Cat6k-v15(config)#interface vlan 100 Cat6k-v15(config-if)#standby arp ? gratuitous Setup gratuitous ARP interval and count Cat6k-v15(config-if)#standby arp gratuitous ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous coun Cat6k-v15(config-if)#standby arp gratuitous count ? <0-60> Number of gratuitous ARPs to send after group is activated (0 for continuous) Cat6k-v15(config-if)#standby arp gratuitous count 0 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval ? <3-1800> Gratuitous ARP Interval (sec) Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 Cat6k-v15(config)#interface vlan 100 Cat6k-v15(config-if)#standby arp ? gratuitous Setup gratuitous ARP interval and count Cat6k-v15(config-if)#standby arp gratuitous ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous coun Cat6k-v15(config-if)#standby arp gratuitous count ? <0-60> Number of gratuitous ARPs to send after group is activated (0 for continuous) Cat6k-v15(config-if)#standby arp gratuitous count 0 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval ? <3-1800> Gratuitous ARP Interval (sec) Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 Cat6k-v15(config)#interface vlan 100 Cat6k-v15(config-if)#standby arp ? gratuitous Setup gratuitous ARP interval and count Cat6k-v15(config-if)#standby arp gratuitous ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count ? <0-60> Number of gratuitous ARPs to send after group is activated (0 for continuous) Cat6k-v15(config-if)#standby arp gratuitous count 0 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval ? <3-1800> Gratuitous ARP Interval (sec) Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 Added Clustering as an MC-LAG option, caveated MC-LAG, and re-worded HSRP repeat count to be more technically correct
Use MC-LAG (aka "MEC" in Cisco documentation). This is your best option. However, though you should understand the detailsdeployment scenarios where MC-LAG can be used (its not a universal solution, and should only be deployed after appropriate research and testing). MC-LAG variants are hardware dependent. Examples are:
a. Stacking (Cat 3k)
b. VSS (Cat4k/6k)
c. VPC (Nexus)
d. Pseudo mLACP (ASR1k)
e. MC-LAG (ASR9k)
f. Clustering (ASA)
Enable HSRP to periodically send Gratuitous ARP packets. Granted, this is similar to altering timers, but it's a much more graceful alteration than manipulating the CAM table and ARP timers. (Note though that this depends on your hardware and software combination, not all HSRP implementations offer this.)
By default, HSRP sends 3 GARPs, at 0, 2, and 4 seconds after the router becomes the forwarding gateway. However, there is a configuration parameter that allows you to choose the number of GARPs (including "forever""infinite") and the interval.
I use MC-LAG pretty extensively, particularly VSS and, VPC, and Clustering (I'm not a fan of stacking).
Use MC-LAG (aka "MEC" in Cisco documentation). This is your best option. However, the details are hardware dependent. Examples are:
a. Stacking (Cat 3k)
b. VSS (Cat4k/6k)
c. VPC (Nexus)
d. Pseudo mLACP (ASR1k)
e. MC-LAG (ASR9k)
Enable HSRP to periodically send Gratuitous ARP packets. Granted, this is similar to altering timers, but it's a much more graceful alteration than manipulating the CAM table and ARP timers. (Note though that this depends on your hardware and software combination, not all HSRP implementations offer this.)
By default, HSRP sends 3 GARPs, at 0, 2, and 4 seconds after the router becomes the forwarding gateway. However, there is a configuration parameter that allows you to choose the number of GARPs (including "forever") and the interval.
I use MC-LAG pretty extensively, particularly VSS and VPC (I'm not a fan of stacking).
Use MC-LAG (aka "MEC" in Cisco documentation). This is your best option, though you should understand the deployment scenarios where MC-LAG can be used (its not a universal solution, and should only be deployed after appropriate research and testing). MC-LAG variants are hardware dependent. Examples are:
a. Stacking (Cat 3k)
b. VSS (Cat4k/6k)
c. VPC (Nexus)
d. Pseudo mLACP (ASR1k)
e. MC-LAG (ASR9k)
f. Clustering (ASA)
Enable HSRP to periodically send Gratuitous ARP packets. Granted, this is similar to altering timers, but it's a much more graceful alteration than manipulating the CAM table and ARP timers. (Note though that this depends on your hardware and software combination, not all HSRP implementations offer this.)
By default, HSRP sends 3 GARPs, at 0, 2, and 4 seconds after the router becomes the forwarding gateway. However, there is a configuration parameter that allows you to choose the number of GARPs (including "infinite") and the interval.
I use MC-LAG pretty extensively, particularly VSS, VPC, and Clustering (I'm not a fan of stacking).
Summary: MC-LAG or HSRP GARP
I've never been a fan of tweaking timers. Timers are set a certain way usually for many reasons. Altering them:
- is potentially operationally intensive to maintain everywhere the same
- makes things more complicated and difficult to troubleshoot
- as a recent commentor showed, can have unexpected side effects
- may not "play nice" with future Cisco enhancements
Alternately:
Use MC-LAG (aka "MEC" in Cisco documentation). This is your best option. However, the details are hardware dependent. Examples are:
a. Stacking (Cat 3k)
b. VSS (Cat4k/6k)
c. VPC (Nexus)
d. Pseudo mLACP (ASR1k)
e. MC-LAG (ASR9k)
Enable HSRP to periodically send Gratuitous ARP packets. Granted, this is similar to altering timers, but it's a much more graceful alteration than manipulating the CAM table and ARP timers. (Note though that this depends on your hardware and software combination, not all HSRP implementations offer this.)
By default, HSRP sends 3 GARPs, at 0, 2, and 4 seconds after the router becomes the forwarding gateway. However, there is a configuration parameter that allows you to choose the number of GARPs (including "forever") and the interval.
I use MC-LAG pretty extensively, particularly VSS and VPC (I'm not a fan of stacking).
Where I can't use MC-LAG or GLBP, this is what I apply to my campus L2/L3 boundary routers (I have a 350-building campus so I use Cat6k pretty heavily):
Cat6k-v15(config)#interface vlan 100 Cat6k-v15(config-if)#standby arp ? gratuitous Setup gratuitous ARP interval and count Cat6k-v15(config-if)#standby arp gratuitous ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous coun Cat6k-v15(config-if)#standby arp gratuitous count ? <0-60> Number of gratuitous ARPs to send after group is activated (0 for continuous) Cat6k-v15(config-if)#standby arp gratuitous count 0 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval ? <3-1800> Gratuitous ARP Interval (sec) Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 ? count Set HSRP gratuitous ARP count interval Set HSRP gratuitous ARP interval <cr> Cat6k-v15(config-if)#standby arp gratuitous count 0 interval 60 (I would post references to all these, but I don't have a high-enough "reputation" on this site to post more than two URLs.)