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Trying to understand gateway on switches (2950's)

nygenxny123
Level 1
Level 1

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 10

timkaye
Level 1
Level 1

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

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

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

glen.grant
VIP Alumni
VIP Alumni

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 .

ok..but I was under the impression that

without a default gateway, a device

is unpingable and unreachable outside its own subnet

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.

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

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

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?

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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