network? and advertise class C network on router A? I thought eigrp was to advertise connected networks only?
I meant that on RouterB you're only advertising 192.168.1.0/24 but not 192.168.2.0/24, 192.168.3.0/24, etc. You're correct that you should only advertise connected routes, therefore 10.0.2.0/24, 10.0.3.0/24, etc. networks should be advertised on the 3550 (which can also run EIGRP). If those 10.x networks aren't advertised, there will be no route for any return traffic (echo reply, etc). The other option is to put static routes on RouterA and RouterB to point them back to the 3550, but since the 3550 can also run routing protocols, why do static routes? |
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| reply to kracksmith
elnino, thank you for pointing this out. yes i forgot to have Eigrp advertise the VLANs other subnets on router B.
i didn't want to run eigrp on 3550 as i wanted to mimick a certain network.
so currently everything truly works now. VLAN 5 host 192.168.5.3 is able to ping 3550, and 3550 switch can ping all VLANs.
right now there are no wildcard but when i put in the wildcard it won't ping, 3550 can ping router a serial of 172.16.1.1 and that is it. switch A can ping router B serial of 172.16.1.2 and that is it. if i remove the wildcard on the eigrp then it works fine. Also i don't see the wildcard mask on all class c subnet on router B even though i entered it. i do see the wildcard subnet on router A class A and B subnets though. i see wildcard mask class B subnet on router B but not subnet C as mentioned. anyways i'm going to discard the wildcard for now as not using it is working.
I'm going to continue expanding this network and hope i don't run into any problems as most of the hard stuff has been completed.
and thanks again! |
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| reply to kracksmith
dang, sorry one more thing doesn't work.
router A can't ping 3550 vlans 2 thru 5 interfaces only vlan 1 can be ping'ed.
since these vlan are class A IP with class C subnet mask the router A eigrp network of 10.0.0.0 should be fine. i also tried the wildcard of 0.0.0.255 and this made it worst.
3550 ip routing has been enabled and ip route for router A has been set.
I think EIGRP doesn't recognize the class A VLAN 2 thru 5 subnet. |
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1 edit | reply to kracksmith
ok i did a tracert from a host on vlan 3 to router A
it can only ping the vlan 3 gateway on the 3550 switch.
the 3550 switch does have ip route configured to router A "ip route 0.0.0.0 0.0.0.0 routerA_IP"
ip route (routing table) on 3550 shows the vlan 1-5 connected
ip route (routing table) on routerA shows 10.0.0.0/24 connected (i have a gut feeling this should be a /16 instead)
With this said i don't see where the problem is?? |
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| reply to kracksmith
Well that was it, the Ethernet interface on routerA had to be within the same subnet of the vlan 2 thru 5 too. I think i need to mess around with the VLSM and not open up /16. |
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aryobaPremium,MVM
join:2002-08-22
kudos:1 | One note about VLSM is that EIGRP is "forgiving" regarding mismatched subnet mask between two neighbors due to the EIGRP original design to support auto summarization. Two neighbors still can form adjacency when one has subnet mask longer than its neighbor as long as the subnet is still part of the larger network. You will also notice some summarization behavior when one router is configured as auto-summary enabled and rest of routers are not.
With OSPF, two neighbors cannot form adjacency without matching subnet mask since OSPF by design supports (and relies heavily) on VLSM. Further, there is no auto summary in OSPF which make sense since there can be summarization at ABR or ASBR. Therefore with OSPF, there should be minimal to no mistake regarding mismatched subnet mask. |
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