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Community Member

Trying to understand gateway on switches (2950's)

We have 2 routers configured for hsrp.

Hanging off these routers is a 2950 switch, configured with an ip address on vlan1

hanging off this switch (switch a) are other 2950's that are daisy chained (switches b-d).

Swithces b-d have the ip-default gateway configuration, which is the the virtual ip address of the hsrp router group.

However, switch A only has an IP address

(not ip-default gateway). Is this configured properly?

switch A

interface Vlan1

ip address 192.168.1.13 255.255.255.0

no ip route-cache

!

ip http server

switch B

!

interface Vlan1

ip address 192.168.1.193 255.255.255.0

no ip route-cache

!

ip default-gateway 192.168.1.252

ip http server

So my question is...How can switch A not be

configured for a ip-default gateway? And the

other switches hanging off it do have it?

We are only running 1 vlan thus far.

10 REPLIES
Community Member

Re: Trying to understand gateway on switches (2950's)

Hello,

Given you only have the one VLAN, its not overly required to have an ip default-gateway for the switch(s).

This is not going to effect traffic for the switches only your ability to manage the switch from beyond your local subnet.

Tim

Community Member

Re: Trying to understand gateway on switches (2950's)

Interesting, becuase I am able to log into that switch with no default gateway from a router in a diff. building that is not in the same subnet. Should this be even possible?

(we have 2 t1's going to the site with

the swith in question)

[Connection to 192.168.1.13 closed by foreign host]

xxxxxxx#sh ip route 192.168.1.13

Routing entry for 192.168.1.0/24

Known via "static", distance 1, metric 0

Routing Descriptor Blocks:

192.168.100.253

Route metric is 0, traffic share count is 1

*192.168.100.249

Route metric is 0, traffic share count is 1

Community Member

Re: Trying to understand gateway on switches (2950's)

looking at this output it says there is a static router in here pointing to that subnet?

Purple

Re: Trying to understand gateway on switches (2950's)

That being said it should have the default gateway statement in their just in case in the future you will have more than 1 vlan and have to route between them .

Community Member

Re: Trying to understand gateway on switches (2950's)

ok..but I was under the impression that

without a default gateway, a device

is unpingable and unreachable outside its own subnet

Purple

Re: Trying to understand gateway on switches (2950's)

You are correct , the switch in its current form would not be pingable outside its own subnet . This is for management of the switch only and has nothing to do with clients hung off this switch.

Community Member

Re: Trying to understand gateway on switches (2950's)

so the fact that i can acces the switch, ping it from a router that is not in the subnet.....makes no sense?

Hall of Fame Super Blue

Re: Trying to understand gateway on switches (2950's)

Richard

You are correct in what you say.

Could you run a traceroute on switch A to the remote router.

Can you also on switch A do a "sh ip def" or "sh ip route" just to make sure it hasn't got one but it's just not showing up in the config.

Jon

Community Member

Re: Trying to understand gateway on switches (2950's)

trace from a router in a different building

again here is the route to the .13 address

from the router in a diff. building. We have 2 t1's statically configured...and as seen the are showing up in the trace route below

routerxxx#sh ip route 192.168.1.13

Routing entry for 192.168.1.0/24

Known via "static", distance 1, metric 0

Routing Descriptor Blocks:

192.168.100.253

Route metric is 0, traffic share count is 1

* 192.168.100.249

Route metric is 0, traffic share count is 1

router XXX#trace 192.168.1.13

Type escape sequence to abort.

Tracing the route to 192.168.1.13

1 192.168.100.253 4 msec

192.168.100.249 8 msec 4 msec

2 192.168.1.13 8 msec * 8 msec

switch A in question

switchxxxx#sho ip def

0.0.0.0

xxxxx#sh ip route

^

% Invalid input detected at '^' marker.

the only ip in the config for switch A

interface Vlan1

ip address 192.168.1.13 255.255.255.0

no ip route-cache

no ip-default gatway configured...any ideas?

Purple

Re: Trying to understand gateway on switches (2950's)

they may have proxy arp enabled on the router in which case it would be able to get to the switch I believe.

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