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SG300 issues with routes

phibertron
Level 1
Level 1

‎08-18-2014 03:47 PM

I am trying to add redundant default gateways, but it will only display one as being in the route table

 

The SG300 is in L3 mode, with the following interfaces

#show ip in

    IP Address         I/F      I/F Status      Type     Directed   Precedence   Status
                                admin/oper               Broadcast
------------------- ---------- ------------- ----------- ---------- ---------- -----------
192.168.10.10/24   vlan 100   UP/UP         Static      disable    No         Valid
192.168.11.1/24    vlan 101   UP/UP         Static      disable    No         Valid
192.168.12.1/24    vlan 102   UP/UP         Static      disable    No         Valid
192.168.13.1/24    vlan 103   UP/UP         Static      disable    No         Valid
192.168.14.1/24    vlan 104   UP/UP         Static      disable    No         Valid
192.168.15.1/24    vlan 105   UP/UP         Static      disable    No         Valid
192.168.16.1/24    vlan 106   UP/UP         Static      disable    No         Valid
192.168.17.1/24    vlan 107   UP/UP         Static      disable    No         Valid
192.168.18.1/24    vlan 108   UP/UP         Static      disable    No         Valid

 

Here is the route table before I attempt to add the gateways

#show ip route
Maximum Parallel Paths: 1 (1 after reset)
IP Forwarding: enabled
Codes: > - best, C - connected, S - static

C   192.168.10.0/24 is directly connected, vlan 100
C   192.168.11.0/24 is directly connected, vlan 101
C   192.168.12.0/24 is directly connected, vlan 102
C   192.168.13.0/24 is directly connected, vlan 103
C   192.168.14.0/24 is directly connected, vlan 104
C   192.168.15.0/24 is directly connected, vlan 105
C   192.168.16.0/24 is directly connected, vlan 106
C   192.168.17.0/24 is directly connected, vlan 107
C   192.168.18.0/24 is directly connected, vlan 108

 

I add the first gateway, with a metric of 1 and it shows in the route table

#ip route 0.0.0.0 0.0.0.0 192.168.10.1 metric 1

#show ip route
Maximum Parallel Paths: 1 (1 after reset)
IP Forwarding: enabled
Codes: > - best, C - connected, S - static

S   0.0.0.0/0 [1/1] via 192.168.10.1, 00:00:39, vlan 100
C   192.168.10.0/24 is directly connected, vlan 100
C   192.168.11.0/24 is directly connected, vlan 101
C   192.168.12.0/24 is directly connected, vlan 102
C   192.168.13.0/24 is directly connected, vlan 103
C   192.168.14.0/24 is directly connected, vlan 104
C   192.168.15.0/24 is directly connected, vlan 105
C   192.168.16.0/24 is directly connected, vlan 106
C   192.168.17.0/24 is directly connected, vlan 107
C   192.168.18.0/24 is directly connected, vlan 108

 

I add the second gateway with a metric of 2, but it does NOT show in the route table

#ip route 0.0.0.0 0.0.0.0 192.168.10.2 metric 2

#show ip route
Maximum Parallel Paths: 1 (1 after reset)
IP Forwarding: enabled
Codes: > - best, C - connected, S - static

S   0.0.0.0/0 [1/1] via 192.168.10.1, 00:03:41, vlan 100
C   192.168.10.0/24 is directly connected, vlan 100
C   192.168.11.0/24 is directly connected, vlan 101
C   192.168.12.0/24 is directly connected, vlan 102
C   192.168.13.0/24 is directly connected, vlan 103
C   192.168.14.0/24 is directly connected, vlan 104
C   192.168.15.0/24 is directly connected, vlan 105
C   192.168.16.0/24 is directly connected, vlan 106
C   192.168.17.0/24 is directly connected, vlan 107
C   192.168.18.0/24 is directly connected, vlan 108

 

If I remove the first gateway, then the second one shows in the route table

#no ip route 0.0.0.0 0.0.0.0 192.168.10.1
1 entry was deleted

#show ip route
Maximum Parallel Paths: 1 (1 after reset)
IP Forwarding: enabled
Codes: > - best, C - connected, S - static

S   0.0.0.0/0 [1/2] via 192.168.10.2, 00:03:28, vlan 100
C   192.168.10.0/24 is directly connected, vlan 100
C   192.168.11.0/24 is directly connected, vlan 101
C   192.168.12.0/24 is directly connected, vlan 102
C   192.168.13.0/24 is directly connected, vlan 103
C   192.168.14.0/24 is directly connected, vlan 104
C   192.168.15.0/24 is directly connected, vlan 105
C   192.168.16.0/24 is directly connected, vlan 106
C   192.168.17.0/24 is directly connected, vlan 107
C   192.168.18.0/24 is directly connected, vlan 108

 

Is there something special I need to do, for multiple gateways?

I tried the same as the above, with just one default gateway, and used two other static routes, resuslts were the same

Any suggestions?

 

 

Labels:
0 Helpful
4 Replies 4

Aleksandra Dargiel
Cisco Employee
Cisco Employee

‎08-21-2014 10:50 PM

Hi,

Redundant gateways should be really handled by redundancy protocols such as HSRP or VRRP.

Regards,

Aleksandra

0 Helpful

phibertron
Level 1
Level 1
In response to Aleksandra Dargiel

‎08-27-2014 10:26 AM

Understood, but...

It still doesnt explain why the route wont show that there is a redundant gateway

 

0 Helpful

V K Moorthy
Level 1
Level 1
In response to phibertron

‎08-27-2014 05:41 PM

Hi,

By default static route as metric of 1.since the second route(with metric 2) it's floating route.Once default static route is deleted floating route is reflected in the output of "show ip route".

 

regards

Moorthy

0 Helpful

phibertron
Level 1
Level 1
In response to V K Moorthy

‎08-28-2014 09:09 AM

Thanks for the explanation on that behavior, much appreciated

 

However,

In the scope of troubleshooting,

say an admin had entered in a secondary default gateway

Whether on purpose or by accident, how would he or any other admin now that?

Because the route would only show that one is present

 

 

0 Helpful
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