09-15-2005 06:14 AM - edited 03-03-2019 12:04 AM
Hello
I am confused about the no keepalive and no shutdown command on different interface type on router. In serial interface, the status is down/down. But in ethernet interface, it is up/up. Could anyone please clear me?
And can this reason apply with Catalyst too?
Thanks a lot,
Nitass
09-16-2005 12:52 AM
Hi Nitaas,
"No keepalive" and No shutdown they both have diffrent use.
Keepalives are used on the routers interfaces as hello mechanism to check the end to end connectivity to the other end.Routers interface used this mechanism to check the interface status.If you have no keepalive command its means that inerface status check mechansim in disabled and router will not transmit any keepalive packet on the link.
No shutdown cmmand is used to bring the interface up from the administratively shutdown state or the shutdown state on an interface which default on the routers. When the routers come up they put the interfaces in the shutdown state and you give the "no shut " command to bring the interface up.
Now, on the fastethernet interfaces the moment you give the no shut command it will bring the interface up but will not come up/up untill you connect the cable to it. On the serial interface if you dont have end to end connectivity through it will be down/down if keep alives are diabled. If keepalive is enable and you have ur CSU/DSU connected it will come up/down untill the connectivity is through.
HTH,
-amit singh
09-16-2005 01:16 AM
Hi amit-singh,
Thanks for reply. I have been set "no keepalive" command on ethernet interface of router for bringing interface to up/up even if it does not have cable connect to it.
So I want to know this case can apply to serial interface of router and ethernet interface of layer 3 switch too or not.
Thanks a lot,
Nitass
09-16-2005 02:05 AM
Hi Nitass,
Yes I see the same on my router.
OKH-PBAGH-GRGNPRNT#sh int fa 0/1
FastEthernet0/1 is up, line protocol is down
Hardware is AmdFE, address is 000b.5faa.6961 (bia 000b.5faa.6961)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
OKH-PBAGH-GRGNPRNT(config)#int fa 0/1
OKH-PBAGH-GRGNPRNT(config-if)#no kee
OKH-PBAGH-GRGNPRNT(config-if)#no keepalive
OKH-PBAGH-GRGNPRNT(config-if)#end
OKH-PBAGH-GRGNPRNT#show int fa 0/1
FastEthernet0/1 is up, line protocol is up
Hardware is AmdFE, address is 000b.5faa.6961 (bia 000b.5f
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not set
I dont have a cable connected to it.
But its not the same on the serial interface and the ethernet interface of the L3 switch. They have different behaviur then this.they stay down/down.
PJB-UPW-PRI#sh int s 0/4
Serial0/4 is down, line protocol is down
Hardware is GT96K Serial
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive set (10 sec)
PJB-UPW-PRI(config)#int s 0/4
PJB-UPW-PRI(config-if)#no kee
PJB-UPW-PRI(config-if)#no keepalive
PJB-UPW-PRI(config-if)#end
PJB-UPW-PRI#sh int s 0/4
Serial0/4 is down, line protocol is down
Hardware is GT96K Serial
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
Keepalive not set
4510_Switch_C48_BASEMENT(config)#int gig 3/19
4510_Switch_C48_BASEMENT(config-if)no keepalive
4510_Switch_C48_BASEMENT(config-if)#end
4510_Switch_C48_BASEMENT#show int g 3/19
GigabitEthernet3/19 is down, line protocol is down (notconnect)
Hardware is Gigabit Ethernet Port, address is 0013.7f65.4582 (b
82)
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
HTH,
-amit singh
09-16-2005 02:33 AM
Hi amit-singh,
Thank you very much. Do you know the reason?
Thanks a lot,
Nitass
09-22-2005 10:04 PM
Nitass,
the serial interfaces rely on the modem signals to detect their status. On the bottom of the "sh int" output you see the signals and when DCD is down the interface is considered down regardless of the keepalive setting.
HTH
Mat
09-25-2005 08:17 AM
Hi mdschaerer,
Sorry to my late. I had Internet access limitation on last week. Thank you very much for reply.
Do you know the reason for Ethernet interface on Catalyst switch?
Thanks for advance,
Nitass
05-28-2013 08:47 PM
no keepalive: - It's used to determine whether the other end is there or not. If you start with a switch with nothing plugged into it. And look at "show interface status", you'll see things are not-connected. Even though ports on a switch aren't shutdown by default, they are still not UP because nothing's plugged in. When you plug something in that changes.
If you were to do "no keepalive" the ports would all show as "up/up" since you lost your ability to determine whether it was REALLY functional or not.
no shutdown:- This command is used to bring the interface up from the administratively shutdown state or the shutdown state on an interface which default on the routers. When the routers come up they put the interfaces in the shutdown state and you give the "no shut " command to bring the interface up.
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