7 Replies Latest reply: Jul 11, 2011 12:34 AM by ISMAIL (CCIE (Written) /CCSP/CCNP/JNCIS-ER/MCSA) RSS

    EtherChannel, PAgP and LACP with Trunk

    Bernard

      Hi,

       

      I was asked to look into core switches and suggests on refinement. I have some questions on etherchannel, pagp and lacp. Can someone advice me on these 3 questions?

       

      Q1. According to the below configuration of a pair of Cat4506 switches, can I say it is just running purely EtherChannel? To enable PAgP, I need to set mode to auto or desirable?

       

      interface Port-channel1
      switchport
      switchport mode trunk

      !

      interface GigabitEthernet3/1
      switchport mode trunk
      channel-group 1 mode on
      !
      interface GigabitEthernet3/2
      switchport mode trunk
      channel-group 1 mode on

      Q2. Coming to LACP, what is the advantage of using LACP since both core switches are Cisco and Cisco Proprietary PAgP should work fine?

       

      Q3. There are 2 VLANs in the network, these 2 cat4506 core switches are running HSRP for both VLANs, below is config for Core 1 (active):

      interface Vlan1

      ip address 172.18.204.3 255.255.254.0

      ip helper-address 172.18.204.106

      no ip redirects

      standby 192 ip 172.18.204.1

      standby 192 priority 105

      standby 192 preempt

      !

      interface Vlan2

      ip address 172.16.204.3 255.255.252.0

      ip helper-address 172.16.204.106

      no ip redirects

      standby 193 ip 172.16.204.1

      standby 193 priority 105

      standby 193 preempt

       

      Looking at the etherchannel configuration (at the top) which sets all ports to trunk but without specifying which vlan to trunk, can I say there is no trunking of vlan 1 and 2 over the etherchannel?

       

      To enable etherchannel with trunking, I think I should be configuring these to allow trunking of both vlan and setting vlan 2 as native?:

      interface Port-channel1
      switchport
      switchport mode trunk

      !

      interface GigabitEthernet3/1

      switchport trunk encapsulation dot1q

      switchport trunk native vlan 2

      switchport mode trunk
      channel-group 1 mode on
      !
      interface GigabitEthernet3/2

      switchport trunk encapsulation dot1q

      switchport trunk native vlan 2

      switchport mode trunk
      channel-group 1 mode on

       

      This post is rather long but I need to get everything right before I make proposal and request for network maintenance window.

       

       

      Thanks,

      Bernard