BCMSN Lab portfolio Q

nel

Hi guys,

Just working my way through some labs while im on my break in between uni semesters and have a Q on etherchannels. Ive been doing the etherchannel labs and i understand the difference between a L2 and L3 channel and how to setup the actual etherchannels. But say you have 2 L3 switches and you create a L3 core between them. You have a single vlan, say 192.168.1.0/24. How would you implement hsrp, vrrp etc in that setup?

Would you have to create a L3 etherchannel with subinterfaces and encapsulate them onto the vlan in a similar fashion to ROAS? or am i being way off here? i looked at the doc's and cant seem to find any clarrification on this?

Thanks

kpjungle

nel wrote: »

Hi guys,

Just working my way through some labs while im on my break in between uni semesters and have a Q on etherchannels. Ive been doing the etherchannel labs and i understand the difference between a L2 and L3 channel and how to setup the actual etherchannels. But say you have 2 L3 switches and you create a L3 core between them. You have a single vlan, say 192.168.1.0/24. How would you implement hsrp, vrrp etc in that setup?

Would you have to create a L3 etherchannel with subinterfaces and encapsulate them onto the vlan in a similar fashion to ROAS? or am i being way off here? i looked at the doc's and cant seem to find any clarrification on this?

Thanks

Not exactly sure what you are asking, will you directly hook up 2 L3 switches with a L3 etherchannel (Basically a routed port/etherchannel), and run HSRP? Not sure I understand it at least Maybe make a little drawing

nel

kpjungle wrote: »

Not exactly sure what you are asking, will you directly hook up 2 L3 switches with a L3 etherchannel (Basically a routed port/etherchannel), and run HSRP? Not sure I understand it at least Maybe make a little drawing

Ha! sorry. No this is just something i was thinkn about when i was labbing using the book.

For example, imagine you have a collapsed core/distribution layer using 2 L3 switches. Then each of your access switches had a trunk to each of the L3 switches. The two L3 switches have a L3 etherchannel connecting them. How would you implement hsrp in this kind of scenario?

networker050184

You would just set up an SVI on both switches and run HSRP on that. Use the standby address as your PCs gateways and boom your cooking with Cisco!

nel

networker050184 wrote: »

You would just set up an SVI on both switches and run HSRP on that. Use the standby address as your PCs gateways and boom your cooking with Cisco!

Well i tried that but it didnt seem to work Should of kept my config...think i'll give it another go later

kpjungle

nel wrote: »

Well i tried that but it didnt seem to work Should of kept my config...think i'll give it another go later

Yeah, you will need to configure the SVI on both L3 switches, with the SVI being on the VLAN you want for your clients. However, I cant on the top of my head, see that you will ever utilize the L3 link between your dist/core switches, because each of them is directly connected to the access-layer, so the directly connected interface (SVI), will have a lower AD, even if you were running a routing protocol between your dist/core. Note that HSRP will use the vlan of the SVI to communicate with the other HSRP switch. It wont use the L3 etherchannel afaik. If it was a L2 etherchannel it would be able to be used (taking spanning-tree into account ofc.).

(This assumes we have the same mental image of the L2/L3 diagram )

nel

Well thats what i thought - configure each svi with an IP from that subnet then use a third IP for the hsrp address. This would then combine with a trunked L2 etherchannel. So is that the correct way of thinking? For some reason its got me "knickers in a twist" haha

kpjungle

nel wrote: »

Well thats what i thought - configure each svi with an IP from that subnet then use a third IP for the hsrp address. This would then combine with a trunked L2 etherchannel. So is that the correct way of thinking? For some reason its got me "knickers in a twist" haha

Yeah, what you are really trying to accomplish with HSRP, is a redundant gateway for end devices. So its needs to be on "their" vlan, hence the SVI on that vlan.