[sdnog] SVIs , Routed ports and L3 etherchannel overview
nishal at controlfreak.co.za
Sun Apr 2 19:38:31 SAST 2017
> On 01 Apr 2017, at 13:22, wadah khalid <engwada7 at gmail.com> wrote:
> [ SVI - routed ports and Layer 3 etherchannals]
> eng. Wadah A Osman .
> Switched networks provide a Wild variety of features including logical segmentation depending on the needed resources .
> The need to provide a function that allow those different logical groups to communicate is important , that's why I decided to show you an overview on some features provided by Cisco to solve these problem .
> First solution
> ¤ SVIs ¤
> Switched virtual interface SVIs is a technology that used to provide inter VLAN routing in the switched network and enables routing on the switch ( layer 3) .
> The idea behind SVI is to make routing possible between different VLANs .
> Enabling routing on the switch requires to change on the sdm prefer and change it to lanbase-routing followed by reloading EXEC command . To reserve some space from ASIC for ip routing table.
one minor correction - it's TCAM that is re-carved for this.
since you're talking about cisco, see: https://supportforums.cisco.com/document/60831/cam-content-addressable-memory-vs-tcam-ternary-content-addressable-memory
although the wikipedia article is also good reading.
there was an earlier thread in the archives about how to reprogram your tcam using the "sdm" feature.
> Then enable routing by #ip routing global command .
> The next step is to add VLANs using interface VLAN ID and ip address commands .
> Second solution
> ¤ Routed ports ¤
> Using the whole switch to perform SVIs is resource wasting thats why routed ports show up .
> A port is to be routed means that port can do layer 3 functions and move from a layer port to layer3 port and will stop learning MAC address on that port .
> For enabling the routed port #no switccport subcommand will be used .
> Then you can assign it with an ip address .
> Creating VLANs with their ips on the switch have the routed port will allow inter VLAN routing .
> ¤ Third solution ¤
> Layer 3 etherchannels .
> It combines the capabilities of providing a redundancy on switched networks and inter VLAN routing through routed ports .
> The engineer first define the ports should participate in etherchannal group
> Issuing #no switchport on these ports with #no ip address subcommands .
> Changing the port status to be routed . Then using #channel-group 1 mode on subcommand .
> The layer 3 information will be assigned to the virtual interface named port channel
> #interface portchannel 1
> #no switchport
> #ip address
> Facing portchannel must be within the same subnet .
one tip to consider regarding etherchannels is that you *want* to use LACP (standard) and not PAGP (cisco proprietary). even if you are a cisco only network now, plan for future compatibility.
otherwise, nice writeup ;-)
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