[c-nsp] MTU on GigE

[Vincent De Keyzer]

Well, when I raise MTU only to 1600, I can ping with 1501-bytes df-bit set;
while I couldn't with MTU = 1500. 

I didn't touch IP MTU. Is this normal?

This has never been clear to me - what is the meaning of "mtu" vs. "ip mtu"?

Vincent


> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> bounces at puck.nether.net] On Behalf Of Aivars
> Sent: mercredi 19 octobre 2005 13:56
> To: Vincent De Keyzer
> Cc: cisco-nsp at puck.nether.net
> Subject: Re[2]: [c-nsp] MTU on GigE
> 
> You have to rise interface MTU and only after that you will be able to
> increase (adjust) IP MTU.
> 
> Aivars
> 
> Wednesday, October 19, 2005, 2:48:40 PM, you wrote:
> 
> VDK> Thanks,
> 
> VDK> it was "mtu":
> 
> VDK> Router(config)#int gigabitEthernet 0/2
> VDK> Router(config-if)#ip mtu 1600
> VDK>                             ^
> VDK> % Invalid input detected at '^' marker.
> 
> VDK> Router(config-if)#ip mtu ?
> VDK>   <68-1500>  MTU (bytes)
> 
> VDK> Vincent
> 
> >> -----Original Message-----
> >> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
> >> bounces at puck.nether.net] On Behalf Of Peter Salanki
> >> Sent: mercredi 19 octobre 2005 10:44
> >> To: Vincent De Keyzer
> >> Cc: cisco-nsp at puck.nether.net
> >> Subject: Re: [c-nsp] MTU on GigE
> >>
> >> try the mtu/ip mtu command.
> >>
> >> 19 okt 2005 kl. 10.35 skrev Vincent De Keyzer:
> >>
> >> > Hello again,
> >> >
> >> >
> >> >
> >> > I was under the impression that the MTU on a GigE interface was
> >> > higher than
> >> > 1500 bytes. Is it true?
> >> >
> >> >
> >> >
> >> > If yes, then why does my 7206VXR/NPE-G1 say the following?
> >> >
> >> >
> >> >
> >> > GigabitEthernet0/2 is up, line protocol is up
> >> >
> >> >   Hardware is BCM1250 Internal MAC, address is 0014.a862.b71a (bia
> >> > 0014.a862.b71a)
> >> >
> >> >   Internet address is x.y.z.198/30
> >> >
> >> >   MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
> >> >
> >> >      reliability 255/255, txload 2/255, rxload 4/255
> >> >
> >> >   Encapsulation ARPA, loopback not set
> >> >
> >> >   Keepalive set (10 sec)
> >> >
> >> >   Full-duplex, 1000Mb/s, link type is auto, media type is SX (.)
> >> >
> >> >
> >> >
> >> > Config is
> >> >
> >> >
> >> >
> >> > interface GigabitEthernet0/2
> >> >
> >> > ip address x.y.z.198 255.255.255.252
> >> >
> >> >  no ip redirects
> >> >
> >> >  no ip unreachables
> >> >
> >> >  no ip proxy-arp
> >> >
> >> >  no ip route-cache cef
> >> >
> >> >  no ip route-cache
> >> >
> >> >  ip ospf cost 15
> >> >
> >> >  duplex full
> >> >
> >> >  speed 1000
> >> >
> >> >  media-type gbic
> >> >
> >> >  negotiation auto
> >> >
> >> >  no clns route-cache
> >> >
> >> > end
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > Vincent
> >> >
> >> >
> >> >
> >> >
> >> >
> >> > _______________________________________________
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> >> >
> >>
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