Comments on: Weekly Open Ended Question #10 http://blog.alwaysthenetwork.com/open-ended-questions/weekly-open-ended-question-10/ Just another Cisco blog Mon, 23 Jan 2012 23:37:03 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Colby http://blog.alwaysthenetwork.com/open-ended-questions/weekly-open-ended-question-10/comment-page-1/#comment-676 Colby Wed, 14 Apr 2010 14:47:04 +0000 http://blog.alwaysthenetwork.com/?p=837#comment-676 Whoa! A celebrity has posted on my blog. This is good stuff. :D Whoa! A celebrity has posted on my blog. This is good stuff. :D

]]> By: EtherealMind http://blog.alwaysthenetwork.com/open-ended-questions/weekly-open-ended-question-10/comment-page-1/#comment-675 EtherealMind Wed, 14 Apr 2010 14:30:32 +0000 http://blog.alwaysthenetwork.com/?p=837#comment-675 The are technologies used for trunking VLAN. ISL encapsulates the Ethernet frame with a 20byte header and CRC check compared to 802.1q which adds a 4 byte shim to the Ethernet header with VLAN Tag information. The are technologies used for trunking VLAN. ISL encapsulates the Ethernet frame with a 20byte header and CRC check compared to 802.1q which adds a 4 byte shim to the Ethernet header with VLAN Tag information.

]]> By: KiLLaBeE http://blog.alwaysthenetwork.com/open-ended-questions/weekly-open-ended-question-10/comment-page-1/#comment-669 KiLLaBeE Wed, 14 Apr 2010 02:53:52 +0000 http://blog.alwaysthenetwork.com/?p=837#comment-669 VLAN tagging protocols. ISL encapsulates the entire frame whereas dot1q does not...it just inserts a field in the frame. ISL is proprietary and dot1q is a standard. ISL just supports 1000 (I think) VLANs whereas dot1q supports up to 4096. VLAN tagging protocols. ISL encapsulates the entire frame whereas dot1q does not…it just inserts a field in the frame. ISL is proprietary and dot1q is a standard. ISL just supports 1000 (I think) VLANs whereas dot1q supports up to 4096.

]]> By: Daniel http://blog.alwaysthenetwork.com/open-ended-questions/weekly-open-ended-question-10/comment-page-1/#comment-655 Daniel Mon, 12 Apr 2010 13:47:34 +0000 http://blog.alwaysthenetwork.com/?p=837#comment-655 ISL = Cisco standard of marking vlans with lots of unused crap in the header. Marks every vlan. Being phased out by Cisco in favor of .1q. Tags on a vlan header at the beging and a new check-sum on the end .1q = standard puts on a vlan header and re-calculates the check-sum at the end. Doesn't do anything to the "native vlan" thus every untagged packet is in the native vlan (gotta watch this or you could have vlan packet leakage) ISL = Cisco standard of marking vlans with lots of unused crap in the header. Marks every vlan. Being phased out by Cisco in favor of .1q. Tags on a vlan header at the beging and a new check-sum on the end

.1q = standard puts on a vlan header and re-calculates the check-sum at the end. Doesn’t do anything to the “native vlan” thus every untagged packet is in the native vlan (gotta watch this or you could have vlan packet leakage)

]]> By: Jason Maynard http://blog.alwaysthenetwork.com/open-ended-questions/weekly-open-ended-question-10/comment-page-1/#comment-644 Jason Maynard Sat, 10 Apr 2010 00:22:54 +0000 http://blog.alwaysthenetwork.com/?p=837#comment-644 Both protocols are used to create Trunks an carry VLANS ISL - Cisco Proprietary, uses 30 byte encapsulation and does not use native VLANs. Dot1q - IEEE standard, insert 4byte tag and uses native VLANs Both protocols are used to create Trunks an carry VLANS

ISL – Cisco Proprietary, uses 30 byte encapsulation and does not use native VLANs.

Dot1q – IEEE standard, insert 4byte tag and uses native VLANs

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