Date: Mon, 15 Jul 2019 08:42:30 +0000 From: "aleksandr.fedorov_itglobal.com (Aleksandr Fedorov)" <phabric-noreply@FreeBSD.org> To: Phabricator <phabric-noreply@FreeBSD.org> Cc: freebsd-net@freebsd.org Subject: [Differential] D19422: if_vxlan(4) Allow set MTU more than 1500 bytes. Message-ID: <3abfc4f42b2894e21966a73e96dc51fe@localhost.localdomain> In-Reply-To: <differential-rev-PHID-DREV-bvtxxu4jwhzdkwqxxgd7-req@reviews.freebsd.org> References: <differential-rev-PHID-DREV-bvtxxu4jwhzdkwqxxgd7-req@reviews.freebsd.org>
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[-- Attachment #1 --] aleksandr.fedorov_itglobal.com updated this revision to Diff 59753. aleksandr.fedorov_itglobal.com added a comment. VXLAN encapsulate ethernet frames within UDP/IP packets. So, we can calculate maximum overhead for IPv4: - IP_MAXPACKET = 65K - constant from netinet/ip.h. - Maximum IP header length IP_MAX_HDR_LEN (There is no suitable constant for it.) = 60 as the Internet Header Length field is the unsigned 4-bit number of 32-bit words - 15 * 32 = 480 bit = 60 bytes. - sizeof(struct udphdr) = 8 bytes. - sizeof(struct vxlan_header) = 8 bytes. - Inner frame ETHER_HDR_LEN = 14 bytes. - Inner frame ETHER_CRC_LEN = 4 bytes. - Inner frame ETHER_VLAN_ENCAP_LEN = 4 bytes. The result VXLAN_MAX_MTU = IP_MAXPACKET - IP_MAX_HDR_LEN - sizeof(struct udphdr) - sizeof(struct vxlan_header) - ETHER_HDR_LEN - ETHER_CRC_LEN - ETHER_VLAN_ENCAP_LEN = 65535 - 60 - 8 - 8 - 14 - 4 - 4 = 65437 So overhead is 98 bytes. Unfortunately for IPv6, the maximum header length is not fixed and can be extended in the future. It is usually 40 bytes. Revision changes: - Calculate VXLAN_MAX_MTU using existing constants. CHANGES SINCE LAST UPDATE https://reviews.freebsd.org/D19422?vs=59684&id=59753 CHANGES SINCE LAST ACTION https://reviews.freebsd.org/D19422/new/ REVISION DETAIL https://reviews.freebsd.org/D19422 AFFECTED FILES sys/net/if_vxlan.c EMAIL PREFERENCES https://reviews.freebsd.org/settings/panel/emailpreferences/ To: aleksandr.fedorov_itglobal.com, bryanv, hrs, #network, rgrimes, krion, jhb Cc: evgueni.gavrilov_itglobal.com, olevole_olevole.ru, ae, freebsd-net-list, krzysztof.galazka_intel.com [-- Attachment #2 --] diff --git a/sys/net/if_vxlan.c b/sys/net/if_vxlan.c --- a/sys/net/if_vxlan.c +++ b/sys/net/if_vxlan.c @@ -84,6 +84,15 @@ int vxlsomc_users; }; +/* + * The maximum MTU of encapsulated ethernet frame within IPv4/UDP packet. + */ +#define VXLAN_MAX_MTU (IP_MAXPACKET - \ + 60 /* Maximum IPv4 header len */ - \ + sizeof(struct udphdr) - \ + sizeof(struct vxlan_header) - \ + ETHER_HDR_LEN - ETHER_CRC_LEN - ETHER_VLAN_ENCAP_LEN) + #define VXLAN_SO_MC_MAX_GROUPS 32 #define VXLAN_SO_VNI_HASH_SHIFT 6 @@ -2247,10 +2256,11 @@ ifr = (struct ifreq *) data; ifd = (struct ifdrv *) data; + error = 0; + switch (cmd) { case SIOCADDMULTI: case SIOCDELMULTI: - error = 0; break; case SIOCGDRVSPEC: @@ -2267,6 +2277,13 @@ error = ifmedia_ioctl(ifp, ifr, &sc->vxl_media, cmd); break; + case SIOCSIFMTU: + if (ifr->ifr_mtu < ETHERMIN || ifr->ifr_mtu > VXLAN_MAX_MTU) + error = EINVAL; + else + ifp->if_mtu = ifr->ifr_mtu; + break; + default: error = ether_ioctl(ifp, cmd, data); break; @@ -2747,8 +2764,8 @@ ifp->if_ioctl = vxlan_ioctl; ifp->if_transmit = vxlan_transmit; ifp->if_qflush = vxlan_qflush; - ifp->if_capabilities |= IFCAP_LINKSTATE; - ifp->if_capenable |= IFCAP_LINKSTATE; + ifp->if_capabilities |= IFCAP_LINKSTATE | IFCAP_JUMBO_MTU; + ifp->if_capenable |= IFCAP_LINKSTATE | IFCAP_JUMBO_MTU; ifmedia_init(&sc->vxl_media, 0, vxlan_media_change, vxlan_media_status); ifmedia_add(&sc->vxl_media, IFM_ETHER | IFM_AUTO, 0, NULL);
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