07-21-2008 03:18 AM - edited 03-06-2019 12:19 AM
Hello all i have a 4500 with a static arp entry for a virtual server. all has been working fine for 6 months. config below.
arp 94.240.129.133 03bf.5ef0.8185 ARPA alias
i have now enabled multicast routing on the 4500 and added a pim statement to the vlan interface.
This has stopped me from pinging the virtual server from the vlan the server is sat in. I can ping the virtual server from other vlans. When i remove the pim statement all works fine ?
confused why enabling pim would cause issue with the static arp entry.
07-25-2008 01:08 PM
Here is the URL for the multicast routing with VLAN configuration which will help you :
http://www.cisco.com/en/US/tech/tk828/technologies_tech_note09186a00800a9a3d.shtml
07-25-2008 07:54 PM
Hello Dave,
I think you have associated an IPv4 unicast IP address 94.240.129.133 to a multicast MAC address 03bf.5ef0.8185 (not a multicast MAC address for IPv4 multicast).
A multicast MAC address is characterized by having the least significant bit (rightmost bit) of the most significant byte ( leftmost byte) set to 1.
This is the I/G bit.
So I suppose that when you enable ip pim on the Vlan some form of additional control is performed.
See the following link for the MAC address format
http://www.cisco.com/en/US/tech/tk828/technologies_white_paper09186a00802d4643.shtml#wp1002302
Layer 2 Multicast Addressing
The IEEE 802.2 specification makes provisions for the transmission of broadcast and multicast packets. As shown in Figure 2, Bit 0 of Octet 0 in an IEEE MAC address indicates whether the destination address is a broadcast/multicast address or a unicast address.
Hope to help
Giuseppe
07-31-2008 10:28 AM
thanks for the post i will have a look at the configuration. and see what happens. I got the mac address from the server guys so maybe a mistake.
regards
dave
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