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HSRP not working for some VLANs

I have 2 3750s supporting a building. They have a direct link betwixt them with a vlan range trunk allowed over this link. Some of the vlan interfaces are not seeing each other and I have no idea why. This is a common config on our environment but this setup is giving me problems. one router can see the a test device in arp the other cannot. The standby shows some HSRP vlan pairs a couple report 'unknown' and each reporting themselves as Active:LOCAL. Shutting down one side does not force traffic flow.

This what I get from a switch with a link to each router. .49 being the HSRP ghost addr.

I'm not understanding how one vlan interface works fine while others do not even through they are in the same trunk vlan range and config'd the same. Ideas?

 

jb

 

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.152.27.49, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
sw1#ping 10.152.27.50

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.152.27.50, timeout is 2 seconds:
U.U.U
Success rate is 0 percent (0/5)
sw1#ping 10.152.27.51

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.152.27.51, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/4/9 ms

 

 

 

 

2 REPLIES

Hi, Not 100% sure about your

Hi,

 

Not 100% sure about your topology and it depends on how you have thinks set up:

  • Router on a Stick: External Router connected to switch, trunk between router and switch, sub-interfaces configured on router. Each subinterfaces needs to have the "encap dot1q <vlan_tag>" configuration
  • Router on Access Port: External Router connects to switch, interface on switch is static access port. In this case, you need to ensure the switch is on the correct Access VLAN on the switch
  • Switches are doing Routing: SVIs are doing HSRP, ensure that all the VLANs are allowed on the trunk ( i.e. no switchport vlan allowed vlan )

 

Post your topology and we should be able to help more.

 

New Member

Hi, Its interesting that the

Hi, 

Its interesting that the HSRP are reporting active/active.  If HSRP is configured correctly, this means the link between the vlans is incorrect in some way.  

I'd check the cabling physically between the switches, then compare the trunk interfaces on either side, and also checking the configuration/status of the vlans in question.

Hope this Helps

Simon

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