The MPLS-OPS Archive

["Tarun Bhalla" <tarun.bhalla@wipro.com>]

Wulf..

 

thanx for the prompt reply.. yeah!! i know

abt cisco/juniper providing certain cmds that

mention things like jumbo frames.. also in many

cases the core consists of Sonet.. where the frame

size is 4470 bytes.. so not a big problem there also..

 

bt as i already told this test is happening on some test

setups.. so for that we have 3 set of Linux machines

(Ingress, Egress and transit) and nothing more and

also having MPLS Linux patch to enable MPLS on them.

 

One option is that i change the NIC cards of the intermediate

interfaces to jumbo cards.. but am not going for that.. so have

to implement fragmentation there.. but that is also not a problem

rather my issue is since this problem is going to be there in

the MPLS networ, how has the community addressed this issue??

 

I mean is there any standd way of fragmentation and reassembly

in Layer 2 which is also not time consuming..

 

Thanks & Regards
Tarun B
_________________________________________________
Tarun Bhalla
Wipro Technologies
26 Hosur Main Road,
Bommanahalli,
Bangalore- 560 068. India
Tel +91-80-5732293, Extn 3139 <http://www.wipro.com/>

 

 

----- Original Message -----

From: Wulf Losee

To: Tarun Bhalla ; mpls-ops@mplsrc.com

Sent: Thursday, March 20, 2003 8:28 PM

Subject: Re: [MPLS-OPS]: MTU problems in EoMpls domain..

Tarun:
You didn't mention what sort of routers you're using. But I know that both Cisco and Juniper offer a way to change the MTU value on the Ethernet interfaces. On Cisco it's 'tag-switching mtu 1504' (actually, 1504 sounds too small, but it's past my bedtime, and I don't have the patience to think it through ;-). And I'm afraid I don't remember the syntax for Juniper.

As I recall Cisco actually allows MTU values of up to 1526 -- maybe that's why I think the 1504 is too small. Push it up to 1526...

If you don't have Cisco or Juniper, it *may* be that the brand of router you're using doesn't support a similar command -- but I think they'd have to! Check your manual...

cheers,
--Wulf

At 10:11 AM 3/21/03 -0800, Tarun Bhalla wrote:

hi all,
 
I am new to this mailing list. so hi to all.. now my problems :((
Actually, I am trying to handle the problem of fragmentation in
Ethernet over MPLS network.
 
This is the existing network topology...
 
LAN A -------> MPLS Domain ----------> LAN B
 
To implement EoMPLS, I am capturing the packet in Ingress of the MPLS domain
and trying to send this as a payload over the MPLS domain.. When I
am doing this the problem is that the frames which are 1500 bytes (normal
ethernet frames) can not be sent across this MPLS domain as the payld
of this domain can only be 1496 bytes... (4 bytes label gets added and leave
the matter when multiple labels are added).. So, I am stuck as i am not
able to send 1500 bytes frames..
 
These all things are being carried on test setups. So, I can not
have the liberty or leisure to use SONET interfaces as my core n/w
interfaces.. also am not sure what to do in order to make use of jumbo
ethernet frames... So, the only option left is to fragment the frames when i
capture the ethernet frames.. but for that i need ur advice..
 
I mean is there any standard methodology that says how to handle
fragmentation in ethernet layer cos I will have to anyway go to this
final resort.. or is there any other way arnd. ??
 
Thanks & Regards
Tarun B
_________________________________________________
Tarun Bhalla
Wipro Technologies
26 Hosur Main Road,
Bommanahalli,
Bangalore- 560 068. India
Tel +91-80-5732293, Extn 3139 <http://www.wipro.com/>