Re: Any 1U - 2U Ethernet switches that can handle 4K VLANs?
ISL _DOES NOT CHANGE_ packet size.
An 802.1q tag adds 4 bytes to the Ethernet frame. ISL encapsulation adds 30 bytes to the Ethernet frame. Steinar Haug, Nethelp consulting, sthaug@nethelp.no
Both the ISL _and_ the Dotq headers are stripped off at the trunk interface so they _both_ change the packet size but neither alters the payload. Scott C. McGrath On Mon, 26 Jan 2004 sthaug@nethelp.no wrote:
ISL _DOES NOT CHANGE_ packet size.
An 802.1q tag adds 4 bytes to the Ethernet frame.
ISL encapsulation adds 30 bytes to the Ethernet frame.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
Sorry; of course, I meant _change MTU_.
Both the ISL _and_ the Dotq headers are stripped off at the trunk interface so they _both_ change the packet size but neither alters the payload.
Scott C. McGrath
On Mon, 26 Jan 2004 sthaug@nethelp.no wrote:
ISL _DOES NOT CHANGE_ packet size.
An 802.1q tag adds 4 bytes to the Ethernet frame.
ISL encapsulation adds 30 bytes to the Ethernet frame.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
So what? Is is a sugnificant drawback? I do not think so. Both ISL and 802.1q require special interface cards (with extended frame size), and I do not see any reason, why 26 bytes vs 4 bytes makes big difference. /May be, the only pro for 802.1q tagging is it's possible implementation on the old interface cards, which did not allowed extra 30 bytes but allowed extra 4 bytes/. I am no saying that ISL is better tha 802.1q, but 802.1q is not much better than ISL, and (in some cases) is even worst. ----- Original Message ----- From: <sthaug@nethelp.no> To: <alex@relcom.net> Cc: <nanog@merit.edu> Sent: Monday, January 26, 2004 9:10 AM Subject: Re: Any 1U - 2U Ethernet switches that can handle 4K VLANs?
ISL _DOES NOT CHANGE_ packet size.
An 802.1q tag adds 4 bytes to the Ethernet frame.
ISL encapsulation adds 30 bytes to the Ethernet frame.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
welcome to 2004. ISL is a thing of the past. let us move on. ./end_flamebait.sh -J (who realized Cisco no longer supports ISL on 2950 and some other newer box) On Mon, Jan 26, 2004 at 11:09:07PM -0800, Alexei Roudnev wrote:
So what? Is is a sugnificant drawback? I do not think so. Both ISL and 802.1q require special interface cards (with extended frame size), and I do not see any reason, why 26 bytes vs 4 bytes makes big difference. /May be, the only pro for 802.1q tagging is it's possible implementation on the old interface cards, which did not allowed extra 30 bytes but allowed extra 4 bytes/.
I am no saying that ISL is better tha 802.1q, but 802.1q is not much better than ISL, and (in some cases) is even worst.
----- Original Message ----- From: <sthaug@nethelp.no> To: <alex@relcom.net> Cc: <nanog@merit.edu> Sent: Monday, January 26, 2004 9:10 AM Subject: Re: Any 1U - 2U Ethernet switches that can handle 4K VLANs?
ISL _DOES NOT CHANGE_ packet size.
An 802.1q tag adds 4 bytes to the Ethernet frame.
ISL encapsulation adds 30 bytes to the Ethernet frame.
Steinar Haug, Nethelp consulting, sthaug@nethelp.no
-- James Jun (formerly Haesu) TowardEX Technologies, Inc. 1740 Massachusetts Ave. Boxborough, MA 01719 Consulting, IPv4 & IPv6 colocation, web hosting, network design & implementation http://www.towardex.com | james@towardex.com Cell: (978)394-2867 | Office: (978)263-3399 Ext. 170 Fax: (978)263-0033 | AIM: GigabitEthernet0 NOC: http://www.twdx.net | POC: HAESU-ARIN, HDJ1-6BONE
participants (4)
-
Alexei Roudnev -
haesu＠towardex.com -
Scott McGrath -
sthaug＠nethelp.no